Study On Characteristics Population And Feeding Organs Morphological Characteristics Of Hemiculter Leucisculus In Chongqing Laixi River

Hemiculter leucisculus is a wild fish that is numerous and widely distributed and almost unaffected by artificial proliferation and discharge.Its life cycle is mainly influenced by natural environment and genetic factors.H.leucisculus and H.tchangi Fang belong to the genus Hemiculter,and their growth characteristics are very similar,and there is the possibility of interspecific hybridization in the same habitat.In the natural environment,hybridization occurs widely,especially in cyprinids.During the process of hybridization,gene introgression will occur continuously.As a result,genetic genes will be transferred between species,and preserved and even continue to spread,thereby changing the genetic diversity,phenotypic characteristics and population structure of the original population.In the spring of 2021,four sampling points were set up in the Lexi River,a tributary of the Tuo jiang River in Chongqing.A total of 421 specimens of H.leucisculus and H.tchangi were collected,of which 31 were H.tchangi,which means that H.leucisculus occupies a larger area in the habitat.The population advantage and the existence of a small number of H.tchangi populations in the same space provide opportunities and possibilities for interspecific hybridization and gene introgression between H.leucisculus and H.tchangi.The introgression of H.tchangi gene may change the population characteristics,feeding organ characteristics and feeding habits of H.leucisculus,thereby affecting the adaptation between the entire H.leucisculus population and the environment.Therefore,this study firstly used the mitochondrial gene Cytb to explore the degree of genetic differentiation of H.leucisculus populations and H.tchangi populations in four geographic groups,and determining that there is a change in heritage distance between H.leucisculus and H.tchangi.Then,for different geographical groups,the age structure,sex ratio and other population characteristics of the H.leucisculus population were discussed,and the body length of the H.leucisculus was compared to explore the differences in the fitness of the four geographical groups.Since body length is closely related to the predation ability and feeding efficiency of fishes,we further analyzed and compared the feeding organs of the four geographic groups of H.leucisculus,including the filter feeding organ gill rakers,and the chewing organs hypopharyngeal bone and hypopharynx tooth,combined with the composition of intestinal contents,to analyze the relationship between the morphological and functional characteristics of feeding organs and feeding preferences,so as to explore the adaptability between the characteristics of feeding organs and the environment of different geographical groups of H.leucisculus.Below are key research findings:(1)The genetic distance of H.leucisculus populations and H.tchangi population in different geographical groups changed,and there was the possibility of hybrid introgression.(2)H.leucisculus populations in the Lexi River are mainly aged from 0 to 2 years old,and the male life expectancy is generally lower than that of females.From upstream to downstream,the proportion of juveniles in the four geographic groups gradually decreased.The proportion of males and females in the upstream KL was equal,the number of females in the downstream HZ was higher than that of the males,and the reproductive potential was stronger.The ratio of males and females in the midstream SW and XN was lower,and the reproductive potential was weaker.(3)From upstream to downstream,the average body length and dominant body length of H.leucisculus gradually increased.H.leucisculus in the downstream area had a greater body length advantage than the upstream,so they had stronger environmental adaptability.(4)Among the four geographical groups,the gill raker spacing and body length of H.leucisculus had a positive correlation(r>0.49,P<0.05).There were no significant correlations between gill raker length and gill raker spacing,gill raker length and body length in the KL,SW and HZ geographic groups,and there was no significant difference in gill raker length among the four geographic groups(P>0.05).(5)There is a certain correlation between the morphology of the hypopharyngeal bones and hypopharyngeal tooth of H.leucisculus(r=-0.157,P<0.05),and there are different bone-tooth assemblages exist among the four geographic groups,and their functions are matched with feeding habits to adapt to different feeding preferences.This study is based on the change in the genetic distance between H.leucisculus populations and H.tchangi populations,the population characteristics and feeding organ characteristics of H.leucisculus were explored.By comparing the differences between different geographical groups,the adaptation of H.leucisculus population to the environment was discussed.sexual changes.In this way,it provides data support for the study of the dynamic development of H.leucisculus populations and the phenotypic differences of feeding organs in Chongqing.It provides a reference for exploring the phenotypic characteristics of feeding organs and feeding preferences of H.leucisculus in other regions.It provides research on the adaptive evolution mechanism of fish hybridization.It also provides a reference for the fluctuation of fish population characteristics and changes in genetic diversity caused by activities such as proliferation and release.