Data from: Adult frogs and tadpoles have different macroevolutionary patterns across the Australian continent

Developmental changes through an animal’s life are generally understood to contribute to the resulting adult morphology. A possible exception are species with complex life cycles, where individuals pass through distinct ecological and morphological life stages during their ontogeny, ending with metamorphosis to the adult form. Antagonistic selection is expected to drive low genetic correlations between life stages, theoretically permitting stages to evolve independently. Using the Australian frog radiation, we examine the evolutionary consequences on morphological evolution when life stages are under different selective pressures. We use morphometrics to characterise body shape of tadpoles and adults across 166 species of frog and investigate similarities in the two resulting morphological spaces (morphospaces) to test for concerted evolution across metamorphosis in trait variation during speciation. A clear pattern emerges: Australian frogs and their tadpoles are evolving independently; their drastically different morphospaces and contrasting estimated evolutionary histories of body shape diversification indicate that different processes are driving morphological diversification at each stage. Tadpole morphospace is characterised by rampant homoplasy, convergent evolution and high lineage density; the adult morphospace by contrast shows greater phylogenetic signal, low lineage density and divergent evolution between the main clades. Our results provide insight into the macroevolutionary consequences of a biphasic life cycle.

通常认为，动物一生中的发育变化会对最终形成的成体形态（adult morphology）产生塑造作用。拥有复杂生活史的物种或为例外：这类物种的个体在个体发育（ontogeny）过程中会经历截然不同的生态与形态生活阶段，最终通过变态发育（metamorphosis）转变为成体形态。拮抗选择（antagonistic selection）被认为会驱动不同生活阶段间产生较低的遗传相关性，理论上允许各阶段独立演化。本研究以澳大利亚蛙类适应辐射（Australian frog radiation）类群为研究对象，探讨当生活史不同阶段面临不同选择压力时，形态演化所产生的进化后果。我们利用形态测量学（morphometrics）对166种蛙类的蝌蚪与成体身体形态进行表征，并对二者构建的形态空间（morphospace）开展相似性分析，以检验物种形成过程中性状变异在变态前后是否存在协同演化。研究结果呈现出清晰的规律：澳大利亚蛙类与其蝌蚪的演化路径相互独立；二者差异显著的形态空间以及截然不同的身体形态多样化演化历史表明，不同的演化过程驱动着两个阶段的形态多样化。蝌蚪的形态空间以广泛的同塑性演化（homoplasy）、趋同演化以及较高的支系（clade）密度为特征；而成体形态空间则展现出更强的系统发育信号（phylogenetic signal）、较低的支系密度以及主要支系间的趋异演化。本研究结果为理解双相生活史（biphasic life cycle）的宏观演化后果提供了新的见解。