Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect St, New Haven, CT 06511, USA.
Department of Biological Sciences, University of Alabama, 1325 Hackberry Ln, Tuscaloosa, AL 35401, USA.
Syst Biol. 2024 Oct 30;73(5):743-757. doi: 10.1093/sysbio/syae041.
Adaptive radiation involves diversification along multiple trait axes, producing phenotypically diverse, species-rich lineages. Theory generally predicts that multi-trait evolution occurs via a "stages" model, with some traits saturating early in a lineage's history, and others diversifying later. Despite its multidimensional nature, however, we know surprisingly little about how different suites of traits evolve during adaptive radiation. Here, we investigated the rate, pattern, and timing of morphological and physiological evolution in the anole lizard adaptive radiation from the Caribbean island of Hispaniola. Rates and patterns of morphological and physiological diversity are largely unaligned, corresponding to independent selective pressures associated with structural and thermal niches. Cold tolerance evolution reflects parapatric divergence across elevation, rather than niche partitioning within communities. Heat tolerance evolution and the preferred temperature evolve more slowly than cold tolerance, reflecting behavioral buffering, particularly in edge-habitat species (a pattern associated with the Bogert effect). In contrast to the nearby island of Puerto Rico, closely related anoles on Hispaniola do not sympatrically partition thermal niche space. Instead, allopatric and parapatric separation across biogeographic and environmental boundaries serves to keep morphologically similar close relatives apart. The phenotypic diversity of this island's adaptive radiation accumulated largely as a by-product of time, with surprisingly few exceptional pulses of trait evolution. A better understanding of the processes that guide multidimensional trait evolution (and nuance therein) will prove key in determining whether the stages model should be considered a common theme of adaptive radiation.
适应辐射涉及沿着多个特征轴的多样化，产生表型多样、物种丰富的谱系。理论通常预测，多特征进化是通过“阶段”模型发生的，一些特征在谱系历史的早期就饱和了，而其他特征则在后期多样化。然而，尽管它具有多维性质，但我们对不同特征套件在适应辐射过程中是如何进化的知之甚少。在这里，我们研究了来自加勒比海伊斯帕尼奥拉岛的变色龙蜥蜴适应辐射中形态和生理进化的速度、模式和时间。形态和生理多样性的速度和模式在很大程度上是不相关的，对应于与结构和热生态位相关的独立选择压力。耐寒性进化反映了沿海拔的并系分歧，而不是群落内的生态位划分。耐热性进化和最适温度的进化比耐寒性进化慢，反映了行为缓冲，特别是在边缘生境物种中（与 Bogert 效应相关的模式）。与附近的波多黎各岛不同，在伊斯帕尼奥拉岛上亲缘关系密切的变色龙并没有同域地划分热生态位空间。相反，生物地理和环境边界的异域和并系分离有助于将形态相似的近亲分开。这个岛屿的适应辐射的表型多样性主要是时间的副产品，很少有特征进化的异常脉冲。更好地理解指导多维特征进化的过程（及其细微差别）将是确定阶段模型是否应被视为适应辐射的一个共同主题的关键。
