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Abstract

Attracting mates, to a male Trinidadian guppy, is of utmost evolutionary significance. Under strong selection for male ornaments, theory predicts and genetic evidence supports that tight linkage may evolve between genetic sex determination and male ornament loci to form a “supergene”. The guppy Poecilia reticulata has long been an outstanding ecological model organism for studying sexual selection. Here we will present our work towards establishing the guppy as a genomic evolutionary model organism. To discover parts of the genome specific to the male, we have separately constructed male and female high-quality genome assemblies from inbred Guanapo guppy siblings (approximately 760Mb; N50: female 5.38Mb; male 2.82Mb). We extend our previous genetic results showing that the guppy linkage group 12 is the sex chromosome and we highlight its evolutionary turnover from rearrangements and transposable element insertions. Combining transcriptomics, population genetic and comparative genomics, we will discuss features of the male-specific genome and potential candidates for the guppy sex determination locus. The genomic resources allow us to consolidate past and current genetic mapping work on male pigment patterns, showing strong yet incomplete linkage with sex determination. Our results herald an exciting new chapter for this classical ecological model organism.