Studies On Biology And Heredity Of Crossochilus Bamaensis

Crossocheilus bamaensis Fang, sp.nov. is a native rare economical fish, itparticularly exists in China, primarily exist in Hongshui River which belongs toXijiang drainage system. It is fed with periphytic algae. It is called ?oil fish‘because itis fat and rich in lipid. Recent years, because of the influence of some factors, such asheavyfishing, human perturbing and building diversion dam, have cut off the migratechannels and have changed the living environment, all of these led the decrease ofcatching fish dramatically and the resources are close to prostration. In order torecover and protect the resources of C. bamaensis, the protection of the existingresources should be enhanced, especially enhance the isolation and protection of C.bamaensis, build the native genetic conservation. At the same time, we should applythe artificial propagation to supplement the populations in the river, and to speed upthe process of resources recovery. It is important to understand and master thebiological and genetic situation to achieve this process. In this article, based on thesamples collected in 2006 and 2007, the phenotypic characters are measured andanalyzed, by using horizontal slab gel electrophoresis technology, mtDNA and Cyt-bsequential analysis, D-loop sequential analysis and AFLP analysis, researched thebiological and genetic situation of age, growth, gonad development, breeding, geneticcharacters and resources situation, the results are as follows:1、There are 18 morphological characteristics of Xijiang drainage system C.bamaensis and Liucheng Crossocheilus appear to significant difference （p<0.05）,head length/body length, eye diameter/body length, eye distance/body length and headlength after eyes/body length of C. bamaensis are significantly smaller than LiuchengCrossocheilus （p<0.05）, other character indexes are significantly larger than LiuchengCrossocheilus （p<0.05）, while tongue length/body length and caudal pedunclelength/body length have no interspecific difference （p>0.05）, the scale amount of sideline of Crossocheilus bamaensis（40⁴2） is significantly larger than LiuchengCrossocheilus （37³9） （p>0.05）, their segment character have no interspecificdifference.2、The four variable for head length/body length, snout length/body length, snoutto origin of pectoral fin/body length and snout to origin of pelvic fin/length of Ba ma population significantly smaller than Du an population （P<0.05）, which displays thegeographical differences of the same group, but the other characters variables have nogeographical differences （P<0.05）. The sexual different phenotype traits of twogeographical populations:â‘ The female‘s body weight, body height and eye length ofthe same body length of Du an population are significantly larger than males.â‘¡Thebody weight, body height and eye length of the same body length of Ba ma populationare no significant differences between female and male. However, the male‘s caudalpeduncle length is significantly larger than female.3、The age 1 of C. bamaensis belongs to juvenile growing stage without maturedgonads in II～III time. The age 2 reaches breeding community with III～Ⅳtimedeveloping gonads and age 3 is the main group for the breeding community. Thematured age of C. bamaensis is two age. The body length is 8.68cm and weight is17.25g for the minimum matured female. The body length is 8.04cm and weight is11.20g for the minimum matured male. The ovarian mature coefficient has theperiodic phenomenon rises from February to the peak value in June and drops fromthat time to the minimum value in October. Hereafter it gradually rises again. It willpresent the peak value once more in June next year and will enter the new cycle.4、The reproductive capacity of C. bamaensis is more closely with the age（relative fecundity and mature coefficient）: the individual reproductive capacityelevates gradually from 1 to 3 age. After age 3, the individual reproductive capacitydrops gradually along with the age growth. So age 3 is the best reproductive age. Thebreeding season of C. bamaensis is from April to August and the breeding busyseason is May and June, which belong to an oviposition type for 1 year. The matureegg of C. bamaensis is green, round sphere and micro stickiness. The spawninggrounds is the gravel, pebbles, sand between substrate and have the water plant, clearwater and certain shore shallow water zone.5、The scale of C. bamaensis is shovel-shaped. The length of scale reflects thegrowth condition. Body length （L） and scale length （R） have linear relations （L =1.7824 + 67.67R）. The body length （L） is positively correlated with the weight （W）like the cube relations, which belongs to the uniform growth type﹝W=0.0334L^2.8302（r=0.9934,n=289），power exponent: b = 2.8302，similar to 3﹞. The growth equationfits its growing characteristic well and the growing rule has coincided with thegrowing equation of von Bertalanffy basically. The growing equation between body length and body weight :L_t = L_∞(1-e^{-k（t-to）}) =16.4677×(1-e^{-0.2190（t + 1.177）})W_t = W_∞(1-e^{-k（t-to）})^b=92.6963×(1-e-^{-0.2190（t + 1.177）2}.83026、The growing relationship between the age of C. bamaensis and body length andweight is very close. The fastest growth rate of body length was at age 1 and declinedafter age 2 and 3. The growth rate of body weight increased slowly before age 2 andreached the maximum at age 3 for a high growth stage then grew slowly after age 4.The age of growth inflection point （ti） is 3.57 age, larger than the age of sexualmaturity.7、A total of 86 C. bamaensis from Ba ma, Du an and Lai Bin populations wereanalyzed by the AFLP of DNA with five pairs of selective primers. The total sites ofthis 3 populations were 308, 304 and 296 and the number of polymorphic loci andthe rates were 58（18.83%）, 52（17.11%） and 45（15.20%）. The highest rate ofpolymorphic locus was Ba ma population, next was Du an population and the Lai binpopulation was the lowest. The degree of genetic variation showed by Shannon‘sdiversity index: Ba ma population （0.0843） > Du an population （0.0798） > Lai binpopulation （0.0728）. 63.35% of genetic variation came from internal populations and36.65% from external populations. The genetic differentiated coefficient of C.bamaensis population was 27.93%. Both the differentiated degree and the geneticdiversity were at a low level.8、The rate of polymorphic locus called MPI* of C. bamaensis was 0.0769 and theobserved heterozygosity was 0, the average expected heterozygosity was 0.0059 andthe average number of effective alleles were 1.1361. The genetic deviation index （d）of Hardy-Weinberg was -1, which shows serious heterozygotes. Just one haplotypeand no insertion and deletion exist in the Cytb gene fragment for 402bp of Ba ma, Duan and Lai bin populations. The diversity indices of haplotype and nucleotide were 0.Both the polymorphism and genetic diversity were very poor.