Retrogene survival is not impacted by linkage relationships.

Abstract

In retrogene evolution, the out-of-the-X pattern is the retroduplication of X-linked housekeeping genes to autosomes, hypothesized to be driven by meiotic sex chromosome inactivation during spermatogenesis. This pattern suggests that some retrogene survival is driven by selection on X-linkage. We asked if selection on linkage constitutes an important evolutionary force in retrogene survival, including for autosomal parents. Specifically, is there a correlation between retrogene survival and changes in linkage with parental gene networks? To answer this question, we compiled data on retrogenes in both Homo sapiens and Drosophila melanogaster and using Monte Carlo methods, we tested whether retrogenes exhibit significantly different linkage relationships than expected under a null assumption of uniform distribution in the genome. Overall, after excluding genes involved in the out-of-the-X pattern, no general pattern was found associating genetic linkage and retrogene survival. This demonstrates that selection on linkage may not represent an overarching force in retrogene survival. However, it remains possible that this type of selection still influences the survival of specific retrogenes.