Meeting Abstract
Recent research in Drosophila melanogaster suggests that the Y-chromosome influences autosomal gene regulation; particularly, immune-related genes. This effect was detected by introgressing Y-chromosomes from independently evolving populations into an isogeneic background. In order for the Y-chromosome to fundamentally shape immune system evolution however, we must first determine if Y-chromosome regulatory variation (1) exists within a population and (2) translates into functional immune response variation. To this end, we collected 30 wild lines of D. melanogaster and placed their Y-chromosomes into an isogenic background. Males and females were then assayed for variation in immune gene expression and survival against a gram-negative pathogen. Our data indicates that males (who were isogenic except for their Y-chromosomes) exhibited significant variation in immune gene expression and survival while females (who were entirely isogenic) did not. In short, our data suggest that Y-chromosome regulatory variation exists within a population and translates into functional immune differences. Our next step is to determine the nature of the Y-chromosome variation. If this variation is largely additive, then the Y-chromosome could facilitate the evolution of sexually dimorphic immune systems. However, if the variation is largely epistatic, then males may be a fundamental constraint to immune system evolution.
