The genetics and evolutionary dynamics of reproductive mode in tadpole shrimps

Since the time of Darwin the diversity of reproductive modes and mating systems has attracted great interest. This is because changes in reproductive mode and mating strategy can be an adaptive response to environmental challenges. Also, changes in reproductive mode have important consequences for the genetics, ecology and future evolutionary potential of species. Notostracans, the tadpole shrimps (a group of freshwater crustaceans), are 'living fossils' whose morphology has remained stable for over 300 million years. However, in contrast their reproductive mode is highly variable. For example some populations have both males and females (dioecy), others just hermaphrodites, or others a mixture of hermaphrodites and males (androdioecy, AD). Such variation makes the group a very good system to investigate the evolutionary dynamics of reproductive mode. The aim of this project is to investigate the evolutionary history and genetic control of reproductive mode variation in notostracans. This will be done by: 1) Building an evolutionary tree using DNA sequences and then mapping the reproductive mode onto the tree. Using this information the change of one reproductive mode to another can be traced. 2) Investigating the genetic inheritance of reproductive mode by controlled breeding experiments of one notostracan, Triops cancriformis, and the formation of a genetic map of reproductive mode. The completion of this project will greatly increase knowledge of the dynamics of reproductive mode change. Furthermore, Triops cancriformis is a declining species worldwide and is a UK Biodiversity Action plan species. Understanding the breeding biology and ecology of species is essential to their successful management and so the results of this project will be useful in future conservation efforts aimed at protecting this species.