Recombination and Speciation: Loci Near Centromeres Are More Differentiated Than Loci Near Telomeres Between Subspecies of the European Rabbit (Oryctolagus cuniculus)

Abstract

Recent empirical and theoretical studies suggest that regions of restricted recombination play an important role in the formation of new species. To test this idea, we studied nucleotide variation in two parapatric subspecies of the European rabbit (Oryctolagus cuniculus). We surveyed five loci near centromeres, where recombination is expected to be suppressed, and five loci near telomeres, where recombination is expected to be higher. We analyzed this multilocus data set using a divergence-with-gene flow framework and we report three main findings. First, we estimated that these subspecies diverged ∼1.8 MYA and maintained large effective population sizes (O. c. algirus Ne ≈ 1,600,000 and O. c. cuniculus Ne ≈ 780,000). Second, we rejected a strict allopatric model of divergence without gene flow; instead, high rates of gene flow were inferred in both directions. Third, we found different patterns between loci near centromeres and loci near telomeres. Loci near centromeres exhibited higher levels of linkage disequilibrium than loci near telomeres. In addition, while all loci near telomeres showed little differentiation between subspecies, three of five loci near centromeres showed strong differentiation. These results support a view of speciation in which regions of low recombination can facilitate species divergence in the presence of gene flow.