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Padilla Perez DJ, DeNardo DF, Angilletta Jr MJ. The correlated evolution of foraging mode and reproductive effort in lizards. Proc Biol Sci 2022; 289:20220180. [PMID: 35673871 PMCID: PMC9174732 DOI: 10.1098/rspb.2022.0180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Life-history theory suggests that the optimal reproductive effort of an organism is affected by factors such as energy acquisition and predation risk. The observation that some organisms actively search for their prey and others ambush them creates the expectation of different energy needs and predation risk associated with each foraging behaviour, the so-called 'foraging-mode paradigm'. Although this paradigm has been around for decades, the empirical evidence consists of conflicting results derived from competing models based on different mechanisms. For instance, models within the foraging-mode paradigm suggest that widely foraging females have evolved low reproductive effort, because a heavy reproductive load decreases their ability to escape from predators. By contrast, a long-standing prediction of evolutionary theory indicates that organisms subject to high extrinsic mortality, should invest more in reproduction. Here, we present the first partial evidence that widely foraging species have evolved greater reproductive effort than have sit-and-wait species, which we attribute to a larger body size and greater mortality among mobile foragers. According to our findings, we propose a theoretical model that could explain the observed pattern in lizards, suggesting ways for evolutionary ecologists to test mechanistic hypotheses at the intraspecific level.
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Affiliation(s)
| | - Dale F. DeNardo
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Padilla Perez DJ, Angilletta MJ. Macroclimatic and maternal effects on the evolution of reproductive traits in lizards. Ecol Evol 2022; 12:e8885. [PMID: 35509612 PMCID: PMC9058792 DOI: 10.1002/ece3.8885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 04/15/2022] [Indexed: 11/17/2022] Open
Abstract
Much of life-history theory rests on fundamental assumptions about constraints on the acquisition and allocation of energy to growth and reproduction. In general, the allocation of energy to reproduction depends on maternal size, which in turn depends on environmental factors experienced throughout the life of the mother. Here, we used phylogenetic path analyses to evaluate competing hypotheses about the environmental and maternal drivers of reproductive traits in lizards. In doing so, we discovered that precipitation, rather than temperature, has shaped the evolution of the life history. Specifically, environments with greater rainfall have enabled the evolution of larger maternal size. In turn, these larger mothers produce larger clutches of larger offspring. However, annual precipitation has a negative direct effect on offspring size, despite the positive indirect effect mediated by maternal size. Possibly, the evolution of offspring size was driven by the need to conserve water in dry environments, because small organisms are particularly sensitive to water loss. Since we found that body size variation among lizards is related to a combination of climatic factors, mainly precipitation and perhaps primary production, our study challenges previous generalizations (e.g., temperature-size rule and Bergmann's rule) and suggests alternative mechanisms underlying the evolution of body size.
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Bansal U, Thaker M. Diet influences latitudinal gradients in life-history traits, but not reproductive output, in ectotherms. GLOBAL ECOLOGY AND BIOGEOGRAPHY : A JOURNAL OF MACROECOLOGY 2021; 30:2431-2441. [PMID: 38560415 PMCID: PMC7615780 DOI: 10.1111/geb.13396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 08/23/2021] [Indexed: 04/04/2024]
Abstract
Aim Latitudinal gradients in life-history traits are apparent in many taxa and are expected to be strong for ectotherms that have temperature-driven constraints on performance and fitness. The strength of these gradients, however, should also be affected by diet. Because diet type (carnivory, omnivory, herbivory) influences accessibility to nutrition and assimilation efficiency, we aim to study how diet affects latitudinal gradients in lifetime reproductive output and the underlying life-history traits in ectotherms. Location Global. Time period Recent. Major taxa studied Lizards (Reptilia, Squamata, Sauria). Methods We used empirical (352 species) and phylogenetically imputed data (563 species) to analyse the interactive effects of latitude and diet on life-history traits (longevity, age at maturity, reproductive life span, hatchling mass, clutch/brood size, clutch/brood frequency, female mass) and lifetime reproductive output of lizards. Results Lifetime reproductive output does not significantly differ in lizards across diet types, and only carnivores exhibit a small increase at higher latitudes. Diet type, however, influences latitudinal patterns of individual life-history traits. Carnivores exhibit a shift towards 'slower-paced' life histories at higher latitudes for most traits (increased longevity, age at maturity, reproductive life span, and decreased clutch frequency). By contrast, herbivores either display 'faster-paced' life histories (reduction in reproductive life span, hatchling mass, female mass) or no change (clutch frequency, clutch size, age at maturity) at higher latitudes. Omnivores exhibit intermediate and muted latitudinal patterns. Main conclusions We suggest that the nutritional challenges of herbivory, compounded by thermal constraints at higher latitudes, may explain differences in life-history characteristics of herbivorous ectotherms. Intermediate patterns exhibited by omnivores highlight how flexibility in diet can buffer environmental challenges at higher latitudes. Our results indicate that lizards with different diet types display various trends in their life histories across latitudes, which eventually balance out to result in similar reproductive outputs throughout their lifetime, with little benefits to carnivory.
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Affiliation(s)
- Udita Bansal
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
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Bock SL, Hale MD, Rainwater TR, Wilkinson PM, Parrott BB. Incubation Temperature and Maternal Resource Provisioning, but Not Contaminant Exposure, Shape Hatchling Phenotypes in a Species with Temperature-Dependent Sex Determination. THE BIOLOGICAL BULLETIN 2021; 241:43-54. [PMID: 34436964 DOI: 10.1086/714572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
AbstractThe environment experienced during embryonic development is a rich source of phenotypic variation, as environmental signals have the potential to both inform adaptive plastic responses and disrupt normal developmental programs. Environment-by-embryo interactions are particularly consequential for species with temperature-dependent sex determination, a mode of sex determination common in non-avian reptiles and fish, in which thermal cues during a discrete period of development drive the formation of either an ovary or a testis. Here we examine the impact of thermal variation during incubation in combination with developmental exposure to a common endocrine-disrupting contaminant on fitness-related hatchling traits in the American alligator (Alligator mississippiensis), a species with temperature-dependent sex determination. Using a factorial design, we exposed field-collected eggs to five thermal profiles (three constant temperatures, two fluctuating temperatures) and two environmentally relevant doses of the pesticide metabolite dichlorodiphenyldichloroethylene; and we quantified incubation duration, sex ratios, hatchling morphometric traits, and growth (9-10 days post-hatch). Whereas dichlorodiphenyldichloroethylene exposure did not generally affect hatchling traits, constant and fluctuating temperatures produced diverse phenotypic effects. Thermal fluctuations led to subtle changes in incubation duration and produced shorter hatchlings with smaller heads when compared to the constant temperature control. Warmer, male-promoting incubation temperatures resulted in larger hatchlings with more residual yolk reserves when compared to cooler, female-promoting temperatures. Together, these findings advance our understanding of how complex environmental factors interact with developing organisms to generate phenotypic variation and raise questions regarding the mechanisms connecting variable thermal conditions to responses in hatchling traits and their evolutionary implications for temperature-dependent sex determination.
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Liang T, Meiri S, Shi L. Sexual size dimorphism in lizards: Rensch's rule, reproductive mode, clutch size, and line fitting method effects. Integr Zool 2021; 17:787-803. [PMID: 34216109 DOI: 10.1111/1749-4877.12569] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rensch's rule relates to a pattern whereby sexual size dimorphism is more female-biased in small-sized species and more male-biased in large-sized ones. We collected literature and museum data on the body size of males and females belonging to 4032 lizard species, as well as data on their reproductive modes and clutch sizes. We used phylogenetic comparative analyses, and general linear mixed models, to test Rensch's rule and examined how reproductive mode and clutch size affect sexual size dimorphism. Sexual size dimorphism was independent of clutch size in lizard species with variable clutch sizes and in oviparous lizards. Large litters were associated with female-biased sexual dimorphism in viviparous and in scincomorph lizards. Inference regarding Rensch's rule depended on the analytical method used to identify it. The widely used, but less conservative, reduced major axis regression usually support Rensch's rule while ordinary least squares regressions mostly show isometric relationships. The rule tended to apply more to oviparous than to viviparous lizards. We infer that Rensch's rule is, at best, a weak pattern in lizards. This is especially true in viviparous lineages where females reproduce infrequently and therefore evolve large sizes to maximise fecundity, resulting in female-biased dimorphism.
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Affiliation(s)
- Tao Liang
- College of Animal Science, Xinjiang Agricultural University, Urumqi, Xinjiang, China.,College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu, China
| | - Shai Meiri
- School of Zoology & the Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel
| | - Lei Shi
- College of Animal Science, Xinjiang Agricultural University, Urumqi, Xinjiang, China
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Doan TM, Sheffer SA, Warmington NR, Evans EE. Population biology of the unusual thermoconforming lizards of the Andes Mountains of Peru (Squamata: Gymnophthalmidae). AUSTRAL ECOL 2021. [DOI: 10.1111/aec.13036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tiffany M. Doan
- Division of Natural Sciences New College of Florida 5800 Bay Shore Road Sarasota FL 34243 USA
| | - Sara A. Sheffer
- Division of Natural Sciences New College of Florida 5800 Bay Shore Road Sarasota FL 34243 USA
| | - Nicholas R. Warmington
- Division of Natural Sciences New College of Florida 5800 Bay Shore Road Sarasota FL 34243 USA
| | - Eliot E. Evans
- Division of Natural Sciences New College of Florida 5800 Bay Shore Road Sarasota FL 34243 USA
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Sakai O. One or two eggs: what underlies clutch size variation within a gecko species? ZOOLOGY 2021; 146:125911. [PMID: 33711783 DOI: 10.1016/j.zool.2021.125911] [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: 09/26/2020] [Revised: 02/25/2021] [Accepted: 02/28/2021] [Indexed: 12/01/2022]
Abstract
Although the majority of reptiles show variable clutch sizes, geckos have a fixed clutch size (one or two eggs) and modify reproductive output by changing the offspring size or clutch frequency. However, the clutch size of several geckos is not strictly fixed at the species level; they actually lay both single- and double-egg clutches. We still do not fully understand if clutch size variation within a gecko species is due to adaptive control or reproductive failure like accidental absorption of one of two eggs. This study investigated differences between single- and double-egg clutches of a gecko species in terms of reproductive frequency, egg size, and offspring trait. I housed mourning geckos Lepidodactylus lugubris in a controlled environment and observed their reproduction for seven years. No large differences between single- and double-egg clutches were detected in reproductive frequency and egg size, indicating that life-history trade-offs do not explain much about clutch size variation. Single-egg was comparable in egg size to double-egg, but hatchlings from single-egg showed significantly lower body condition than did those from double-egg. These results suggest that the single-egg is not only a reduction of reproductive output per clutch, but it may provide negative effect on ontogeny.
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Affiliation(s)
- Osamu Sakai
- Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake, Sakyo, Kyoto, 606-8502, Japan.
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Meiri S, Murali G, Zimin A, Shak L, Itescu Y, Caetano G, Roll U. Different solutions lead to similar life history traits across the great divides of the amniote tree of life. ACTA ACUST UNITED AC 2021; 28:3. [PMID: 33557958 PMCID: PMC7869468 DOI: 10.1186/s40709-021-00134-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/15/2021] [Indexed: 02/07/2023]
Abstract
Amniote vertebrates share a suite of extra-embryonic membranes that distinguish them from anamniotes. Other than that, however, their reproductive characteristics could not be more different. They differ in basic ectothermic vs endothermic physiology, in that two clades evolved powered flight, and one clade evolved a protective shell. In terms of reproductive strategies, some produce eggs and others give birth to live young, at various degrees of development. Crucially, endotherms provide lengthy parental care, including thermal and food provisioning—whereas ectotherms seldom do. These differences could be expected to manifest themselves in major differences between clades in quantitative reproductive traits. We review the reproductive characteristics, and the distributions of brood sizes, breeding frequencies, offspring sizes and their derivatives (yearly fecundity and biomass production rates) of the four major amniote clades (mammals, birds, turtles and squamates), and several major subclades (birds: Palaeognathae, Galloanserae, Neoaves; mammals: Metatheria and Eutheria). While there are differences between these clades in some of these traits, they generally show similar ranges, distribution shapes and central tendencies across birds, placental mammals and squamates. Marsupials and turtles, however, differ in having smaller offspring, a strategy which subsequently influences other traits.
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Affiliation(s)
- Shai Meiri
- School of Zoology, Tel Aviv University, 6997801, Tel Aviv, Israel. .,The Steinhardt Museum of Natural History, Tel Aviv University, 6997801, Tel Aviv, Israel.
| | - Gopal Murali
- Mitrani Department of Desert Ecology, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion, Israel
| | - Anna Zimin
- School of Zoology, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Lior Shak
- School of Zoology, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Yuval Itescu
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), 12587, Berlin, Germany.,Institute of Biology, Freie Universität Berlin, 14195, Berlin, Germany
| | - Gabriel Caetano
- Mitrani Department of Desert Ecology, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion, Israel
| | - Uri Roll
- Mitrani Department of Desert Ecology, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Midreshet Ben Gurion, Israel
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10
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Legendre LJ, Rubilar-Rogers D, Musser GM, Davis SN, Otero RA, Vargas AO, Clarke JA. A giant soft-shelled egg from the Late Cretaceous of Antarctica. Nature 2020; 583:411-414. [DOI: 10.1038/s41586-020-2377-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/19/2020] [Indexed: 11/09/2022]
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Hallmann K, Griebeler EM. An identification of invariants in life history traits of amphibians and reptiles. Ecol Evol 2020; 10:1233-1251. [PMID: 32076510 PMCID: PMC7029084 DOI: 10.1002/ece3.5978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 12/01/2019] [Accepted: 12/06/2019] [Indexed: 11/11/2022] Open
Abstract
While many morphological, physiological, and ecological characteristics of organisms scale with body size, some do not change under size transformation. They are called invariant. A recent study recommended five criteria for identifying invariant traits. These are based on that a trait exhibits a unimodal central tendency and varies over a limited range with body mass (type I), or that it does not vary systematically with body mass (type II). We methodologically improved these criteria and then applied them to life history traits of amphibians, Anura, Caudata (eleven traits), and reptiles (eight traits). The numbers of invariant traits identified by criteria differed across amphibian orders and between amphibians and reptiles. Reproductive output (maximum number of reproductive events per year), incubation time, length of larval period, and metamorphosis size were type I and II invariant across amphibians. In both amphibian orders, reproductive output and metamorphosis size were type I and II invariant. In Anura, incubation time and length of larval period and in Caudata, incubation time were further type II invariant. In reptiles, however, only number of clutches per year was invariant (type II). All these differences could reflect that in reptiles body size and in amphibians, Anura, and Caudata metamorphosis (neotenic species go not through it) and the trend toward independence of egg and larval development from water additionally constrained life history evolution. We further demonstrate that all invariance criteria worked for amphibian and reptilian life history traits, although we corroborated some known and identified new limitations to their application.
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Affiliation(s)
- Konstantin Hallmann
- Institute of Organismic and Molecular Evolution – Evolutionary EcologyJohannes Gutenberg‐University MainzMainzGermany
| | - Eva Maria Griebeler
- Institute of Organismic and Molecular Evolution – Evolutionary EcologyJohannes Gutenberg‐University MainzMainzGermany
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12
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Lin JW, Chen YR, Li TW, Shaner PJL, Lin SM. Long-term monitoring reveals invariant clutch size and unequal reproductive costs between sexes in a subtropical lacertid lizard. ZOOLOGICAL LETTERS 2020; 6:1. [PMID: 31921441 PMCID: PMC6945589 DOI: 10.1186/s40851-019-0152-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 12/12/2019] [Indexed: 06/10/2023]
Abstract
Based on 20,000 records representing c. 11,000 individuals from an 8-year capture-mark-recapture (CMR) study, we tested and confirmed a new case of invariant clutch size (ICS) in a sexually dichromatic lacertid lizard, Takydromus viridipunctatus. In the grassland habitat of the early succession stage, females showed strictly low and invariant clutch size, multiple clutches in a breeding season, high reproductive potential, and annual breeding cycles that correspond to the emergence of male courtship coloration. The hatchlings mature quickly, and join the adult cohort for breeding within a few months, whereas adults show low survival rates and a short lifespan, such that most die within one year. Mortality increased in both sexes during the breeding season, especially in females, indicating an unequal cost of reproduction in survival. These life history characters may be explained by two non-exclusive hypotheses of ICS-arboreal hypothesis and predation hypothesis-within the ecological context of their habitat. Our study highlights a confirmed case of ICS, which adapts well to this r-selected grassland habitat that experiences seasonal fluctuation and frequent disturbance.
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Affiliation(s)
- Jhan-Wei Lin
- School of Life Science, National Taiwan Normal University, No. 88, Sec. 4, Tingzhou Rd., Taipei, Taiwan
- Department of Biology, National Museum of Natural Science, No. 1, Guanqian Rd., Taichung, Taiwan
| | - Ying-Rong Chen
- School of Life Science, National Taiwan Normal University, No. 88, Sec. 4, Tingzhou Rd., Taipei, Taiwan
| | - Tsui-Wen Li
- School of Life Science, National Taiwan Normal University, No. 88, Sec. 4, Tingzhou Rd., Taipei, Taiwan
| | - Pei-Jen L. Shaner
- School of Life Science, National Taiwan Normal University, No. 88, Sec. 4, Tingzhou Rd., Taipei, Taiwan
| | - Si-Min Lin
- School of Life Science, National Taiwan Normal University, No. 88, Sec. 4, Tingzhou Rd., Taipei, Taiwan
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Benun Sutton F, Wilson AB. Where are all the moms? External fertilization predicts the rise of male parental care in bony fishes. Evolution 2019; 73:2451-2460. [PMID: 31660613 DOI: 10.1111/evo.13846] [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] [Received: 06/11/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 01/11/2023]
Abstract
Parental care shows remarkable variation across the animal kingdom, but while maternal and biparental care are common in terrestrial organisms, male-only care dominates in aquatic species that provide care. Using the most complete phylogenetic tree of bony fishes to date, we test whether the opportunity for external fertilization in aquatic environments can explain the more frequent evolution of male care in this group. We show that paternal care has evolved at least 30 times independently in fish and is found exclusively in externally fertilizing species. Male care is positively associated with pair spawning, suggesting that confidence in paternity is an important determinant of the evolution of care. Crucially, while female care is constrained by other forms of reproductive investment, male care occurs more frequently when females invest heavily in gamete production. Our results suggest that moving control of fertilization outside of the female reproductive tract raises male confidence in parentage and increases the potential for paternal care, highlighting that in an aquatic environment in which fertilization is external, paternal care is an effective reproductive strategy.
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Affiliation(s)
- Frieda Benun Sutton
- Department of Biology, Brooklyn College and The Graduate Center, City University of New York, Brooklyn, New York, 11210
| | - Anthony B Wilson
- Department of Biology, Brooklyn College and The Graduate Center, City University of New York, Brooklyn, New York, 11210
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Meiri S. Endothermy, offspring size and evolution of parental provisioning in vertebrates. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Mammals and birds provide food for their young after birth, but such provisioning is almost absent in other vertebrates. A recent theory suggested that, in addition to thermoregulation, the large discrepancy in size between adult and young ectothermic vertebrates precludes them from providing for their young, whereas the relatively large offspring of endotherms are easier to provision. I show here that reptile neonates and hatchlings are as large as those of mammals and birds. Differences in size between adults and young thus cannot explain the lack of parental provisioning in reptiles. I suggest that the large size at birth is the ancestral condition in amniotes as a whole and that provisioning has thus evolved after endothermy.
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Affiliation(s)
- Shai Meiri
- School of Zoology, The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel
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Abstract
Given the current species extinction rates, evidence-based policies to conserve at-risk species are urgently needed. Ultimately, the extinction of a species is determined by birth and death rates, which drive populations to increase or decline. Therefore, demographic data are essential to inform species conservation policies or to develop extinction risk assessments. Demographic information provides an indispensable bedrock for insights to tackle species sustainable management and deepens understanding of ecological and evolutionary processes. We develop a Demographic Species Knowledge Index that classifies the demographic information for 32,144 tetrapod species. We found comprehensive information on birth and survival for only 1.3% (613) of the species, and show the major potential of zoos and aquariums to significantly increase our demographic knowledge. Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species.
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Barve S, Koenig WD, Haydock J, Walters EL. Habitat Saturation Results in Joint-Nesting Female Coalitions in a Social Bird. Am Nat 2019; 193:830-840. [PMID: 31094599 DOI: 10.1086/703188] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Joint nesting by females and cooperative polyandry-cooperatively breeding groups with a male-biased breeder sex ratio-are little-understood, rare breeding systems. We tested alternative hypotheses of factors potentially driving these phenomena in a population of joint-nesting acorn woodpeckers (Melanerpes formicivorus). During periods of high population density and thus low independent breeding opportunities, acorn woodpecker females formed joint-nesting coalitions with close kin. Coalitions were typically associated with groups with a male bias. We found strong evidence for both inter- and intrasexual conflict, as joint nesting conferred a fitness benefit to some males, a significant fitness cost to females, and no gain in per capita reproductive output for either sex. Such conflict, particularly the cost to females, may be an important reason why joint nesting is rare among cooperatively breeding taxa.
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Sexual size dimorphism, allometry and fecundity in a lineage of South American viviparous lizards (Liolaemidae: Phymaturus). ZOOL ANZ 2019. [DOI: 10.1016/j.jcz.2019.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kubička L, Schořálková T, Červenka J, Kratochvíl L. Ovarian control of growth and sexual size dimorphism in a male-larger gecko. ACTA ACUST UNITED AC 2017; 220:787-795. [PMID: 27956485 DOI: 10.1242/jeb.146597] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 12/07/2016] [Indexed: 11/20/2022]
Abstract
Sexual size dimorphism (SSD) reflects sex-specific solutions to the allocation of energy among growth, reproduction and survival; however, the proximate mechanisms behind these solutions are still poorly known even in vertebrates. In squamates, sexual differences in body size used to be attributed to direct energy allocation to energetically demanding processes, largely to reproduction. In addition, SSD is assumed to be controlled by specific endogenous mechanisms regulating growth in a sex-specific manner, namely masculinization by male gonadal androgens or feminization by ovarian hormones. We performed a manipulative growth experiment in females of the male-larger gecko Paroedura picta in order to test the reproductive cost hypothesis, the male androgen hypothesis and the ovarian hormone hypothesis. Specifically, we investigated the effect of total ovariectomy, prepubertal ovariectomy, unilateral ovariectomy, and total ovariectomy followed by exogenous estradiol, dihydrotestosterone or testosterone treatment, on female growth in comparison to males and reproductively active females. The present results and the results of our previous experiments do not support the hypotheses that SSD reflects direct energy allocation to reproduction and that male gonadal androgens are involved. However, all lines of evidence, particularly the comparable growth of reproducing intact and unilaterally ovariectomized females, were concordant with the control of SSD by ovarian hormones. We suggest that feminization of growth by female gonadal hormones should be taken into consideration as an endogenous pathway responsible for the ontogeny of SSD in squamates.
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Affiliation(s)
- Lukáš Kubička
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Praha 2 128 44, Czech Republic
| | - Tereza Schořálková
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Praha 2 128 44, Czech Republic
| | - Jan Červenka
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Praha 2 128 44, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Praha 2 128 44, Czech Republic
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