The search for sexually antagonistic genes: practical insights from studies of local adaptation and statistical genomics

Sexually antagonistic (SA) genetic variation—in which alleles favored in
one sex are disfavored in the other—is predicted to be common and has been
documented in several animal and plant populations, yet we currently know
little about its pervasiveness among species or its population genetic
basis. Recent applications of genomics in studies of SA genetic variation
have highlighted considerable methodological challenges to the
identification and characterization of SA genes, raising questions about
the feasibility of genomic approaches  for inferring SA
selection. The related fields of local adaptation and statistical genomics
have previously dealt with similar challenges, and lessons from these
disciplines can therefore help overcome current difficulties in applying
genomics to study SA genetic variation. Here, we integrate theoretical and
analytical concepts from local adaptation and statistical genomics
research—including FST and FIS statistics, genome‐wide association studies, pedigree analyses, reciprocal transplant studies, and evolve‐and‐resequence experiments—to evaluate methods for identifying SA genes and genome‐wide signals of SA genetic variation. We begin by developing theoretical models for between‐sex FST and FIS, including explicit null distributions for each statistic, and using them to critically evaluate putative multilocus signals of sex‐specific selection in previously published datasets. We then highlight new statistics that address some of the limitations of FSTand FIS, along with applications of more direct approaches for characterizing SA genetic variation, which incorporate explicit fitness measurements. We finish by presenting practical guidelines for the validation and evolutionary analysis of candidate SA genes and discussing promising empirical systems for future work.