| Gymnocypris eckloni eckloni belongs to subfamily Schizothoracinae, family Cyprinidae and order Cypriniformes. It is an endemic freshwater fish species in China,mainly distributing in main stream and tributaries of the upper Yellow River, as well as Gyaring Lake, Xunmu Lake and Golmud River basin in the Qaidam Basin.Recently, resources of this species have been sharply decreased because of natural environment changing and human activities, so it has been seen as endangered species and urgent to be protected.In this study, age and growth of Gymnocypris eckloni eckloni living in Xunhua and Guide streams in the upper Yellow River had been deeply studied from individual biological level. Through comparing shape of annual ring and accuracy of age result based on vertebra, anal scale, otolith and operculum, vertebra was determined as the best material to identify age of Gymnocypris eckloni eckloni. According to identified results of vertebra, maximum age of this species in survey region was eight and individuals concentrated in 2 and 3 age groups. Standard length and body weight of Gymnocypris eckloni eckloni in survey region concentrated in range of 90-120 mm and less than 100 g, respectively. Equation of length-weight relationship was W=1.808×10-5L2.98( r=0.9752), which indicated its growth was not allometric.Equation of Von Bertalanffy were L∞=559.49(1-e-0.07085(t-0.1748)), maximum standard length was 559.49 mm, W∞=2790.0986(1-e-0.07085(t-0.1748))2.98, maximum body weight was 2970 g, and growth inflexion was 16.68. On the basis of analysis on above results,population of Gymnocypris eckloni eckloni in survey region showed situation of small-sized and low-aged, which maybe closely related to overfishing and invasivespecies. We also made researches on genetic characters of parent population without effects from reproduction and releasing, as well as Xunhua and Guide populations with effects from reproduction and releasing, using mitochondrial DNA control region(D-Loop, 574 bp) and cytochrome b(Cytb,1140 bp) genes. Sequence of D-Loop had101 variation sites, among them 51 parsimony-informative sites and 50 Single mutation sites, as well as conversion / transition was 3.71. Sequence of Cytb had 130 variation sites, among them 121 parsimony-informative sites and 9 Single mutation sites, as well as conversion / transition was 5.77. Based on comparison of nucleotide composition of two genes, A+T in D-Loop(63.0%) was higher than that in Cytb(57.2%), and A+T was higher than G+C in both genes, which was same to nucleotide composition of other Schizothoracinae species. Haplotype diversity(h) and nucleotide diversity(π) were also compared between parent population and Xunhua and Guide populations respectively, and results showed that indexes of h(0.994±0.019) andπ(0.032±0.01) were significantly higher in parent population than that in other two geographical populations. According to results of genetic distance and fixation indices,two indexes between parent and Xunhua populations as well as between parent and Guide populations respectively were higher than that between Xunhua and Guide populations. Through analysis of molecular variation(AMOVA), genetic divergence of Gymnocypris eckloni eckloni was mainly from individual differences internal population. Neighbor-Joining(NJ) and Maximum Likelihood(ML) phylogenetic trees and haplotype network both indicated there was no significant genetic divergence between populations, as well as individuals of three populations all existed crossing and each population had not formed independent monophyletic group. Above results all indicated panrent with Xunhua and Guide population had not form significant genetic differentiation.On the basis of results of age, growth and genetic characters of Gymnocypris eckloni eckloni, considering present environment problems such as habitat changing,overfishing and alien species in our survey region, we gave some advises including protecting habitats, controlling alien species and overfishing, as well as reasonably arranging artificial resource releasing and planning natural reserves. |
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