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

摘要: ‘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 rates being underestimated. Notostraca, or tadpole shrimps, is an ancient, globally distributed order branchiopod crustaceans regarded ‘living fossils’ because their rich fossil record dates back the early Devonian morphology highly conserved. Recent phylogenetic reconstructions have shown strong biogeographic signal, suggesting due continental breakup, widespread cryptic speciation. However, conservatism makes it difficult place taxa in context. Here we reveal for time timing tempo shrimp inferring robust multilocus phylogeny Branchiopoda applying Bayesian divergence dating techniques using reliable calibrations external Notostraca. Our results suggest at least two bouts global radiation one them recent, so questioning validity concept groups where speciation widespread.