Difference And Evolution Of Reproductive Traits Of Gobioninae In Jialing River

Gobioninae is one of the speciose subfamilies of Cyprinidae,the survival status of which is seriously polarized.Some species are numerous and in need of control,while some others are endangered and need to conserved.Reproduction is an important life history process for fish to maintain population stability and development,which would determine whether the species prospers or becomes endangered.Understanding the reproductive traits associated with survival status will help us predict the current population status of species and develop scientifically effective conservation measures.Therefore,the multigene of Gobioninae in Jialing River was obtained by molecular sequencing and Gene Bank database,and the phylogenetic relationship of Gobioninae was constructed based on multigene.We obtained the reproductive traits of Gobioninae through literature and experiments,and compared the differences in reproductive traits among different species.With the constructed phylogenetic framework,phylogenetic comparative methods were used to analyze the relationship between survival status and reproductive traits of Gobioninae,and the ancestral state reconstruction analysis,phylogenetic signal detection,and evolutionary correlation between reproductive traits were conducted to explore the evolution of reproductive characteristics.This study will provide an important reference for the formation,adaptation and evolution of Gobioninae,and species conservation.The main results in this study are as follows:1.The literature review and field investigation showed that there were 14 genera and 25 species of Gobioninae in Jialing River.The Phylogenetic analysis of Gobioninae in Jialing River based on multigene displayed that this group could be divided into four lineages: Hemibarbus-Squalidus group,Coreius group,Gobionini and Sarcocheilichthyini.Meanwhile,the controversial problems of phylogenetic position of Platysmacheilus,Coreius and Rhinogobio were also resolved.The result showed that the monophyly of Platysmacheilus was disapproved,and the Coreius was approved as a separate lineage and formed a sister group with Gobionini and Sarcocheilichthyini,and the Rhinogobio was supported as the member of Sarcocheilichthyini and formed sister group relationship with Sarcocheilichthys and Paracanthobrama.2.The reproductive traits of Gobioninae in Jialing River were diverse,and the seven reproductive traits analyzed showed different degrees of diversity.1)The breeding seasons were divided into four types: spring,spring-summer,summer,and spring-summer-autumn,accounting for 44%,48%,4%,and 4% of the studied species,respectively.2)The age of first sexual maturity was divided into three types of 1 year,2 years,and 2-3 years,accounting for 57.14%,19.05%,and 23.81%,respectively.3)The egg types were classified into adhesive eggs,adhesive-demersal eggs,pelagic eggs,adhesive-pelagic eggs,and demersal eggs accounted for 16.67%,29.17%,45.83%,4.17%and 4.17%,respectively.4)Secondary sexual characteristics included two types: 70.83%of studied species with that,and 29.17% of studied species without that.5)The spawning included two types: 46.67% of one-time spawning,and 53.33% of batch spawning.6)Egg size included five types: very small,small,medium,large and very large,accounting for 17.65%,23.53%,17.65%,29.41%,and 11.76%,respectively.7)The relative fecundity included four types: extremely low,low,medium and high,accounting for 12.5%,50%,18.75%,and 18.75%,respectively.The results of ANOVA and pairwise comparison between different types of egg size and relative fecundity according to the classification results showed significant differences in egg size and relative fecundity between different types,and there were significant differences between the two types(P<0.05).3.Vulnerability and resilience were used as parameters of survival status,and the relationship between reproductive traits and vulnerability and resilience were analyzed using PGLS(Genetic Generalized Least Squares)and MCMCglmm(Markov Chain Monte Carlo GLMMs),respectively.The results showed that the vulnerability was negative correlated with relative fecundity(P<0.01),and it was positive correlated with egg size(P<0.05).In addition to,the population resilience was negatively correlated with age of sexual maturity(Pmcmc<0.01),while resilience was not correlated with egg type,breeding season,secondary sexual characteristics,or spawning type.4.The evolution of 24 reproductive traits were analyzed,including breeding season,age of first sexual maturity,egg type,head,trunk,caudal peduncle,fin,et al.The results showed that the evolution of egg type from pelagic egg to other egg types,the age of sexual maturity was evolved from early to late,the evolution of secondary sexual characteristics from existence to non-existence,the relative length between ventral fin and rhynchodaeum(length between ventral fin and rhynchodaeum/standard length)was evolved from small to large,and the ancestral status of other characteristics is not clear.There were 10 characters had significant phylogenetic signals,including age of sexual maturity,spawning type,egg type,secondary sexual characteristics,relative body depth(body depth/standard length),relative dorsal fin length(dorsal fin length/standard length)and so on.There were significant evolutionary correlations among reproductive characteristics.For example,the relative head length(head length/standard length),relative head width(head width/standard length),and relative head depth(head depth/standard length)were significantly positively correlated with the relative length between ventral fin and rhynchodaeum(0.67≤ r ≤0.94,P<0.05),and the relative caudal peduncle length(caudal peduncle length/standard length)was significantly negatively correlated with the relative pectoral fin length(pectoral fin length/standard length)(-0.85≤ r ≤-0.67,P<0.05).