Genetics of ecological speciation in Ostrinia nubilalis.
Kahne, Shoshanna C.
- Though significant progress in genome sequencing has advanced the search for post- zygotic reproductively isolating speciation genes, few pre-zygotic reproductive isolating barriers have been identified at the genetic level. In this study a sex-linked candidate ecological speciation gene, Pdd, was located by linkage mapping and Quantitative Trait Locus (QTL) mapping. Linkage maps were constructed ... read morefor four univoltine Z-strain (UZ) and bivoltine Z-strain (BZ) backcross families by genotyping polymorphic markers using gel electrophoresis, Sanger sequencing, or Sequenom genotyping assay. This is the most dense linkage map of the ECB sex- chromosome to map within a region previously found to be inverted between ECB pheromone strains (Wadsworth et al., 2014). Linkage maps reveal substantial rearrangement (more than half the linkage map) of gene order relative to Bombyx mori (the silk worm) including at least two inverted regions. A consensus QTL map including genotypes from twelve families was also analyzed for the location of a single QTL (estimation of a 95% Bayesian credible interval) and assessed for the likelihood of multiple interacting QTLs. Significant additive QTL interactions were detected when the existence of two QTLs was assumed (p < 0.05). This is the first evidence that the genetic basis of PDD, a trait responsible for as much as 85% reproductive isolation between pheromone strains (Dopman et al., 2010), is polygenic. Investigation of strong, pre- zygotic reproductive isolating barriers between incipient species can provide important information about the origins of the speciation process, particularly at the genetic and genomic levels, for populations living sympatrically.read less