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，动物整个生命周期的发育变化会共同塑造其最终的成体形态（adult morphology）。存在一类潜在例外，即拥有复杂生活史的物种：此类物种的个体在个体发育（ontogeny）进程中会经历截然不同的生态与形态生活阶段，最终经变态发育（metamorphosis）转变为成体形态。拮抗选择（antagonistic selection）被认为会推动不同生活史阶段间形成较低的遗传相关性，从而在理论上允许各阶段独立演化。本研究以澳大利亚蛙类辐射演化（Australian frog radiation）为研究体系，探究当不同生活史阶段承受差异化选择压力时，形态演化所产生的进化后果。本研究采用形态测量学（morphometrics）对166种蛙类的蝌蚪与成体体型进行形态表征，并基于二者构建的形态空间（morphospace）分析两者的形态相似性，以检验物种形成过程中，性状变异在变态发育前后是否存在协同演化（concerted evolution）。研究结果呈现出清晰的演化模式：澳大利亚蛙类与其蝌蚪正独立演化；二者差异显著的形态空间，以及截然不同的成体体型多样化演化历史表明，不同的演化过程驱动着各阶段的形态多样化。蝌蚪的形态空间以频发的同塑性（homoplasy）、趋同演化（convergent evolution）以及较高的支系密度为典型特征；相较之下，成体的形态空间则表现出更强的系统发育信号（phylogenetic signal）、较低的支系密度以及主要演化支间的趋异演化。本研究结果为理解两阶段生活史（biphasic life cycle）的宏观演化后果提供了全新的研究视角。