Deep genetic divergence and paraphyly in cryptic species of Mugil fishes (Actinopterygii: Mugilidae)

Abstract

Morphological conservatism among closely related species often results in incongruent taxonomic classification between studies, leading to disagreements about the inferred evolutionary history of the species. This is the case in Mugil fishes, where extreme morphologic conservatism contrasts with wide distributions and high genetic divergence. To understand how these morphologically similar species evolved, it is necessary to 1) test whether taxonomically recognized species are independently evolving lineages, and 2) evaluate the timing and geographic context of the diversification of these lineages. Based on three mitochondrial genes and fossil data, we estimated a comprehensive time-calibrated phylogeny for 13 out of the 16 valid species of Mugil and tested the monophyly of each species. Our results indicate that the diversification of Mugil began nearly 30 MYA, during a period of large temperature fluctuations. Mugil cephalus, M. curema and M. rubrioculus all form relatively old groups (between 5 and 10 MYA) and form paraphyletic entities. Our study reinforces the general finding that morphologically and ecologically similar species may have long and independent evolutionary histories, which must be considered when assessing the evolution and conservation of such ecologically and economically important species.

Key words:

• conservation
• fossil calibration
• grey mullets
• molecular dating
• monophyly
• species complex

Acknowledgements

JMMN thanks to scholarship provided by Coordination of Improvement of Higher Level Personnel – CAPES (#88887.137815/2017-00 and #88881.189448/2018-01) TM thanks to CNPq fellowship (#309904/2015–3) and FAPEAL fellowship (#60030 000406/2017). JPFAA thanks to FAPEAL (#23038.023347/2016-74). We would also like to thank to the editors: Elliot Shubert and Kevin Conway, and the two anonymous reviewers for the constructive comments on the previous version of the manuscript, as well R. Ladle and C. Thomas for revising the grammar, and Dr. Ana L. Ibáñez and Dr. Alfredo P. Lozano for the tissue samples kindly provided.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2020.1729892.

Associate Editor: Kevin Conway

Additional information

Funding

This work is part of the Long Term Ecological Research – Brazil site PELD-CCAL (Projeto Ecológico de Longa Duração – Costa dos Corais, Alagoas) funded by the Brazilian National Council for Scientific and Technological Development – CNPq (#441657/2016-8), the Brazilian Coordination for the Improvement of Higher Education Personnel – PELD/CAPES (23038.000452/2017-16) and the Research Support Foundation of the State of Alagoas – FAPEAL (#60030.1564/2016). This work was also funded by Bayerisches Hochschulzentrum für Lateinamerika – BAYLAT (#914-20.1.1).