Data from: Convergent evolution across the Australian continent: ecotype diversification drives morphological convergence in two distantly related clades of Australian frogs

Animals from different clades but subject to similar environments often evolve similar body shapes and physiological adaptations due to convergent evolution, but this has been rarely tested at the transcontinental level and across entire classes of animal. Australia's biome diversity, isolation and aridification history provide excellent opportunities for comparative analyses on broad-scale macroevolutionary patterns. We collected morphological and environmental data on eighty-four (98%) Australian hylid frog species and categorized them into ecotypes. Using a phylogenetic framework, we tested the hypothesis that frogs from the same ecotype display similar body shape patterns: (i) across all the Australian hylids, and (ii) through comparison with a similar previous study on 127 (97%) Australian myobatrachid species. Body size and shape variation did not follow a strong phylogenetic pattern and was not tightly correlated with environment, but there was a stronger association between morphotype and ecotype. Both arboreal and aquatic frogs had long limbs, whereas limbs of fossorial species were shorter. Other terrestrial species were convergent on the more typical frog body shape. We quantified the strength of morphological convergence at two levels: (i) between fossorial myobatrachid and hylid frogs, and (ii) in each ecomorph within the hylids. We found strong convergence within ecotypes, especially in fossorial species. Ecotypes were also reflected in physiological adaptations: both arboreal and cocooned fossorial frogs tend to have higher rates of evaporative water loss. Our results illustrate how adaptation to different ecological niches plays a crucial role in morphological evolution, boosting phenotypic diversity within a clade. Despite phylogenetic conservatism, morphological adaptation to repeatedly emerging new environments can erase the signature of ancestral morphotypes, resulting in phenotypic diversification and convergence both within and between diverse clades.

尽管属于不同演化支（clade），但受相似环境作用的动物常因趋同演化（convergent evolution）演化出相似的体型与生理适应特征，不过这类现象很少在跨大陆尺度、乃至整个动物类群层面得到验证。澳大利亚多样的生物群系（biome）、地理隔离及其干旱化演化历史，为开展大尺度宏观演化格局的比较分析提供了绝佳契机。我们收集了84种（占澳大利亚雨蛙科（Hylidae）物种的98%）蛙类的形态学与环境数据，并将其划分为不同生态型（ecotype）。我们依托系统发育框架（phylogenetic framework），验证了两项相关假说：其一，在澳大利亚全部雨蛙科类群中，归属同一生态型的蛙类会呈现相似的体型模式；其二，通过与此前一项针对127种（占澳大利亚龟蟾科（Myobatrachidae）物种的97%）蛙类的类似研究开展对比，进一步验证该假说。体型与体型变异并未呈现显著的系统发育模式，也未与环境呈现紧密关联，但形态型（morphotype）与生态型之间却存在更强的相关性。树栖（arboreal）与水生（aquatic）蛙类均具有较长的四肢，而穴居（fossorial）蛙类的四肢则相对较短。其余陆栖（terrestrial）蛙类则趋向于更具代表性的蛙类体型模式。我们从两个层面量化了形态趋同的强度：一是穴居的龟蟾科与雨蛙科蛙类之间的形态趋同，二是雨蛙科内部各生态形态类群（ecomorph）间的形态趋同。我们发现生态型内部存在显著的形态趋同，尤以穴居蛙类为甚。生态型差异同样体现在生理适应特征上：树栖蛙类与结茧穴居蛙类的蒸发失水率（evaporative water loss）普遍更高。本研究结果阐明了适应不同生态位（ecological niche）如何在体型演化中发挥关键作用，并推动了单一演化支内部的表型多样性（phenotypic diversity）提升。尽管存在系统发育保守性（phylogenetic conservatism），但针对反复出现的新环境的形态适应，能够抹去祖先形态型的特征印记，进而在多个不同演化支内部及之间引发表型分化与趋同演化。