Population genetics of S. papillosus

S. papillosus, have a different karyotype compare with its sister species S. ratti. The X chromosome is fused with one of the autosomes, resulting in a pair of large chromosomes (L) and a pair of medium chromosomes (M) in females. In males, an internal portion of one L chromosome is removed and this eliminated region corresponds evolutionarily to the X chromosome of S. ratti. This has been described as chromatin diminution and functionally restores an XX/XO sex-determining system. Earlier study in our group suggested the recombination is absent in the diminished chromosomal region also in females. To test this hypothesis, 24 free-living S. papillosus adults were isolated from sheep and each individual were sequenced at the whole genome. The goal is to analysis the linkage disequilibrium.