Abstract Monitor lizards (Varanidae) inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes, thus providing an ideal model for examining the role of mainland versus island in driving species evolution. Here we use phylogenetic comparative methods to examine whether a link exists between body size-driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes, body size, and life-history traits (offspring number and size). We predict that: 1) since body size drives rapid diversification in groups, a link exists between body size-driven diversification and body size-frequency distributions; 2) because of various environments on island, island species will have higher speciation, extinction, and dispersal rates, compared with mainland species; 3) as a response to stronger intraspecific competition, island species will maximize individual ability associated with body size to outcompete closely-related species, and island species will produce smaller clutches of larger eggs to increase offspring quality. Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards. There is a link between body size-driven diversification and body size-frequency distributions, and the speciation rate is maximized at medium body sizes. Island species will have higher speciation, equal extinction, and higher dispersal rates compared with mainland species. Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.

中文翻译：

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varanid 蜥蜴的地理多样化：大陆与岛屿在推动物种进化中的作用

摘要 巨蜥（Varanidae）栖息在所有地质类型的大陆和岛屿上，并且已经分化成异常广泛的体型，从而为研究大陆与岛屿在推动物种进化中的作用提供了理想的模型。在这里，我们使用系统发育比较方法来检查蜥蜴蜥蜴的体型驱动多样化和体型频率分布之间是否存在联系，并检验岛蜥在进化过程、体型和生活史方面与大陆物种不同的假设性状（后代数量和大小）。我们预测：1）由于体型驱动群体的快速多样化，因此体型驱动的多样化与体型频率分布之间存在联系；2）由于岛上的各种环境，与大陆物种相比，岛屿物种将具有更高的物种形成、灭绝和扩散速度；3）作为对更强烈的种内竞争的反应，岛屿物种将最大化与体型相关的个体能力以战胜密切相关的物种，岛屿物种将产生较小的较大卵子以提高后代质量。我们的结果证实，不同宏观进化速率的联合效应塑造了蜥蜴蜥蜴的物种丰富度模式。体型驱动的多样化和体型频率分布之间存在联系，并且物种形成率在中等体型时最大化。与大陆物种相比，岛屿物种将具有更高的物种形成、平等的灭绝和更高的扩散率。