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Meter B, Kratochvíl L, Starostová Z, Kučera T, Kubička L. Complex ontogeny of sexual size dimorphism in a female-larger gecko: Implications of determinate growth for lizard body size and life-history evolution. Evol Dev 2024:e12490. [PMID: 39129398 DOI: 10.1111/ede.12490] [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: 01/29/2024] [Revised: 07/26/2024] [Accepted: 07/26/2024] [Indexed: 08/13/2024]
Abstract
Ectothermic vertebrates such as reptiles were assumed to be indeterminate growers, which means that there is no terminal point in time or size for growth in their lifetime. In recent years, evidence for the determinate nature of growth in lizards has accumulated, necessitating a re-examination of models of their ontogeny and evolution of sexual size dimorphism (SSD). In the female-larger gecko Paroedura vazimba, we monitored post-embryonic growth over a period of 15 months. After hatching, females grew faster than males but also reached their final body size, that is, closed growth of their vertebrae, earlier than males. The closure of bone growth in females correlates with the onset of reproductive maturation. We compared this pattern with the previously minutely studied, male-larger species Paroedura picta, where we documented determinate growth as well. We propose a model to explain the evolutionary switches in the direction of SSD in lizards based on bipotential effects of ovarian hormones on growth. In this model, male growth is assumed to require no male-specific growth modifier, such as sex-limited hormonal regulators, while growth is feminized by ovarian hormones in females. Low levels of ovarian hormones can promote bone growth, but high levels associated with maturation of the reproductive organs promote senescence of bone growth plates and thus cessation of bone growth. We suggest that models on growth, life-history and evolution of body size in many lizards should acknowledge their determinate nature of growth.
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Affiliation(s)
- Brandon Meter
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Zuzana Starostová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Tomáš Kučera
- Institute of Histology and Embryology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Lukáš Kubička
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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2
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Hults CM, Francis RC, Clint EK, Smith W, Sober ER, Garland T, Rhodes JS. Still little evidence sex differences in spatial navigation are evolutionary adaptations. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231532. [PMID: 38234440 PMCID: PMC10791541 DOI: 10.1098/rsos.231532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/20/2023] [Indexed: 01/19/2024]
Abstract
A putative male advantage in wayfinding ability is the most widely documented sex difference in human cognition and has also been observed in other animals. The common interpretation, the sex-specific adaptation hypothesis, posits that this male advantage evolved as an adaptive response to sex differences in home range size. A previous study a decade ago tested this hypothesis by comparing sex differences in home range size and spatial ability among 11 species and found no relationship. However, the study was limited by the small sample size, the lack of species with a larger female home range and the lack of non-Western human data. The present study represents an update that addresses all of these limitations, including data from 10 more species and from human subsistence cultures. Consistent with the previous result, we found little evidence that sex differences in spatial navigation and home range size are related. We conclude that sex differences in spatial ability are more likely due to experiential factors and/or unselected biological side effects, rather than functional outcomes of natural selection.
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Affiliation(s)
- Connor M. Hults
- Department of Psychology, University of Illinois, 603 E. Daniel St., Champaign, IL 61820, USA
| | | | - Edward K. Clint
- Department of Humanities and Social Sciences, Oregon Institute of Technology, Klamath Falls, OR, USA
| | - Winter Smith
- Department of Humanities and Social Sciences, Oregon Institute of Technology, Klamath Falls, OR, USA
| | - Elliott R. Sober
- Department of Philosophy, University of Wisconsin, Madison, WI, USA
| | - Theodore Garland
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Justin S. Rhodes
- Department of Psychology, University of Illinois, 603 E. Daniel St., Champaign, IL 61820, USA
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3
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Conrad H, Pollock NB, John‐Alder H. Chigger mite ( Eutrombicula alfreddugesi) ectoparasitism does not contribute to sex differences in growth rate in eastern fence lizards ( Sceloporus undulatus). Ecol Evol 2023; 13:e10590. [PMID: 37829181 PMCID: PMC10565727 DOI: 10.1002/ece3.10590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 09/15/2023] [Accepted: 09/22/2023] [Indexed: 10/14/2023] Open
Abstract
Parasitism is nearly ubiquitous in animals and is frequently associated with fitness costs in host organisms, including reduced growth, foraging, and reproduction. In many species, males tend to be more heavily parasitized than females and thus may bear greater costs of parasitism. Sceloporus undulatus is a female-larger, sexually size dimorphic lizard species that is heavily parasitized by chigger mites (Eutrombicula alfreddugesi). In particular, the intensity of mite parasitism is higher in male than in female juveniles during the period of time when sex differences in growth rate lead to the development of sexual size dimorphism (SSD). Sex-biased differences in fitness costs of parasitism have been documented in other species. We investigated whether there are growth costs of mite ectoparasitism, at a time coinciding with sex differences in growth rate and the onset of SSD. If there are sex-biased growth costs of parasitism, then this could suggest a contribution to the development of SSD in S. undulatus. We measured growth and mite loads in two cohorts of unmanipulated, field-active yearlings by conducting descriptive mark-recapture studies during the activity seasons of 2016 and 2019. Yearling males had consistently higher mid-summer mite loads and consistently lower growth rates than females. However, we found that growth rate and body condition were independent of mite load in both sexes. Furthermore, growth rates and mite loads were higher in 2019 than in 2016. Our findings suggest that juveniles of S. undulatus are highly tolerant of chigger mites and that any costs imposed by mites may be at the expense of functions other than growth. We conclude that sex-biased mite ectoparasitism does not contribute to sex differences in growth rate and, therefore, does not contribute to the development of SSD.
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Affiliation(s)
- Hailey Conrad
- Department of Ecology, Evolution, and Natural ResourcesRutgers UniversityNew BrunswickNew JerseyUSA
- Present address:
Department of Biological SciencesVirginia Polytechnic Institute and State UniversityBlacksburgVirginiaUSA
| | - Nicholas B. Pollock
- Graduate Program in Ecology and EvolutionRutgers UniversityNew BrunswickNew JerseyUSA
- Present address:
Department of BiologyUniversity of Texas at ArlingtonArlingtonTexasUSA
| | - Henry John‐Alder
- Department of Ecology, Evolution, and Natural ResourcesRutgers UniversityNew BrunswickNew JerseyUSA
- Rutgers Pinelands Field StationRutgers UniversityNew LisbonNew JerseyUSA
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4
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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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5
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Benítez HA, Sukhodolskaya RA, Avtaeva TA, Escobar-Suárez S, Órdenes-Claveria R, Laroze D, Hernández-P R, Vavilov DN. Quantifying elevational effect on the geometric body shape of Russian beetle Carabus exaratus (Coleoptera: Carabidae). ZOOL ANZ 2022. [DOI: 10.1016/j.jcz.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Liang T, Wang L, Shi L. Sexual and natural selection interplay in sexual head shape dimorphism of two sympatric racerunners (Squamata: Lacertidae). Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1016885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Both natural and sexual selection can shape sexual dimorphism. However, determination of the contribution of these selection pressures is challenging. In lizards, sexual selection can contribute to the larger head size of males than that of females. However, males and females can also diverge in their head size to prey on different food resources under conditions of limited resources (and/or high competitors). Here, 109 individuals from two sympatric desert racerunners (Eremias grammica: 28 males and 30 females; Eremias velox: 25 males and 26 females) were studied to determine their sexual head shape (head length, width, and depth). Additionally, 191 and 169 feces samples of E. grammica and E. velox, respectively, were collected to assess the niche divergence hypothesis (a proxy for natural selection). We found that both species had dimorphic head shapes; male heads (i.e., length, width, and depth) were significantly larger than female heads (P < 0.05, in all cases) in E. grammica, and male heads of E. velox were significantly longer than those of females (P < 0.05). Chi-square test revealed that there were significant differences in the proportion (Hymenopteran and Orthopteran) and sizes of prey type between the two sexes of E. grammica; conspecific males and females of E. velox differed in the proportion of Coleopteran and Hymenopteran prey. Both males and females of these two species had a high niche overlap index (range from ∼ 0.78 to 0.99) with each other. There were also significant differences in the sizes of the heads and prey between the two species (P < 0.05). However, the interspecific differences were mainly caused by interspecific male–male differences in morphological and prey traits. In summary, we believe that both natural (pressures from resource competition) and sexual selection drive sexual head shape dimorphism in these two sympatric lizards, owing to high food resource competition in arid regions. Therefore, head trait divergence can reduce competition by resulting in a preference for different prey types.
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7
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Condition- and context-dependent variation of sexual dimorphism across lizard populations at different spatial scales. Sci Rep 2022; 12:16969. [PMID: 36216914 PMCID: PMC9550790 DOI: 10.1038/s41598-022-21358-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 09/26/2022] [Indexed: 12/29/2022] Open
Abstract
The evolution of sexual dimorphism (SD) is driven by intricate interplays between sexual and natural selection. When it comes to SD variation within populations, however, environmental factors play a major role. Sexually selected traits are expected to be strongly dependent on individual body condition, which is influenced by the local environment that individuals experience. As a consequence, the degree of SD may also depend on resource availability. Here, we investigated the potential drivers of SD expression at two sexually dimorphic morphometric traits, body size (snout vent length) and head shape (head geometric morphometrics), in the Italian wall lizard (Podarcis siculus). We assessed the existence of condition- and context-dependent SD across ten islands of the Aeolian archipelago (southern Italy), at within- and among-population scales. We observed strong geographical variation of SD among islands, and tested three potential SD predictors related to resource availability (individual body condition, ecosystem productivity, temperature). Body condition and ecosystem productivity were the main drivers of body size SD variation, and body condition was also the main driver for head shape SD. Our results highlight that the expression of SD in the Italian wall lizard is both condition- and context-dependent. These results are congruent at within- and among-populations scales highlighting that spatial multi-scale analysis represents a useful approach to understand patterns of SD expression.
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8
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Meisel RP. Ecology and the evolution of sex chromosomes. J Evol Biol 2022; 35:1601-1618. [PMID: 35950939 DOI: 10.1111/jeb.14074] [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: 12/17/2021] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/29/2022]
Abstract
Sex chromosomes are common features of animal genomes, often carrying a sex determination gene responsible for initiating the development of sexually dimorphic traits. The specific chromosome that serves as the sex chromosome differs across taxa as a result of fusions between sex chromosomes and autosomes, along with sex chromosome turnover-autosomes becoming sex chromosomes and sex chromosomes 'reverting' back to autosomes. In addition, the types of genes on sex chromosomes frequently differ from the autosomes, and genes on sex chromosomes often evolve faster than autosomal genes. Sex-specific selection pressures, such as sexual antagonism and sexual selection, are hypothesized to be responsible for sex chromosome turnovers, the unique gene content of sex chromosomes and the accelerated evolutionary rates of genes on sex chromosomes. Sex-specific selection has pronounced effects on sex chromosomes because their sex-biased inheritance can tilt the balance of selection in favour of one sex. Despite the general consensus that sex-specific selection affects sex chromosome evolution, most population genetic models are agnostic as to the specific sources of these sex-specific selection pressures, and many of the details about the effects of sex-specific selection remain unresolved. Here, I review the evidence that ecological factors, including variable selection across heterogeneous environments and conflicts between sexual and natural selection, can be important determinants of sex-specific selection pressures that shape sex chromosome evolution. I also explain how studying the ecology of sex chromosome evolution can help us understand important and unresolved aspects of both sex chromosome evolution and sex-specific selection.
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Affiliation(s)
- Richard P Meisel
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
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9
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Cox CL, Logan ML, Nicholson DJ, Chung AK, Rosso AA, McMillan WO, Cox RM. Species-Specific Expression of Growth-Regulatory Genes in 2 Anoles with Divergent Patterns of Sexual Size Dimorphism. Integr Org Biol 2022; 4:obac025. [PMID: 35958165 PMCID: PMC9362763 DOI: 10.1093/iob/obac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 05/20/2022] [Accepted: 06/30/2022] [Indexed: 11/13/2022] Open
Abstract
Synopsis
Sexual size dimorphism is widespread in nature and often develops through sexual divergence in growth trajectories. In vertebrates, the growth hormone/insulin-like growth factor (GH/IGF) network is an important regulator of growth, and components of this network are often regulated in sex-specific fashion during the development of sexual size dimorphism. However, expression of the GH/IGF network is not well characterized outside of mammalian model systems, and the extent to which species differences in sexual size dimorphism are related to differences in GH/IGF network expression is unclear. To begin bridging this gap, we compared GH/IGF network expression in liver and muscle from 2 lizard congeners, one with extreme male-biased sexual size dimorphism (brown anole, Anolis sagrei), and one that is sexually monomorphic in size (slender anole, A. apletophallus). Specifically, we tested whether GH/IGF network expression in adult slender anoles resembles the highly sex-biased expression observed in adult brown anoles or the relatively unbiased expression observed in juvenile brown anoles. We found that adults of the 2 species differed significantly in the strength of sex-biased expression for several key upstream genes in the GH/IGF network, including insulin-like growth factors 1 and 2. However, species differences in sex-biased expression were minor when comparing adult slender anoles to juvenile brown anoles. Moreover, the multivariate expression of the entire GH/IGF network (as represented by the first two principal components describing network expression) was sex-biased for the liver and muscle of adult brown anoles, but not for either tissue in juvenile brown anoles or adult slender anoles. Our work suggests that species differences in sex-biased expression of genes in the GH/IGF network (particularly in the liver) may contribute to the evolution of species differences in sexual size dimorphism.
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Affiliation(s)
- Christian L Cox
- Florida International University , 11200 SW 8th St, Miami, FL 33199 , USA
- Smithsonian Tropical Research Institute , Amador Causeway, Panama City , Panama
- Georgia Southern University , 1332 Southern Dr, Statesboro, GA 30458 , USA
| | - Michael L Logan
- Smithsonian Tropical Research Institute , Amador Causeway, Panama City , Panama
- University of Nevada Reno , 1664 N Virginia St, Reno, NV 89557 , USA
| | - Daniel J Nicholson
- Smithsonian Tropical Research Institute , Amador Causeway, Panama City , Panama
- Queen Mary University , Mile End Rd, Bethnal Green, London E1 4NS , UK
- University of Texas-Arlington , 701 S Nedderman Dr. Arlington, TX 76019 , USA
| | - Albert K Chung
- Smithsonian Tropical Research Institute , Amador Causeway, Panama City , Panama
- Georgia Southern University , 1332 Southern Dr, Statesboro, GA 30458 , USA
- University of Texas-Arlington , 701 S Nedderman Dr. Arlington, TX 76019 , USA
- Princeton University , Princeton, NJ 08544 , USA
| | - Adam A Rosso
- Georgia Southern University , 1332 Southern Dr, Statesboro, GA 30458 , USA
| | - W Owen McMillan
- Smithsonian Tropical Research Institute , Amador Causeway, Panama City , Panama
| | - Robert M Cox
- University of Virginia , Charlottesville, VA 22904 , USA
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10
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Hoops D, Whiting MJ, Keogh JS. A Smaller Habenula is Associated with Increasing Intensity of Sexual Selection. BRAIN, BEHAVIOR AND EVOLUTION 2022; 97:265-273. [PMID: 34983044 DOI: 10.1159/000521750] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 12/18/2021] [Indexed: 11/19/2022]
Abstract
The habenula is a small structure in the brain that acts as a relay station for neural information, helping to modulate behaviour in response to variable and unpredictable stimuli. Broadly, it is evolutionarily conserved in structure and connectivity across vertebrates and is the most prominent bilaterally asymmetric structure in the brain. Nonetheless, comparative evolutionary studies of the habenula are virtually non-existent. Here, we examine the volumes of the medial and lateral habenular subregions, in both hemispheres, across a group of Australian agamid lizards in the genus Ctenophorus. In males, we found bilaterally asymmetrical selection on the lateral habenula to become smaller with increasing intensity of sexual selection, possibly as a mechanism to increase aggressive responses. In females, we found bilaterally symmetrical selection on both the medial and lateral subregions to become smaller with increasing sexual selection. This is consistent with sexual selection increasing motivation to reproduce and the habenula's well-characterized role in controlling and modifying responses to rewarding stimuli. However, as there are currently no studies addressing habenular function in reptiles, it is difficult to draw more precise conclusions. As has happened recently in biomedical neuroscience, it is time for the habenula to receive greater attention in evolutionary neuroscience.
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Affiliation(s)
- Daniel Hoops
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia.,Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Martin J Whiting
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - J Scott Keogh
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
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11
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Sexual Dimorphism in the Chinese Endemic Species Hynobius maoershanensis (Urodela: Hynobiidae). Animals (Basel) 2022; 12:ani12131712. [PMID: 35804611 PMCID: PMC9265018 DOI: 10.3390/ani12131712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/29/2022] [Accepted: 06/29/2022] [Indexed: 11/21/2022] Open
Abstract
Simple Summary In the present study, we examined the sexual dimorphism of Hynobius maoershanensis. The results showed that it exhibits sexual shape dimorphism, with five morphological traits being male-biased and one being female-biased. The observed sexual shape dimorphism between males and females could be explained using the sexual selection and fecundity theory hypotheses. Abstract Sexual dimorphism is common in most vertebrate species and has diverse manifestations. The study of sexual dimorphism has critical significance for evolutionary biological and ecological adaptation. In this study, we analysed the morphometric data of Hynobius maoershanensis, a rare and endangered species, to examine sexual dimorphism in size and shape. A total of 61 H. maoershanensis individuals (9 adult females and 52 adult males) were used in this study. We measured 14 morphological variables and weight of each individual. Analysis of covariance using snout–vent length (SVL) as the covariate showed significant differences in head width (HW), tail length (TL), tail height (TH), forelimb length (FLL), hindlimb length (HLL) and space between axilla and groin (AGS) between the male and female. The female AGS was greater than that of the male, whereas males had greater HW, TL, TH, FLL and HLL than females. The findings show that sexual dimorphism is present in terms of shape but not in terms of size. The wider head of the male could improve mating success, and its thicker limbs and longer tail might facilitate courtship. The females’ wider AGS may increase reproductive output. Our results support sexual dimorphism in H. maoershanensis, which could be explained by the sexual selection and fecundity theory hypothesis.
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Xiong J, Bai Y, Li G, You Z. Sexual dimorphism in the mountain dragon, Diploderma micangshanensis (Squamata: Lacertilia: Agamidae) from central China. ANIM BIOL 2022. [DOI: 10.1163/15707563-bja10085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Sexual dimorphism (SD) is a common phenomenon in the animal kingdom, especially in lizards. The mountain dragon (Diploderma micangshanensis) is a Chinese endemic that is widely distributed in montane regions of northern Sichuan, western Hubei Province, southern Gansu, Henan, and Shanxi Provinces. However, little is known about its morphology, ecology, behavior, physiology, and natural history. In this study, SD in size and shape in a population of D. micangshanensis from Henan Province, Central China was examined based on a sample of 35 males and 23 females. Sexual dimorphism was observed in a few body shape variables (e.g., head and trunk length) but not in body size (snout-vent length). Males had longer and wider heads and shorter trunks. Sexual dimorphism in these traits can be explained by the sexual selection, ecological divergence, and fecundity advantage hypotheses. Additional studies of the ecology, reproductive biology, natural history, and behavior of D. micangshanensis are needed to evaluate the relative contributions of these mechanisms to determining the patterns of SD observed in this population.
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Affiliation(s)
- Jianli Xiong
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, 621000, Sichuan, China
| | - Yinlong Bai
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471023, Henan, China
| | - Guanglu Li
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471023, Henan, China
| | - Zhangqiang You
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, 621000, Sichuan, China
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13
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Lu HL, Gao JF, Guo K, Ji X. Sexual size monomorphism may evolve in lizards with a body size maximizing reproductive performance for both sexes. Curr Zool 2022. [DOI: 10.1093/cz/zoac033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
We used Takydromus septentrionalis, a sexually size-monomorphic lacertid lizard, as a model system to test the hypothesis that sexual size monomorphism may evolve in lizards where reproductive performance is maximized at a similar body size for both sexes. We allowed lizards housed in laboratory enclosures to lay as many clutches (for females) as they could or to mate as many times (for males) as they could in a breeding season. Size-assortative mating was weak but evident in T. septentrionalis, as revealed by the fact that male and female snout-vent lengths (SVLs) in mating pairs were significantly and positively correlated. Mating frequency (indicative of male reproductive performance) varied from 1 to 8 per breeding season, generally increasing as SVL increased in adult males smaller than 67.4 mm snout-vent length (SVL). Clutch frequency varied from 1 to 7 per breeding season, with female reproductive performance (determined by clutch frequency, annual fecundity and annual reproductive output) maximized in females with a SVL of 68.0 mm. Accordingly to our hypothesis, the reproductive performance was maximized in the intermediate-sized rather than the largest individuals in both sexes, and the body size maximizing reproductive performance was similar for both sexes. Future work could usefully investigate other lineages of lizards with sexually monomorphic species in a phylogenetic context to corroborate the hypothesis of this study.
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Affiliation(s)
- Hong-Liang Lu
- Hangzhou Key Laboratory for Ecosystem Protection and Restoration, School of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Jian-Fang Gao
- Hangzhou Key Laboratory for Ecosystem Protection and Restoration, School of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Kun Guo
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang, 325035, China
| | - Xiang Ji
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang, 325035, China
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14
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Variation in size and shape sexual dimorphism in the Sceloporus scalaris species group (Squamata: Phrynosomatidae) from the Transvolcanic Belt of Mexico. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blab169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We attempted to identify the factors influencing size and shape dimorphism between sexes, as well as among populations and species in the Sceloporus scalaris group (Sceloporus aeneus, S. scalaris, S. bicanthalis and S. subniger). Our analysis focused on five morphological characteristics: snout–vent length, head length, head width, forearm length and tibia length. The effect of environmental variables (precipitation and temperature) on these variables was also tested. We found differences in morphological traits between sexes, and among populations of the same species. The oviparous species (S. aeneus and S. scalaris) were larger in overall body size than the viviparous species (S. bicanthalis and S. subniger). Differences in overall body size among populations were recorded only in S. aeneus and S. scalaris. Male-biased sexual size dimorphism occurred in oviparous but not viviparous lizards (except for one population of S. bicanthalis). An absence of sexual size dimorphism was also recorded in S. subniger and some populations of the remaining species. Two different shape patterns were found; the first was female-biased with larger relative body length in almost all populations, which could be explained by fecundity, and the second was male-biased with relatively larger head and limbs in a few populations, which may be explained by sexual selection. The patterns of sexual size and shape dimorphism show that environment, rather than phylogeny, may be determining the extent of sexual dimorphism. These types of studies show the importance of an integrated evaluation of interpopulation and interspecies variation to determine the factors that generate sexual dimorphism.
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15
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OUP accepted manuscript. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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16
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Abstract
A well-known property of sexual selection combined with a cross-sex genetic correlation (rmf) is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection + rmf balance with the constraints imposed by such sexual antagonism, to affect the macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when rmf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual selection leads to a sexually concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.
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Affiliation(s)
- Stephen P De Lisle
- Evolutionary Ecology Unit, Department of Biology, Lund University, Sölvegatan 37 223 62, Lund, Sweden
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17
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Verdú Ricoy J, Mashinini P, Goedhals J, Heideman N. Reproduction, sexual dimorphism and predation in Mochlus sundevallii in southern Africa (Reptilia: Sauria, Scincidae). AFRICAN ZOOLOGY 2021. [DOI: 10.1080/15627020.2021.1976077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Joaquín Verdú Ricoy
- Department of Zoology & Entomology, University of the Free State, Bloemfontein, South Africa
| | - Phomolo Mashinini
- Department of Herpetology, Ditsong Museum of Natural History, Pretoria, South Africa
| | - Jacqueline Goedhals
- Department of Anatomical Pathology, University of the Free State and National Health Laboratory Service, Bloemfontein, South Africa
| | - Neil Heideman
- Department of Zoology & Entomology, University of the Free State, Bloemfontein, South Africa
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18
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Janicke T, Fromonteil S. Sexual selection and sexual size dimorphism in animals. Biol Lett 2021; 17:20210251. [PMID: 34520680 PMCID: PMC8440037 DOI: 10.1098/rsbl.2021.0251] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/23/2021] [Indexed: 11/12/2022] Open
Abstract
Sexual selection is often considered as a critical evolutionary force promoting sexual size dimorphism (SSD) in animals. However, empirical evidence for a positive relationship between sexual selection on males and male-biased SSD received mixed support depending on the studied taxonomic group and on the method used to quantify sexual selection. Here, we present a meta-analytic approach accounting for phylogenetic non-independence to test how standardized metrics of the opportunity and strength of pre-copulatory sexual selection relate to SSD across a broad range of animal taxa comprising up to 95 effect sizes from 59 species. We found that SSD based on length measurements was correlated with the sex difference in the opportunity for sexual selection but showed a weak and statistically non-significant relationship with the sex difference in the Bateman gradient. These findings suggest that pre-copulatory sexual selection plays a limited role for the evolution of SSD in a broad phylogenetic context.
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Affiliation(s)
- Tim Janicke
- Centre d’Écologie Fonctionnelle et Évolutive, UMR 5175 CNRS, Université de Montpellier, École Pratique des Hautes Études, Montpellier, France
- Applied Zoology, Technical University Dresden, Zellescher Weg 20b, Dresden 01062, Germany
| | - Salomé Fromonteil
- Centre d’Écologie Fonctionnelle et Évolutive, UMR 5175 CNRS, Université de Montpellier, École Pratique des Hautes Études, Montpellier, France
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Laakso LK, Ilvonen JJ, Suhonen J. Phenotypic variation in male Calopteryx splendens damselflies: the role of wing pigmentation and body size in thermoregulation. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
For ectothermic insects, their colour and size are important determinants of body temperature: larger bodies require more heat to reach a certain temperature, and dark colours absorb heat more efficiently. These dark colours are expressed using melanin, which has been intimately linked with the thermoregulatory capabilities of insects. Melanin is also linked with immune defence and is often used as a secondary sexual character in insects. There is a potential trade-off situation between thermoregulatory capabilities, immune defence and secondary sexual characters, all of which use melanin. Some Calopteryx damselflies, such as Calopteryx splendens, have melanin-based wing pigmentation that is sexually selected and drives intra- and interspecific territorial aggression. Our goal was to study experimentally how the wing pigmentation and body size of C. splendens males affect their thermoregulation and, especially, their ability to become active (hereafter, ‘activate’) after being cooled down. Our results were in line with our hypotheses, showing that individuals with larger wing spots had significantly faster activation times than those with smaller wing spots, and that individuals with larger body size had significantly slower activation times than those with smaller body size. Both variables showed an interaction and are therefore important in damselfly warm-up and activation. We discuss the role of wing pigmentation and thermoregulation in the behavioural patterns observed in Calopteryx species.
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Affiliation(s)
- Linda K Laakso
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Jaakko J Ilvonen
- Finnish Environmental Institute SYKE, Biodiversity Center, Latokartanonkaari 11,00790 Helsinki, Finland
| | - Jukka Suhonen
- Department of Biology, University of Turku, FI-20014 Turku, Finland
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20
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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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21
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Chelini MC, Brock K, Yeager J, Edwards DL. Environmental drivers of sexual dimorphism in a lizard with alternative mating strategies. J Evol Biol 2021; 34:1241-1255. [PMID: 34101919 DOI: 10.1111/jeb.13881] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/29/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022]
Abstract
Understanding the relative importance of sexual and natural selection in shaping morphological traits is a long-standing goal of evolutionary ecology. Male-biased sexual size dimorphism (SSD) is typically associated with male-male competition. Similarly, male polymorphisms are considered a consequence of competitive social interactions. This classic paradigm overlooks the fact that environmental factors mediate social interactions and can lead to ecological adaptations. Common side-blotched lizards, Uta stansburiana, are a model system for this paradigm due to well-known rock-paper-scissors social dynamics between male morphs. SSD in this species has been considered primarily a consequence of social interactions, with male size resulting from the number of morphs in each population and female size being constrained through fecundity benefits. We test if the environment explains intraspecific variation in SSD and number of male morphs in U. stansburiana. By compiling data from 49 populations, we show that environmental variables are stronger predictors of SSD than the number of male morphs. Similarly, we show that the environment mediates SSD and potentially contributes to morph loss in colder environments. We propose that the environment favours smaller males in areas of high seasonality. Our results demonstrate the importance of the environment as a mediator of SSD.
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Affiliation(s)
| | - Kinsey Brock
- School of Natural Sciences, University of California, Merced, Merced, CA, USA
| | - Justin Yeager
- School of Natural Sciences, University of California, Merced, Merced, CA, USA
| | - Danielle L Edwards
- School of Natural Sciences, University of California, Merced, Merced, CA, USA
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22
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Duncan CA, Cohick WS, John-Alder HB. Testosterone Reduces Growth and Hepatic IGF-1 mRNA in a Female-Larger Lizard, Sceloporus undulatus: Evidence of an Evolutionary Reversal in Growth Regulation. Integr Org Biol 2021; 2:obaa036. [PMID: 33791574 PMCID: PMC7715992 DOI: 10.1093/iob/obaa036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous research has demonstrated that testosterone (T) can inhibit growth in female-larger species and stimulate growth in male-larger species, but the underlying mechanisms of this regulatory bipotentiality have not been investigated. In this study, we investigated the effects of T on the expression of hepatic insulin-like growth factor-1 (IGF-1) mRNA and circulating IGF-1 hormone in Sceloporus undulatus, a species of lizard in which females grow faster to become larger than males and in which T inhibits growth. Experiments were performed in captivity on mature female and male adults in the asymptotic phase of their growth curve and on actively growing, pre-reproductive juveniles. In adult males, the expression of hepatic IGF-1 mRNA increased following surgical castration and returned to control levels with T replacement; in intact adult females, exogenous T had no effect on IGF-1 mRNA expression. In juveniles, T significantly reduced both growth and the expression of hepatic IGF-1 mRNA to similar extents in intact females and in castrated males. The relative inhibitory effects of T on mRNA expression were greater in juveniles than in adults. Plasma IGF-1 hormone was about four times higher in juveniles than in adults, but T had no significant effect on IGF-1 hormone in either sex or in either age group. Our finding of inhibition of the expression of hepatic IGF-1 mRNA stands in contrast to the stimulatory effects of T in the published body of literature. We attribute our novel finding to our use of a species in which T inhibits rather than stimulates growth. Our findings begin to explain how T has the regulatory bipotentiality to be stimulatory in some species and inhibitory in others, requiring only an evolutionary reversal in the molecular regulation of growth-regulatory genes including IGF-1. Further comparative transcriptomic studies will be required to fully resolve the molecular mechanism of growth inhibition.
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Affiliation(s)
| | - Wendie S Cohick
- Graduate Program in Endocrinology and Animal Biosciences, Rutgers University, 84 Lipman Drive, New Brunswick, NJ 08901, USA
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23
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Vilaseca C, Méndez MA, Pinto CF, Lemic D, Benítez HA. Unraveling the Morphological Variation of Triatoma infestans in the Peridomestic Habitats of Chuquisaca Bolivia: A Geometric Morphometric Approach. INSECTS 2021; 12:insects12020185. [PMID: 33671621 PMCID: PMC7926573 DOI: 10.3390/insects12020185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/27/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022]
Abstract
Morphometrics has been used on Triatomines, a well-known phenotypically variable insect, to understand the process of morphological plasticity and infer the changes of this phenomenon. The following research was carried out in two regions of the inter-Andean valleys and two Chaco regions of Chuquisaca-Bolivia. Triatoma infestans adults were collected from the peridomestic (pens and chicken coops) along a geographic gradient in order to evaluate the morphological differentiation between groups and their pattern of sexual shape dimorphism. Geometric morphometric methods were applied on the wings and heads of T. infestans. The main findings include that we proved sexual dimorphism in heads and wings, determined the impact of environmental factors on size and shape and validated the impact of nutrition on head shape variation. These results show that geometric morphometric procedures can be used to provide key insight into the biological adaptation of T. infestans on different biotic (nutrition) and abiotic (environment) conditions, which could serve in understanding and evaluating infestation processes and further vector control programs.
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Affiliation(s)
- Carolina Vilaseca
- Laboratorio de Ecología Química, Universidad Mayor Real y Pontificia San Francisco Xavier de Chuquisaca, Sucre, Bolivia; (C.V.); (C.F.P.)
| | - Marco A. Méndez
- Laboratorio de Genética y Evolución, Facultad de Ciencias, Instituto de Ecología y Biodiversidad, Universidad de Chile, Santiago 6640022, Chile;
| | - Carlos F. Pinto
- Laboratorio de Ecología Química, Universidad Mayor Real y Pontificia San Francisco Xavier de Chuquisaca, Sucre, Bolivia; (C.V.); (C.F.P.)
| | - Darija Lemic
- Department of Agricultural Zoology, Faculty of Agriculture, University of Zagreb, Svetošimunska 25, 10000 Zagreb, Croatia;
| | - Hugo A. Benítez
- Laboratorio de Ecología y Morfometría Evolutiva, Centro de Investigación de Estudios Avanzados del Maule, Universidad Católica del Maule, Talca 3466706, Chile
- Correspondence:
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25
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Ramírez‐Bautista A, Cruz‐Elizalde R, Stephenson BP, Hernández‐Salinas U. Geographic variation in female body size and clutch size of the lizard
Sceloporus variabilis
(Squamata: Phrynosomatidae) in Mexico. ACTA ZOOL-STOCKHOLM 2021. [DOI: 10.1111/azo.12372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Aurelio Ramírez‐Bautista
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo Hidalgo México
| | - Raciel Cruz‐Elizalde
- Museo de Zoología “Alfonso L. Herrera” Departamento de Biología Evolutiva Facultad de Ciencias Universidad Nacional Autónoma de México (UNAM) Ciudad de México México
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26
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Bury S. Sex-specific growth is mirrored in feeding rate but not moulting frequency in a sexually dimorphic snake. Naturwissenschaften 2021; 108:6. [PMID: 33415456 DOI: 10.1007/s00114-020-01712-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 11/06/2020] [Accepted: 11/16/2020] [Indexed: 11/30/2022]
Abstract
Sexual size dimorphism (SSD), commonly observed in snakes, may arise from a different growth rate between the sexes. This indicates a sex-specific resource intake that is in fact observable in free-living snakes. It is not so well known whether the sexes can express differential feeding rates under conditions unconstrained by spatial accessibility, competition, etc. Here, I studied sex-specific variation in growth, its correlate-moulting frequency, and feeding rate in a captive group of sexually dimorphic banded water snakes (Nerodia fasciata) with access to food unconstrained by predation, competition or space. I showed that the sexes did indeed differ in relative mass growth in that females grew faster than males (p = 0.02), but such differences were not apparent in the moulting rate (p = 0.19). Such differential growth was mirrored in the sex-specific feeding rate, with females ingesting a larger number of meals than males (p = 0.004). Such variation in feeding rate may be governed by an individual's energy expenditure and can be interpreted as a behavioural tendency that contributes to SSD development, independently of other behavioural characteristics. Sex-specific resource demands may drive the differential effects of increasing resource scarcity on both sexes.
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Affiliation(s)
- Stanisław Bury
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland. .,Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland. .,NATRIX Herpetological Association, Legnicka 65, 54-206, Wrocław, Poland.
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27
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Noble DWA, Kar F, Nakagawa S, Keogh JS, Whiting MJ. Sexual selection on performance traits in an Australian lizard with alternative reproductive tactics. J Evol Biol 2020; 34:451-464. [PMID: 33296538 DOI: 10.1111/jeb.13752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 11/29/2020] [Accepted: 12/01/2020] [Indexed: 11/30/2022]
Abstract
Sexual selection shapes the adaptive landscape in complex ways that lead to trait integration. Much of our understanding of selection comes from studies of morphological traits. However, few studies attempt to quantify the form and direction of selection on performance even though it is predicted to be a more direct target of selection in nature. We measured sexual selection on performance traits (bite force, sprint speed and endurance) in an Australian lizard, the Eastern water skink (Eulamprus quoyii). We first staged 123 contests between size-matched males to investigate whether performance traits were important in determining contest outcome. In a second experiment, we established six breeding populations in large replicate semi-natural enclosures to estimate whether performance traits predicted reproductive success. Our results show that none of the performance measures were important in predicting contest outcome and were not generally strong predictors of reproductive success. However, our analyses suggest a complex fitness landscape driven by males adopting different alternative reproductive tactics (ARTs). We provide a rare test of the role performance plays in sexual selection and highlight the need to test common assumptions regarding the link between maximal performance and fitness. Our results suggest that performance traits may not necessarily be direct targets of sexual selection, but rather indirect targets through their integration with morphological and/or behavioural traits, highlighting a need for more explicit tests of the predicted links between performance and fitness.
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Affiliation(s)
- Daniel W A Noble
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia.,School of Biological, Earth and Environmental Sciences, Ecology and Evolution Research Centre, University of New South Wales, Sydney, NSW, Australia.,Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Fonti Kar
- School of Biological, Earth and Environmental Sciences, Ecology and Evolution Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Shinichi Nakagawa
- School of Biological, Earth and Environmental Sciences, Ecology and Evolution Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - J Scott Keogh
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Martin J Whiting
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
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28
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Gainsbury AM. Influence of size, sex, and reproductive status on the thermal biology of endemic Florida scrub lizards. Ecol Evol 2020; 10:13080-13086. [PMID: 33304518 PMCID: PMC7713916 DOI: 10.1002/ece3.6897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 11/11/2022] Open
Abstract
Climate change is impacting species globally, with many populations declining at an accelerated rate toward extinction. Ectothermic species are particularly vulnerable given their reproductive success is linked to environmental temperatures. Studies of the effect of temperature on reproductive success in oviparous squamates have focused mostly on nest temperatures, after eggs are deposited. However, in some species gravid females are known to thermoregulate differently than other adults to increase reproductive success. It is essential to understand what influences the thermal biology of breeding adults in a population to implement targeted conservation strategies. The Florida scrub lizard Sceloporus woodi is an endemic species listed as near-threatened due to decreasing populations. This study is the first to document the thermal biology of these breeding adults in relation to size, sex, and reproductive status. A t test was used to determine whether sexual dimorphism was present in the sampled S. woodi. Full linear mixed-effects models were used to test the influence of size, sex, and reproductive status on the thermal biology of S. woodi. Despite female-biased sexual size dimorphism, there were no sex-based differences in body temperature in the studied population. Interestingly, reproductive status influenced thermal biology of females during the breeding season, with gravid females maintaining lower body temperatures compared to nongravid females. However, gravid females did not regulate their body temperatures more precisely compared to nongravid females. These results indicate the population viability of this endemic species is potentially linked to the different thermoregulatory requirements of gravid females as compared to other adults. Lower body temperatures of gravid females, exacerbated by their lack of thermal precision, have disconcerting conservation implications in the face of climate warming. Future studies focusing on gravid females are warranted to attain effective biodiversity conservation strategies mitigating the impacts of climate warming.
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Affiliation(s)
- Alison M. Gainsbury
- Department of Integrative BiologyUniversity of South FloridaSt. PetersburgFLUSA
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Lozano A, Ramírez-Bautista A, Cruz-Elizalde R. Intraspecific variation in a lizard from the Central Mexican Plateau: intersexual differences in size and shape explored. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Morphological adaptations of individuals are directly (or indirectly) determined by the environment. Depending on sex, these adaptations may vary in different ways, given that different selective forces may be operating on organisms. Here, we evaluate intraspecific morphological variation (size and shape) in two populations of Sceloporus grammicus that occur in different structural habitats (trees and rocks). No difference in overall body size was found between the two populations. However, strong differences were found in body shape; the tree population was characterized by having shorter hindlimb proportions than the rock population, which agrees with the theory of biomechanical models. Furthermore, our results show that this species is dimorphic in size and shape, both in sex and population effects. A review of the literature suggests that the large overall body size and relatively longer distal segments of males could be an advantage for defending their territory, and the observation that females had relatively longer head length may be related to trophic niche divergence; however, this remains to be tested. Detailed quantification of behaviour, performance and reproductive characteristics must be performed to shed light on the evolution of sexual dimorphism in this widely distributed species in Mexico.
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Affiliation(s)
- Abraham Lozano
- CIIDIR Unidad Durango, Instituto Politécnico Nacional, Durango, México
| | - Aurelio Ramírez-Bautista
- Laboratorio de Ecología de Poblaciones, Centro de Investigaciones Biológicas, Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Mineral de La Reforma, Hidalgo, México
| | - Raciel Cruz-Elizalde
- Museo de Zoología “Alfonso L. Herrera”, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Ciudad de México CP, México
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30
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López Juri G, Rossi N, Chiaraviglio M, Cardozo G. Phenotypic diversity and its relationship to reproductive potential in changing social contexts in a lizard model. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Phenotype in lizards is related to reproductive function, and hence to reproductive output. Besides the intraspecific diversity in phenotypes, their temporal variation throughout the reproductive season in relation to the variation of social contexts builds extra complexity into sexual selection scenarios. One useful model for understanding phenotypic diversity dynamics is Tropidurus spinulosus because it presents sexual dimorphism in different phenotypic traits, dichromatism in regions related to reproductive behaviour, and it has intense social reproductive interactions. We aimed to evaluate how the reproductive and phenotypic traits of individuals vary with changing social contexts, and how intrasexual phenotypic diversity and reproductive potential are explained by the phenotypic traits. In this study, we used data obtained during four consecutive breeding seasons (2015–2018) in a wild population. The social context, characterized according to the operational sex ratio, varied between months and, therefore, some phenotypic and reproductive traits also varied. We found that body robustness and chromatic diversity were the main sources of phenotypic diversity and were related to reproductive traits in both sexes. Our results help to understand the dynamics and reproductive implications of phenotypic diversity in changing social contexts in a lizard social model.
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Affiliation(s)
- Guadalupe López Juri
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
| | - Nicola Rossi
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
| | - Margarita Chiaraviglio
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
| | - Gabriela Cardozo
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
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Adams DC, Glynne E, Kaliontzopoulou A. Interspecific allometry for sexual shape dimorphism: Macroevolution of multivariate sexual phenotypes with application to Rensch's rule. Evolution 2020; 74:1908-1922. [PMID: 32578880 DOI: 10.1111/evo.14049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 06/19/2020] [Indexed: 12/31/2022]
Abstract
Allometric trends in the degree of sexual dimorphism with body size have long fascinated evolutionary biologists. Many male-biased clades display more prominent sexual dimorphism in larger taxa (Rensch's rule), with most examples documenting this pattern for body size dimorphism. Although sexual dimorphism in traits other than body size is equally functionally relevant, characterizing allometric patterns of sexual dimorphism in such traits is hampered by lack of an analytical framework that can accommodate multivariate phenotypes. In this article, we derive a multivariate equivalency for investigating trends in sexual dimorphism-relative to overall body size-across taxa and provide a generalized test to determine whether such allometric patterns correspond with Rensch's rule. For univariate linear traits such as body size, our approach yields equivalent results to those from standard procedures, but our test is also capable of detecting trends in multivariate datasets such as shape. Computer simulations reveal that the method displays appropriate statistical properties, and an empirical example in Mediterranean lizards provides the first demonstration of Rensch's rule in a multivariate phenotype (head shape). Our generalized procedure substantially extends the analytical toolkit for investigating macroevolutionary patterns of sexual dimorphism and seeking a better understanding of the processes that underlie them.
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Affiliation(s)
- Dean C Adams
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50011
| | - Elizabeth Glynne
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50011
| | - Antigoni Kaliontzopoulou
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus de Vairão, Vila do Conde, Porto, 4099-002, Portugal
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Portik DM, Blackburn DC, McGuire JA. Macroevolutionary Patterns of Sexual Size Dimorphism Among African Tree Frogs (Family: Hyperoliidae). J Hered 2020; 111:379-391. [DOI: 10.1093/jhered/esaa019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/19/2020] [Indexed: 11/13/2022] Open
Abstract
Abstract
Sexual size dimorphism (SSD) is shaped by multiple selective forces that drive the evolution of sex-specific body size, resulting in male or female-biased SSD. Stronger selection on one sex can result in an allometric body size scaling relationship consistent with Rensch’s rule or its converse. Anurans (frogs and toads) generally display female-biased SSD, but there is variation across clades and the mechanisms driving the evolution of SSD remain poorly understood. We investigated these topics in a diverse family of African treefrogs (Hyperoliidae). Hyperoliids display traits considered rare among amphibians, including sexual dichromatism and protogynous sex change. Using phylogenetic comparative methods, we tested if adult ecology, sexual dichromatism, and sex change were predictors of body size or SSD. We also tested whether hyperoliids displayed allometric interspecific body size scaling relationships. We found a majority of hyperoliid taxa display female-biased SSD, but that adult ecology and sexual dichromatism are poor predictors of sex-specific body size and SSD. Regardless of the groupings analyzed (partitioned by clades or traits), we found support for isometric body size scaling. However, we found that sex change is a significant predictor of SSD variation. Species in the Hyperolius viridiflavus complex, which putatively display this trait, show a significant reduction in SSD and are frequently sexually monomorphic in size. Although protogynous sex change needs to be validated for several of these species, we tentatively propose this trait is a novel mechanism influencing anuran body size evolution. Beyond this association, additional factors that shape the evolution of anuran body size and SSD remain elusive.
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Affiliation(s)
- Daniel M Portik
- California Academy of Sciences, San Francisco, CA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA
| | - David C Blackburn
- Florida Museum of Natural History, University of Florida, Gainesville, FL
| | - Jimmy A McGuire
- Museum of Vertebrate Zoology, University of California, Berkeley, CA
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Benítez HA, Sukhodolskaya RA, Órdenes-Clavería R, Avtaeva TA, Kushalieva SA, Saveliev AA. Measuring the Inter and Intraspecific Sexual Shape Dimorphism and Body Shape Variation in Generalist Ground Beetles in Russia. INSECTS 2020; 11:insects11060361. [PMID: 32531974 PMCID: PMC7349662 DOI: 10.3390/insects11060361] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/25/2020] [Accepted: 05/29/2020] [Indexed: 11/30/2022]
Abstract
Ground beetles in multiple species vary greatly in the expression of the shape on sexual traits, resulting in a sexual shape dimorphism as a consequence of sexual selection differences. The present research focuses on the study of inter and intrasexual sexual shape dimorphism of two generalist genera of ground beetles Pterostichus and Carabus. Geometric morphometric methods were applied to five generalist species of ground beetles Carabus exaratus, C. granulatus, Pterostichus melanarius, P. niger, and P. oblongopunctatus and several multivariate analyses were applied for two different traits, abdomen and elytra. Three of the five species analyzed showed high levels of sex-based shape dimorphism. However, the most generalist species, P. melanarius and P. oblongopunctatus, did not evidence shape-based sexual dimorphism differentiation in both of the analyzed traits, as statistically confirmed based on the permutation of pairwise comparison of the Mahalanobis distances of a sex–species classifier. It is generally known that environmental stress in natural populations can affect the fitness expression, principally related to sexual fecundity, being that this pattern is more evident in non-generalist species. In our results, the contrary pattern was found, with the absence of sexual shape dimorphism for two of the three generalist species analyzed. On the other hand, the interspecies shape variation was clearly identified using principal component analysis of both of the analyzed traits. Finally, this research is the first to analyze the relationship between sexual shape dimorphism in Russian ground beetles, evidencing the lack of understanding of the mechanism underlying the sexual dimorphism, especially in species living in extreme environments.
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Affiliation(s)
- Hugo A. Benítez
- Laboratorio de Ecología y Morfometría Evolutiva, Centro de Investigación de Estudios Avanzados del Maule, Universidad Católica del Maule, Talca 3466706, Chile;
- Correspondence: ; Tel.: +56-978895630
| | - Raisa A. Sukhodolskaya
- Institute of Ecology and Mineral Resource Management Academy of Sciences of Tatarstan Republic, Tatarstan, Kazan 420000, Russia;
| | - Rodrigo Órdenes-Clavería
- Laboratorio de Ecología y Morfometría Evolutiva, Centro de Investigación de Estudios Avanzados del Maule, Universidad Católica del Maule, Talca 3466706, Chile;
| | - Tamara A. Avtaeva
- Kh. Ibragimov Complex Institute of the Russian Academy of Sciences, Grozny 364014, Russia;
| | - Shapaat A. Kushalieva
- Department of Biology and Methods of Teaching (Head), Chechen State Pedagogical University, Grozny 364014, Russia;
| | - Anatoly A. Saveliev
- Department of Ecosystem Modeling, Kazan (Volga Region) Federal University, Kazan 420000, Russia;
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Naretto S, Chiaraviglio M. Factors driving sexual dimorphism and colour variability in the Achala Copper Lizard (Pristidactylus achalensis), an endemic species to the highland mountains in central Argentina. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whereas other traits, such as colouration, varies seasonally only in males. Our results underline the intriguing possibility of seasonal morphological changes related to mating, and more broadly that sex differences are influenced by sexual selection pressures mediated by temporal variation in mate competition.
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Affiliation(s)
- S. Naretto
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
| | - M. Chiaraviglio
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
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35
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Roitberg ES, Orlova VF, Bulakhova NA, Kuranova VN, Eplanova GV, Zinenko OI, Arribas O, Kratochvíl L, Ljubisavljević K, Starikov VP, Strijbosch H, Hofmann S, Leontyeva OA, Böhme W. Variation in body size and sexual size dimorphism in the most widely ranging lizard: testing the effects of reproductive mode and climate. Ecol Evol 2020; 10:4531-4561. [PMID: 32551042 PMCID: PMC7297768 DOI: 10.1002/ece3.6077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/07/2020] [Accepted: 01/13/2020] [Indexed: 11/23/2022] Open
Abstract
Reproductive mode, ancestry, and climate are hypothesized to determine body size variation in reptiles but their effects have rarely been estimated simultaneously, especially at the intraspecific level. The common lizard (Zootoca vivipara) occupies almost the entire Northern Eurasia and includes viviparous and oviparous lineages, thus representing an excellent model for such studies. Using body length data for >10,000 individuals from 72 geographically distinct populations over the species' range, we analyzed how sex-specific adult body size and sexual size dimorphism (SSD) is associated with reproductive mode, lineage identity, and several climatic variables. Variation in male size was low and poorly explained by our predictors. In contrast, female size and SSD varied considerably, demonstrating significant effects of reproductive mode and particularly seasonality. Populations of the western oviparous lineage (northern Spain, south-western France) exhibited a smaller female size and less female-biased SSD than those of the western viviparous (France to Eastern Europe) and the eastern viviparous (Eastern Europe to Far East) lineages; this pattern persisted even after controlling for climatic effects. The phenotypic response to seasonality was complex: across the lineages, as well as within the eastern viviparous lineage, female size and SSD increase with increasing seasonality, whereas the western viviparous lineage followed the opposing trends. Altogether, viviparous populations seem to follow a saw-tooth geographic cline, which might reflect the nonmonotonic relationship of body size at maturity in females with the length of activity season. This relationship is predicted to arise in perennial ectotherms as a response to environmental constraints caused by seasonality of growth and reproduction. The SSD allometry followed the converse of Rensch's rule, a rare pattern for amniotes. Our results provide the first evidence of opposing body size-climate relationships in intraspecific units.
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Affiliation(s)
| | - Valentina F. Orlova
- Zoological Research MuseumMoscow M.V. Lomonosov State UniversityMoscowRussia
| | - Nina A. Bulakhova
- Institute of Biological Problems of the NorthMagadanRussia
- Research Institute of Biology and BiophysicsTomsk State UniversityTomskRussia
| | | | | | | | | | | | | | | | | | - Sylvia Hofmann
- Helmholtz‐Centre for Environmental Research – UfZLeipzigGermany
| | - Olga A. Leontyeva
- Department of BiogeographyMoscow M. V. Lomonosov State UniversityMoscowRussia
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36
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Meter B, Starostová Z, Kubička L, Kratochvíl L. The limits of the energetical perspective: life-history decisions in lizard growth. Evol Ecol 2020. [DOI: 10.1007/s10682-020-10054-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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37
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Siliceo‐Cantero HH, Benítez‐Malvido J, Suazo‐Ortuño I. Insularity effects on the morphological space and sexual dimorphism of a tropical tree lizard in western Mexico. J Zool (1987) 2020. [DOI: 10.1111/jzo.12783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- H. H. Siliceo‐Cantero
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad Universidad Nacional Autónoma de México Morelia Michoacán Mexico
| | - J. Benítez‐Malvido
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad Universidad Nacional Autónoma de México Morelia Michoacán Mexico
| | - I. Suazo‐Ortuño
- Instituto de Investigaciones Sobre los Recursos Naturales Universidad Michoacana de San Nicolás Hidalgo Morelia Michoacán Mexico
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38
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Sexual dimorphism in size and shape among populations of the lizard Sceloporus variabilis (Squamata: Phrynosomatidae). ZOOLOGY 2020; 140:125781. [PMID: 32388120 DOI: 10.1016/j.zool.2020.125781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 02/19/2020] [Accepted: 02/25/2020] [Indexed: 11/22/2022]
Abstract
Sexual dimorphism in lizards is determined by ecological and environmental factors. Broadly distributed species may show variation in patterns of sexual dimorphism toward either sex, as well as exhibiting variation in morphological dimensions. In the present study, sexual dimorphism in size and shape attributes was evaluated in three populations of the lizard Sceloporus variabilis from different environments in Mexico. We evaluated the size attributes of 10 morphological variables: snout-vent length (SVL), tibia length (TL), femur length (FeL), forearm length (FoL), interaxial distance (ID), head length (HL), head width (HW), head height (HH), jaw length (JL), and jaw width (JW). We also evaluated the attributes of shape (relative dimensions of the 10 morphological variables). In the size attribute, sexual dimorphism was found, with males being larger than females. In the case of shape, sexual dimorphism was found, with the females being larger in relative dimensions of ID and JW. Also, the males showed larger relative dimensions in TL, FeL and FoL. Differences were found between populations in the dimension of the variables analyzed in each sex. The pattern in size can be explained by sexual selection, where the males of each population maintain larger dimensions to compete for territory and access to females. In shape, females can be favored if they have larger relative ID and JW, as it promotes maintenance of clutch sizes, and use of microhabitats and different consumption of prey types than males. In the case of males, relative dimensions of TL, FeL and FoL may be functioning as important traits for escape from predators. The present study shows the importance of incorporating size and shape variables into analyses of sexual dimorphism among populations of a single species with a wide distribution. These types of studies help to identify the causes that promote sexual dimorphism, as well as the degree of difference among populations that inhabit different environments.
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39
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Cruz‐Elizalde R, Villamar‐Duque TE, Ramírez‐Bautista A. Sexual dimorphism in size and shape in the viviparous lizard
Abronia taeniata
(Squamata: Anguidae) in central Mexico. ACTA ZOOL-STOCKHOLM 2020. [DOI: 10.1111/azo.12329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Raciel Cruz‐Elizalde
- Museo de Zoología ‘‘Alfonso L. Herrera’’ Departamento de Biología Evolutiva Facultad de Ciencias Universidad Nacional Autónoma de México (UNAM) México City México
| | - Tomás E. Villamar‐Duque
- Bioterio General Facultad de Estudios Superiores Iztacala Universidad Nacional Autónoma de México México City México
| | - Aurelio Ramírez‐Bautista
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo México City México
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40
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Common LK, O'Connor JA, Dudaniec RY, Peters KJ, Kleindorfer S. Evidence for rapid downward fecundity selection in an ectoparasite (Philornis downsi) with earlier host mortality in Darwin's finches. J Evol Biol 2020; 33:524-533. [PMID: 31961983 PMCID: PMC7217188 DOI: 10.1111/jeb.13588] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 01/09/2020] [Accepted: 01/15/2020] [Indexed: 01/05/2023]
Abstract
Fecundity selection is a critical component of fitness and a major driver of adaptive evolution. Trade‐offs between parasite mortality and host resources are likely to impose a selection pressure on parasite fecundity, but this is little studied in natural systems. The ‘fecundity advantage hypothesis’ predicts female‐biased sexual size dimorphism whereby larger females produce more offspring. Parasitic insects are useful for exploring the interplay between host resource availability and parasite fecundity, because female body size is a reliable proxy for fecundity in insects. Here we explore temporal changes in body size in the myiasis‐causing parasite Philornis downsi (Diptera: Muscidae) on the Galápagos Islands under conditions of earlier in‐nest host mortality. We aim to investigate the effects of decreasing host resources on parasite body size and fecundity. Across a 12‐year period, we observed a mean of c. 17% P. downsi mortality in host nests with 55 ± 6.2% host mortality and a trend of c. 66% higher host mortality throughout the study period. Using specimens from 116 Darwin's finch nests (Passeriformes: Thraupidae) and 114 traps, we found that over time, P. downsi pupae mass decreased by c. 32%, and male (c. 6%) and female adult size (c. 11%) decreased. Notably, females had c. 26% smaller abdomens in later years, and female abdomen size was correlated with number of eggs. Our findings imply natural selection for faster P. downsi pupation and consequently smaller body size and lower parasite fecundity in this newly evolving host–parasite system.
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Affiliation(s)
- Lauren K Common
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia
| | - Jody A O'Connor
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia.,Department for Environment and Water, Government of South Australia, Adelaide, SA, Australia
| | - Rachael Y Dudaniec
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Katharina J Peters
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia
| | - Sonia Kleindorfer
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia.,Konrad Lorenz Research Center for Behaviour and Cognition and Department of Behavioural and Cognitive Biology, University of Vienna, Vienna, Austria
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41
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Ramírez‐Bautista A, Sites JW, Marshall JC, Cruz‐Elizalde R, Díaz‐Marín CA, Hernández‐Salinas U, Berriozabal‐Islas C, García‐Rosales A. Reproduction and sexual dimorphism in the viviparous lizard
Sceloporus palaciosi
(Squamata: Phrynosomatidae) from the Trans‐Mexican Volcanic Belt, Mexico. ACTA ZOOL-STOCKHOLM 2019. [DOI: 10.1111/azo.12315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aurelio Ramírez‐Bautista
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo Mineral de La Reforma Mexico
| | - Jack W. Sites
- Department of Biology Austin Peay State University Clarksville TN USA
| | | | - Raciel Cruz‐Elizalde
- Museo de Zoología “Alfonso L. Herrera” Facultad de Ciencias Universidad Nacional Autónoma de México (UNAM) Ciudad de México Mexico
| | - César A. Díaz‐Marín
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo Mineral de La Reforma Mexico
| | | | - Christian Berriozabal‐Islas
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo Mineral de La Reforma Mexico
| | - Aaron García‐Rosales
- Laboratorio de Ecología de Poblaciones Centro de Investigaciones Biológicas Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo Mineral de La Reforma Mexico
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42
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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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43
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Burbrink FT, Futterman I. Female-biased gape and body-size dimorphism in the New World watersnakes (tribe: Thamnophiini) oppose predictions from Rensch's rule. Ecol Evol 2019; 9:9624-9633. [PMID: 31534680 PMCID: PMC6745821 DOI: 10.1002/ece3.5492] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 06/21/2019] [Accepted: 07/02/2019] [Indexed: 01/19/2023] Open
Abstract
ABSTRACT Sexual-size dimorphism (SSD) is ubiquitous across animals and often biased in the direction of larger females in snakes and other ectothermic organisms. To understand how SSD evolves across species, Rensch's rule predicts that in taxa where males are larger, SSD increases with body size. In contrast, where females are larger, SSD decreases with body size. While this rule holds for many taxa, it may be ambiguous for others, particularly ectothermic vertebrates. Importantly, this rule suggests that the outcomes of SSD over phylogenetic time scales depend on the direction of dimorphism predicated on the difference in reproductive efforts between males and females. Here, we examine SSD in the context of Rensch's rule in Thamnophiini, the gartersnakes and watersnakes, a prominent group that in many areas comprises the majority of the North American snake biota. Using a dated phylogeny, measurements of gape, body, and tail size, we show that these snakes do not follow Rensch's rule, but rather female-biased SSD increases with body size. We in turn find that this allometry is most pronounced with gape and is correlated with both neonate and litter size, suggesting that acquiring prey of increased size may be directly related to fecundity selection. These changes in SSD are not constrained to any particular clade; we find no evidence of phylogenetic shifts in those traits showing SSD. We suggest several ways forward to better understand the anatomical units of selection for SSD and modularity. OPEN RESEARCH BADGES This article has been awarded Open Data and Open Materials Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.5061/dryad.3pn57h0.
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Affiliation(s)
- Frank T. Burbrink
- Department of HerpetologyThe American Museum of Natural HistoryNew YorkNYUSA
| | - India Futterman
- Department of HerpetologyThe American Museum of Natural HistoryNew YorkNYUSA
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44
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Reedy AM, Evans WJ, Cox RM. Sexual dimorphism explains residual variance around the survival‐reproduction tradeoff in lizards: Implications for sexual conflict over life‐history evolution*. Evolution 2019; 73:2324-2332. [DOI: 10.1111/evo.13799] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron M. Reedy
- Department of BiologyUniversity of Virginia Charlottesville Virginia 22904
- Department of Biological SciencesAuburn University Auburn Alabama 36849
| | - William J. Evans
- Department of BiologyUniversity of Virginia Charlottesville Virginia 22904
| | - Robert M. Cox
- Department of BiologyUniversity of Virginia Charlottesville Virginia 22904
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45
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Yang C, Zhao J, Diaz RE, Lyu N. Development of sexual dimorphism in two sympatric skinks with different growth rates. Ecol Evol 2019; 9:7752-7760. [PMID: 31346437 PMCID: PMC6636199 DOI: 10.1002/ece3.5358] [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: 08/21/2018] [Revised: 05/07/2019] [Accepted: 05/14/2019] [Indexed: 11/18/2022] Open
Abstract
Sexual size dimorphism (SSD) is widespread in animals, especially in lizards (Reptilia: Squamata), and is driven by fecundity selection, male-male competition, or other adaptive hypotheses. However, these selective pressures may vary through different life history periods; thus, it is essential to assess the relationship between growth and SSD. In this study, we tracked SSD dynamics between a "fading-tail color skink" (blue tail skink whose tail is only blue during its juvenile stage: Plestiodon elegans) and a "nonfade color" tail skink (retains a blue tail throughout life: Plestiodon quadrilineatus) under a controlled experimental environment. We fitted growth curves of morphological traits (body mass, SVL, and TL) using three growth models (Logistic, Gompertz, and von Bertalanffy). We found that both skinks have male-biased SSD as adults. Body mass has a higher goodness of fit (as represented by very high R 2 values) using the von Bertalanffy model than the other two models. In contrast, SVL and TL for both skinks had higher goodness of fit when using the Gompertz model. Two lizards displayed divergent life history tactics: P. elegans grows faster, matures earlier (at 65 weeks), and presents an allometric growth rate, whereas P. quadrilineatus grows slower, matures later (at 106 weeks), and presents an isometric growth rate. Our findings imply that species- and sex-specific trade-offs in the allocation of energy to growth and reproduction may cause the growth patterns to diverge, ultimately resulting in the dissimilar patterns of SSD.
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Affiliation(s)
- Chen Yang
- Chengdu Institute of BiologyChinese Academy of SciencesChengduChina
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education)China West Normal UniversityNanchongChina
| | - Jinming Zhao
- School of Resources and Environmental EngineeringAnhui UniversityHefeiChina
| | - Raul E. Diaz
- Department of Biological SciencesSoutheastern Louisiana UniversityHammondLouisiana
| | - Nan Lyu
- Ministry of Education Key Laboratory for Biodiversity and Ecological EngineeringCollege of Life SciencesBeijing Normal UniversityBeijingChina
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Recknagel H, Elmer KR. Differential reproductive investment in co-occurring oviparous and viviparous common lizards (Zootoca vivipara) and implications for life-history trade-offs with viviparity. Oecologia 2019; 190:85-98. [PMID: 31062164 PMCID: PMC6535419 DOI: 10.1007/s00442-019-04398-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 04/02/2019] [Indexed: 01/31/2023]
Abstract
Live-bearing reproduction (viviparity) has evolved from egg-laying (oviparity) independently many times and most abundantly in squamate reptiles. Studying life-history trade-offs between the two reproductive modes is an inherently difficult task, as most transitions to viviparity are evolutionarily old and/or are confounded by environmental effects. The common lizard (Zootoca vivipara) is one of very few known reproductively bimodal species, in which some populations are oviparous and others viviparous. Oviparous and viviparous populations can occur in sympatry in the same environment, making this a unique system for investigating alternative life-history trade-offs between oviparous and viviparous reproduction. We find that viviparous females exhibit larger body size, smaller clutch sizes, a larger reproductive investment, and a higher hatching success rate than oviparous females. We find that offspring size and weight from viviparous females was lower compared to offspring from oviparous females, which may reflect space constraints during pregnancy. We suggest that viviparity in common lizards is associated with increased reproductive burden for viviparous females and speculate that this promoted the evolution of larger body size to create more physical space for developing embryos. In the context of life-history trade-offs in the evolution of viviparity, we suggest that the extent of correlation between reproductive traits, or differences between reproductive modes, may also depend on the time since the transition occurred.
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Affiliation(s)
- Hans Recknagel
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Kathryn R Elmer
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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Littleford‐Colquhoun BL, Clemente C, Thompson G, Cristescu RH, Peterson N, Strickland K, Stuart‐Fox D, Frere CH. How sexual and natural selection shape sexual size dimorphism: Evidence from multiple evolutionary scales. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13337] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Christofer Clemente
- School of Science and Engineering University of the Sunshine Coast Sippy Downs Queensland Australia
| | - Graham Thompson
- Terrestrial Ecosystems Mount Claremont Western Australia Australia
| | - Romane H. Cristescu
- School of Science and Engineering University of the Sunshine Coast Sippy Downs Queensland Australia
| | - Nicola Peterson
- School of Science and Engineering University of the Sunshine Coast Sippy Downs Queensland Australia
| | - Kasha Strickland
- School of Science and Engineering University of the Sunshine Coast Sippy Downs Queensland Australia
| | - Devi Stuart‐Fox
- School of Biosciences The University of Melbourne Melbourne Victoria Australia
| | - Celine H. Frere
- School of Science and Engineering University of the Sunshine Coast Sippy Downs Queensland Australia
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48
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Satomi D, Koshio C, Tatsuta H, Kudo S, Takami Y. Latitudinal variation and coevolutionary diversification of sexually dimorphic traits in the false blister beetle Oedemera sexualis. Ecol Evol 2019; 9:4949-4957. [PMID: 31031956 PMCID: PMC6476772 DOI: 10.1002/ece3.5101] [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: 12/20/2018] [Revised: 02/28/2019] [Accepted: 03/04/2019] [Indexed: 11/25/2022] Open
Abstract
Sexual traits are subject to evolutionary forces that maximize reproductive benefits and minimize survival costs, both of which can depend on environmental conditions. Latitude explains substantial variation in environmental conditions. However, little is known about the relationship between sexual trait variation and latitude, although body size often correlates with latitude. We examined latitudinal variation in male and female sexual traits in 22 populations of the false blister beetle Oedemera sexualis in the Japanese Archipelago. Males possess massive hind legs that function as a female-grasping apparatus, while females possess slender hind legs that are used to dislodge mounting males. Morphometric analyses revealed that male and female body size (elytron length), length and width of the hind femur and tibia, and allometric slopes of these four hind leg dimensions differed significantly among populations. Of these, three traits showed latitudinal variation, namely, male hind femur was stouter; female hind tibia was slenderer, and female body was smaller at lower latitudes than at higher latitudes. Hind leg sizes and shapes, as measured by principal component analysis of these four hind leg dimensions in each sex, covaried significantly between sexes, suggesting coevolutionary diversification in sexual traits. Covariation between sexes was weaker when variation in these traits with latitude was removed. These results suggest that coevolutionary diversification between male and female sexual traits is mediated by environmental conditions that vary with latitude.
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Affiliation(s)
- Daisuke Satomi
- Graduate School of Human Development and EnvironmentKobe UniversityKobeJapan
| | - Chiharu Koshio
- Department of BiologyNaruto University of EducationTokushimaJapan
| | - Haruki Tatsuta
- Faculty of AgricultureUniversity of the RyukyusOkinawaJapan
| | - Shin‐ichi Kudo
- Department of BiologyNaruto University of EducationTokushimaJapan
| | - Yasuoki Takami
- Graduate School of Human Development and EnvironmentKobe UniversityKobeJapan
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Alternative reproductive adaptations predict asymmetric responses to climate change in lizards. Sci Rep 2019; 9:5093. [PMID: 30911069 PMCID: PMC6433898 DOI: 10.1038/s41598-019-41670-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/15/2019] [Indexed: 11/28/2022] Open
Abstract
Anthropogenic climate change ranks among the major global-scale threats to modern biodiversity. Extinction risks are known to increase via the interactions between rapid climatic alterations and environmentally-sensitive species traits that fail to adapt to those changes. Accumulating evidence reveals the influence of ecophysiological, ecological and phenological factors as drivers underlying demographic collapses that lead to population extinctions. However, the extent to which life-history traits influence population responses to climate change remains largely unexplored. The emerging ‘cul-de-sac hypothesis’ predicts that reptilian viviparity (‘live-bearing’ reproduction), a ‘key innovation’ facilitating historical invasions of cold climates, increases extinction risks under progressively warming climates compared to oviparous reproduction – as warming advances polewards/mountainwards, historically cold-climates shrink, leading viviparous species to face demographic collapses. We present the first large-scale test of this prediction based on multiple lizard radiations and on future projections of climate-based ecological niche models. Viviparous species were found to experience stronger elevational range shifts (and potentially increased extinctions) in coming decades, compared to oviparous lizards. Therefore, our analyses support the hypothesis’s fundamental prediction that elevational shifts are more severe in viviparous species, and highlight the role that life-history adaptations play in the responses of biodiversity to ongoing climate change.
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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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