| DNA barcoding gene is a gene fragment of 5’end of mitochondrial cytochrome c antioxidant subunit I（COI）gene and has been widely used in species identification.The main aims of DNA barcoding were to distinguish species and discover cryptic species.In addition,DNA barcoding gene can be employed to conduct genetic diversity study via combining with other genes and has been widely reported in different taxa.In the current study,we choose DNA barcoding gene as a molecular marker and combined different types of molecular gene to study cryptic species of Micronemacheilus pulcher and to resolve genetic diversity of Mastacembelus armatus populations in Southern China,respectively.The main outcomes were shown below.1、This study collected 107 M.pulcher specimens from 18 geographic locations in multiple southern drainages and sequenced DNA barcodes standard gene（mitochondrial cytochrome c oxidase I;COI）from overall samples and Glycosyl transferase gene（Glyt）from partial samples.Multiple analyzed approaches like phylogenetic analyses,genetic distance calculations,allele network and species delimitation analyses were employed.Phylogenetic outcomes on the basis of COI gene showed that two major clades（I and II）were detected in M.pulcher populations.The members of Clade I contained populations from the Pearl River drainage,the Moyangjiang drainage and the Nanliujiang drainage,while the representatives of Clade II only comprised of Hainan Island populations.In addition,Clade I could be divided into three subclades（I-1,I-2 and I-3）with strict geographic patterns.Subclade I-1 consisted of populations from the Xijiang River and Beijiang River within the Pearl River drainage and the Nanliujiang drainage.Subclades I-2 and I-3 contained populations from the Dongjiang River within the Pearl River drainage and the Moyangjiang drainage,respectively.Genetic distance calculations based on COI gene indicated genetic distance between two major clades reached 5.64%,which was larger than the acknowledged species delimitation threshold value（2%）.With regard to Glyt gene,phylogenetic analyses did not obtain the robust pattern of lineage split,but allele network supported evolutionary independence of Mainland populations and Hainan Island population.ABGD（Automatic Barcode Gap Discovery）and PTP（Poisson Tree Process）analyses utilizing COI gene and BPP（Bayesian Phylogenetics and Phylogeography）using both genes consistently supported the two major clades could be regarded as two putative species,supporting M.pulcher populations harbored two cryptic species at least.In sum,our results demonstrated that genetic diversity of M.pulcher was underestimated,future studies including morphometrics,larger sample coverage and more types of genetic loci should be imminently conducted and provide important scientific support for all-sided management and conservation of this species.2、We sampled 140 individuals from 16 populations that belong to seven independent drainages in Southern China and sequenced two mitochondrial genes（COI and Cytb）via Sanger sequencing to reveal the genetic structure and demographic history of M.armatus populations.Multiple analyzed approaches were employed.The results revealed that M.armatus populations consistedof three lineages（I,II and III）and split between 0.596and 0.676 million years ago（Ma）.Haplotypenet work uncovered that some populations belonging to different lineages occurred in sympatric and two dispersal routes were detected between Hainan Island populations and mainland populations Population genetic analyses demonstrated significant genetic differentiation(FST=0.676,P<0.001)and isolation by distance pattern（R=0.463,P=0.001）were observed among M.armatus populations.Demographic analyses revealed that M.armatus populations might experience population expansion at 0.025 Ma.The results provided important and scientific basis for the management and protection of the genetic resourcesof M.armatus. |
