Reproductive mode evolution in lizards revisited: updated analyses examining geographic, climatic and phylogenetic effects support the cold‐climate hypothesis
Reproductive mode evolution in lizards revisited: updated analyses examining geographic, climatic and phylogenetic effects support the cold‐climate hypothesis
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DOI：
10.1111/jeb.12536
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发表时间：
2014-12
影响因子：
2.1
通讯作者：
Charles M. Watson;R. Makowsky;Justin C. Bagley
中科院分区：
文献类型：
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作者：
Charles M. Watson;R. Makowsky;Justin C. Bagley
胎生，即生育活的幼崽，在有鳞爬行动物中已经进化了100多次。这种繁殖策略被假设为允许母体控制胎儿的热环境，从而增加父母和后代的适应性。有两种假说可以解释这种现象：（i）寒冷气候假说（CCH），主张低温是主要的选择力;（ii）母体操纵假说（MMH），主张温度变化是主要的选择力。在这里，我们调查是否与CCH与MMH相关的气候和地理变量最好地解释了目前的地理分布的蜥蜴胎生，同时结合比较方法的最新进展，鳞片遗传学和地理空间分析。为了做到这一点，我们比较了非系统发育和系统发育模型预测胎生，这些模型基于来自20994个博物馆标本（代表215种蜥蜴）的捕获点数据，以及空间上明确的生物气候和地理（海拔和纬度）数据层。我们分析的数据库强调了来自三个物种丰富的属（Phrynosoma，Plestiodon和Sceloporus）的新北蜥蜴;然而，我们还分析了一个不太重要但世界范围内的物种样本，以验证我们的新北结果的普遍性。我们发现，最温暖的月份的最高温度（和，不太常见，海拔和最高温度的最干燥的季度）往往是胎生的最佳预测，并显示出与CCH一致的关联。我们的研究结果强烈支持CCH的MMH在解释蜥蜴生殖方式的进化。
Viviparity, the bearing of live young, has evolved well over 100 times among squamate reptiles. This reproductive strategy is hypothesized to allow maternal control of the foetus' thermal environment and thereby to increase the fitness of the parents and offspring. Two hypotheses have been posited to explain this phenomenon: (i) the cold‐climate hypothesis (CCH), which advocates low temperatures as the primary selective force; and (ii) the maternal manipulation hypothesis (MMH), which advocates temperature variability as the primary selective force. Here, we investigate whether climatic and geographic variables associated with the CCH vs. the MMH best explain the current geographical distributions of viviparity in lizards while incorporating recent advances in comparative methods, squamate phylogenetics and geospatial analysis. To do this, we compared nonphylogenetic and phylogenetic models predicting viviparity based on point‐of‐capture data from 20 994 museum specimens representing 215 lizard species in conjunction with spatially explicit bioclimatic and geographic (elevation and latitude) data layers. The database we analysed emphasized Nearctic lizards from three species‐rich genera (Phrynosoma, Plestiodon and Sceloporus); however, we additionally analysed a less substantial, but worldwide sample of species to verify the universality of our Nearctic results. We found that maximum temperature of the warmest month (and, less commonly, elevation and maximum temperature of the driest quarter) was frequently the best predictor of viviparity and showed an association consistent with the CCH. Our results strongly favour the CCH over the MMH in explaining lizard reproductive mode evolution.