Meeting Abstract
Non-protein coding regions of the Y-chromosome have been shown to influence the expression of hundreds of autosomal and X-linked genes in multiple species. This Y-linked regulatory variation (YRV) may provide the sex-specific variation in gene expression needed for the adaptive evolution of sexually dimorphic traits. Our previous work in Drosophila melanogaster suggests that this variation exists where selection operates suggesting that YRV can influence how autosomal traits evolve. In order for YRV to adaptively facilitate the evolution of sexually dimorphic traits, it must be comprised of additive genetic variation. Non-additive Y-linked effects can facilitate or constrain adaptive evolution depending on how these effects translate into genetic variance components at the population level. We investigated the ability for selection to shape immune related YRV by crossing 4 D. mel Y-chromosomes into 4 genetic backgrounds, estimating the additive and non-additive effects on response to gram-negative and gram-positive bacteria. Significant Y-linked effects were only detected in response to gram-negative bacteria. Potential reasons for the lack of detection of Y-linked effects in response to gram-positive bacteria are discussed. The Y-linked effect detected in response to gram-negative bacteria was completely epistatic showing no additive effects. This suggests that the potential for YRV to facilitate sexually dimorphic immune evolution via large additive effects that can be shaped by natural selection is small. However, small amounts of additive YRV may exist in the population and we investigate the potential consequences that may arise from large non-additive Y-linked effects on autosomal gene expression ranging from the potential facilitation of adaptive evolution to massive constraints.
