Using Y chromosome haplotype diversity to test for selection within and between natural populations of the plant Silene latifolia.

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This proposal is to combine data on sequence differences of various kinds, with different mutational time-scales, and information on the geographical distributions of variants, in order to test whether selection is affecting the frequencies of different Y-chromosomes in Silene latifolia and S. dioica. We propose to do this by isolating new Y-linked genes, and resequencing them in plants from multiple wild European populations, so as to define haplotypes based on low mutation rate variants, and to study the ages of the haplotypes in finer detail using higher mutation rate variants (microsatellites). This can indicate whether certain Y chromosome genotypes are locally adapted, or are advantageous across different populations. As well as providing interesting data on the effects of selection on Y chromosomes, the results will allow us to test whether selection causing local adaptation can explain the puzzling observation that Y chromosome variants in these species tend to be at intermediate frequencies, and whether such adaptation contributes to lower diversity of Y-linked variants, compared with variants in the X-linked homologues.