Subterranean Fishes of the World

5414

2020

bioRxiv preprint

221986

The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. All rights reserved. Now published in Proceedings of the Royal Society B: Biological Sciences doi:10.1098/rspb.2020.2205

Morphological diversification during adaptive radiation may depend on factors external or internal to the lineage. We provide evidence for the latter in characiform fishes (tetras and piranhas), which exhibit extensive dental diversity. Phylogenetic character mapping supported regain of lost teeth as contributing to this diversity. To test for latent potential for dentition that would facilitate its evolutionary expansion, we overexpressed a tooth initiation signal, the tumor necrosis factor pathway ligand ectodysplasin, in a model characiform, the Mexican Tetra (Astyanax mexicanus). This manipulation resulted in extensive ectopic dentition, in contrast to its previously-reported limited effect in the Zebrafish (Danio rerio). Tooth location in the Order Cypriniformes, to which the Zebrafish belongs, is much more restricted than in characiforms, a pattern that may be explained by differences in the retention of ancestral developmental potential. Our results suggest that differences in evolvability between lineages may lead to contrasting patterns of diversification.

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