Species Delimitation Of The Abies Delavayi Species Complex And Abies Fargesii Species Complex

Abies is the second largest genus in the family Pinaceae except Pinus, about 50 species. Fir forests are the most important cold-temperate conifer forests in alpine or subalpine areas in the north Hemisphere. China is rich in species diversity of firs and nearly half of the all species of the world can only be found in China. However Subdivision of the genus and species delimitation has been controversial because of the complex morphological variation and restiction of sampling and molecular marker in previous studies, especially for the Chinese subtropical region of Abies plants. In this study, we choose the species complex of Abies delavayi and Abies fargesii as examples to explore the delimitation of closely related fir species by applying morphological data and DNA evidence based on population sampling.In the study, on one hand, we combined morphological and molecular data to conduct a series of morphometric and genetic differentitation analyses to delimit species in the Abies delavayi complex occurring in subtropical China. On the other hand, we collected molecular data of Abies fargesii complex to conduct a series of molecular analyses, such as genetic lineage and phylogenetic relationships, nucleotide polymorphisms, genetic differentiation and genetic structure, in order to delimit species. Main results and conclusions are as follows: 1. Species delimitation of the Abies delavayi complexIn order to delimit the species boundary in the complex, 22 morphological characters of 71 herbarium specimens were collected to conduct the multivariate analyses. In addition, two mitochondrial DNA fragments, nad1 intron 2 and nad5 intron 4, one plastid DNA intergenic spacer trnS-G, and three plastid DNA microsatellite loci of 163 individuals from 15 populations were sequenced for the molecular analyses.Both morphological and mitochondrial analyses obtained the consistent results, unable to divide the species of complex completely. Also, both climate factors and chloroplast analyses came to the consistent results, Abies fabri was shown as a well-defined lineage, while the other members in the complex were divided into two species, Abies delavayi and Abies fansipanensis, and one variety, Abies delavayi var. nukiangensis. 2. Species delimitation of the Abies fargesii complexIn this study, with a total sampling of 149 individuals collected from 10 populations of Abies fargesii complex, we sequenced the maternal inherited mitochondrial DNA nad1 intron 2, nad5 intron 4 and paternal inherited chloroplast trnS-G region. The sequence alignment is 887 bp in length of nad1-2 and nad5-4, 21 point mutations, 4 indels and a continuous mutation of 3bp are detected. From these variations 17 mitotypes can be recognized. The sequence alignment is 715 bp in length of trnS-G region. Nine point mutations, two indels and a continuous mutation of 5bp, a continuous mutation of 3bp are detected, which can be classified into 17 chlorotypes. The mitochondrial haplotype network showed A. fanjingshanensis is a well-defined sublineage, and based on the combined the mitochondrial and the chloroplast data, the other members of this complex could be divided into one species and one variety, Abies fargesii and Abies fargesii var. faxoniana.In summary, this study applied three molecular markers, namely the two segments of mitochondria nad1-2, nad5-4, and one segment of chloroplast trnS-G. to explore the species delimitation in two fir species complex and provided the reference to conservation and systematic research.