Ecology and Biogeography of Sexual Size Dimorphism in Squamates

IF 6.3 1区环境科学与生态学 Q1 ECOLOGY

Global Ecology and Biogeography Pub Date : 2025-06-25 DOI:10.1111/geb.70076

Tao Liang, Gopal Murali, Anna Zimin, Jacob Dembitzer, Roberta Graboski, Uri Roll, Shai Meiri

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Abstract

Aim

Sexual size dimorphism (SSD) is widespread in the animal kingdom. The direction and magnitude of SSD differ considerably across taxa, potentially due to different selective forces acting on female and male sizes. We assembled a comprehensive database of mean body sizes for female and male squamate species. We then tested for associations between the degree and direction of sexual size dimorphism and environmental factors, clutch/litter sizes, reproductive modes, substrate types, and species richness (a common measure of interspecific competition).

Location

Global.

Time Period

Present.

Major Taxa Studied

Squamata (Reptilia).

Methods

We studied SSD patterns and their correlates for 11792 squamate species. We also tested the effect of the number of putative competitors on SSD within (~9915 km²) grid cells. We applied phylogenetic path analysis and phylogenetic generalised least squares regression (PGLS) at the species level and applied spatial auto-regressive (SAR) multiple regressions at assemblage levels.

Results

In general, snake females are larger than males, whereas male lizards are larger, on average, than females. Female squamates in general are larger than males in cold regions, while in warm regions, particularly in deserts, males are usually larger than females. SSD became more female-biased (i.e., larger females) as clutch size increased, and viviparous taxa had more female-biased SSD. There was little relationship between the magnitude of SSD and species richness. Sexual size dimorphism did not vary significantly across substrate types.

Main Conclusion

We suggest that the mechanisms driving squamate SSD differ between oviparous and viviparous taxa. The more female-biased SSD in colder regions is likely driven by fecundity selection, while a male bias in warmer regions may be associated with sexual selection. However, we found little evidence to suggest that natural selection for substrates, or resource-based competition, affects squamate sexual size dimorphism and suspect the underlying hypotheses may be flawed, and/or that species richness is a poor measure of the intensity of interspecific competition.

Abstract Image

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鳞片两性大小二形现象的生态学和生物地理学

目的雌雄大小二态现象在动物界普遍存在。在不同的分类群中，SSD的方向和大小有很大的不同，这可能是由于不同的选择力作用于雌性和雄性的大小。我们收集了一个完整的雌性和雄性鳞片动物的平均体型数据库。然后，我们测试了性别大小二态性的程度和方向与环境因素、窝/窝数、繁殖模式、基质类型和物种丰富度（种间竞争的一种常见衡量标准）之间的关系。位置全球。时间：现在。鳞片目（爬行纲）的主要分类群。方法对11792种鳞科动物的SSD模式及其相关因素进行研究。我们还在（~9915 km2）网格单元内测试了假定竞争对手的数量对SSD的影响。在物种水平上应用系统发育路径分析和系统发育广义最小二乘回归（PGLS），在组合水平上应用空间自回归（SAR）多元回归。结果一般情况下，雌蛇比雄蛇大，而雄蜥蜴平均比雌蛇大。在寒冷地区，雌性鳞片通常比雄性鳞片大，而在温暖地区，特别是在沙漠中，雄性鳞片通常比雌性鳞片大。随着卵数的增加，固态固态动物更偏向于雌性（即更大的雌性），而胎生类群的固态固态动物更偏向于雌性。物种丰富度与固态降水的大小关系不大。两性大小二态性在不同底物类型间差异不显著。结论卵生和胎生类群中鳞片SSD的发生机制存在差异。在较冷的地区，更偏向于女性的SSD可能是由生育选择驱动的，而在较温暖的地区，更偏向于男性的SSD可能与性选择有关。然而，我们发现很少有证据表明自然选择底物或资源竞争影响鳞片性别大小二态性，并怀疑潜在的假设可能有缺陷，并且/或者物种丰富度是衡量种间竞争强度的不良指标。

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来源期刊

Global Ecology and Biogeography 环境科学-生态学

CiteScore

12.10

自引率

3.10%

发文量

170

审稿时长

3 months

期刊介绍： Global Ecology and Biogeography (GEB) welcomes papers that investigate broad-scale (in space, time and/or taxonomy), general patterns in the organization of ecological systems and assemblages, and the processes that underlie them. In particular, GEB welcomes studies that use macroecological methods, comparative analyses, meta-analyses, reviews, spatial analyses and modelling to arrive at general, conceptual conclusions. Studies in GEB need not be global in spatial extent, but the conclusions and implications of the study must be relevant to ecologists and biogeographers globally, rather than being limited to local areas, or specific taxa. Similarly, GEB is not limited to spatial studies; we are equally interested in the general patterns of nature through time, among taxa (e.g., body sizes, dispersal abilities), through the course of evolution, etc. Further, GEB welcomes papers that investigate general impacts of human activities on ecological systems in accordance with the above criteria.