1
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Potel H, Niatou Singa FS, Cipolletta C, Neba Fuh T, Bardino G, Konyal E, Strampelli P, Henschel P, Masi S. Lethal combats in the forest among wild western gorillas. iScience 2024; 27:109437. [PMID: 38523787 PMCID: PMC10960106 DOI: 10.1016/j.isci.2024.109437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/13/2024] [Accepted: 03/04/2024] [Indexed: 03/26/2024] Open
Abstract
Lethal intergroup encounters occur in many species because of sexual selection. While documented in mountain gorillas, they are absent in western gorillas as, instead, it is predicted by their higher feeding (frugivory) and mate competition (single-vs. multi-male groups). We investigate whether the injuries on three dead silverbacks and one adult female from four groups of western gorillas in the Central African Republic, resulted from interactions with gorillas or leopards. We identified two distinct injury patterns caused by gorillas (isolated lacerations, round wounds) and leopards (punctures clustered on head/neck) by analyzing injuries caused by mountain gorillas and leopards to gorillas and non-gorilla species, respectively. The western gorilla injury pattern is similar to that of mountain gorillas suggesting that lethal encounters occur, albeit infrequently, as predicted by sexual selection in a one-male society. While sexual dimorphism and polygynous sociality favored the evolution of violent encounters, multiple males in groups may influence their frequency.
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Affiliation(s)
- Hugo Potel
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
| | | | - Chloé Cipolletta
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Terence Neba Fuh
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Giulia Bardino
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
- “La Sapienza” University, Department of Environmental and Evolutionary Biology, Rome, Italy
| | - Emmanuel Konyal
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | | | | | - Shelly Masi
- Ecoanthropologie, Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturelle, University Paris Diderot, Sorbonne Paris Cité, Musée de l’Homme, Paris, France
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2
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Correa LA, Aspillaga-Cid A, León C, Bauer CM, Ramírez-Estrada J, Hayes LD, Soto-Gamboa M, Ebensperger LA. Social environment and anogenital distance length phenotype interact to explain testosterone levels in a communally rearing rodent: Part 2: The female side. Horm Behav 2024; 160:105486. [PMID: 38295731 DOI: 10.1016/j.yhbeh.2024.105486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 03/26/2024]
Abstract
Testosterone is known as a "male" hormone; however, females also synthetize testosterone, which influences female sexual and aggressive behavior. In female vertebrates, as in males, testosterone levels can vary seasonally. However, female testosterone levels may also be related with female anogenital distance (AGD) length phenotype (a proxy of prenatal androgen exposure), and the social group environment. We used data from a long-term rodent study (2009-2019) in a natural population of degus (Octodon degus) to examine the potential associations between female serum testosterone levels, season, female AGD phenotype, and social group composition. We quantified female serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in social groups, as well the composition of groups, in terms of the AGD of the female and male group mates. Our results indicate that female testosterone levels vary with season, being highest during the offspring rearing season. Additionally, female testosterone levels were associated with the number of male group-members and the AGD of male group-members but were not associated with female social environment and focal female AGD phenotype. Together, our results suggest that female testosterone levels are sensitive to intersexual interactions. Our results also reveal that female and male testosterone levels do not differ between the sexes, a finding previously reported only in rock hyraxes. We discuss how the complex social system of degus could be driving this physiological similarity between the sexes.
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Affiliation(s)
- Loreto A Correa
- Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino la Pirámide 5750, Huechuraba, Santiago, Chile.
| | - Antonia Aspillaga-Cid
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Carolyn M Bauer
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Loren D Hayes
- Department of Biology, Geology and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA
| | - Mauricio Soto-Gamboa
- Laboratorio de Ecología Conductual y Conservación, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
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3
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Jones ME, Sheard C. The macroevolutionary dynamics of mammalian sexual size dimorphism. Proc Biol Sci 2023; 290:20231211. [PMID: 37964522 PMCID: PMC10646455 DOI: 10.1098/rspb.2023.1211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 10/13/2023] [Indexed: 11/16/2023] Open
Abstract
Sexual size dimorphism (SSD) is a common phenomenon across the animal kingdom. Mammals are unusual in primarily displaying male-biased SSD, where males of a species are typically larger than females. The driving factors behind the evolution of this SSD have been much debated, with popular hypotheses invoking the influence of mating system and social organization via sexual selection, dietary niche divergence and broad-scale correlations with body size (Rensch's rule). Here, we investigate the macroevolutionary origins and maintenance of SSD among mammals, using phylogenetic general mixed linear models and a comprehensive global dataset to evaluate correlations of diet, body mass, seasonality, social organization and mating system with SSD type. We find that SSD as a whole is lost at a greater rate than it is gained, with female-biased SSD being particularly unstable. Non-monogamous mating systems, vertebrate prey consumption and temperature seasonality correlate with male-biased SSD, while polyandry correlates with female-biased SSD, and both types of SSD are positively correlated with body mass. This is in partial contrast to the predictions of Rensch's rule, which predicts that female-biased SSD would correlate negatively with body size. Taken together, our results highlight the importance of considering multiple ecological and social drivers when evaluating the macroevolutionary trajectory of sex differences in body size.
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Affiliation(s)
- Megan E. Jones
- Department of Earth and Environmental Sciences, University of Manchester, 176 Oxford Road, Manchester M13 9QQ, UK
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Catherine Sheard
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- School of Biological Sciences, University of Aberdeen, Tillydrone Ave, Aberdeen, AB24 2TZ, UK
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4
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Duncan C, Thorley J, Manser MB, Clutton-Brock T. Dominance loss and tenure maintenance in Kalahari meerkats. Behav Ecol 2023; 34:979-991. [PMID: 37969548 PMCID: PMC10636735 DOI: 10.1093/beheco/arad066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/10/2023] [Accepted: 07/31/2023] [Indexed: 11/17/2023] Open
Abstract
In many social species, both the acquisition of dominance and the duration that individuals maintain their status are important determinants of breeding tenure and lifetime reproductive success. However, few studies have yet examined the extent and causes of variation in dominance tenure and the duration of breeding lifespans. Here, we investigate the processes that terminate dominance tenures and examine how they differ between the sexes in wild Kalahari meerkats (Suricata suricatta), a cooperative breeder where a dominant breeding pair produces most of the young recruited into each group. Mortality and displacement by resident subordinate competitors were important forms of dominance loss for both sexes. However, dominant males (but rarely females) were also at risk of takeovers by extra-group invading males. Dominant males also differed from dominant females in that they abandoned their group after the death of their breeding partner, when no other breeding opportunities were present, whereas dominant females that lost their partner remained and continued to breed in the same group. We show that a larger number of processes can terminate dominance tenure in males with the result that the average male tenure of breeding positions was shorter than that of females, which contributes to the reduced variance in the lifetime reproductive success in males compared to females. Our analysis suggests that sex differences in emigration and immigration may often have downstream consequences for sex differences in reproductive variance and for the selection pressures operating on females and males.
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Affiliation(s)
- Chris Duncan
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Kalahari Research Centre, Kuruman River Reserve, Northern Cape 8467, South Africa
| | - Jack Thorley
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Kalahari Research Centre, Kuruman River Reserve, Northern Cape 8467, South Africa
| | - Marta B Manser
- Kalahari Research Centre, Kuruman River Reserve, Northern Cape 8467, South Africa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Mammal Research Institute, University of Pretoria, 0028 Pretoria, South Africa
| | - Tim Clutton-Brock
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Kalahari Research Centre, Kuruman River Reserve, Northern Cape 8467, South Africa
- Mammal Research Institute, University of Pretoria, 0028 Pretoria, South Africa
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5
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Moreira LAA, Merrigan-Johnson C, Fetherstonhaugh L, Parr NA, Higham JP, Melin AD. Assessing color cues of development, breeding status and reproductive condition in captive golden lion tamarins (Leontopithecus rosalia). Am J Primatol 2023; 85:e23543. [PMID: 37560915 DOI: 10.1002/ajp.23543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 06/21/2023] [Accepted: 07/28/2023] [Indexed: 08/11/2023]
Abstract
Color signals play an important role in intraspecific communication and are well studied in catarrhine primates, which exhibit uniform trichromatic vision that is well suited to detecting such signals. Platyrrhine primates exhibit polymorphic color vision with different individuals possessing different color vision types in most species. Intriguingly, some platyrrhine species exhibit bare faces, which are convergent with those of catarrhines. However, putative functions of bare-faced color signals in platyrrhines remain largely unexplored. We measured facial skin color of five captive golden lion tamarins (Leontopithecus rosalia) using color-calibrated digital photography and modeled these colors to the visual systems of the species. Our results show that facial coloration is different between infant and older adults and varies across reproductive condition, but not between breeding and nonbreeding adults. While preliminary, our study suggests that facial coloration may be involved in sociosexual signaling in golden lion tamarins, and provides intriguing evidence that we hope might stimulate more studies of bare-faced signaling in platyrrhines.
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Affiliation(s)
- Lais A A Moreira
- Department of Anthropology & Archaeology, University of Calgary, Calgary, Canada
| | | | | | - Nigel A Parr
- Department of Wildlife Care, Toronto Zoo, Toronto, Canada
| | - James P Higham
- Department of Anthropology, New York University, New York, USA
| | - Amanda D Melin
- Department of Anthropology & Archaeology, University of Calgary, Calgary, Canada
- Department of Medical Genetics, University of Calgary, Calgary, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
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6
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Zipple MN, Vogt CC, Sheehan MJ. Re-wilding model organisms: Opportunities to test causal mechanisms in social determinants of health and aging. Neurosci Biobehav Rev 2023; 152:105238. [PMID: 37225063 PMCID: PMC10527394 DOI: 10.1016/j.neubiorev.2023.105238] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/14/2023] [Accepted: 05/17/2023] [Indexed: 05/26/2023]
Abstract
Social experiences are strongly associated with individuals' health, aging, and survival in many mammalian taxa, including humans. Despite their role as models of many other physiological and developmental bases of health and aging, biomedical model organisms (particularly lab mice) remain an underutilized tool in resolving outstanding questions regarding social determinants of health and aging, including causality, context-dependence, reversibility, and effective interventions. This status is largely due to the constraints of standard laboratory conditions on animals' social lives. Even when kept in social housing, lab animals rarely experience social and physical environments that approach the richness, variability, and complexity they have evolved to navigate and benefit from. Here we argue that studying biomedical model organisms outside under complex, semi-natural social environments ("re-wilding") allows researchers to capture the methodological benefits of both field studies of wild animals and laboratory studies of model organisms. We review recent efforts to re-wild mice and highlight discoveries that have only been made possible by researchers studying mice under complex, manipulable social environments.
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Affiliation(s)
- Matthew N Zipple
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
| | - Caleb C Vogt
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Michael J Sheehan
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
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7
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Pritchard AJ, Carter AJ, Palombit RA. Individual differences in coping styles and associations with social structure in wild baboons (Papio anubis). Anim Behav 2023. [DOI: 10.1016/j.anbehav.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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8
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Dyble M, Clutton-Brock TH. Turnover in male dominance offsets the positive effect of polygyny on within-group relatedness. Behav Ecol 2023; 34:261-268. [PMID: 36998996 PMCID: PMC10047635 DOI: 10.1093/beheco/arac121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 11/12/2022] [Accepted: 12/05/2022] [Indexed: 02/07/2023] Open
Abstract
Abstract
Evidence of an association between cooperative breeding systems and average coefficients of relatedness between group members in vertebrates have led to increased interest in the social and ecological factors affecting average kinship within groups. Previous studies have suggested that polygynous mating systems and high degrees of male reproductive skew increase average relatedness because they increase the proportion of offspring born in each group that are paternal siblings. Although this may be the case in semelparous organisms, in many multiparous polygynous animals, intense competition between males shortens the breeding tenure of males and leads to their frequent replacement by competitors which reduces paternal relatedness and average kinship between members of multigenerational groups. Here, we explore the interaction between male reproductive skew and the frequency of turnover in breeding males and its effects on within-group relatedness. Our theoretical model shows that increases in rates of dominance turnover in polygynous systems can offset the positive effect of male skew on relatedness between group members within seasons, showing that polygynous mating systems will not necessarily lead to significant increases in average relatedness, especially in species where there is extensive overlap between generations among group members.
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Affiliation(s)
- Mark Dyble
- Department of Anthropology, University College London , 14 Taviton Street, London WC1H 0BW , UK
| | - Tim H Clutton-Brock
- Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK
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9
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A systematic review of sex differences in rough and tumble play across non-human mammals. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03260-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
It is widely believed that juvenile male mammals typically engage in higher rates of rough and tumble play (RTP) than do females, in preparation for adult roles involving intense physical competition between males. The consistency of this sex difference across diverse mammalian species has, however, not yet been systematically investigated, limiting our current understanding of its possible adaptive function. This review uses narrative synthesis to (i) evaluate the ubiquity of male-biased RTP across non-human mammals, (ii) identify patterns of variation within and between taxonomic groups, and (iii) propose possible predictors of variation in these differences, including methodological and socio-ecological factors, for investigation by future studies. We find that most species studied do exhibit higher rates or RTP in males than females, while female-biased RTP is rare. Sex differences are smaller and less consistent than expected, with many studies finding similar rates of RTP in males and females. We identify multiple potential socio-ecological predictors of variation in sex differences in RTP, such as intrasexual competition and dietary niche. However, variation is not strongly phylogenetically patterned, suggesting that methodological and environmental factors, such as sample size and play partner availability, are important to consider in future comparative analyses.
Significance statement
Rough and tumble play (RTP) is thought to be vital for developing physical skills necessary for aggressive competition in adulthood, explaining an apparently widespread sex difference in RTP in mammals whereby immature males are more likely to engage in this behaviour than females. However, no prior study has systematically investigated the extent to which a male bias in RTP is consistent across diverse mammalian species. We find that although RTP is commonly male biased, findings were highly variable both within- and between-species, and equal participation in RTP by males and females is more common than widely assumed. Our review suggests several potential predictors of variation in sex differences in RTP, particularly levels of intrasexual competition in both males and females. However, our findings also suggest the importance of considering methodological in addition to socio-ecological factors for future research.
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10
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Drea CM, Davies CS. Meerkat manners: Endocrine mediation of female dominance and reproductive control in a cooperative breeder. Horm Behav 2022; 145:105245. [PMID: 35988450 DOI: 10.1016/j.yhbeh.2022.105245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/18/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022]
Abstract
This article is part of a Special Issue (Hormones and Hierarchies). To gain more balanced understanding of sexual selection and mammalian sexual differentiation processes, this review addresses behavioral sex differences and hormonal mediators of intrasexual competition in the meerkat (Suricata suricatta) - a cooperative breeder unusual among vertebrates in its female aggression, degree of reproductive skew, and phenotypic divergence. Focused on the evolution, function, mechanism, and development of female dominance, the male remains a key reference point throughout. Integrated review of endocrine function does not support routine physiological suppression in subordinates of either sex, but instead a ramp up of weight, reproduction, aggression, and sex steroids, particularly androgens, in dominant females. Important and timely questions about female competition are thus addressed by shifting emphasis from mediators of reproductive suppression to mediators of reproductive control, and from organizational and activational roles of androgens in males to their roles in females. Unusually, we ask not only how inequity is maintained, but how dominance is acquired within a lifetime and across generations. Antiandrogens administered in the field to males and pregnant dominant females confirm the importance of androgen-mediated food competition. Moreover, effects of maternal endocrine milieu on offspring development reveal a heritable, androgenic route to female aggression, likely promoting reproductive priority along dominant matrilines. Integrating endocrine measures with long-term behavioral, ecological, morphological, and life-history data on normative and experimental individuals, across life stages and generations, provides better appreciation of the role of naturally circulating androgens in regulating the female phenotype, and sheds new light on the evolution of female dominance, reproductive inequity, and cooperative breeding.
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Affiliation(s)
- Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708-0383, USA; Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.
| | - Charli S Davies
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708-0383, USA; Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
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11
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Dantzer B, Newman AEM. Expanding the frame around social dynamics and glucocorticoids: From hierarchies within the nest to competitive interactions among species. Horm Behav 2022; 144:105204. [PMID: 35689971 DOI: 10.1016/j.yhbeh.2022.105204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/10/2022] [Accepted: 05/18/2022] [Indexed: 11/25/2022]
Abstract
The effect of the social environment on individual state or condition has largely focused on glucocorticoid levels (GCs). As metabolic hormones whose production can be influenced by nutritional, physical, or psychosocial stressors, GCs are a valuable (though singular) measure that may reflect the degree of "stress" experienced by an individual. Most work to date has focused on how social rank influences GCs in group-living species or how predation risk influences GCs in prey. This work has been revealing, but a more comprehensive assessment of the social environment is needed to fully understand how different features of the social environment influence GCs in both group living and non-group living species and across life history stages. Just as there can be intense within-group competition among adult conspecifics, it bears appreciating there can also be competition among siblings from the same brood, among adult conspecifics that do not live in groups, or among heterospecifics. In these situations, dominance hierarchies typically emerge, albeit, do dominants or subordinate individuals or species have higher GCs? We examine the degree of support for hypotheses derived from group-living species about whether differential GCs between dominants and subordinates reflect the "stress of subordination" or "costs of dominance" in these other social contexts. By doing so, we aim to test the generality of these two hypotheses and propose new research directions to broaden the lens that focuses on social hierarchies and GCs.
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Affiliation(s)
- Ben Dantzer
- Department of Psychology, University of Michigan, 48109 Ann Arbor, MI, USA; Department of Ecology and Evolutionary Biology, University of Michigan, 48109, Ann Arbor, MI, USA.
| | - Amy E M Newman
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G2W1, Canada
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12
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Klug H, Langley C, Reyes E. Resource acquisition and pre-copulatory sexual selection. Ecol Evol 2022; 12:e9137. [PMID: 35898422 PMCID: PMC9309035 DOI: 10.1002/ece3.9137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/27/2022] [Accepted: 07/01/2022] [Indexed: 11/30/2022] Open
Abstract
Sexual selection influences the evolution of phenotypic traits and contributes to patterns of biodiversity. In many animals, mating involves sequential steps. Often, individuals must secure resources that are essential for mating (nests, territories, food), and then after securing a resource, individuals engage in competition for access to limited opposite sex mates and gametes. A large body of empirical research and some verbal models have illustrated that resource acquisition can influence sexual selection. In general, though, we lack a priori predictions of when and how resource acquisition will influence sexual selection. Here, we use a mathematical framework to explore the link between resource acquisition and sexual selection on an advantageous mate‐acquisition trait across biologically relevant trade‐off scenarios. Our findings provide a set of testable predictions of how resource acquisition can influence sexual selection on mating traits. In general, selection on mate‐acquisition traits is expected to be heavily influenced by: (1) the episode of selection considered, and in particular, whether one considers selection associated with the mating pool only or selection associated with both the mating pool and pre‐mating pool; (2) whether resource‐acquisition and mate‐acquisition traits are positively associated or whether they trade off; and (3) the proportion of males with the resource‐ and mate‐acquisition traits.
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Affiliation(s)
- Hope Klug
- Department of Biology, Geology, and Environmental Science University of Tennessee at Chattanooga Chattanooga Tennessee USA.,SimCenter University of Tennessee at Chattanooga Chattanooga Tennessee USA
| | - Chelsea Langley
- Department of Biology, Geology, and Environmental Science University of Tennessee at Chattanooga Chattanooga Tennessee USA
| | - Elijah Reyes
- Department of Biological Sciences Simon Fraser University Burnaby British Columbia Canada
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13
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Davidian E, Surbeck M, Lukas D, Kappeler PM, Huchard E. The eco-evolutionary landscape of power relationships between males and females. Trends Ecol Evol 2022; 37:706-718. [PMID: 35597702 DOI: 10.1016/j.tree.2022.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022]
Abstract
In animal societies, control over resources and reproduction is often biased towards one sex. Yet, the ecological and evolutionary underpinnings of male-female power asymmetries remain poorly understood. We outline a comprehensive framework to quantify and predict the dynamics of male-female power relationships within and across mammalian species. We show that male-female power relationships are more nuanced and flexible than previously acknowledged. We then propose that enhanced reproductive control over when and with whom to mate predicts social empowerment across ecological and evolutionary contexts. The framework explains distinct pathways to sex-biased power: coercion and male-biased dimorphism constitute a co-evolutionary highway to male power, whereas female power emerges through multiple physiological, morphological, behavioural, and socioecological pathways.
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Affiliation(s)
- Eve Davidian
- Ngorongoro Hyena Project, Ngorongoro Conservation Area, Arusha, Tanzania.
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Dieter Lukas
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Peter M Kappeler
- German Primate Center, Behavioral Ecology Unit, Leibniz Institute of Primate Biology, Göttingen, Germany; Department of Sociobiology and Anthropology, University of Göttingen, Göttingen, Germany
| | - Elise Huchard
- Anthropologie Évolutive, Institut des Sciences de l'Évolution de Montpellier (ISEM), Montpellier, France.
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14
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Klug H, Langley C, Reyes E. Cascading effects of pre-adult survival on sexual selection. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211973. [PMID: 35425633 PMCID: PMC9006037 DOI: 10.1098/rsos.211973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/18/2022] [Indexed: 05/03/2023]
Abstract
Sexual selection influences broad-scale patterns of biodiversity. While a large body of research has investigated the effect of mate competition on sexual selection, less work has examined how pre-adult life history influences sexual selection. We used a mathematical framework to explore the influence of pre-adult survival on sexual selection. Our model suggests that pre-adult male mortality will affect the strength of sexual selection when a fixed number of adult males have an advantageous mate-acquisition trait. When a fixed number of males have an advantageous mate-acquisition trait, sexual selection is expected to increase when pre-adult mortality is relatively low. By contrast, if a fixed proportion (rather than number) of adult males have a mate-acquisition trait, pre-adult male mortality is not expected to affect the strength of sexual selection. Further, if the advantageous mating trait affects pre-adult survival, natural and sexual selection can interact to influence the overall selection on the mating trait. Given that pre-adult mortality is often shaped by natural selection, our results highlight conditions under which natural selection can have cascading effects on sexual selection.
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Affiliation(s)
- Hope Klug
- Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, TN, USA
- SimCenter, University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Chelsea Langley
- Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Elijah Reyes
- Department of Biological Sciences, Simon Fraser University, Burnaby, CA, USA
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15
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Grebe NM, Sheikh A, Drea CM. Integrating the female masculinization and challenge hypotheses: Female dominance, male deference, and seasonal hormone fluctuations in adult blue-eyed black lemurs (Eulemur flavifrons). Horm Behav 2022; 139:105108. [PMID: 35033896 DOI: 10.1016/j.yhbeh.2022.105108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/22/2021] [Accepted: 01/03/2022] [Indexed: 11/19/2022]
Abstract
In the decades since female social dominance was first described in strepsirrhine primates, researchers have sought to uncover the proximate and ultimate explanations for its development. In the females of various female-dominant species, androgens have been implicated as regulators of behavior and/or predictors of seasonal fluctuations in aggression (the 'Female Masculinization Hypothesis'). Males, more generally, respond to changing social demands via seasonal fluctuations in androgen-mediated behavior (the 'Challenge Hypothesis'), that may also entail changes in activation of the hypothalamic-pituitary-adrenal axis. Here, we explore if androgens, glucocorticoids, and intersexual behavior fluctuate seasonally in the female-dominant, blue-eyed black lemur (Eulemur flavifrons), with potential consequences for understanding female aggression and male deference. Across two studies conducted during the breeding and nonbreeding seasons, we assessed rates of mixed-sex, dyadic social behavior (aggression and affiliation) and concentrations of fecal glucocorticoid metabolites (Study 1) and serum sex hormones (androstenedione, testosterone, and estradiol; Study 2). Our results align with several predictions inspired by the Female Masculinization and Challenge Hypotheses for intersexual relations: During the breeding season, specifically, both aggression and androstenedione peaked in females, while female-initiated affiliation decreased, potentially to facilitate female resource access and reproductive control. By comparison, all target hormones (androgens, estrogen, and glucocorticoids) peaked in males, with glucocorticoid concentrations potentially increasing in response to the surge in female aggression, and unusually high estrogen concentrations year-round potentially facilitating male deference via male-initiated affiliation. These results suggest complex, seasonally and hormonally mediated behavior in Eulemur flavifrons.
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Affiliation(s)
- Nicholas M Grebe
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, United States of America.
| | - Alizeh Sheikh
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, United States of America
| | - Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, United States of America; Department of Biology, Duke University, Durham, NC 27708, United States of America
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16
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Hamilton IM, Benincasa MD. Emergence of size-structured dominance hierarchies through size-dependent feedback. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200449. [PMID: 35000447 PMCID: PMC8743889 DOI: 10.1098/rstb.2020.0449] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Size-based dominance hierarchies influence fitness, group size and population dynamics and link dominance structure to evolutionary and ecological outcomes. While larger individuals often gain dominance, social status may influence growth and size in return, resulting in feedbacks among status, growth and size. Here, we present two models evaluating how these feedbacks influence the emergence of size structure in a dominance hierarchy. In the first, size influences competition for food and investment in suppressing growth of groupmates. Stable size differences emerged when suppression was greatest for similarly sized individuals and size had little effect on competition for food. The model predicted size divergence when size strongly affected competition for food. In the second model, we used a dynamic game to solve for optimal investment in growth suppression as a function of size structure. Investment in growth suppression was favoured only when dominants and subordinates were similar in size, generating size ratios different than those expected by chance. Variation in the feedbacks among growth, size and status can explain variation in emergent size structure of dominance hierarchies and its consequences for conflict within groups. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
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Affiliation(s)
- Ian M Hamilton
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 318 W 12th Avenue, Columbus, OH 43210, USA.,Department of Mathematics, The Ohio State University, 318 W 12th Avenue, Columbus, OH 43210, USA
| | - Macie D Benincasa
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 318 W 12th Avenue, Columbus, OH 43210, USA
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17
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Drea CM, Davies CS, Greene LK, Mitchell J, Blondel DV, Shearer CL, Feldblum JT, Dimac-Stohl KA, Smyth-Kabay KN, Clutton-Brock TH. An intergenerational androgenic mechanism of female intrasexual competition in the cooperatively breeding meerkat. Nat Commun 2021; 12:7332. [PMID: 34921140 PMCID: PMC8683399 DOI: 10.1038/s41467-021-27496-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 11/22/2021] [Indexed: 12/27/2022] Open
Abstract
Female intrasexual competition can be intense in cooperatively breeding species, with some dominant breeders (matriarchs) limiting reproduction in subordinates via aggression, eviction or infanticide. In males, such tendencies bidirectionally link to testosterone, but in females, there has been little systematic investigation of androgen-mediated behaviour within and across generations. In 22 clans of wild meerkats (Suricata suricatta), we show that matriarchs 1) express peak androgen concentrations during late gestation, 2) when displaying peak feeding competition, dominance behaviour, and evictions, and 3) relative to subordinates, produce offspring that are more aggressive in early development. Late-gestation antiandrogen treatment of matriarchs 4) specifically reduces dominance behaviour, is associated with infrequent evictions, decreases social centrality within the clan, 5) increases aggression in cohabiting subordinate dams, and 6) reduces offspring aggression. These effects implicate androgen-mediated aggression in the operation of female sexual selection, and intergenerational transmission of masculinised phenotypes in the evolution of meerkat cooperative breeding.
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Affiliation(s)
- Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA.
- Department of Biology, Duke University, Durham, NC, 27708, USA.
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.
| | - Charli S Davies
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Lydia K Greene
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Duke Lemur Center, Duke University, Durham, NC, 27705, USA
| | - Jessica Mitchell
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Nuffield Centre for International Health and Development, University of Leeds, Leeds, West Yorkshire, LS2 9JT, UK
| | - Dimitri V Blondel
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Department of Biology, North Carolina Wesleyan College, Rocky Mount, NC, 27804, USA
| | - Caroline L Shearer
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
| | - Joseph T Feldblum
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Department of Anthropology and Society of Fellows, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kristin A Dimac-Stohl
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Department of Biology, Duke University, Durham, NC, 27708, USA
| | - Kendra N Smyth-Kabay
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Boston Consulting Group, Bethesda, MD, 20814, USA
| | - Tim H Clutton-Brock
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK
- Mammal Research Institute, University of Pretoria, 0002, Pretoria, South Africa
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18
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Evans JC, Lindholm AK, König B. Family dynamics reveal that female house mice preferentially breed in their maternal community. Behav Ecol 2021. [DOI: 10.1093/beheco/arab128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Whether females breed in their natal group is an important factor in the evolution of extended families in animal sociality. Breeding in natal groups comes with costs and benefits, depending on group size and presence of older relatives, including mothers. Studying the consequences of breeding in the natal versus another group provides insight into the decisions and trade-offs governing the formation and structure of family groups. We investigated the family dynamics of a population of free-ranging commensal house mice. Using dynamic community detection on long-term datasets, we determined which females first bred in their natal group. We then looked at how this influenced breeding success. We found most females (77%) exhibited strong philopatry, breeding in their natal groups. Breeding elsewhere was only somewhat predictable at very large and very small group sizes. Despite their philopatric preference, breeding elsewhere made no difference in how quickly and successfully a female bred. However, presence of their mother did lead females to breed sooner when born during high breeding activity, when competition over reproduction is high. Based on these results, potential loss of reproductive success from leaving the natal group does not seem to be the main driver of philopatry in female house mice. The effect of the presence of mothers suggests that benefiting from established social connections promotes breeding in the natal group. Mothers providing benefits also implies a lack of conflict between generations, which will be important for the development of stable social groups.
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Affiliation(s)
- Julian C Evans
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Anna K Lindholm
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Barbara König
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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19
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Duncan C, Manser MB, Clutton‐Brock T. Decline and fall: The causes of group failure in cooperatively breeding meerkats. Ecol Evol 2021; 11:14459-14474. [PMID: 34765119 PMCID: PMC8571573 DOI: 10.1002/ece3.7655] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/15/2021] [Accepted: 02/28/2021] [Indexed: 12/30/2022] Open
Abstract
In many social vertebrates, variation in group persistence exerts an important effect on individual fitness and population demography. However, few studies have been able to investigate the failure of groups or the causes of the variation in their longevity. We use data from a long-term study of cooperatively breeding meerkats, Suricata suricatta, to investigate the different causes of group failure and the factors that drive these processes. Many newly formed groups failed within a year of formation, and smaller groups were more likely to fail. Groups that bred successfully and increased their size could persist for several years, even decades. Long-lived groups principally failed in association with the development of clinical tuberculosis, Mycobacterium suricattae, a disease that can spread throughout the group and be fatal for group members. Clinical tuberculosis was more likely to occur in groups that had smaller group sizes and that had experienced immigration.
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Affiliation(s)
- Chris Duncan
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
| | - Marta B. Manser
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
- Animal BehaviourDepartment of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Tim Clutton‐Brock
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
- Mammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
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20
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Josi D, Flury JM, Reyes-Contreras M, Tanaka H, Taborsky M, Frommen JG. Sex-Specific Routes to Independent Breeding in a Polygynous Cooperative Breeder. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.750483] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
How can individuals obtain a breeding position and what are the benefits associated with philopatry compared to dispersal? These questions are particularly intriguing in polygamous cooperative breeders, where dispersal strategies reflect major life history decisions, and routes to independent breeding may utterly differ between the sexes. We scrutinized sex-dependent life-history routes by investigating dispersal patterns, growth rates and mortality in a wild colony of the cooperatively breeding cichlid Neolamprologus savoryi. Our data reveal that female helpers typically obtain dominant breeding positions immediately after reaching sexual maturity, which is associated with strongly reduced growth. In contrast, males obtain breeder status only at twice the age of females. After reaching sexual maturity, males follow one of two strategies: (i) they may retain their subordinate status within the harem of a dominant male, which may provide protection against predators but involves costs by helping in territory maintenance, defence and brood care; or (ii) they may disperse and adopt a solitary status, which diminishes survival chances and apparently reflects a best-of-a-bad-job strategy, as there are no obvious compensating future fitness benefits associated with this pathway. Our study illustrates that sex-dependent life history strategies strongly relate to specific social structures and mating patterns, with important implications for growth rates, the age at which breeding status is obtained, and survival.
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21
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Houslay TM, Nielsen JF, Clutton-Brock TH. Contributions of genetic and nongenetic sources to variation in cooperative behavior in a cooperative mammal. Evolution 2021; 75:3071-3086. [PMID: 34647327 DOI: 10.1111/evo.14383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 08/17/2021] [Accepted: 09/30/2021] [Indexed: 11/29/2022]
Abstract
The evolution of cooperative behavior is a major area of research among evolutionary biologists and behavioral ecologists, yet there are few estimates of its heritability or its evolutionary potential, and long-term studies of identifiable individuals are required to disentangle genetic and nongenetic components of cooperative behavior. Here, we use long-term data on over 1800 individually recognizable wild meerkats (Suricata suricatta) collected over 30 years and a multigenerational genetic pedigree to partition phenotypic variation in three cooperative behaviors (babysitting, pup feeding, and sentinel behavior) into individual, additive genetic, and other sources, and to assess their repeatability and heritability. In addition to strong effects of sex, age, and dominance status, we found significant repeatability in individual contributions to all three types of cooperative behavior both within and across breeding seasons. Like most other studies of the heritability of social behavior, we found that the heritability of cooperative behavior was low. However, our analysis suggests that a substantial component of the repeatable individual differences in cooperative behavior that we observed was a consequence of additive genetic variation. Our results consequently indicate that cooperative behavior can respond to selection, and suggest scope for further exploration of the genetic basis of social behavior.
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Affiliation(s)
- Thomas M Houslay
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, United Kingdom.,Kuruman River Reserve, Kalahari Research Centre, Van Zylsrus, 8467, South Africa
| | - Johanna F Nielsen
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom
| | - Tim H Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, United Kingdom.,Kuruman River Reserve, Kalahari Research Centre, Van Zylsrus, 8467, South Africa.,Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0028, South Africa
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22
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Abstract
[Figure: see text].
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23
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Pacheco XP, Madden JR. Does the social network structure of wild animal populations differ from that of animals in captivity? Behav Processes 2021; 190:104446. [PMID: 34147575 DOI: 10.1016/j.beproc.2021.104446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 08/16/2020] [Accepted: 06/14/2021] [Indexed: 12/27/2022]
Abstract
The social behaviour of wild animals living in groups leads to social networks with structures that produce group-level effects and position individuals within them with differential consequences for an individual's fitness. Social dynamics in captivity can differ greatly from those in wild conspecifics given the different constraints on social organization in wild populations, e.g. group size, predation pressure, distribution of resources (food, mates), which are all regulated by human carers in captive populations. The social networks of animals in zoos is expected to differ from those of free-living conspecifics. While many studies have described the social networks of a wide diversity of wild and captive animals, none has directly compared the networks of multiple groups of a single species both in the wild and in captivity. Meerkats, Suricata suricatta, are an excellent species to compare the social networks of wild and captive groups. We replicated the methods of Madden et al. (2009, 2011), who studied eight groups in the wild, in fifteen captive groups. We tested how network structures and individual positions in grooming, foraging competition and dominance networks differed between wild and captive groups. Groups of wild and captive meerkats differed in various aspects of their social network structure. Differences in the network may be due to individuals occupying different network positions and the difference in the number and strength of their connections to other individuals. This distinct way of interacting and associating could be a result of group specific attributes, such as group size, and/or the attributes of the donor and recipient, including sex, status or age. Critically, the differences may be explained by the dissimilar living environment that each encounters.
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Affiliation(s)
- Xareni P Pacheco
- Centre for Research in Animal Behaviour, Psychology, Washington Singer Building, University of Exeter, Perry Road, Exeter EX4 4QG, UK; Centre for Research in Applied Biological Sciences, Autonomous University of the State of Mexico, Instituto Literario 100, Centro, 50000 Toluca, Mexico.
| | - Joah R Madden
- Centre for Research in Animal Behaviour, Psychology, Washington Singer Building, University of Exeter, Perry Road, Exeter EX4 4QG, UK.
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24
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25
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Pandit SA, Pradhan GR, van Schaik CP. Why Class Formation Occurs in Humans but Not among Other Primates : A Primate Coalitions Model. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2021; 31:155-173. [PMID: 32676890 DOI: 10.1007/s12110-020-09370-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Most human societies exhibit a distinct class structure, with an elite, middle classes, and a bottom class, whereas animals form simple dominance hierarchies in which individuals with higher fighting ability do not appear to form coalitions to "oppress" weaker individuals. Here, we extend our model of primate coalitions and find that a division into a bottom class and an upper class is inevitable whenever fitness-enhancing resources, such as food or real estate, are exploitable or tradable and the members of the bottom class cannot easily leave the group. The model predicts that the bottom class has a near flat, low payoff and always comprises at least half the society. The upper class may subdivide into one or more middle class(es), resulting in improved payoff for the topmost members (elite). The model predicts that the bottom class on its own is incapable of mounting effective counter-coalitions against the upper class, except when receiving support from dissatisfied members of the middle class(es). Such counter-coalitions can be prevented by keeping the payoff to the lowest-ranked members of the middle classes (through concessions) well above that of the bottom class. This simple model explains why classes are also absent in nomadic hunter-gatherers and predominate in (though are not limited to) societies that produce and store food. Its results also agree well with various other known features of societies with classes.
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Affiliation(s)
- Sagar A Pandit
- Department of Physics, University of South Florida, Tampa, FL, 33620, USA
| | - Gauri R Pradhan
- Department of Physics, University of South Florida, Tampa, FL, 33620, USA.
| | - Carel P van Schaik
- Department of Anthropology, University of Zurich, CH-8051, Zurich, Switzerland
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26
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Johnston RA, Vullioud P, Thorley J, Kirveslahti H, Shen L, Mukherjee S, Karner CM, Clutton-Brock T, Tung J. Morphological and genomic shifts in mole-rat 'queens' increase fecundity but reduce skeletal integrity. eLife 2021; 10:e65760. [PMID: 33843584 PMCID: PMC8104968 DOI: 10.7554/elife.65760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/11/2021] [Indexed: 12/21/2022] Open
Abstract
In some mammals and many social insects, highly cooperative societies are characterized by reproductive division of labor, in which breeders and nonbreeders become behaviorally and morphologically distinct. While differences in behavior and growth between breeders and nonbreeders have been extensively described, little is known of their molecular underpinnings. Here, we investigate the consequences of breeding for skeletal morphology and gene regulation in highly cooperative Damaraland mole-rats. By experimentally assigning breeding 'queen' status versus nonbreeder status to age-matched littermates, we confirm that queens experience vertebral growth that likely confers advantages to fecundity. However, they also upregulate bone resorption pathways and show reductions in femoral mass, which predicts increased vulnerability to fracture. Together, our results show that, as in eusocial insects, reproductive division of labor in mole-rats leads to gene regulatory rewiring and extensive morphological plasticity. However, in mole-rats, concentrated reproduction is also accompanied by costs to bone strength.
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Affiliation(s)
- Rachel A Johnston
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
| | - Philippe Vullioud
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | - Jack Thorley
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | - Henry Kirveslahti
- Department of Statistical Science, Duke UniversityDurhamUnited States
| | - Leyao Shen
- Department of Orthopaedic Surgery, Duke Orthopaedic Cellular, Developmental, and Genome Laboratories, Duke University School of MedicineDurhamUnited States
| | - Sayan Mukherjee
- Department of Statistical Science, Duke UniversityDurhamUnited States
- Department of Computer Science, Duke UniversityDurhamUnited States
- Department of Mathematics, Duke UniversityDurhamUnited States
- Department of Bioinformatics & Biostatistics, Duke UniversityDurhamUnited States
| | - Courtney M Karner
- Department of Orthopaedic Surgery, Duke Orthopaedic Cellular, Developmental, and Genome Laboratories, Duke University School of MedicineDurhamUnited States
- Department of Cell Biology, Duke UniversityDurhamUnited States
| | - Tim Clutton-Brock
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
- Department of Zoology and Entomology, Mammal Research Institute, University of PretoriaPretoriaSouth Africa
| | - Jenny Tung
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
- Department of Biology, Duke UniversityDurhamUnited States
- Duke Population Research Institute, Duke UniversityDurhamUnited States
- Canadian Institute for Advanced ResearchTorontoCanada
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27
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Anderson JA, Johnston RA, Lea AJ, Campos FA, Voyles TN, Akinyi MY, Alberts SC, Archie EA, Tung J. High social status males experience accelerated epigenetic aging in wild baboons. eLife 2021; 10:e66128. [PMID: 33821798 PMCID: PMC8087445 DOI: 10.7554/elife.66128] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/18/2021] [Indexed: 12/14/2022] Open
Abstract
Aging, for virtually all life, is inescapable. However, within populations, biological aging rates vary. Understanding sources of variation in this process is central to understanding the biodemography of natural populations. We constructed a DNA methylation-based age predictor for an intensively studied wild baboon population in Kenya. Consistent with findings in humans, the resulting 'epigenetic clock' closely tracks chronological age, but individuals are predicted to be somewhat older or younger than their known ages. Surprisingly, these deviations are not explained by the strongest predictors of lifespan in this population, early adversity and social integration. Instead, they are best predicted by male dominance rank: high-ranking males are predicted to be older than their true ages, and epigenetic age tracks changes in rank over time. Our results argue that achieving high rank for male baboons - the best predictor of reproductive success - imposes costs consistent with a 'live fast, die young' life-history strategy.
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Affiliation(s)
- Jordan A Anderson
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
| | - Rachel A Johnston
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
| | - Amanda J Lea
- Department of Biology, Duke UniversityDurhamUnited States
- Lewis-Sigler Institute for Integrative Genomics, Carl Icahn Laboratory, Princeton UniversityPrincetonUnited States
- Department of Ecology and Evolution, Princeton UniversityPrincetonUnited States
| | - Fernando A Campos
- Department of Biology, Duke UniversityDurhamUnited States
- Department of Anthropology, University of Texas at San AntonioSan AntonioUnited States
| | - Tawni N Voyles
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
| | - Mercy Y Akinyi
- Institute of Primate Research, National Museums of KenyaNairobiKenya
| | - Susan C Alberts
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
- Department of Biology, Duke UniversityDurhamUnited States
| | - Elizabeth A Archie
- Department of Biological Sciences, University of Notre DameNotre DameUnited States
| | - Jenny Tung
- Department of Evolutionary Anthropology, Duke UniversityDurhamUnited States
- Department of Biology, Duke UniversityDurhamUnited States
- Duke Population Research Institute, Duke UniversityDurhamUnited States
- Canadian Institute for Advanced ResearchTorontoCanada
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28
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Morehouse AT, Loosen AE, Graves TA, Boyce MS. The smell of success: Reproductive success related to rub behavior in brown bears. PLoS One 2021; 16:e0247964. [PMID: 33657186 PMCID: PMC7928475 DOI: 10.1371/journal.pone.0247964] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 02/16/2021] [Indexed: 11/25/2022] Open
Abstract
Several species of bears are known to rub deliberately against trees and other objects, but little is known about why bears rub. Patterns in rubbing behavior of male and female brown bears (Ursus arctos) suggest that scent marking via rubbing functions to communicate among potential mates or competitors. Using DNA from bear hairs collected from rub objects in southwestern Alberta from 2011–2014 and existing DNA datasets from Montana and southeastern British Columbia, we determined sex and individual identity of each bear detected. Using these data, we completed a parentage analysis. From the parentage analysis and detection data, we determined the number of offspring, mates, unique rub objects where an individual was detected, and sampling occasions during which an individual was detected for each brown bear identified through our sampling methods. Using a Poisson regression, we found a positive relationship between bear rubbing behavior and reproductive success; both male and female bears with a greater number of mates and a greater number of offspring were detected at more rub objects and during more occasions. Our results suggest a fitness component to bear rubbing, indicate that rubbing is adaptive, and provide insight into a poorly understood behaviour.
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Affiliation(s)
- Andrea T. Morehouse
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Winisk Research and Consulting, Bellevue, Alberta, Canada
- * E-mail:
| | - Anne E. Loosen
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Inland Norway University of Applied Sciences, Koppang, Norway
| | - Tabitha A. Graves
- U.S. Geological Survey, Northern Rocky Mountain Science Center, West Glacier, Montana, United States of America
| | - Mark S. Boyce
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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29
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Preston EFR, Thompson FJ, Ellis S, Kyambulima S, Croft DP, Cant MA. Network-level consequences of outgroup threats in banded mongooses: Grooming and aggression between the sexes. J Anim Ecol 2021; 90:153-167. [PMID: 33428240 DOI: 10.1111/1365-2656.13323] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 06/17/2020] [Indexed: 01/10/2023]
Abstract
Animal groups are heterogeneous assemblages of individuals with differing fitness interests, which may lead to internal conflict over investment in group territorial defence. Differences between individuals may lead to different behavioural responses to intergroup conflict, particularly between the sexes. These potential impacts have been little studied. We used social network analysis to investigate the impact of simulated intergroup conflicts on social relationships in groups of wild banded mongooses Mungos mungo, in which intergroup fights are more costly for males than females. We predicted that social cohesion (specifically male-to-male and female-to-male grooming) would increase after conflict, and aggression would decrease, to minimize conflict between the sexes. Simulated intergroup conflicts were performed by exposing banded mongoose groups to scents, 'war cry' playbacks, and live intruders from a rival group. All grooming and aggression interactions between individuals were recorded, and grooming and aggression social networks were created for the 2 days preceding a simulated intergroup conflict (pre-conflict network) and the 2 days after (post-conflict network). We found no evidence of an increase in social cohesion after simulated conflicts, measured as grooming eigenvector centrality. Male-to-male, male-to-female and female-to-male grooming strength decreased after simulated intrusions compared to female-to-female grooming strength. However, male-female aggression decreased in intrusion trials compared to other interaction types, consistent with the hypothesis that intergroup encounters reduce the level of intragroup conflict between males and females. Males were more affected socially by intergroup encounters than females, which may be because they are investing in defence rather than internal relationships. Focusing on individual relationship changes, using social network analysis, can reveal changes in the directionality of behaviour in response to intergroup encounters, and highlight how individual responses to conflict may scale up to affect social networks and, potentially, group performance. This study highlights the importance of studying both group-level behaviours and individual relationships to more fully understand responses to intergroup encounters.
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Affiliation(s)
- Elizabeth F R Preston
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall, UK
| | - Faye J Thompson
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall, UK
| | - Samuel Ellis
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | - Darren P Croft
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Michael A Cant
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall, UK
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30
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Desrochers L, Branconi R, Schlatter E, Dent B, Buston P. Sensory cues underlying competitive growth in the clown anemonefish (Amphiprion percula). Behav Processes 2020; 181:104276. [PMID: 33091543 DOI: 10.1016/j.beproc.2020.104276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/01/2020] [Accepted: 10/15/2020] [Indexed: 01/09/2023]
Abstract
In some animal societies, access to breeding depends on the individual's position in a hierarchy, which often depends on an individual's size. In such societies, individuals may try to outgrow one another to attain a higher rank by engaging in a form of strategic growth (competitive growth). This suggests that members of the hierarchy can track changes in the growth and size of potential competitors and respond accordingly. The clown anemonefish, Amphiprion percula, is one species known to exhibit competitive growth at the initiation of size hierarchies. Here, we use 5 combinations of sensory cues to determine which cues must be available for individuals to engage in competitive growth. Our results show that mechanosensory (pressure and/or touch) cues or unobstructed interactions are necessary for competitive growth to occur. This study provides an understanding of the relationship between sensory cues and phenotypic responses to different social contexts.
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Affiliation(s)
- Leah Desrochers
- Boston University, 5 Cummington Mall, Boston, MA, 02115, USA.
| | | | - E Schlatter
- Boston University, 5 Cummington Mall, Boston, MA, 02115, USA.
| | - Brianne Dent
- Boston University, 5 Cummington Mall, Boston, MA, 02115, USA.
| | - Peter Buston
- Boston University, 5 Cummington Mall, Boston, MA, 02115, USA.
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31
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Wright E, Galbany J, McFarlin SC, Ndayishimiye E, Stoinski TS, Robbins MM. Dominance rank but not body size influences female reproductive success in mountain gorillas. PLoS One 2020; 15:e0233235. [PMID: 32492071 PMCID: PMC7269200 DOI: 10.1371/journal.pone.0233235] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 04/30/2020] [Indexed: 12/03/2022] Open
Abstract
According to life history theory, natural selection has shaped trade-offs for allocating energy among growth, reproduction and maintenance to maximize individual fitness. In social mammals body size and dominance rank are two key variables believed to influence female reproductive success. However, few studies have examined these variables together, particularly in long-lived species. Previous studies found that female dominance rank correlates with reproductive success in mountain gorillas (Gorilla beringei beringei), which is surprising given they have weak dominance relationships and experience seemingly low levels of feeding competition. It is not currently known whether this relationship is primarily driven by a positive correlation between rank and body size. We used the non-invasive parallel laser method to measure two body size variables (back breadth and body length) of 34 wild adult female mountain gorillas, together with long-term dominance and demography data to investigate the interrelationships among body size, dominance rank and two measures of female reproductive success (inter-birth interval N = 29 and infant mortality N = 64). Using linear mixed models, we found no support for body size to be significantly correlated with dominance rank or female reproductive success. Higher-ranking females had significantly shorter inter-birth intervals than lower-ranking ones, but dominance rank was not significantly correlated with infant mortality. Our results suggest that female dominance rank is primarily determined by factors other than linear body dimensions and that high rank provides benefits even in species with weak dominance relationships and abundant year-round food resources. Future studies should focus on the mechanisms behind heterogeneity in female body size in relation to trade-offs in allocating energy to growth, maintenance and lifetime reproductive success.
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Affiliation(s)
- Edward Wright
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- * E-mail:
| | - Jordi Galbany
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, United States of America
- Department of Clinical Psychology and Psychobiology, University of Barcelona, Barcelona, Spain
| | - Shannon C. McFarlin
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, United States of America
| | - Eric Ndayishimiye
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, United States of America
| | - Tara S. Stoinski
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, United States of America
| | - Martha M. Robbins
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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32
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Thorley J. The case for extended lifespan in cooperatively breeding mammals: a re-appraisal. PeerJ 2020; 8:e9214. [PMID: 32477839 PMCID: PMC7243813 DOI: 10.7717/peerj.9214] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 04/27/2020] [Indexed: 12/04/2022] Open
Abstract
Recent comparative studies have suggested that cooperative breeding is associated with increases in maximum lifespan among mammals, replicating a pattern also seen in birds and insects. In this study, we re-examine the case for increased lifespan in mammalian cooperative breeders by analysing a large dataset of maximum longevity records. We did not find any consistent, strong evidence that cooperative breeders have longer lifespans than other mammals after having controlled for variation in body mass, mode of life and data quality. The only possible exception to this general trend is found in the African mole-rats (the Bathyergid family), where all members are relatively long-lived, but where the social, cooperatively breeding species appear to be much longer-lived than the solitary species. However, solitary mole-rat species have rarely been kept in captivity or followed longitudinally in the wild and so it seems likely that their maximum lifespan has been underestimated when compared to the highly researched social species. Although few subterranean mammals have received much attention in a captive or wild setting, current data instead supports a causal role of subterranean living on lifespan extension in mammals.
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Affiliation(s)
- Jack Thorley
- Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge, UK
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33
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Thorley J, Duncan C, Sharp SP, Gaynor D, Manser MB, Clutton-Brock T. Sex-independent senescence in a cooperatively breeding mammal. J Anim Ecol 2020; 89:1080-1093. [PMID: 31943191 DOI: 10.1111/1365-2656.13173] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/28/2019] [Indexed: 11/30/2022]
Abstract
Researchers studying mammals have frequently interpreted earlier or faster rates of ageing in males as resulting from polygyny and the associated higher costs of reproductive competition. Yet, few studies conducted on wild populations have compared sex-specific senescence trajectories outside of polygynous species, making it difficult to make generalized inferences on the role of reproductive competition in driving senescence, particularly when other differences between males and females might also contribute to sex-specific changes in performance across lifespan. Here, we examine age-related variation in body mass, reproductive output and survival in dominant male and female meerkats, Suricata suricatta. Meerkats are socially monogamous cooperative breeders where a single dominant pair virtually monopolizes reproduction in each group and subordinate group members help to rear offspring produced by breeders. In contrast to many polygynous societies, we find that neither the onset nor the rate of senescence in body mass or reproductive output shows clear differences between males and females. Both sexes also display similar patterns of age-related survival across lifespan, but unlike most wild vertebrates, survival senescence (increases in annual mortality with rising age) was absent in dominants of both sexes, and as a result, the fitness costs of senescence were entirely attributable to declines in reproductive output from mid- to late-life. We suggest that the potential for intrasexual competition to increase rates of senescence in females-who are hormonally masculinized and frequently aggressive-is offset by their ability to maintain longer tenures of dominance than males, and that these processes when combined lead to similar patterns of senescence in both sexes. Our results stress the need to consider the form and intensity of sexual competition as well as other sex-specific features of life history when investigating the operation of senescence in wild populations.
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Affiliation(s)
- Jack Thorley
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa
| | - Christopher Duncan
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa
| | - Stuart P Sharp
- Lancaster Environment Centre, Lancaster University, Lancashire, UK
| | - David Gaynor
- Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Marta B Manser
- Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa.,Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Tim Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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34
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Firman RC, Rubenstein DR, Moran JM, Rowe KC, Buzatto BA. Extreme and Variable Climatic Conditions Drive the Evolution of Sociality in Australian Rodents. Curr Biol 2020; 30:691-697.e3. [DOI: 10.1016/j.cub.2019.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 10/29/2019] [Accepted: 12/04/2019] [Indexed: 12/23/2022]
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35
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Brouwer L, Cockburn A, van de Pol M. Integrating Fitness Components Reveals That Survival Costs Outweigh Other Benefits and Costs of Group Living in Two Closely Related Species. Am Nat 2020; 195:201-215. [PMID: 32017615 DOI: 10.1086/706475] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Group living can be beneficial when individuals reproduce or survive better in the presence of others, but, simultaneously, there might be costs due to competition for resources. Positive and negative effects on various fitness components might thus counteract each other, so integration is essential to determine their overall effect. Here, we investigated how an integrated fitness measure (reproductive values [RVs]) based on six fitness components varied with group size among group members in cooperatively breeding red-winged and superb fairy wrens (Malurus elegans and Malurus cyaneus, respectively). Despite life-history differences between the species, patterns of RVs were similar, suggesting that the same behavioral mechanisms are important. Group living reduced RVs for dominant males, but for other group members, this was true only in large groups. Decomposition analyses showed that our integrated fitness proxy was most strongly affected by group size effects on survival and was amplified through carryover effects between years. Our study shows that integrative consideration of fitness components and subsequent decomposition analysis provide much needed insights into the key behavioral mechanisms shaping the costs and benefits of group living. Such attribution is crucial if we are to synthesize the relative importance of the myriad group size costs and benefits currently reported in the literature.
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36
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Dyble M, Houslay TM, Manser MB, Clutton-Brock T. Intergroup aggression in meerkats. Proc Biol Sci 2019; 286:20191993. [PMID: 31847765 DOI: 10.1098/rspb.2019.1993] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Violent conflicts between groups have been observed among many species of group living mammals and can have important fitness consequences, with individuals being injured or killed and with losing groups surrendering territory. Here, we explore between-group conflict among meerkats (Suricata suricatta), a highly social and cooperatively breeding mongoose. We show that interactions between meerkat groups are frequently aggressive and sometimes escalate to fighting and lethal violence and that these interactions have consequences for group territories, with losing groups moving to sleeping burrows closer to the centre of their territories following an intergroup interaction and with winning groups moving further away. We find that larger groups and groups with pups are significantly more likely to win contests, but that the location of the contest, adult sex ratio, and mean within-group genetic relatedness do not predict contest outcome. Our results suggest that intergroup competition may be a major selective force among meerkats, reinforcing the success of large groups and increasing the vulnerability of small groups to extinction. The presence of both within-group cooperation and between-group hostility in meerkats make them a valuable point of comparison in attempts to understand the ecological and evolutionary roots of human warfare.
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Affiliation(s)
- Mark Dyble
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.,Jesus College, Jesus Lane, Cambridge CB5 8BL, UK.,Department of Anthropology, UCL, 14 Taviton Street, London WC1H 0BW, UK.,Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
| | - Thomas M Houslay
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.,Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
| | - Marta B Manser
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Tim Clutton-Brock
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.,Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
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37
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Carlitz EHD, Runge JN, König B, Winkler L, Kirschbaum C, Gao W, Lindholm AK. Steroid hormones in hair reveal sexual maturity and competition in wild house mice (Mus musculus domesticus). Sci Rep 2019; 9:16925. [PMID: 31729421 PMCID: PMC6858357 DOI: 10.1038/s41598-019-53362-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/24/2019] [Indexed: 01/31/2023] Open
Abstract
Endocrine data from wild populations provide important insight into social systems. However, obtaining samples for traditional methods involves capture and restraint of animals, and/or pain, which can influence the animal’s stress level, and thereby undesirable release of hormones. Here, we measured corticosterone, testosterone and progesterone in the hair of 482 wild-derived house mice that experienced sexual competition while living under semi-natural conditions. We tested whether sex, age, weight and indicators of sexual maturity, reproduction and social conflicts predict hormone concentrations measured in hair (sampling at endpoint). We show that body weight, sex and age significantly predict cumulative testosterone and progesterone levels, allowing the differentiation between subadults and adults in both sexes. Corticosterone was only slightly elevated in older males compared to older females and increased with the level of visible injuries or scars. Testosterone in males positively correlated with body weight, age, testes size, and sperm number. Progesterone in females significantly increased with age, body weight, and the number of embryos implanted throughout life, but not with the number of litters when controlled for age and weight. Our results highlight the biological validity of hair steroid measurements and provide important insight into reproductive competition in wild house mice.
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Affiliation(s)
- Esther H D Carlitz
- Department of Psychology, Biological Psychology, Technical University of Dresden, Dresden, Germany.
| | - Jan-Niklas Runge
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
| | - Barbara König
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
| | - Lennart Winkler
- Department of Applied Zoology, Technical University of Dresden, Dresden, Germany
| | - Clemens Kirschbaum
- Department of Psychology, Biological Psychology, Technical University of Dresden, Dresden, Germany
| | - Wei Gao
- Department of Psychology, Biological Psychology, Technical University of Dresden, Dresden, Germany
| | - Anna K Lindholm
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
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38
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Strandburg-Peshkin A, Clutton-Brock T, Manser MB. Burrow usage patterns and decision-making in meerkat groups. Behav Ecol 2019. [DOI: 10.1093/beheco/arz190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Choosing suitable sleeping sites is a common challenge faced by animals across a range of taxa, with important implications for the space usage patterns of individuals, groups, and ultimately populations. A range of factors may affect these decisions, including access to resources nearby, shelter from the elements, safety from predators, territorial defense, and protection of offspring. We investigated the factors driving patterns of sleeping site use in wild Kalahari meerkats (Suricata suricatta), a cooperatively breeding, territorial mongoose species that forages on scattered resources and makes use of multiple sleeping sites (burrows). We found that meerkat groups used some burrows much more often than others. In particular, large burrows near the center of the territory were used more often than small and peripheral burrows, and groups became even more biased toward central burrows when rearing pups. Meerkats also used their sleeping burrows in a nonrandom order. When they changed sleeping burrows, they moved disproportionately to nearby burrows but did not always select the closest burrow. Burrow decisions also reflected responses to short-term conditions: rates of switching burrows increased after encounters with predators and when resources were depleted, whereas group splits were associated with a reduced probability of switching. The group’s dominant female appeared to have disproportionate influence over burrow decisions, as groups were more likely to switch burrows when her foraging success was low. Our results link behavioral and movement ecology to show that a multitude of environmental and social factors shape daily group decisions of where to spend the night.
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Affiliation(s)
- Ariana Strandburg-Peshkin
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurstrasse 190, Zürich, Switzerland
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Department of Biology, University of Konstanz, Universitätsstrasse 10, Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Universitätsstrasse 10, Konstanz, Germany
| | - Tim Clutton-Brock
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, UK
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Marta B Manser
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurstrasse 190, Zürich, Switzerland
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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39
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Grebe NM, Fitzpatrick C, Sharrock K, Starling A, Drea CM. Organizational and activational androgens, lemur social play, and the ontogeny of female dominance. Horm Behav 2019; 115:104554. [PMID: 31276664 DOI: 10.1016/j.yhbeh.2019.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/06/2019] [Accepted: 07/01/2019] [Indexed: 11/18/2022]
Abstract
The role of androgens in shaping "masculine" traits in males is a core focus in behavioral endocrinology, but relatively little is known about an androgenic role in female aggression and social dominance. In mammalian models of female dominance, including the ring-tailed lemur (Lemur catta), links to androgens in adulthood are variable. We studied the development of ring-tailed lemurs to address the behavioral basis and ontogenetic mechanisms of female dominance. We measured behavior and serum androgen concentrations in 24 lemurs (8 males, 16 females) from infancy to early adulthood, and assessed their 'prenatal' androgen milieu using serum samples obtained from their mothers during gestation. Because logistical constraints limited the frequency of infant blood sampling, we accounted for asynchrony between behavioral and postnatal hormone measurements via imputation procedures. Imputation was unnecessary for prenatal hormone measurements. The typical sex difference in androgen concentrations in young lemurs was consistent with adult conspecifics and most other mammals; however, we found no significant sex differences in rough-and-tumble play. Female (but not male) aggression increased beginning at approximately 15 months, coincident with female puberty. In our analyses relating sexually differentiated behavior to androgens, we found no relationship with activational hormones, but several significant relationships with organizational hormones. Notably, associations of prenatal androstenedione and testosterone with behavior were differentiated, both by offspring sex and by type of behavior within offspring sexes. We discuss the importance of considering (1) missing data in behavioral endocrinology research, and (2) organizational androgens other than testosterone in studies of female dominance.
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Affiliation(s)
- Nicholas M Grebe
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA.
| | | | - Katherine Sharrock
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
| | - Anne Starling
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
| | - Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA; Department of Biology, Duke University, Durham, NC, USA; University Program in Ecology, Duke University, Durham, NC, USA
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40
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Cram DL, Jungwirth A, Spence-Jones H, Clutton-Brock T. Reproductive conflict resolution in cooperative breeders. Behav Ecol 2019. [DOI: 10.1093/beheco/arz143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Female infanticide is common in animal societies where groups comprise multiple co-breeding females. To reduce the risk that their offspring are killed, mothers can synchronize breeding and pool offspring, making it hard for females to avoid killing their own young. However, female reproductive conflict does not invariably result in reproductive synchrony, and we lack a general hypothesis explaining the variation in conflict resolution strategies seen across species. Here, we investigate the fitness consequences of birth timing relative to other females and the prevalence of birth synchrony in cooperatively breeding Kalahari meerkats (Suricata suricatta). We show that, although there would be substantial benefits to females in synchronizing births and reducing their risk of infanticide, birth synchrony is rare. Since precise breeding synchrony has evolved in a related species with similar infanticidal female reproductive conflict, its absence in meerkats requires an evolutionary explanation. We therefore explore the costs and benefits of synchronizing breeding in two theoretical models, each of which contrasts synchrony with an alternative reproductive strategy: (i) breeding opportunistically and accepting fitness losses to infanticide or (ii) suppressing the reproduction of others to prevent infanticide. Our models show that the costs of synchrony constrain its development if subordinates breed infrequently, and that selection instead favors the suppression of subordinate reproduction by the dominant and opportunistic reproduction by subordinates. Together, our results suggest that the resolution of reproductive conflict in animal societies is shaped by differential breeding propensities among female group members, leading to divergent conflict resolution strategies even in closely related species.
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Affiliation(s)
- Dominic L Cram
- Department of Zoology, University of Cambridge, Cambridge, UK
- Kalahari Meerkat Project, Kalahari Research Centre, Van Zylsrus, Northern Cape, South Africa
| | - Arne Jungwirth
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Helen Spence-Jones
- Kalahari Meerkat Project, Kalahari Research Centre, Van Zylsrus, Northern Cape, South Africa
| | - Tim Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, UK
- Kalahari Meerkat Project, Kalahari Research Centre, Van Zylsrus, Northern Cape, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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41
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Grinsted L, Deutsch EK, Jimenez-Tenorio M, Lubin Y. Evolutionary drivers of group foraging: A new framework for investigating variance in food intake and reproduction. Evolution 2019; 73:2106-2121. [PMID: 31420977 DOI: 10.1111/evo.13826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/27/2019] [Accepted: 07/24/2019] [Indexed: 11/29/2022]
Abstract
A proposed fundamental driver of group living is more reliable, predictable foraging and reproduction, i.e., reduced variance in food intake and reproductive output. However, existing theories on variance reduction in group foraging are simplistic, refer to variance at the level of individuals and groups without linking the two, and do not spell out crucial underlying assumptions. We provide a new, widely applicable framework for identifying when variance reduction conveys fitness benefits of group foraging in a wide range of organisms. We discuss critical limitations of established theories, the Central Limit Theorem and Risk-Sensitive Foraging Theory applied to group foraging, and incorporate them into our framework while addressing the confusion over the levels of variance and identifying previously unaddressed assumptions. Through a field study on colonial spiders, Cyrtophora citricola, we demonstrate the importance of evaluating the level of food sharing as a critical first step, previously overlooked in the literature. We conclude that variance reduction provides selective advantages only under narrow conditions and does not provide a universal benefit to group foraging as previously proposed. Our framework provides an important tool for identifying evolutionary drivers of group foraging and understanding the role of fitness variance in the evolution of group living.
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Affiliation(s)
- Lena Grinsted
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, United Kingdom
| | - Ella K Deutsch
- School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Manuel Jimenez-Tenorio
- Department CMIM y Química Inorgánica-INBIO, Facultad de Ciencias, Universidad de Cádiz, 11510, Puerto Real, Cadiz, Spain
| | - Yael Lubin
- Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet, Ben-Gurion, 8499000, Israel
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42
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Morales-González A, Ruíz-Villar H, Ozgul A, Maag N, Cozzi G. Group size and social status affect scent marking in dispersing female meerkats. Behav Ecol 2019. [DOI: 10.1093/beheco/arz124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Many animal species use scent marks such as feces, urine, and glandular secretions to find mates, advertise their reproductive status, and defend an exclusive territory. Scent marking may be particularly important during dispersal, when individuals emigrate from their natal territory searching for mates and a new territory to settle and reproduce. In this study, we investigated the scent-marking behavior of 30 dispersing female meerkats (Suricata suricatta) during the three consecutive stages of dispersal—emigration, transience, and settlement. We expected marking patterns to differ between dispersal stages, depending on social circumstances such as presence of unrelated mates and social status of the individuals within each dispersing coalition and also to be influenced by water and food availability. We showed that defecation probability increased with group size during the settlement stage, when newly formed groups are expected to signal their presence to other resident groups. Urination probability was higher in subordinate than in dominant individuals during each of the three dispersal stages and it decreased overall as the dispersal process progressed. Urine may, thus, be linked to advertisement of the social status within a coalition. Anal marking probability did not change across dispersal stages but increased with the presence of unrelated males and was higher in dominants than in subordinates. We did not detect any effect of rain or foraging success on defecation and urination probability. Our results suggest that feces, urine, and anal markings serve different communication purposes (e.g., within and between-group communication) during the dispersal process.
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Affiliation(s)
| | - Héctor Ruíz-Villar
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus, South Africa
| | - Arpat Ozgul
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus, South Africa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Nino Maag
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus, South Africa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Gabriele Cozzi
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus, South Africa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
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43
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Holekamp KE, Sawdy MA. The evolution of matrilineal social systems in fissiped carnivores. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180065. [PMID: 31303158 DOI: 10.1098/rstb.2018.0065] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We review matrilineal relationships in the societies of fissiped mammalian carnivores, focusing on how the most complex of these may have evolved from simpler systems. Although competition for food is very intense at the trophic level occupied by most carnivores, and although most species of extant fissiped carnivores therefore lead solitary lives, some species show at least rudimentary clustering of maternal kin and matrilineal resource-sharing or transmission of critical resources between generations. The resources shared or transmitted range from individual food items and territories to entire networks of potential allies. The greatest elaboration of matrilineal relationships has occurred in two large carnivores, lions and spotted hyenas, which occur sympatrically throughout much of Africa. The societies of both these species apparently evolved in response to a shared suite of ecological conditions. The highly matrilineal societies of spotted hyenas are unique among carnivores and closely resemble the societies of many cercopithecine primates. The conditions favouring the evolution of matrilineal societies in carnivores include male-biased dispersal, female philopatry, the need for assistance in protecting or provisioning offspring, reliance on large or abundant prey, particularly in open habitat, high population density and kin-structured cooperative interactions that have strong positive effects on fitness. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.
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Affiliation(s)
- Kay E Holekamp
- 1 Department of Integrative Biology, Michigan State University , East Lansing, MI , USA.,2 Program in Ecology, Evolutionary Biology and Behavior, Michigan State University , East Lansing, MI , USA
| | - Maggie A Sawdy
- 1 Department of Integrative Biology, Michigan State University , East Lansing, MI , USA.,2 Program in Ecology, Evolutionary Biology and Behavior, Michigan State University , East Lansing, MI , USA
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44
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Rauber R, Clutton-Brock TH, Manser MB. Drought decreases cooperative sentinel behavior and affects vocal coordination in meerkats. Behav Ecol 2019. [DOI: 10.1093/beheco/arz112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Cooperative breeding often evolved in harsh and arid habitats characterized by high levels of environmental uncertainty. Most forms of cooperative behavior have energetic costs and previous studies have shown that the contributions of individuals to alloparental provisioning are conditional on their food intake. However, the effect of naturally occurring, extreme environmental conditions on the persistence of costly forms of cooperative behaviors and their coordination by communication remain unknown. Here, we show that in meerkats (Suricata suricatta) the probability to act as sentinel, a cooperative vigilance behavior, was the same for typically occurring dry and wet conditions, but significantly reduced during a drought condition with almost no rain, especially in young individuals, members of small groups and groups with pups. The duration an individual stayed on sentinel guard, however, was most reduced during dry conditions. Besides reductions in sentinel behavior, the vocal coordination of foraging meerkats differed when comparing drought and wet conditions. Individuals responded more strongly to playbacks of sentinel “all-clear” calls and close calls, resulting in less vigilance and more foraging behavior during the drought condition. We conclude that while meerkats are adapted to commonly occurring dry periods with low rainfall, the extreme drought period with almost no rain, led to a decrease of the frequency of costly forms of cooperative behaviors in favor of behaviors that maximize direct fitness benefits and also affected the vocal coordination among group members.
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Affiliation(s)
- Ramona Rauber
- Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
| | - Tim H Clutton-Brock
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge, UK
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Marta B Manser
- Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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45
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Perez A, Montiglio PO, Wey TW, Sih A. Male social plasticity influences transient dynamics in the emergence of alternative mating systems in water striders. Behav Ecol 2019. [DOI: 10.1093/beheco/arz108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
AbstractAnimal mating systems are often studied with the goal of understanding why species, populations, or groups vary from one another in the system they display. Although these differences are often treated as basically stable, it is also known that mating systems may shift over time (e.g., from one breeding season to the next). There has been some study of how ecological factors correlate with these changes; however, few, if any, studies have investigated how the phenotypic composition of a group governs the timing and probability of these mating system transitions. Groups of stream water striders (Aquarius remigis) can experience rapid changes in mating system dynamics, with small groups often transitioning into a system in which a single, large male monopolizes mating opportunities. We asked if variation in individual- and group-level traits associated with morphology and behavior (e.g., size of the largest individual, average activity behavioral type in the group) could partially explain the variability in how rapidly groups make this transition, if they make it at all. We show that groups with males that exhibit higher social plasticity tended to take longer to transition to a mating system dominated by a single male. Our results, therefore, suggest that groups in identical ecological conditions can diverge in their mating systems based on how much individuals in the group change their behavior in response to the behavior of other members of the group.
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Affiliation(s)
- Adrian Perez
- Department of Entomology, University of California at Davis, Davis, CA, USA
| | - Pierre-Olivio Montiglio
- Department of Environmental Sciences and Policy, University of California at Davis, Davis, CA, USA
- Université du Québec à Montréal, Montréal, Quebec, Canada
| | - Tina W Wey
- Department of Environmental Sciences and Policy, University of California at Davis, Davis, CA, USA
- Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Andrew Sih
- Department of Environmental Sciences and Policy, University of California at Davis, Davis, CA, USA
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46
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Thorley J, Clutton-Brock TH. A unified-models analysis of the development of sexual size dimorphism in Damaraland mole-rats, Fukomys damarensis. J Mammal 2019. [DOI: 10.1093/jmammal/gyz082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractIndividual variation in growth rates often generates variation in fitness. However, the ability to draw meaningful inferences from growth data depends on the use of growth models that allow for direct comparisons of growth between the sexes, between populations, and between species. Unlike traditional sigmoid functions, a recently parameterized family of unified growth models provides a reliable basis for comparisons since each parameter affects a single curve characteristic and parameters are directly comparable across the unified family. Here, we use the unified-models approach to examine the development of sexual size dimorphism in Damaraland mole-rats (Fukomys damarensis), where breeding males are larger than breeding females. Using skeletal measurements, we show here that the larger size of male Damaraland mole-rats arises from an increased growth rate across the entire period of development, rather than through sex differences in the duration or timing of growth. Male-biased skeletal size dimorphism is not unusual among rodents, and our measures of sex differences in size in captive mole-rats are close to sexual size differences in the wild, where size dimorphism = 1.04 (male:female). We hope our study will encourage the wide use of unified growth models by mammalogists.
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Affiliation(s)
- Jack Thorley
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Mammal Research Institute, University of Pretoria, Pretoria, Hatfield, South Africa
| | - Tim H Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Mammal Research Institute, University of Pretoria, Pretoria, Hatfield, South Africa
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47
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Culbert BM, Balshine S, Gilmour KM. Physiological Regulation of Growth during Social Ascension in a Group-Living Fish. Physiol Biochem Zool 2019; 92:211-222. [PMID: 30735088 DOI: 10.1086/702338] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In social groups, dominant animals typically are larger and have better access to resources than subordinates. When subordinates are given the opportunity to ascend to a dominant position, they will elevate their rates of growth to help secure dominance. This study investigated the physiological mechanisms facilitating this increased growth. Using the group-living cichlid, Neolamprologus pulcher, we investigated whether the insulin-like growth factor (IGF) system-a key regulator of growth-is involved in the regulation of growth during social ascension. We also assessed differences in energy storage and expenditure among dominant, subordinate, and ascending males to determine the energetic costs associated with ascension. Daily growth rates tripled during ascension, and ascending males expended more energy after ascension, owing to higher rates of energetically costly social behaviors, increased locomotor activity, and larger home ranges. Ascenders did not increase food intake to offset increasing energetic costs but had half the liver glycogen energy stores of subordinates. Together, these results indicate a reliance on stockpiled energy reserves to fuel the high energetic demands associated with ascension. Transcript abundance of IGF binding proteins 1 (igfbp1) and 2a (igfbp2a) were low in ascenders relative to subordinates, suggesting a higher capacity for growth during ascension through increased bioavailability of circulating IGF-1. Our findings provide clear evidence of the energetic costs of social ascension and offer novel insight into the physiological mechanisms modulating the social regulation of growth.
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Affiliation(s)
- Brett M Culbert
- 1 Department of Psychology, Neuroscience, and Behaviour, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Sigal Balshine
- 1 Department of Psychology, Neuroscience, and Behaviour, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Kathleen M Gilmour
- 2 Department of Biology, University of Ottawa, 30 Marie Curie Private, Ottawa, Ontario K1N 6N5, Canada
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48
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Reed C, Branconi R, Majoris J, Johnson C, Buston P. Competitive growth in a social fish. Biol Lett 2019; 15:20180737. [PMID: 30958131 PMCID: PMC6405469 DOI: 10.1098/rsbl.2018.0737] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/14/2019] [Indexed: 11/12/2022] Open
Abstract
Many animal societies have dominance hierarchies in which social rank is correlated with size. In such societies, the growth and size of individuals can be a strategic response to their social environment: in fishes, individuals may decrease their growth rate to remain small and retain a subordinate position; in mammals, individuals may increase their growth rate to become large and attain a dominant position-a strategy called competitive growth. Here, we investigate whether the clown anemonefish, Amphiprion percula, exhibits competitive growth also. We show that juvenile clownfish paired with a size-matched reproductive rival increase their growth rate and size relative to solitary controls. Remarkably, paired individuals achieved this, despite being provided with the same amount of food as solitary controls. Our results demonstrate that clownfish are able to increase their growth rate in response to social competition. This study adds to the growing body of evidence that the growth of social vertebrates can be a fine-tuned plastic response to their social environment.
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Affiliation(s)
| | | | | | | | - Peter Buston
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
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49
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Romano V, Martins AF, Ruiz-Miranda CR. Unraveling the dispersal patterns and the social drivers of natal emigration of a cooperative breeding mammal, the golden lion tamarin. Am J Primatol 2019; 81:e22959. [PMID: 30811068 DOI: 10.1002/ajp.22959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 01/25/2019] [Accepted: 01/29/2019] [Indexed: 11/10/2022]
Abstract
The study of the social drivers of animal dispersal is key to understanding the evolution of social systems. Among the social drivers of natal emigration, the conspecific attraction, aggressive eviction, and reduced social integration hypotheses predict that sexually mature individuals who receive more aggressive behavior and are engaged in less affiliative interactions are more likely to disperse. Few reports have explored these proximate factors affecting emigration in cooperatively breeding species, particularly of Neotropical primates. In this study, we investigated the dispersal patterns and tested the social drivers of natal emigration in the golden lion tamarin (Leontopithecus rosalia) - an endangered species inhabiting Atlantic rainforests fragments in Brazil. We used behavioral and demographic data collected during 7 years from 68 groups of tamarins inhabiting 20 forest fragments. Our analyses from the 160 dispersing individuals showed that dispersal success is higher for males and for those engaged in parallel dispersal, but that males and females use different strategies to enhance their dispersal success, males immigrate into established groups while females form new groups. We did not find high levels of agonistic behavior among group members before natal emigration. Instead we found that conspecific attraction drives natal emigration in both sexes, while additionally the low level of affiliative interactions within the natal group triggers male emigration. We discuss natal emigration in the broader perspective of the cooperative breeding system and the implications of these findings for the conservation of the species.
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Affiliation(s)
- Valéria Romano
- Center for International Collaboration and Advanced Studies in Primatology, Primate Research Institute, Kyoto University, Inuyama, Japan.,Laboratório de Ciências Ambientais, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | | | - Carlos R Ruiz-Miranda
- Laboratório de Ciências Ambientais, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, Brazil.,Associação Mico-Leão-Dourado, Silva Jardim, Rio de Janeiro, Brazil
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50
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Rico-Guevara A, Hurme KJ. Intrasexually selected weapons. Biol Rev Camb Philos Soc 2019; 94:60-101. [PMID: 29924496 DOI: 10.1111/brv.12436] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/24/2023]
Abstract
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from 'sexually selected weapons', and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same-sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo- or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better-developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non-hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
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Affiliation(s)
- Alejandro Rico-Guevara
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A.,Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Código Postal 11001, Bogotá DC, Colombia
| | - Kristiina J Hurme
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A
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