Reproductive systems of myxomycetes: How does evolution shape the relative proportion of sexual and asexual reproduction in species that are able to do both?

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The sustainability of sexual reproduction is paradoxical since it has many immediate costs compared to asexual reproduction. How does evolution shape the relative proportion of sexual and asexual reproduction in species that are able to do both? We will investigate this question using the acellular slime-moulds (Myxomycetes, Amoebozoa), a group of common and widespread unicellular organisms that have a sexual as well as an entirely asexual life cycle. Both culminate with the formation of macroscopic fruiting bodies. Because they represent the offspring of two parents, the millions of spores released from the fruiting bodies will be a tool to identify which modes of reproduction occur in nature. We will use different methods and develop others – cell-cycle analysis and molecular tools such as SSU and ITS-based phylogenies, microsatellites and other markers to investigate the rate of sexual versus asexual reproduction in selected species in nature. We will present a substantial set of empirical data along with phylogenetic, ecological and phylogeographic patterns of clonality and sexuality. The models we aim to establish will take into account finite and spatially delimited populations, and will address the evolutionary impact of sex in natural populations of an early diverging group of eukaryotes.