Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.08.05.238378v1?rss=1

Authors: Adhikari, K., Son, J. H., Rensink, A. H., Jaweria, J., Bopp, D., Beukeboom, L., Meisel, R. P.

Abstract:

Sex determination, the developmental process by which sexually dimorphic phenotypes are established, evolves fast. Species with polygenic sex determination, in which master regulatory genes are found on multiple different proto-sex chromosomes, are informative models to study the evolution of sex determination. House flies are such a model system, with male determining loci possible on all six chromosomes and a female-determiner on one of the chromosomes as well. The distributions of the two most common male-determining proto-Y chromosomes across natural populations suggests that temperature variation is an important selection pressure responsible for maintaining polygenic sex determination in this species. To test that hypothesis, we used RNA-seq to identify temperature-dependent effects of the proto-Y chromosomes on gene expression. We find no evidence for ecologically meaningful temperature-dependent expression of sex determining genes between male genotypes, but we identified hundreds of other genes whose expression depends on the interaction between proto-Y chromosome genotype and temperature. Notably, genes with genotype-by-temperature interactions on expression are not enriched on the proto-sex chromosomes. Moreover, there is no evidence that temperature-dependent expression is driven by chromosome-wide expression divergence between the proto-Y and proto-X alleles. Therefore, if temperature-dependent gene expression is responsible for differences in phenotypes and fitness of proto-Y genotypes across house fly populations, these effects are driven by a small number of temperature-dependent alleles on the proto-Y chromosomes.

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