Study On The Sexual Dimorphism Of Murina Huttoni

Murina huttoni belongs to Murina,Vespertilionidae,Chiroptera,a typical forest inhabitant,occurring generally in the dense vegetation.Therefore,this elusive species is often unnoticed,not captured,hence lacks baseline biological information.Key Laboratory of Conservation and Application in Biodiversity of South China,Guangzhou University focused survey on forest dwelling bats and conducted surveys in Southern China since 2009.During which 125 specimens including 54 female and 71 male of the species were collected from Guangdong,Jiangxi,Hunan,Hubei,Zhejiang and Yunnan.Morphological analysis of the specimens revealed “female biased sexual size dimorphism” in the species.However,there had been no information on the potential intrinsic factors for the phenomenon.Therefore,the current study deployed integrated approach of traditional morphology(external morphology,wing and skull length measurement indicators),geometric morphology(two-dimensional wing characteristics and three-dimensional skull model reconstruction),multivariate statistics,kinship geography and other technical means to quantify the sexual size dimorphism in the species.In addition,we also applied reconstruction of the genetic structure and the population history,and explored the potential driving force for the phenomenon.The main results of this study are as follows:(1)Multivariate statistical analysis of the external length index,the wing length index,the two-dimensional wing geometric shape index,the wing area index,the skull length index and the three-dimensional skull geometric shape index depicts that: there are significant differences between male and female(female larger than male in the wing area,two-dimensional wing geometry morphology,skull measurement and three-dimensional skull geometry morphology).It can be interpreted that allometric growth in some parts,and the differentiation of the relevant area may be related to carrying the cub during the flight in female.Moreover,it will improve the wing loading and flexibility,the teeth occlusion and food chewing.In addition,this study also revealed that the male and female individuals differ in external morphology in different locations,and females exhibit more obvious such spatial differences than males.Compared with male and female present overall enlargement in external morphology and wing,and female present specific amplification in the attachment area for cub.Indicating that female show larger wing area to increase wing loading to adapt to the attachment of cub,to improve the reproductive success rate,it is consistent with the “Big mother” hypothesis.On the other hand,male adapt to long-distance flight in order to reduce the competition of intra-species resource,and there is a significant phenomenon of allometric between male and female in skull,it is indicating that male and female tends to stagger in food habit,which is consistent with the “resource competition” hypothesis.(2)Phylogeography studies based on mitochondrial CoI gene,nuclear gene RAG2 gene and 18 pairs of microsatellite markers revealed that: although the haplotype network topologies of the two genes were mixed,the genetic structure of mitochondrial markers was more obvious.In terms of genetic information,the genetic diversity of mitochondrial CoI gene is higher than that of RAG2 gene.Moreover,the two markers showed inconsistent population history.CoI gene showed obvious expansion after bottleneck,while RAG2 gene showed no significant changes.This can be interpreted probably due to the greater dispersal behavior in males than females.Results from the microsatellite markers showed that there was a confounding relationship between the genetic structure of the species population,and there was no significant regional difference or sexual difference.The results of the relationship analysis indicate that the females from the same locations are more likely to be related,but the males from different locations are more likely to be related.The result is consistent with the mitochondrial gene results and further suggest that gender bias exists between males and females.Furthermore,the difference in dispersal behavior between male and female to reduce the intra-species competition,male shows a tendency to go out to reduce the competition of resource between male and female.Under the circumstances,inbreeding is avoided to improve the survival rate of cubs,which is consistent with the hypothesis of “resource competition” hypothesis.However,mechanism of drivers for sexual dimorphism is complex in Murina huttoni.The species exhibit functional area specific amplification supporting “Big mother" hypothesis.The phenomenon not only impact the female reproductive success,but also help males and females stagger the ecological niche.Females tend to stay in birthplace and male spread outside to reduce the intraspecific competition “resource competition” hypothesis.