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

Abstract

Developmental changes through an animal's life are generally understood to contribute to the resulting adult morphology. Possible exceptions 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. Here we describe, using Australian frog radiation, the evolutionary consequences on morphological evolution when life stages are under different selective pressures. We use morphometrics to characterize 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 markedly 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 characterized by rampant homoplasy, convergent evolution and high lineage density. By contrast, the adult morphospace 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.

Differences in responsiveness and sensitivity to exogenous disruptors of the thyroid gland in three anuran species

“…This suggests that evolutionary changes in the sensitivity and responsiveness of the jaws to TH may in part account for the diversity in jaw length and diet among different anuran lineages. At present, there are gene expression and phenotypic evidence that larval and adult phases may evolve independently (Sherratt, Vidal‐García, Anstis, & Keogh, ; Wollenberg Valero, Garcia‐Porta, Rodriguez, ). However, it is possible that TH signals, tadpole ecomorphology, and the magnitude of metamorphosis changes provide an epigenetic link in the evolution of larval and adult phases [Color figure can be viewed at wileyonlinelibrary.com]…”

Ecomorphological diversity of Australian tadpoles

“…Our sampling is extensive from the continent of Australia, which is home to 242 native anuran species (AmphibiaWeb), excluding the recent invasive migrant, the cane toad ( Bufo marinus ) and the migrant Papurana daemeli (Ranidae; formerly Hylarana ). In total, we sampled 187 species with a distinct larval stage (Supporting information Table , details of these are given below) from the precise drawings of preserved specimens in the comprehensive work of Anstis (), which have been used in previous studies (Sherratt, Vidal‐García, Anstis, & Keogh, ; van Buskirk, ). The sampled tadpoles are at a similar stage in their development (mean Gosner stage 35.4, ±3.09) when the hindlimb bud is visible with very short toe nubs.…”

Journeys through discrete‐character morphospace: synthesizing phylogeny, tempo, and disparity

“…Page & Cooper ; Sherratt et al . ). In its implementation it is usually faster, as it is applied after the dimensionality of the data has been reduced by ordination, and it has the theoretical advantage of allowing phylogenetic uncertainty to be expressed visually in the same space (as changing the tree does not ‘move’ the tip values in the ordination), although I am not aware of this being done.…”