Environmental correlates of phenotypic evolution in ecologically diverse Liolaemus lizards

Evolutionary correlations between phenotypic and environmental traits characterize adaptive radiations. However, the lizard genus Liolaemus, one of the most ecologically diverse terrestrial vertebrate radiations on earth, has so far shown limited or mixed evidence of adaptive diversification in phenotype. Restricted use of comprehensive environmental data, incomplete taxonomic representation and not considering phylogenetic uncertainty may have led to contradictory evidence. We compiled a 26 taxon dataset for the L. gracilis species group, representing much of the ecological diversity represented within Liolaemus, and used environmental data to characterize how environments occupied by species' relate to phenotypic evolution. Our analyses, explicitly accounting for phylogenetic uncertainty, suggest diversification in phenotypic traits toward the present, with body shape evolution rapidly evolving in this group. Body shape evolution correlates with the occupation of different structural habitats indicated by vegetation axes suggesting species have adapted for maximal locomotory performance in these habitats. Our results also imply that the effects of phylogenetic uncertainty and model misspecification may be more extensive on univariate, relative to multivariate analyses of evolutionary correlations, which is an important consideration of analyzing data from rapidly radiating adaptive radiations.表型性状与环境性状之间的演化相关性是适应性辐射（adaptive radiations）的典型特征。然而，作为全球生态多样性最为丰富的陆生脊椎动物适应性辐射类群之一的平腹蜥属（Liolaemus），目前关于其表型适应性分化的研究证据仍较为有限且存在矛盾。此前研究得出相悖结论的潜在原因可能包括：综合环境数据的应用受限、分类群采样不完整，以及未纳入系统发育不确定性（phylogenetic uncertainty）因素。 本研究构建了涵盖平腹蜥属绝大多数生态多样性的细平腹蜥物种群（L. gracilis species group）26个分类单元数据集，并利用环境数据解析物种所占据的生境与表型演化之间的关联。我们的分析明确纳入了系统发育不确定性因素，结果显示该类群的表型性状随演化进程逐步分化，其中体形演化速率较快。体形演化与基于植被轴所表征的不同结构生境的占据情况显著相关，这表明物种已针对其所在生境的最优运动性能产生适应性演化。 本研究结果还表明，相较于演化相关性的多变量分析，系统发育不确定性与模型设定偏误（model misspecification）对单变量（univariate）分析的影响更为显著，这是开展快速辐射适应性辐射类群数据分析时需重点考量的关键因素。