Sexual conflict over survival in Trinidadian Guppies

ABSTRACT Sexual conflict over survival produces two distinct population genetic signatures. Fluctuating selection in males and females produces balancing selection. Additionally, at conception, allele frequencies are the same in males and females. However, loci with alleles that benefit the survival of one sex at some survival cost to the other should diverge over the course of a generation. We therefore expect that sexual conflict over survival would produce both signatures of allelic differentiation between the sexes and balancing selection. However, given the substantial mortality costs required to produce allelic differences between males and females, it remains unclear how many loci within the genome, if any at all, experience significant sexual conflict over survival. We assessed the genomes of 120 wild-caught guppies, which are expected to experience substantial predation- and pathogen-induced mortality. We identified a core list of 15 high confidence genes that show allelic differences between male and female adults. However, eight of these show evidence of having duplicated copies on the Y chromosome, suggesting that the male-specific region of the guppy Y chromosome may act as a hotspot for the resolution of conflict. We recovered just seven genes with significant male-female allelic differentiation without evidence of Y duplication, and these show elevated Tajima’s D, consistent with balancing selection from sexual conflict. Only one of these seven genes, Puf60b, shows substantial intersexual FST. Puf60b has roles in cognition and the immune system, suggesting substantial ongoing, unresolved sexual conflict related to predator and pathogen avoidance strategies.