Replicated hybrid zones of Xiphophorus swordtails along an elevational gradient

摘要: Natural hybrid zones provide opportunities to study a range of evolutionary phenomena from speciation the genetic basis fitness-related traits. We show that widespread hybridization has occurred between two neo-tropical stream fishes with partial reproductive isolation. Phylogenetic analyses mitochondrial sequence data showed swordtail fish Xiphophorus birchmanni is monophyletic and X. malinche part an independent clade other species. Using informative single nucleotide polymorphisms in one three nuclear intron loci, we genotyped 776 specimens collected twenty-three sites along seven separate reaches. Hybrid replicated fashion all reaches gradient high low elevation. Genotyping revealed substantial variation parental frequencies among localities. Tests F(IS) linkage disequilibrium (LD) generally LD except five populations where both species hybrids were found suggesting incomplete In these locations, heterozygote deficiency high, which suggests either selection against early generation or assortative mating. These lay foundation adaptive zone structure for future integration behaviour genetics determine processes lead population patterns observed zones.