Multiple global radiations in tadpole shrimps challenge the concept of 'living fossils'

Mathers, Thomas C.; Hammond, Robert L.; Jenner, Ronald A.; Hänfling, Bernd; Gomez, Africa

Abstract

‘Living fossils’, a phrase first coined by Darwin, are defined as species with limited recent diversification and high morphological stasis over long periods of evolutionary time. Morphological stasis, however, can potentially lead to diversification rates being underestimated. Notostraca, or tadpole shrimps, is an ancient, globally distributed order of branchiopod crustaceans regarded as ‘living fossils’ because their rich fossil record dates back to the early Devonian and their morphology is highly conserved. Recent phylogenetic reconstructions have shown a strong biogeographic signal, suggesting diversification due to continental breakup, and widespread cryptic speciation. However, morphological conservatism makes it difficult to place fossil taxa in a phylogenetic context. Here we reveal for the first time the timing and tempo of tadpole shrimp diversification by inferring a robust multilocus phylogeny of Branchiopoda and applying Bayesian divergence dating techniques using reliable fossil calibrations external to Notostraca. Our results suggest at least two bouts of global radiation in Notostraca, one of them recent, so questioning the validity of the ‘living fossils’ concept in groups where cryptic speciation is widespread.

Citation

Mathers, T. C., Hammond, R. L., Jenner, R. A., Hänfling, B., & Gomez, A. (2013). Multiple global radiations in tadpole shrimps challenge the concept of 'living fossils'. PeerJ, 1, e62. https://doi.org/10.7717/peerj.62

• Acceptance Date: Mar 14, 2013
• Online Publication Date: Apr 2, 2013
• Publication Date: Apr 2, 2013
• Publicly Available Date: Apr 30, 2018
• Electronic ISSN: 2167-8359
• Publisher: PeerJ
• Peer Reviewed: Peer Reviewed
• Volume: 1
• Article Number: e62
• Pages: e62
• DOI: https://doi.org/10.7717/peerj.62
• Keywords: General Biochemistry, Genetics and Molecular Biology; General Neuroscience; General Agricultural and Biological Sciences; General Medicine
• Public URL: https://hull-repository.worktribe.com/output/428996
• Publisher URL: https://peerj.com/articles/62/