The Research On Sexual Selection Of Facial Coloration In Male Golden Snub-Nosed Monkey(Rhinopithecus Roxellana) In Shennongjia National Park,China

The functions of animal colors are various.The role of phenotypic coloration in sexual selection deserves to receive considerable critical attention.Non-human primates are excellent model for investigate the role of phenotypic coloration in sexual selection,owing to primates are noted for their varied and complex pelage and bare skin coloration and mating systems and visual systems.The beautiful skin color of individual may have an advantage in intrasexual selection,because it indicates the strong social status.Meantime,the beautiful skin color is preferred by mates,because it indicates excellent quality.The golden snub-nosed monkey(Rhinopithecus roxellana)deserves to study because of bule skin.The study aim was to explore the sexual selection mechanism of facial blue skin in golden snub-nosed monkeys.We studied semi-free-ranging population golden snub-nosed monkeys in Shennongjia from May 2021 to July 2022.The cheek skin color of adult male was obtained by digital photography technology.The male testosterone and individual body was measured.The aggression and submission behaviors were recorded by behavior observation to calculate the rank sequence,and the mating behaviors and female migration behaviors were recorded as the basis for female selection.A comparative study was conducted in both reproductive season and anestrous season.Our study findings were summarized below:The facial blueness of adult male golden snub-nosed monkeys did not have seasonal variation,but there were significant differences among individuals in facial blueness;The blueness of adult males’ skin color in golden snub-nosed monkeys were no significant correlation,but the comparison of blueness between individuals can be used as a reference for the comparison of male testosterone levels in the same period;Golden snub-nosed monkey adult males’ scaled mass index were significant differences between individuals;The blueness of resident males’ skin color showed significant positive correlation with the rank in reproductive season.In anestrous season,senior resident males suffered less attacks and challenges.The blueness of resident males’ skin color in reproductive season could more accurately reflect the rank of individual;The facial colouration of young adult male golden snub-nosed monkeys are bluer than their senile adult counterparts;During the reproductive season,most of females chose the bluest resident male as their cheating partner;Females tend to choose bluer adult males during individual migration.Combined with the above data to verify the sexual selection theory,the following inferences are obtained:In anestrous season,senior resident males suffered less attacks and challenges.This suggests that high rank has a deterrent effect.The blueness of resident males’ skin color in reproductive season could more accurately reflect the rank of individual.Therefore,it is speculated that the blue skin of adult male serves as an "status badge".Most of females chose the bluest resident male as their cheating partner during the reproductive season.It is speculated that female prefer adult males with bluer facial skin in reproductive season.The results about testosterone and age may provide some support for this female mating preference.