High lability of sexual system over 250 million years of evolution in morphologically conservative tadpole shrimps

BMC Evolutionary Biology

Research Article

Robert L Hammond¹  Ronald A Jenner²  Africa Gómez³  Bernd Hänfling³  Thomas C Mathers³  Thorid Zierold⁴ 

[1] Department of Biology, University of Leicester, University Road, LE1 7RH, Leicester, UK;Department of Life Sciences, The Natural History Museum, Cromwell Road, SW7 5BD, London, United Kingdom;School of Biological, Biomedical and Environmental Sciences, University of Hull, HU6 7RX, Hull, UK;School of Biological, Biomedical and Environmental Sciences, University of Hull, HU6 7RX, Hull, UK;Museum für Naturkunde Chemnitz, Moritzstrasse 20, D-09111, Chemnitz, Germany;

关键词: Androdioecy;    Character evolution;    Sexual system;    Notostraca;    Phylogeny;   

DOI  :  10.1186/1471-2148-13-30

 received in 2012-03-20, accepted in 2013-01-25,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundSexual system is a key factor affecting the genetic diversity, population structure, genome structure and the evolutionary potential of species. The sexual system androdioecy – where males and hermaphrodites coexist in populations – is extremely rare, yet is found in three crustacean groups, barnacles, a genus of clam shrimps Eulimnadia, and in the order Notostraca, the tadpole shrimps. In the ancient crustacean order Notostraca, high morphological conservatism contrasts with a wide diversity of sexual systems, including androdioecy. An understanding of the evolution of sexual systems in this group has been hampered by poor phylogenetic resolution and confounded by the widespread occurrence of cryptic species. Here we use a multigene supermatrix for 30 taxa to produce a comprehensive phylogenetic reconstruction of Notostraca. Based on this phylogenetic reconstruction we use character mapping techniques to investigate the evolution of sexual systems. We also tested the hypothesis that reproductive assurance has driven the evolution of androdioecy in Notostraca.ResultsCharacter mapping analysis showed that sexual system is an extremely flexible trait within Notostraca, with repeated shifts between gonochorism and androdioecy, the latter having evolved a minimum of five times. In agreement with the reproductive assurance hypothesis androdioecious notostracans are found at significantly higher latitudes than gonochoric ones indicating that post glacial re-colonisation may have selected for the higher colonisation ability conferred by androdioecy.ConclusionsIn contrast to their conserved morphology, sexual system in Notostraca is highly labile and the rare reproductive mode androdioecy has evolved repeatedly within the order. Furthermore, we conclude that this lability of sexual system has been maintained for at least 250 million years and may have contributed to the long term evolutionary persistence of Notostraca. Our results further our understanding of the evolution of androdioecy and indicate that reproductive assurance is a recurrent theme involved in the evolution of this sexual system.

【 授权许可】

CC BY   
© Mathers et al; licensee BioMed Central Ltd. 2013