Evolution of limb development in cephalopod mollusks
Oscar A. Tarazona, Davys H. Lopez, Leslie A Slota, View ORCID ProfileMartin J. Cohn
This article is a preprint and has not been peer-reviewed [what does this mean?].
Abstract
Cephalopod mollusks evolved numerous anatomical innovations, including specialized arms and tentacles, but little is known about the developmental mechanisms underlying the evolution of cephalopod limbs. Here we report that all three axes of cuttlefish limbs are patterned by the same signaling networks that act in vertebrates and arthropods, although they evolved limbs independently. In cuttlefish limb buds, Hedgehog is expressed anteriorly. Posterior transplantation of Hedgehog-expressing cells induced mirror-image limb duplications. Bmp and Wnt signaling, which establishes dorsoventral polarity in vertebrate and arthropod limbs, is similarly polarized in cuttlefish. Inhibition of the dorsal Bmp signal caused ectopic expression of Notum, a ventral sucker field marker, and development of ectopic suckers. Cuttlefish limbs also show proximodistally regionalized expression of Htx, Exd, Dll, Dac, Sp8, and Wnt genes, which delineate arm and tentacle sucker fields. These results suggest that cephalopod limbs evolved by parallel activation of an ancient developmental genetic program that was present in the bilaterian common ancestor
Copyright
The copyright holder for this preprint is the author/funder. All rights reserved. No reuse allowed without permission.
FREE PREPRINT: bioRxiv
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Comentário de um gigante em Biologia:
"Se os resultados reportados neste trabalho se sustentarem, eles adicionam para a quase completa destruição do conceito neodarwinista de homologia anatômica. Hoje, a homologia significa quase que muita coisa na biologia evolucionária. Este conceito tem se livrado de quaisquer âncoras evidenciais consistentes, por contra-exemplos tão numerosos que eles poderiam encher um livro-texto dedicado simplesmente por sua diversidade taxonômica, abundância, e valor de impacto.
Se você tivesse perguntado um biólogo evolucionário nos anos 1980s se os membros de cefalópodos, artrópodes, e vertebrados usariam os mesmos elementos reguladores de desenvolvimento, ele teria dito “Com os diabos, não! — essas são estruturas classicamente não homólogas.”
Pano rápido!
