Periodic Report Summary 1 - POMASE (Mechanisms of post-mating sexual selection in a marine invertebrate)
Despite the fact that post-mating sexual selection (PMSS) act as a powerful evolutionary force in the nature, our knowledge about its mechanisms is still very limited. The primary aim of the POMASE is to produce new information about the mechanistic basis of PMSS. During the outgoing phase of the POMASE (1.9.2014-31.8.2015) we clarified the role of the sperm surface carbohydrates and gamete-level chemical communication as a mediator of this process in a marine mussel Mytilys galloprovincialis. We first developed a flow cytometric method for the quantification of female (‘egg water’) -induced sperm acrosome reaction and sperm surface glycan modifications in our model species. Then we demonstrated that both of these sperm surface reorganizations are strongly dependent on the specific identities of males and females (male-by-female interaction) and that Ca2+ and RNA influx to the sperm may form the mechanistic basis of this sexual selection. Together, these results demonstrate previously unknown, molecular-level mechanism of post-mating sexual selection. Thus, it is likely that the expected final results of the POMASE will significantly increase our understanding about the mechanisms of PMSS. Given that better understanding of the molecular level recognition mechanisms between gametes is believed to revolutionize our understanding of both sperm biology and sexual selection (Holt & Fazeli 2015, Mol. Hum. Reprod. 21: 491-501), the scientific impact of the project can be significant. Furthermore, as PMSS is a ubiquitous phenomenon in the Animal Kingdom, clarifying its mechanistic basis in broadcast spawning species can help us to better understand patterns of selection and evolution in general, both of which are common topics in everyday life and of widespread interest among the general public. Finally, due to the universal nature of gamete communication mechanisms, proposed project may also produce useful new information e.g. for clinical purposes such as for the development of male contraceptives.