Thursday, April 04, 2013
Tadpole Shrimps and Evolution
‘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, the 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. The timing and tempo of tadpole shrimp diversification has been revealed by inferring a robust multilocus phylogeny of Branchiopoda and applying Bayesian divergence dating techniques using reliable fossil calibrations external to Notostraca. These 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.
Multiple global radiations in tadpole shrimps challenge the concept of ‘living fossils’. (2013) PeerJ 1:e62 http://dx.doi.org/10.7717/peerj.62
Interesting stuff. But I don't normally write about biology here - so why this article? Because as far as I'm concerned, the Evolution in the title of this post is about the evolution of academic publishing - the tadpole shrimps can look after themselves. My Department of Biology colleague Rob Hammond has become the first person from the University to publish in PeerJ. I talked to Rob this morning, and he had nothing but good things to say about the experience of publishing with PeerJ.
I only wish I could follow his lead, but sadly, that isn't possible :-(