Study of morphological variation of northern Neotropical Ariidae reveals conservatism despite macrohabitat transitions

Abstract

BackgroundMorphological convergence triggered by trophic adaptations is a common pattern in adaptive radiations. The study of shape variation in an evolutionary context is usually restricted to well-studied fish models. We take advantage of the recently revised systematics of New World Ariidae and investigate skull shape evolution in six genera of northern Neotropical Ariidae. They constitute a lineage that diversified in the marine habitat but repeatedly adapted to freshwater habitats. 3D geometric morphometrics was applied for the first time in catfish skulls and phylogenetically informed statistical analyses were performed to test for the impact of habitat on skull diversification after habitat transition in this lineage.ResultsWe found that skull shape is conserved throughout phylogeny. A morphospace analysis revealed that freshwater and marine species occupy extreme ends of the first principal component axis and that they exhibit similar Procrustes variances. Yet freshwater species occupy the smallest shape space compared to marine and brackish species (based on partial disparity), and marine and freshwater species have the largest Procrustes distance to each other. We observed a single case of shape convergence as derived from ‘C-metrics’, which cannot be explained by the occupation of the same habitat.ConclusionsAlthough Ariidae occupy such a broad spectrum of different habitats from sea to freshwater, the morphospace analysis and analyses of shape and co-variation with habitat in a phylogenetic context shows that conservatism dominates skull shape evolution among ariid genera.Electronic supplementary materialThe online version of this article (10.1186/s12862-018-1152-y) contains supplementary material, which is available to authorized users.

Variation in cross‐sectional shape and biomechanical properties of the bat humerus under Wolff's law

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Diversification of the shell shape and size in Baikal Candonidae ostracods inferred from molecular phylogeny

“…As a result of adaptive radiation, these conflicts often coincide with a fast morphological diversification 40 . Combining LBGM and phylogeny can stipulate adaptive radiation, with the convergent evolution as its main outcome 41 , 42 . This can be applied on a vast range of geological time scales 43 , 44 , and these methods can elucidate correlation between morphological and taxonomic diversity 45 .…”

Diversification of the shell shape and size in Baikal Candonidae ostracods in the light of molecular phylogeny

“…As a result of adaptive radiation, these con icts often coincide with a fast morphological diversi cation 40 . Combining LBGM and phylogeny can stipulate adaptive radiation, with the convergent evolution as its main outcome 41,42 . This can be applied on a vast range of geological time scales 43,44 , and these methods can elucidate correlation between morphological and taxonomic diversity 45 .…”