title: Multiple global radiations in tadpole shrimps challenge the concept of 'living fossils'.
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.
authors: School of Biological, Biomedical and Environmental Sciences, University of Hull , Hull , UK.
authors: Thomas C
authors: TC
authors: Mathers
authors: Robert L
authors: RL
authors: Hammond
authors: Ronald A
authors: RA
authors: Jenner
authors: Bernd
authors: B
authors: Hänfling
authors: Africa
authors: A
authors: Gómez
keywords: Bayesian analysis; Biogeography; Divergence time; Diversification; Fossil; Lepidurus; Notostraca; Triops; ‘Living fossil’
references: PLoS One. 2012;7(4):e34998
references: 22529967
references: Mol Phylogenet Evol. 1998 Aug;10(1):23-36
references: 9751915
references: Syst Biol. 2009 Jun;58(3):367-80
references: 20525591
references: BMC Evol Biol. 2007 Sep 13;7:161
references: 17854482
references: Nature. 2009 Feb 12;457(7231):837-42
references: 19212402
references: Nature. 2010 Feb 25;463(7284):1079-83
references: 20147900
references: Mol Biol Evol. 2011 Oct;28(10):2731-9
references: 21546353
references: Zootaxa. 2016 Oct 25;4178(3):328-346
references: 27811712
references: Syst Biol. 2006 Aug;55(4):595-609
references: 16967577
references: Syst Biol. 2012 May;61(3):539-42
references: 22357727
references: Nature. 1983 Sep 22-28;305(5932):269-72
references: 6353241
references: Bioinformatics. 2006 Nov 1;22(21):2688-90
references: 16928733
references: BMC Evol Biol. 2013 Feb 05;13:30
references: 23384124
references: Mol Biol Evol. 2012 Jun;29(6):1695-701
references: 22319168
references: Nucleic Acids Res. 2004 Mar 19;32(5):1792-7
references: 15034147
references: BMC Evol Biol. 2011 May 19;11:129
references: 21595889
references: Evolution. 2010 Apr 1;64(4):934-43
references: 19895554
references: PLoS Biol. 2008 Mar 25;6(3):e71
references: 18366256
references: Mol Biol Evol. 2011 Jun;28(6):1927-42
references: 21242529
references: PLoS Biol. 2006 May;4(5):e88
references: 16683862
references: Evol Bioinform Online. 2007 Feb 14;2:273-6
references: 19455217
references: Evolution. 1994 Dec;48(6):1986-2001
references: 28565169
references: Mol Biol Evol. 2012 Aug;29(8):1969-73
references: 22367748
references: Evolution. 2012 Dec;66(12):3670-86
references: 23206127
references: Bioessays. 2013 Apr;35(4):332-8
references: 23382020
references: Science. 2011 Nov 11;334(6057):796-9
references: 22021670
references: Mol Phylogenet Evol. 2012 Jan;62(1):21-6
references: 21939777
references: Mol Biol Evol. 2012 Mar;29(3):1031-45
references: 22049065
references: Heredity (Edinb). 2008 May;100(5):496-505
references: 18285812
references: Proc Natl Acad Sci U S A. 2012 Jan 31;109(5):1589-94
references: 22307616