Data from: Life-history patterns of lizards of the world

Identification of mechanisms that promote variation in life history traits is critical to understand the evolution of divergent reproductive strategies. Here we compiled a large life-history dataset (674 lizard populations, representing 297 species from 263 sites globally) to test a number of hypotheses regarding the evolution of life history traits in lizards. We found significant phylogenetic signal in most life history traits, although phylogenetic signal was not particularly high. Climatic variables influenced the evolution of many traits, with clutch frequency being positively related to precipitation and clutches of tropical lizards being smaller than those of temperate species. This result supports the hypothesis that in tropical and less seasonal climates, many lizards tend to reproduce repeatedly through the season producing smaller clutches during each reproductive episode. Our analysis also supported the hypothesis that viviparity has evolved in lizards as a response to cooler climates. Finally, we also found that variation in trait values explained by clade membership is unevenly distributed among lizard clades with basal clades and a few younger clades showing most variation. Our global analyses are largely consistent with life history theory and previous results based on smaller and scattered datasets, suggesting that these patterns are remarkably consistent across geographic and taxonomic scales.

阐明驱动生活史性状（life history traits）变异的内在机制，对于理解多样化繁殖策略的演化进程至关重要。本研究构建了一套大型蜥蜴生活史数据集——涵盖全球263个采样点的297个物种、共计674个蜥蜴种群——用以检验诸多关于蜥蜴生活史性状演化的科学假说。研究发现，多数生活史性状存在显著的系统发育信号（phylogenetic signal），尽管该信号的强度并不极高。气候变量对诸多性状的演化存在显著影响：繁殖窝次（clutch frequency）与降水量呈正相关，且热带蜥蜴的单窝卵数显著小于温带物种。这一结果支持如下假说：在热带及季节节律较弱的气候环境中，多数蜥蜴倾向于在繁殖季内多次繁殖，且每次繁殖仅产出较少的窝卵。本研究的分析同时支持"胎生（viviparity）在蜥蜴类群中是对寒冷气候的适应性演化"这一科学假说。此外，我们还发现，由支系（clade）归属所解释的性状值变异在蜥蜴支系间的分布并不均匀：基干支系与少数年轻支系承载了绝大多数的性状变异。我们的全球尺度分析大体与生活史理论及基于小型零散数据集的既往研究结果一致，表明这些演化模式在地理与分类学尺度上均具有高度的一致性。