1
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Bravo C, Bautista-Sopelana LM, Alonso JC. Revisiting niche divergence hypothesis in sexually dimorphic birds: Is diet overlap correlated with sexual size dimorphism? J Anim Ecol 2024; 93:460-474. [PMID: 38462717 DOI: 10.1111/1365-2656.14058] [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: 01/23/2023] [Accepted: 01/04/2024] [Indexed: 03/12/2024]
Abstract
The evolution of sexual size dimorphism (SSD) is a long-standing topic in evolutionary biology, but there is little agreement on the extent to which SSD is driven by the different selective forces. While sexual selection and fecundity selection have traditionally been proposed as the two leading hypotheses, SSD may also result from natural selection through mechanisms such as sexual niche divergence, which might have reduced resource competition between sexes. Here, we revisited the niche divergence hypothesis by testing the relationship between the sexual overlap in diet and SSD of 56 bird species using phylogenetic comparative analyses. We then assessed how SSD variation relates to the three main hypotheses: sexual selection, fecundity selection, and sexual niche divergence using phylogenetic generalized least squares (PGLS). Then, we compared sexual selection, fecundity selection and niche divergence selection as SSD drivers through phylogenetic confirmatory path analyses to disentangle the possible causal evolutionary relationships between SSD and the three hypotheses. Phylogenetic generalized least squares showed that SSD was negatively correlated with diet overlap, that is, the greater the difference in body size between males and females, the less diet overlap. As predicted by sexual selection theory, the difference in body size between sexes was higher in polygynous species. Confirmatory phylogenetic path analyses suggested that the most likely evolutionary path might include the mating system as a main driver in SSD and niche divergence as a result of SSD. We found no evidence of a role of fecundity selection in the evolution of female-biased SSD. Our study provides evidence that sexual selection has likely been the main cause of SSD and that dietary divergence is likely an indirect effect of SSD.
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Affiliation(s)
- Carolina Bravo
- Instituto de Investigación en Recursos Cinegéticos (IREC)-(CSIC-UCLM-JCCM), Ciudad Real, Spain
| | | | - Juan Carlos Alonso
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales (MNCN), CSIC, Madrid, Spain
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2
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Ouled-Cheikh J, March D, Borras-Chavez R, Drago M, Goebel ME, Fariña JM, Gazo M, Coll M, Cardona L. Future climate-induced distribution shifts in a sexually dimorphic key predator of the Southern Ocean. GLOBAL CHANGE BIOLOGY 2024; 30:e17191. [PMID: 38433338 DOI: 10.1111/gcb.17191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 03/05/2024]
Abstract
The response to climate change in highly dimorphic species can be hindered by differences between sexes in habitat preferences and movement patterns. The Antarctic fur seal, Arctocephalus gazella, is the most abundant pinniped in the Southern Hemisphere, and one of the main consumers of Antarctic krill, Euphausia superba, in the Southern Ocean. However, the populations breeding in the Atlantic Southern Ocean are decreasing, partly due to global warming. Male and female Antarctic fur seals differ greatly in body size and foraging ecology, and little is known about their sex-specific responses to climate change. We used satellite tracking data and Earth System Models to predict changes in habitat suitability for male and female Antarctic fur seals from the Western Antarctic Peninsula under different climate change scenarios. Under the most extreme scenario (SSP5-8.5; global average temperature +4.4°C projected by 2100), suitable habitat patches will shift southward during the non-breeding season, leading to a minor overall habitat loss. The impact will be more pronounced for females than for males. The reduction of winter foraging grounds might decrease the survival of post-weaned females, reducing recruitment and jeopardizing population viability. During the breeding season, when males fast on land, suitable foraging grounds for females off the South Shetland Islands will remain largely unmodified, and new ones will emerge in the Bellingshausen Sea. As Antarctic fur seals are income breeders, the foraging grounds of females should be reasonably close to the breeding colony. As a result, the new suitable foraging grounds will be useful for females only if nearby beaches currently covered by sea ice emerge by the end of the century. Furthermore, the colonization of these new, ice-free breeding locations might be limited by strong female philopatry. These results should be considered when managing the fisheries of Antarctic krill in the Southern Ocean.
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Affiliation(s)
- Jazel Ouled-Cheikh
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- iMARES group, Departament de Recursos Marins Renovables, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
| | - David March
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Paterna, València, Spain
- Centre for Ecology and Conservation, College of Life and Environmental Science, University of Exeter, Penryn, Cornwall, UK
| | - Renato Borras-Chavez
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Biology, Baylor University, Waco, Texas, USA
| | - Massimiliano Drago
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Michael E Goebel
- Institute of Marine Sciences, University of California Santa Cruz (UCSC), Santa Cruz, California, USA
- Antarctic Ecosystem Research Division, SWFSC, NMFS, NOAA, La Jolla, California, USA
| | - José M Fariña
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Manel Gazo
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Marta Coll
- iMARES group, Departament de Recursos Marins Renovables, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
- Ecopath International Initiative (EII), Barcelona, Spain
| | - Luis Cardona
- Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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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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Aung T, Hill AK, Pfefferle D, McLester E, Fuller J, Lawrence JM, Garcia-Nisa I, Kendal RL, Petersdorf M, Higham JP, Galat G, Lameira AR, Apicella CL, Barelli C, Glenn ME, Ramos-Fernandez G, Puts DA. Group size and mating system predict sex differences in vocal fundamental frequency in anthropoid primates. Nat Commun 2023; 14:4069. [PMID: 37429846 PMCID: PMC10333282 DOI: 10.1038/s41467-023-39535-w] [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: 08/03/2022] [Accepted: 06/16/2023] [Indexed: 07/12/2023] Open
Abstract
Vocalizations differ substantially between the sexes in many primates, and low-frequency male vocalizations may be favored by sexual selection because they intimidate rivals and/or attract mates. Sexual dimorphism in fundamental frequency may be more pronounced in species with more intense male mating competition and in those with large group size, where social knowledge is limited and efficient judgment of potential mates and competitors is crucial. These non-mutually exclusive explanations have not been tested simultaneously across primate species. In a sample of vocalizations (n = 1914 recordings) across 37 anthropoid species, we investigated whether fundamental frequency dimorphism evolved in association with increased intensity of mating competition (H1), large group size (H2), multilevel social organization (H3), a trade-off against the intensity of sperm competition (H4), and/or poor acoustic habitats (H5), controlling for phylogeny and body size dimorphism. We show that fundamental frequency dimorphism increased in evolutionary transitions towards larger group size and polygyny. Findings suggest that low-frequency male vocalizations in primates may have been driven by selection to win mating opportunities by avoiding costly fights and may be more important in larger groups, where limited social knowledge affords advantages to rapid assessment of status and threat potential via conspicuous secondary sexual characteristics.
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Affiliation(s)
- Toe Aung
- Department of Anthropology, Pennsylvania State University, University Park, PA, USA
- Psychology and Counseling Department, Immaculata University, Immaculata, PA, USA
| | - Alexander K Hill
- Department of Anthropology, University of Washington, Seattle, WA, USA
| | - Dana Pfefferle
- Welfare and Cognition Group, Cognitive Neuroscience Laboratory, German Primate Center - Leibniz Institute for Primate Research, Goettingen, Germany & Leibniz-ScienceCampus Primate Cognition, German Primate Center & University of Goettingen, Goettingen, Germany
| | - Edward McLester
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany
| | - James Fuller
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, NY, USA
| | - Jenna M Lawrence
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, NY, USA
| | | | | | | | - James P Higham
- Department of Anthropology, New York University, 25 Waverly Place, New York, NY, USA
| | - Gérard Galat
- IRD (French National Research Institute for Sustainable Development), Montpellier, France
| | | | - Coren L Apicella
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Claudia Barelli
- Department of Biology, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Mary E Glenn
- Department of Anthropology, California State Polytechnic University Humboldt, Arcata, CA, USA
| | - Gabriel Ramos-Fernandez
- Institute for Research on Applied Mathematics and Systems and C3-Centro de Ciencias de la Complejidad, Universidad Nacional Autonoma de Mexico, Mexico, Mexico City, Mexico
| | - David A Puts
- Department of Anthropology, Pennsylvania State University, University Park, PA, USA.
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5
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Cassini MH. Role of sexual and natural selection in the evolution of sexual size dimorphism in primates. J Zool (1987) 2023. [DOI: 10.1111/jzo.13052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- M. H. Cassini
- Instituto de Biologia y Medicina Experimental Buenos Aires Argentina
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6
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Dugo-Cota A, Vilà C, Rodríguez A, Gonzalez-Voyer A. Influence of microhabitat, fecundity, and parental care on the evolution of sexual size dimorphism in Caribbean Eleutherodactylus frogs. Evolution 2022; 76:3041-3053. [PMID: 36210654 PMCID: PMC10091758 DOI: 10.1111/evo.14642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 07/31/2022] [Accepted: 08/29/2022] [Indexed: 01/22/2023]
Abstract
Rensch's rule suggests that sexual size dimorphism (SSD) increases with species size when males are the larger sex, whereas it decreases when females are the larger sex. However, the process responsible for this pattern remains obscure. SSD can result from sexual selection, such as intrasexual competition for access to mates, or from natural selection, due to resource partitioning or fecundity selection. We studied SSD in Caribbean Eleutherodactylus frogs using phylogenetic comparative methods to investigate the influence of microhabitat, fecundity, and parental care. Our results show that in Caribbean Eleutherodactylus females tend to be larger and, contrary to Rensch's rule, dimorphism increases with species size. SSD was not related to microhabitat use. However, SSD was positively correlated with fecundity, mediated by a greater increase in female size. SSD was also influenced by parental care, suggesting that male care promotes larger male size and reduces the female bias in SSD. As suggested for other anurans, female-biased SSD in Caribbean Eleutherodactylus results from fecundity selection, although the magnitude is countered by increased male size in species with paternal care. Our results highlight the importance of considering various selective forces that may act in concert to influence the evolution of SSD.
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Affiliation(s)
- Alvaro Dugo-Cota
- Conservation and Evolutionary Genetics Group, Doñana Biological Station (EBD-CSIC), Seville, 41092, Spain
| | - Carles Vilà
- Conservation and Evolutionary Genetics Group, Doñana Biological Station (EBD-CSIC), Seville, 41092, Spain
| | - Ariel Rodríguez
- Institut für Zoologie, Stiftung Tierärztliche Hochschule Hannover, DE-30559, Hannover, Germany
| | - Alejandro Gonzalez-Voyer
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, 04510, México
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7
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Cárdenas-Alayza S, Adkesson MJ, Edwards MR, Hirons AC, Gutiérrez D, Tremblay Y, Franco-Trecu V. Sympatric otariids increase trophic segregation in response to warming ocean conditions in Peruvian Humboldt Current System. PLoS One 2022; 17:e0272348. [PMID: 35951498 PMCID: PMC9371314 DOI: 10.1371/journal.pone.0272348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/18/2022] [Indexed: 11/26/2022] Open
Abstract
Determining trophic habits of predator communities is essential to measure interspecific interactions and response to environmental fluctuations. South American fur seals, Arctocephalus australis (SAFS) and sea lions Otaria byronia (SASL), coexist along the coasts of Peru. Recently, ocean warming events (2014–2017) that can decrease and impoverish prey biomass have occurred in the Peruvian Humboldt Current System. In this context, our aim was to assess the effect of warming events on long-term inter- and intra-specific niche segregation. We collected whisker from SAFS (55 females and 21 males) and SASL (14 females and 22 males) in Punta San Juan, Peru. We used δ13C and δ15N values serially archived in otariid whiskers to construct a monthly time series for 2005–2019. From the same period we used sea level anomaly records to determine shifts in the predominant oceanographic conditions using a change point analysis. Ellipse areas (SIBER) estimated niche width of species-sex groups and their overlap. We detected a shift in the environmental conditions marking two distinct periods (P1: January 2005—October 2013; P2: November 2013—December 2019). Reduction in δ15N in all groups during P2 suggests impoverished baseline values with bottom-up effects, a shift towards consuming lower trophic level prey, or both. Reduced overlap between all groups in P2 lends support of a more redundant assemblage during the colder P1 to a more trophically segregated assemblage during warmer P2. SASL females show the largest variation in response to the warming scenario (P2), reducing both ellipse area and δ15N mean values. Plasticity to adapt to changing environments and feeding on a more available food source without fishing pressure can be more advantageous for female SASL, albeit temporary trophic bottom-up effects. This helps explain larger population size of SASL in Peru, in contrast to the smaller and declining SAFS population.
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Affiliation(s)
- Susana Cárdenas-Alayza
- Centro para la Sostenibilidad Ambiental, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorio de Ciencias del Mar, Universidad Peruana Cayetano Heredia, Lima, Peru
- UMR 248 MARBEC: IRD–Univ. Montpellier–CNRS–Ifremer, Sète cedex, France
- * E-mail:
| | - Michael J. Adkesson
- Chicago Zoological Society, Brookfield Zoo, Brookfield, Illinois, United States of America
| | - Mickie R. Edwards
- Halmos College of Arts and Sciences, Nova Southeastern University, Dania Beach, Florida, United States of America
| | - Amy C. Hirons
- Halmos College of Arts and Sciences, Nova Southeastern University, Dania Beach, Florida, United States of America
| | - Dimitri Gutiérrez
- Laboratorio de Ciencias del Mar, Universidad Peruana Cayetano Heredia, Lima, Peru
- Programa Maestría en Ciencias del Mar, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Yann Tremblay
- UMR 248 MARBEC: IRD–Univ. Montpellier–CNRS–Ifremer, Sète cedex, France
| | - Valentina Franco-Trecu
- Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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8
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Cassini MH. Evolution of sexual size dimorphism and sexual segregation in artiodactyls: the chicken or the egg? Mamm Biol 2021. [DOI: 10.1007/s42991-021-00193-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Bocedi G. Ecological sexual dimorphism is modulated by the spatial scale of intersexual resource competition. J Anim Ecol 2021; 90:1810-1813. [PMID: 34346069 DOI: 10.1111/1365-2656.13556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 06/16/2021] [Indexed: 12/01/2022]
Abstract
In Focus: Li, X-Y., & H. Kokko. (2021). Sexual dimorphism driven by intersexual resource competition: Why is it rare, and where to look for it? Journal of Animal Ecology, 00, 1-13. Ecological sexual dimorphism, that is differences between the sexes in traits that are naturally selected as opposed to sexually selected, is gaining increasing attention after having often been dismissed as the 'less-parsimonious' explanation for differences between sexes. One potential driver of ecological sexual dimorphism is intersexual resource competition, in a process analogous to ecological character displacement between species; yet, clear empirical examples are scarce. Li and Kokko present mathematical models that introduce novel pieces to the puzzle: the role of the scale of mating competition and the spatial variation in resource availability. They show that ecological sexual dimorphism evolves when local mating groups are small (e.g. monogamous pairs) and when different resources are homogeneously available across habitats. Counterintuitively, larger mating groups (e.g. polygyny), and consequently higher intralocus sexual conflict, lead to sexual monomorphism. Habitat heterogeneity also leads to overlapping niches, although it can sometimes drive polymorphism within sexes. This study highlights why the conditions for intrasexual resource competition to drive evolution of sexual dimorphism are stringent, even in the absence of genetic constraints or competing species. Crucially, it highlights the importance of considering the mating system and the spatial scale of resource competition for understanding the occurrence of ecological sexual dimorphism, showing a large potential for future work considering different aspects of species' life histories and spatial dynamics.
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Affiliation(s)
- Greta Bocedi
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
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10
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Sexual segregation in juvenile Antarctic fur seals. Oecologia 2021; 197:339-352. [PMID: 34309704 DOI: 10.1007/s00442-021-04983-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Sexual segregation, the differential space, habitat or resource use by males and females, can have profound implications for conservation, as one sex may be more vulnerable to environmental and anthropogenic stressors. The drivers of sexual segregation, such as sex differences in body size, breeding constraints, and social behaviour, have been well studied in adults but are poorly understood in immature animals. To determine whether sexual segregation occurs in juvenile Antarctic fur seals, Arctocephalus gazella, and investigate the underlying drivers, we deployed Global Location Sensors on 26 males and 19 females of 1-3 years of age at Bird Island, South Georgia. Sexual segregation occurred in foraging distribution, primarily in latitude, with females foraging closer to South Georgia and the Polar Front, and males foraging further south near the Antarctic Peninsula. This segregation was particularly evident in Feb-Apr and May-Nov, and males spent more time hauled out than females in May-Nov. Although juveniles have no immediate reproductive commitments, reproductive selection pressures are still likely to operate and drive sex differences in body size, risk-taking, and social roles. These factors, coupled with prey distribution, likely contributed to sexual segregation in juvenile Antarctic fur seals. Consequently, male and female juveniles may compete with different fisheries and respond differently to environmental change, highlighting the importance of considering sex and age groups in species conservation efforts.
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11
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Brusa JL, Rotella JJ, Banner KM, Hutchins PR. Challenges and opportunities for comparative studies of survival rates: An example with male pinnipeds. Ecol Evol 2021; 11:7980-7999. [PMID: 34188866 PMCID: PMC8216918 DOI: 10.1002/ece3.7627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 03/11/2021] [Accepted: 04/13/2021] [Indexed: 11/30/2022] Open
Abstract
Survival rates are a central component of life-history strategies of large vertebrate species. However, comparative studies seldom investigate interspecific variation in survival rates with respect to other life-history traits, especially for males. The lack of such studies could be due to the challenges associated with obtaining reliable datasets, incorporating information on the 0-1 probability scale, or dealing with several types of measurement error in life-history traits, which can be a computationally intensive process that is often absent in comparative studies. We present a quantitative approach using a Bayesian phylogenetically controlled regression with the flexibility to incorporate uncertainty in estimated survival rates and quantitative life-history traits while considering genetic similarity among species and uncertainty in relatedness. As with any comparative analysis, our approach makes several assumptions regarding the generalizability and comparability of empirical data from separate studies. Our model is versatile in that it can be applied to any species group of interest and include any life-history traits as covariates. We used an unbiased simulation framework to provide "proof of concept" for our model and applied a slightly richer model to a real data example for pinnipeds. Pinnipeds are an excellent taxonomic group for comparative analysis, but survival rate data are scarce. Our work elucidates the challenges associated with addressing important questions related to broader ecological life-history patterns and how survival-reproduction trade-offs might shape evolutionary histories of extant taxa. Specifically, we underscore the importance of having high-quality estimates of age-specific survival rates and information on other life-history traits that reasonably characterize a species for accurately comparing across species.
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Affiliation(s)
- Jamie L. Brusa
- Department of EcologyMontana State UniversityBozemanMTUSA
- School of Environmental and Forest SciencesUniversity of WashingtonSeattleWAUSA
| | - Jay J. Rotella
- Department of EcologyMontana State UniversityBozemanMTUSA
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12
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Li XY, Kokko H. Sexual dimorphism driven by intersexual resource competition: Why is it rare, and where to look for it? J Anim Ecol 2021; 90:1831-1843. [PMID: 33759459 PMCID: PMC8453853 DOI: 10.1111/1365-2656.13487] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/22/2021] [Indexed: 12/24/2022]
Abstract
Sexes often differ more obviously in secondary sexual characteristics than in traits that appear naturally selected, despite conceivable benefits to intersexual niche partitioning. Genetic constraints may play a role in limiting sex‐specific niche evolution; however, it is not clear why this limit should apply to naturally selected traits more than those under sexual selection; the latter routinely produces dimorphism. We ask whether ecological factors and/or features of the mating system limit dimorphism in resource use, or conversely, what conditions are the most permissible ones for sexual niche differences. The scale of mating competition and spatial variation in resource availability can help predict sexually dimorphic niches or the lack thereof. We investigate why and when dimorphism might fail to evolve even if genetic covariation between the sexes posed no constraint. Our analytical model incorporates the first aspect of spatial interactions (scale of mating competition). It is followed by simulations that explore broader conditions, including multiple resources with habitat heterogeneity, genetic correlations and non‐Gaussian resource‐use efficiency functions. We recover earlier known conditions for favourable conditions for the evolution of niche partitioning between sexes, such as narrow individual niche and low degrees of genetic constraint. We also show spatial considerations to alter this picture. Sexual niche divergence occurs more readily when local mating groups are small and different resources occur reliably across habitats. Polygyny (medium‐sized or large mating groups) can diminish the prospects for dimorphism even if no genetic constraints are present. Habitat heterogeneity typically also disfavours niche dimorphism but can also lead to polymorphism within a sex, if it is beneficial to specialize to be very competitive in one habitat, even at a cost to performance in the other. Sexual conflict is usually used to explain dimorphic traits or behaviours. Our models highlight that introducing conflict (achieved by switching from monogamy to polygamy) can also be responsible for sexual monomorphism. Under monogamy, males benefit from specializing to consume other resources than what feeds the female best. Polygyny makes males disregard this female benefit, and both sexes compete for the most profitable resource, leading to overlapping niches.
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Affiliation(s)
- Xiang-Yi Li
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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13
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Barsbai T, Lukas D, Pondorfer A. Local convergence of behavior across species. Science 2021; 371:292-295. [PMID: 33446557 DOI: 10.1126/science.abb7481] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 11/12/2020] [Indexed: 12/25/2022]
Abstract
Behavior is a way for organisms to respond flexibly to the environmental conditions they encounter. Our own species exhibits large behavioral flexibility and occurs in all terrestrial habitats, sharing these environments with many other species. It remains unclear to what extent a shared environment constrains behavior and whether these constraints apply similarly across species. Here, we show that foraging human populations and nonhuman mammal and bird species that live in a given environment exhibit high levels of similarity in their foraging, reproductive, and social behaviors. Our findings suggest that local conditions may select for similar behaviors in both humans and nonhuman animals.
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Affiliation(s)
- Toman Barsbai
- School of Economics, University of Bristol, Bristol, UK. .,Research Center International Development, Kiel Institute for the World Economy, Kiel, Germany
| | - Dieter Lukas
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
| | - Andreas Pondorfer
- Department of Economics, University of Bonn, Bonn, Germany. .,TUMCS for Biotechnology and Sustainability, Technical University of Munich, Munich, Germany
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14
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Richardson ES, Davis C, Stirling I, Derocher AE, Lunn NJ, Malenfant RM. Variance in lifetime reproductive success of male polar bears. Behav Ecol 2020. [DOI: 10.1093/beheco/araa074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Despite the important role that population density plays in ecological and evolutionary processes, studies of solitary species that occur at low densities remain scarce. In the context of mating systems, density is expected to influence the ability of males to find and monopolize mates, in turn, influencing variance in lifetime mating/reproductive success and the opportunity for selection. Herein, we investigate variance in male lifetime mating success (LMS), lifetime reproductive success (LRS), and the mating system of a sexually dimorphic carnivore that occurs at low densities, the polar bear (Ursus maritimus). Across 17 cohorts, born from 1975 to 1991, male LMS ranged from 0 to10 mates and LRS from 0 to 14 cubs; 40% of known-age males were not known to have reproduced. The opportunity for sexual selection (Is = 1.66, range = 0.60–4.99) and selection (I = 1.76, range: 0.65–4.89) were low compared to species with similar levels of sexual size dimorphism. Skew in male LRS was also low but significant for most cohorts indicating nonrandom reproductive success. Age-specific reproductive success was biased toward males from 11 to 17 years of age, with variation in fecundity (54%) but not longevity (10%) playing an important role in male reproduction. Our results support a growing body of evidence that suggests that male-biased size dimorphism and polygynous mating systems need not be associated with high variance in male mating and/or reproductive success.
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Affiliation(s)
- Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Winnipeg, Manitoba, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Corey Davis
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ian Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
| | - René M Malenfant
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
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15
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Determinants of genetic variation across eco-evolutionary scales in pinnipeds. Nat Ecol Evol 2020; 4:1095-1104. [PMID: 32514167 DOI: 10.1038/s41559-020-1215-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 04/28/2020] [Indexed: 11/09/2022]
Abstract
The effective size of a population (Ne), which determines its level of neutral variability, is a key evolutionary parameter. Ne can substantially depart from census sizes of present-day breeding populations (NC) as a result of past demographic changes, variation in life-history traits and selection at linked sites. Using genome-wide data we estimated the long-term coalescent Ne for 17 pinniped species represented by 36 population samples (total n = 458 individuals). Ne estimates ranged from 8,936 to 91,178, were highly consistent within (sub)species and showed a strong positive correlation with NC ([Formula: see text] = 0.59; P = 0.0002). Ne/NC ratios were low (mean, 0.31; median, 0.13) and co-varied strongly with demographic history and, to a lesser degree, with species' ecological and life-history variables such as breeding habitat. Residual variation in Ne/NC, after controlling for past demographic fluctuations, contained information about recent population size changes during the Anthropocene. Specifically, species of conservation concern typically had positive residuals indicative of a smaller contemporary NC than would be expected from their long-term Ne. This study highlights the value of comparative population genomic analyses for gauging the evolutionary processes governing genetic variation in natural populations, and provides a framework for identifying populations deserving closer conservation attention.
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16
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Jones KA, Wood H, Ashburner JP, Forcada J, Ratcliffe N, Votier SC, Staniland IJ. Risk exposure trade-offs in the ontogeny of sexual segregation in Antarctic fur seal pups. Behav Ecol 2020; 31:719-730. [PMID: 32595270 PMCID: PMC7303822 DOI: 10.1093/beheco/araa018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/31/2020] [Accepted: 02/26/2020] [Indexed: 11/21/2022] Open
Abstract
Sexual segregation has important ecological implications, but its initial development in early life stages is poorly understood. We investigated the roles of size dimorphism, social behavior, and predation risk on the ontogeny of sexual segregation in Antarctic fur seal, Arctocephalus gazella, pups at South Georgia. Beaches and water provide opportunities for pup social interaction and learning (through play and swimming) but increased risk of injury and death (from other seals, predatory birds, and harsh weather), whereas tussock grass provides shelter from these risks but less developmental opportunities. One hundred pups were sexed and weighed, 50 on the beach and 50 in tussock grass, in January, February, and March annually from 1989 to 2018. Additionally, 19 male and 16 female pups were GPS-tracked during lactation from December 2012. Analysis of pup counts and habitat use of GPS-tracked pups suggested that females had a slightly higher association with tussock grass habitats and males with beach habitats. GPS-tracked pups traveled progressively further at sea as they developed, and males traveled further than females toward the end of lactation. These sex differences may reflect contrasting drivers of pup behavior: males being more risk prone to gain social skills and lean muscle mass and females being more risk averse to improve chances of survival, ultimately driven by their different reproductive roles. We conclude that sex differences in habitat use can develop in a highly polygynous species prior to the onset of major sexual size dimorphism, which hints that these sex differences will increasingly diverge in later life.
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Affiliation(s)
- Kayleigh A Jones
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
- College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, UK
| | - Hannah Wood
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
| | - Jonathan P Ashburner
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
| | - Jaume Forcada
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
| | - Norman Ratcliffe
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
| | - Stephen C Votier
- College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, UK
| | - Iain J Staniland
- Ecosystems Team, British Antarctic Survey, High Cross, Madingley road, Cambridge, UK
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17
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Affiliation(s)
- Marcelo H. Cassini
- Laboratorio de Biología del Comportamiento IBYME‐CONICET Obligado 25901429Buenos Aires Argentina
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18
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Abstract
Abstract
Sexual size dimorphism is biased toward males in most mammalian species. The most common explanation is precopulatory intramale sexual selection. Large males win fights and mate more frequently. In artiodactyls, previous tests of this hypothesis consisted of interspecific correlations of sexual dimorphism with group size as a surrogate for the intensity of sexual selection (Is). However, group size is not a proper measure of sexual selection for several reasons as is largely recognized in other mammalian taxa. I conducted an interspecific test on the role of sexual selection in the evolution of sexual dimorphism using the variance in genetic paternity as a proxy for the Is. I reviewed the literature and found 17 studies that allowed estimating Is= V/(W2), where V and W are the variance and mean number of offspring per male, respectively. A phylogenetic generalized least squares analysis indicated that dimorphism (Wm/Wf) showed a significant positive regression with the intensity of sexual selection but not group size (multiple r2= 0.40; F3,17= 12.78, P = 0.002). This result suggests that sexual selection may have played a role in the evolution of sexual size dimorphism in Artiodactyla. An alternative hypothesis based on natural selection is discussed.
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Affiliation(s)
- Marcelo H Cassini
- Laboratorio de Biología del Comportamiento, IBYME, CONICET, Obligado, Buenos Aires, Argentina
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19
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Huck M, Di Fiore A, Fernandez-Duque E. Of Apples and Oranges? The Evolution of “Monogamy” in Non-human Primates. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2019.00472] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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20
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Cassini MH. A mixed model of the evolution of polygyny and sexual size dimorphism in mammals. Mamm Rev 2019. [DOI: 10.1111/mam.12171] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marcelo H. Cassini
- Laboratorio de Biología del Comportamiento IBYME CONICET Obligado 2490, 1429 Buenos Aires Argentina
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21
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Solitary meat-eaters: solitary, carnivorous carnivorans exhibit the highest degree of sexual size dimorphism. Sci Rep 2019; 9:15344. [PMID: 31653949 PMCID: PMC6814822 DOI: 10.1038/s41598-019-51943-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/09/2019] [Indexed: 12/15/2022] Open
Abstract
Although sexual size dimorphism (SSD) is widespread across the animal tree of life, the underlying evolutionary processes that influence this phenomenon remains elusive and difficult to tease apart. In this study, I examined how social system (as a proxy for sexual selection) and diet (as a proxy for natural selection) influenced the evolution of SSD in terrestrial carnivorans (Carnivora; Mammalia). Using phylogenetic comparative methods, I found that are territorial solitary and carnivorous carnivorans exhibited selection towards increased degree of male-biased SSD compared to other carnivorans with alternative social systems and diets. I also found the absence of Rensch’s rule across most carnivoran clades, suggestion a relaxation of the influences of sexual selection on SSD. These results together suggest that sexual selection and niche divergence together are important processes influencing the evolution of male-biased SSD in extant terrestrial carnivorans.
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22
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Litzke V, Ottensmann M, Forcada J, Heitzmann L, Ivan Hoffman J. Heterozygosity at neutral and immune loci is not associated with neonatal mortality due to microbial infection in Antarctic fur seals. Ecol Evol 2019; 9:7985-7996. [PMID: 31380066 PMCID: PMC6662382 DOI: 10.1002/ece3.5317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/02/2019] [Accepted: 05/08/2019] [Indexed: 11/08/2022] Open
Abstract
Numerous studies have reported correlations between the heterozygosity of genetic markers and fitness. These heterozygosity-fitness correlations (HFCs) play a central role in evolutionary and conservation biology, yet their mechanistic basis remains open to debate. For example, fitness associations have been widely reported at both neutral and functional loci, yet few studies have directly compared the two, making it difficult to gauge the relative contributions of genome-wide inbreeding and specific functional genes to fitness. Here, we compared the effects of neutral and immune gene heterozygosity on death from bacterial infection in Antarctic fur seal (Arctocephalus gazella) pups. We specifically developed a panel of 13 microsatellites from expressed immune genes and genotyped these together with 48 neutral loci in 234 individuals, comprising 39 pups that were classified at necropsy as having most likely died of bacterial infection together with a five times larger matched sample of healthy surviving pups. Identity disequilibrium quantified from the neutral markers was positive and significant, indicative of variance in inbreeding within the study population. However, multilocus heterozygosity did not differ significantly between healthy and infected pups at either class of marker, and little evidence was found for fitness associations at individual loci. These results support a previous study of Antarctic fur seals that found no effects of heterozygosity at nine neutral microsatellites on neonatal survival and thereby help to refine our understanding of how HFCs vary across the life cycle. Given that nonsignificant HFCs are underreported in the literature, we also hope that our study will contribute toward a more balanced understanding of the wider importance of this phenomenon.
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Affiliation(s)
- Vivienne Litzke
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
| | | | | | | | - Joseph Ivan Hoffman
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
- British Antarctic Survey, High CrossCambridgeUK
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23
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Kalberer S, DeRango E, Trillmich F, Krüger O. Evolution of age at primiparity in pinnipeds in the absence of the quality-quantity trade-off in reproduction. Ecol Evol 2019; 9:5450-5456. [PMID: 31110693 PMCID: PMC6509388 DOI: 10.1002/ece3.5138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 03/01/2019] [Accepted: 03/13/2019] [Indexed: 12/05/2022] Open
Abstract
Age at primiparity (AP) is a key life history trait which is crucial to the evolution of life history strategies. This trait is particularly interesting in pinnipeds (walrus, eared seals, and true seals), which are monotocous animals. Thus, the commonly observed trade-off between offspring quality and quantity does not apply to this taxon. Therefore, comparative studies on the evolution of AP might shed light on other important evolutionary correlates when litter size is fixed. Using phylogenetic generalized least squares analyses, we found a strong negative and robust correlation between relative birth mass (mean pup birth mass as a proportion of mean adult female mass) and AP. Rather than trading-off an early start of reproduction with light relative offspring mass, this result suggests that pinnipeds exhibit either faster (i.e., higher relative offspring mass leading to shorter lactation length, and thus shorter interbirth interval) or slower life histories and that an early AP and a heavy relative offspring mass co-evolved into a comparatively fast life history strategy. On the other hand, AP was positively related to lactation length: A later start of reproduction was associated with a longer lactation length. Consequently, variation in AP in pinnipeds seems to be affected by an interplay between costs and benefits of early reproduction mediated by relative investment into the single offspring via relative birth mass and lactation length.
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Affiliation(s)
| | - Eugene DeRango
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
| | - Fritz Trillmich
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
| | - Oliver Krüger
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
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24
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Kienle SS, Cacanindin A, Kendall T, Richter B, Ribeiro-French C, Castle L, Lentes G, Costa DP, Mehta RS. Hawaiian monk seals exhibit behavioral flexibility when targeting prey of different size and shape. ACTA ACUST UNITED AC 2019; 222:jeb.194985. [PMID: 30679244 DOI: 10.1242/jeb.194985] [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: 10/24/2018] [Accepted: 01/17/2019] [Indexed: 11/20/2022]
Abstract
Animals use diverse feeding strategies to capture and consume prey, with many species switching between strategies to accommodate different prey. Many marine animals exhibit behavioral flexibility when feeding to deal with spatial and temporal heterogeneity in prey resources. However, little is known about flexibility in the feeding behavior of many large marine predators. Here, we documented the feeding behavior and kinematics of the endangered Hawaiian monk seal (Neomonachus schauinslandi, n=7) through controlled feeding trials. Seals were fed multiple prey types (e.g. night smelt, capelin, squid and herring) that varied in size and shape to examine behavioral flexibility in feeding. Hawaiian monk seals primarily used suction feeding (91% of all feeding trials) across all prey types, but biting, specifically pierce feeding, was also observed (9% of all feeding trials). Suction feeding was characterized by shorter temporal events, a smaller maximum gape and gape angle, and a fewer number of jaw motions than pierce feeding; suction feeding kinematic performance was also more variable compared with pierce feeding. Seals showed behavioral flexibility in their use of the two strategies. Suction feeding was used most frequently when targeting small to medium sized prey and biting was used with increasing frequency on larger prey. The feeding kinematics differed between feeding strategies and prey types, showing that Hawaiian monk seals adjusted their behaviors to particular feeding contexts. Hawaiian monk seals are opportunistic marine predators and their ability to adapt their feeding strategy and behavior to specific foraging scenarios allows them to target diverse prey resources.
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Affiliation(s)
- Sarah S Kienle
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| | - Aliya Cacanindin
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| | - Traci Kendall
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| | - Beau Richter
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| | - Courtney Ribeiro-French
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA.,Monterey Bay Aquarium, Monterey, CA 93940, USA
| | - Leann Castle
- University of Hawai'i at Manoa, Waikiki Aquarium, Honolulu, HI 96815, USA
| | - Gwen Lentes
- University of Hawai'i at Manoa, Waikiki Aquarium, Honolulu, HI 96815, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| | - Rita S Mehta
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
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25
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Salogni E, Galimberti F, Sanvito S, Miller E. Male and female pups of the highly sexually dimorphic northern elephant seal (Mirounga angustirostris) differ slightly in body size. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In mammals, males generally are larger than females, though such sexual-size differences have been documented primarily in adults and are relatively poorly known in early life. We studied sexual-size differences in pups of the northern elephant seal (Mirounga angustirostris (Gill, 1866)), which in adulthood is one of the most sexually dimorphic mammals. We studied body size at birth and weaning, at Islas San Benito, Mexico, at the southernmost limit of the species’ breeding range. Males were 10% heavier and 2% longer than females at birth. Sexes did not differ significantly in either measure of body size at weaning, although males were slightly heavier (4%) and longer (1%) than females. Neither growth rate nor suckling duration differed between the sexes. In previous studies in California, USA, pups at weaning were heavier than in our study, and males were heavier than females. These differences may reflect ecological, temporal, or life-history differences across populations. The modest difference in sexual-size dimorphism early in life in this species compared with the great difference in adulthood likely reflects multiple selective forces, including constraints on neonatal size set by body size of females, and the weakness of sexual selection at that stage of life.
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Affiliation(s)
- E. Salogni
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL A1B 3X9, Canada
- Elephant Seal Research Group, Sea Lion Island, Falkland Islands, FIQQ 1ZZ
| | - F. Galimberti
- Elephant Seal Research Group, Sea Lion Island, Falkland Islands, FIQQ 1ZZ
| | - S. Sanvito
- Elephant Seal Research Group, Sea Lion Island, Falkland Islands, FIQQ 1ZZ
| | - E.H. Miller
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL A1B 3X9, Canada
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26
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Kappeler PM, Nunn CL, Vining AQ, Goodman SM. Evolutionary dynamics of sexual size dimorphism in non-volant mammals following their independent colonization of Madagascar. Sci Rep 2019; 9:1454. [PMID: 30723219 PMCID: PMC6363729 DOI: 10.1038/s41598-018-36246-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 11/15/2018] [Indexed: 01/16/2023] Open
Abstract
As predicted by sexual selection theory, males are larger than females in most polygynous mammals, but recent studies found that ecology and life history traits also affect sexual size dimorphism (SSD) through evolutionary changes in either male size, female size, or both. The primates of Madagascar (Lemuriformes) represent the largest group of mammals without male-biased SSD. The eco-evo-devo hypothesis posited that adaptations to unusual climatic unpredictability on Madagascar have ultimately reduced SSD in lemurs after dispersing to Madagascar, but data have not been available for comparative tests of the corresponding predictions that SSD is also absent in other terrestrial Malagasy mammals and that patterns of SSD changed following the colonization of Madagascar. We used phylogenetic methods and new body mass data to test these predictions among the four endemic radiations of Malagasy primates, carnivorans, tenrecs, and rodents. In support of our prediction, we found that male-biased SSD is generally absent among all Malagasy mammals. Phylogenetic comparative analyses further indicated that after their independent colonization of Madagascar, SSD decreased in primates and tenrecs, but not in the other lineages or when analyzed across all species. We discuss several mechanisms that may have generated these patterns and conclude that neither the eco-evo-devo hypothesis, founder effects, the island rule nor sexual selection theory alone can provide a compelling explanation for the observed patterns of SSD in Malagasy mammals.
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Affiliation(s)
- Peter M Kappeler
- Wissenschaftskolleg zu Berlin, Berlin, Germany.
- Behavioral Ecology and Sociobiology Unit, German Primate Center - Leibniz Institute of Primatology, Göttingen, Germany.
- Department Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany.
| | - Charles L Nunn
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Alexander Q Vining
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
| | - Steven M Goodman
- Field Museum of Natural History, Chicago, IL, USA
- Association Vahatra, Antananarivo, Madagascar
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27
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Stoffel MA, Humble E, Paijmans AJ, Acevedo-Whitehouse K, Chilvers BL, Dickerson B, Galimberti F, Gemmell NJ, Goldsworthy SD, Nichols HJ, Krüger O, Negro S, Osborne A, Pastor T, Robertson BC, Sanvito S, Schultz JK, Shafer ABA, Wolf JBW, Hoffman JI. Demographic histories and genetic diversity across pinnipeds are shaped by human exploitation, ecology and life-history. Nat Commun 2018; 9:4836. [PMID: 30446730 PMCID: PMC6240053 DOI: 10.1038/s41467-018-06695-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 09/18/2018] [Indexed: 12/22/2022] Open
Abstract
A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and population viability. In an era of biodiversity loss and climate change, understanding the determinants and consequences of bottlenecks is therefore an important challenge. However, as most studies focus on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we combined genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to evaluate the consequences of commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong signatures of recent population declines. Bottleneck strength is associated with breeding habitat and mating system variation, and together with global abundance explains much of the variation in genetic diversity across species. Overall, bottleneck intensity is unrelated to IUCN status, although the three most heavily bottlenecked species are endangered. Our study reveals an unforeseen interplay between human exploitation, animal biology, demographic declines and genetic diversity. Historical hunting has caused documented declines in pinnipeds, but the extent to which hunting caused genetic bottlenecks among species was unknown. Here, the authors show evidence of severe bottlenecks in several pinniped species, particularly those that breed on land.
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Affiliation(s)
- M A Stoffel
- Department of Animal Behaviour, Bielefeld University, Postfach 100131, 33501, Bielefeld, Germany.,School of Natural Sciences and Psychology, Faculty of Science, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - E Humble
- Department of Animal Behaviour, Bielefeld University, Postfach 100131, 33501, Bielefeld, Germany.,British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - A J Paijmans
- Department of Animal Behaviour, Bielefeld University, Postfach 100131, 33501, Bielefeld, Germany
| | - K Acevedo-Whitehouse
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Avenida de las Ciencias S/N, Queretaro, 76230, Mexico
| | - B L Chilvers
- Wildbase, Institute of Veterinary, Animal and Biomedical Science, Massey University, Private Bag 11222, Palmerston North, 4442, New Zealand
| | - B Dickerson
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, 98115, WA, USA
| | - F Galimberti
- Elephant Seal Research Group, Sea Lion Island, FIQQ 1ZZ, Falkland Islands
| | - N J Gemmell
- Department of Anatomy, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - S D Goldsworthy
- South Australian Research and Development Institute, West Beach, SA, 5024, Australia
| | - H J Nichols
- School of Natural Sciences and Psychology, Faculty of Science, Liverpool John Moores University, Liverpool, L3 3AF, UK.,Department of Animal Behaviour Bielefeld University, Postfach 100131 33501, Bielefeld, Germany.,Department of Biosciences, Swansea University, Swansea, SA2 8PP, UK
| | - O Krüger
- Department of Animal Behaviour, Bielefeld University, Postfach 100131, 33501, Bielefeld, Germany
| | - S Negro
- UMR de Génétique Quantitative et Évolution - Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Gif-sur-Yvette, 91190, France.,GIGA-R, Medical Genomics - BIO3, Université of Liège, Liège, 4000, Belgium
| | - A Osborne
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand, 8140
| | - T Pastor
- EUROPARC Federation, Carretera de l'Església, 92, 08017, Barcelona, Spain
| | - B C Robertson
- Department of Zoology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - S Sanvito
- Elephant Seal Research Group, Sea Lion Island, FIQQ 1ZZ, Falkland Islands
| | - J K Schultz
- National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East West Highway, Silver Spring, MD, 20910, USA
| | - A B A Shafer
- Forensic Science & Environmental Life Sciences, Trent University, Peterborough, ON, Canada, K9J 7B8
| | - J B W Wolf
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinstried, Munich, 82152, Germany.,Science of Life Laboratory and Department of Evolutionary Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - J I Hoffman
- Department of Animal Behaviour, Bielefeld University, Postfach 100131, 33501, Bielefeld, Germany. .,British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK.
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28
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Keevil M, Hewitt B, Brooks R, Litzgus J. Patterns of intraspecific aggression inferred from injuries in an aquatic turtle with male-biased size dimorphism. CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0182] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Patterns of sexual size dimorphism (SSD) in turtles are correlated with ecological mode, and it has been hypothesized that mating systems are also shaped by ecological mode. Male combat and coercive mating are competing explanations for male-biased SSD, but are difficult to assess empirically in aquatic species with cryptic behaviour. We quantified SSD and compiled observations of putative combat wounds collected from over 500 captures of Snapping Turtles (Chelydra serpentina (L., 1758)) in Algonquin Provincial Park, Ontario, to test hypotheses of mate competition and coercion. We found that both sex and body size were important predictors of risk of wounding, consistent with the hypothesis that male–male sexual competition is the primary driver of intraspecific aggression. Low wounding rates among females suggests that resource competition and coercive mating are not important causes of injuries. The risk of wounding increased monotonically with body size in adult males but not in adult females, and small males were less likely to be injured, suggesting that they employ a risk-averse strategy by avoiding direct competition for mates. There was no evidence of asymptotic or decreasing wounding probability in the largest males, which is consistent with the hypothesis that large males compete most intensively to monopolize mates.
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Affiliation(s)
- M.G. Keevil
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada
| | - B.S. Hewitt
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada
| | - R.J. Brooks
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - J.D. Litzgus
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada
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Disentangling the Correlated Evolution of Monogamy and Cooperation. Trends Ecol Evol 2016; 31:503-513. [DOI: 10.1016/j.tree.2016.03.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 11/17/2022]
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Hiadlovská Z, Mikula O, Macholán M, Hamplová P, Vošlajerová Bímová B, Daniszová K. Shaking the myth: Body mass, aggression, steroid hormones, and social dominance in wild house mouse. Gen Comp Endocrinol 2015; 223:16-26. [PMID: 26433061 DOI: 10.1016/j.ygcen.2015.09.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/19/2015] [Accepted: 09/29/2015] [Indexed: 10/23/2022]
Abstract
In social mammals, the position of a male in the group's hierarchy strongly affects his reproductive success. Since a high social rank is often gained through competition with other males, selection should favour bigger males over smaller ones. We may therefore predict faster growth and/or delayed sexual maturity in dominant males. Likewise, dominants should have higher levels of testosterone, hormone important in many aspects of male dominance. Less obvious is the relationship between dominance and levels of corticosterone but generally higher concentrations are expected in subordinate individuals. We studied body growth, sexual maturation and endocrinal changes in males of two house mouse subspecies, raised in fraternal pairs. Since Mus musculus domesticus is the subspecies which dominates mutual encounters with Mus musculus musculus we predicted higher growth rate, delayed puberty and aggression, and higher testosterone and corticosterone levels in domesticus males compared to musculus. In all comparisons, no differences were found between dominant and subordinate musculus brothers. On the other hand, in M. m. domesticus, dominant males revealed a different growth trajectory and lower corticosterone levels than subordinate males but not delayed puberty and higher testosterone concentrations, thus contradicting our predictions. In inter-subspecific comparisons, musculus males matured earlier but became aggressive at the same time as domesticus males. The musculus testosterone ontogeny suggests that social positions in this subspecies remain unfixed for an extended period and that the increasing levels probably reflect prolonged hierarchy contests. It appears that the ontogeny of behaviour and physiological traits diverge cryptically between the two subspecies.
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Affiliation(s)
- Z Hiadlovská
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic.
| | - O Mikula
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic
| | - M Macholán
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic; Institute of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - P Hamplová
- Institute of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - B Vošlajerová Bímová
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic; Institute of Vertebrate Biology, ASCR, Květná 8, CZ-603 65 Brno, Czech Republic
| | - K Daniszová
- Institute of Vertebrate Biology, ASCR, Květná 8, CZ-603 65 Brno, Czech Republic; Biodiversity Research Group, Department of Zoology, Faculty of Science, Charles University, 13 Viničná 7, CZ-128 44 Prague, Czech Republic
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Kappeler PM, Fichtel C. Eco-evo-devo of the lemur syndrome: did adaptive behavioral plasticity get canalized in a large primate radiation? Front Zool 2015; 12 Suppl 1:S15. [PMID: 26816515 PMCID: PMC4722368 DOI: 10.1186/1742-9994-12-s1-s15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Comprehensive explanations of behavioral adaptations rarely invoke all levels famously admonished by Niko Tinbergen. The role of developmental processes and plasticity, in particular, has often been neglected. In this paper, we combine ecological, physiological and developmental perspectives in developing a hypothesis to account for the evolution of 'the lemur syndrome', a combination of reduced sexual dimorphism, even adult sex ratios, female dominance and mild genital masculinization characterizing group-living species in two families of Malagasy primates. RESULTS We review the different components of the lemur syndrome and compare it with similar adaptations reported for other mammals. We find support for the assertion that the lemur syndrome represents a unique set of integrated behavioral, demographic and morphological traits. We combine existing hypotheses about underlying adaptive function and proximate causation by adding a potential developmental mechanism linking maternal stress and filial masculinization, and outline an evolutionary scenario for its canalization. CONCLUSIONS We propose a new hypothesis linking ecological, physiological, developmental and evolutionary processes to adumbrate a comprehensive explanation for the evolution of the lemur syndrome, whose assumptions and predictions can guide diverse future research on lemurs. This hypothesis should also encourage students of other behavioral phenomena to consider the potential role of developmental plasticity in evolutionary innovation.
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Affiliation(s)
- Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | - Claudia Fichtel
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
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Rioux-Paquette E, Garant D, Martin AM, Coulson G, Festa-Bianchet M. Paternity in eastern grey kangaroos: moderate skew despite strong sexual dimorphism. Behav Ecol 2015. [DOI: 10.1093/beheco/arv052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Piedrahita P, Meise K, Werner C, Krüger O, Trillmich F. Lazy sons, self-sufficient daughters: are sons more demanding? Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.09.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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