Phylogeographic Analysis Of The Fir Species In Southern China Suggests Complex Origins And Genetic Admixture

Fir species are mainly distributed across the high latitudes, preferring cold climates. The phylogeographic origins of those subtropical fir species that occur in low latitudes in southern China remain elusive, as does the nature of any inter-lineage hybridization. In fir species, mitochondrial DNA (mtDNA) is maternally inherited and chloroplast DNA (cpDNA) is paternally inherited, and the genetic variations in the two make them particularly useful for examining species' hybridizations and evolutionary histories. We sequenced four fragments of DNA:two of mtDNA and two of cpDNA from 161 individuals of four subtropical endangered fir species (Abies beshanzuensis, A. ziyuanensis, A. yuanbaoshanensis, and A. fanjingshanensis) and two more northerly distributed ones (A. recurvata and A. fargesii) from central and southwest China. Three mitotypes and four chlorotypes were recovered from the four southern species, respectively. Three mitotypes were grouped into two distinct clades, each associated with one of the northern species examined. One mitotype was found in A. fanjingshanensis, A. yuanbaoshanensis, and A. ziyuanensis while the other two belonged to the other clade and were present in both A. beshanzuensis and A. ziyuanensis. For four chlorotypes, one occurred in A, ziyuanensis, A. beshanzuensis, A. fargesii and A. recurvata, another in A. ziyuanensis and A. recurvata, the remaining two differed from others by two mutations exclusively in A. fangjingshanenis and A. yuanbaoshanensis. Phylogeographic origins of the subtropical fir species are complex and genetic admixtures occurred during the evolutionary history of A. ziyuanensis. The genotyped populations further provide basic frames for genetic delimitation and effective conservation of these endangered species in the future.