Study On The Population Status And Genetic Diversity Of Cygnus Columbianus Bewickii In Eurasia Based On Telemetry And Molecular Data

Changes in the number and distribution of species can intuitively reflect the status of the species,and the genetic diversity can reflect the adaptability of the species to environmental changes.The migratory waterbirds are one of the focuses of ornithological research.Understanding flyway,population size and genetic diversity provides a scientific basis for the conservation and management of migratory waterbirds.Migratory waterbirds change their temporal and spatial distribution following seasonal resources,and grasping the connectivity between their breeding,moulting,staging and wintering areas is the basis for studying population dynamics and genetic diversity.Bewick's Swans(Cygnus columbianus bewickii),a migratory waterbird,distributed widely in Eurasia,and there was lack of research to comprehensively estimate the status of this species.We combined satellite tracking data,wintering survey data,and molecular data to study population status and genetic diversity of the Bewick's Swan in Eurasia.The main reults were as follows:(1)Identified the distribution,population size and trends of Bewick's Swans in East Asia and update the population status:we combined GPS telemetry data,survey data and expert knowledge for the first time to define two distinct flyways(the East Asian continental and West Pacific flyways),migration routes and abundance for the Eastern population.the East Asian continental flyway included birds bred in the Russian Arctic from the Yamal Peninsula to approximately 140°E(including the Lena and Yana Deltas),wintered in the middle and lower reaches of the Yangtze River in China.The population number is currently estimateds as c.65,000 birds.Chinese-wintering swans now concentrate mainly(c.80%)at Poyang lake in Jiangxi Province and Hubei Lakes(mostly in Longgan Lake).Bewick's Swans of the West Pacific flyway bred from the Indigirka River east to the Koluchin Bay,and wintered in Japan,mostly in Niigata,Yamagata and Ishikawa Prefectures.Bewick's Swans of West Pacific flyway now numbers c.40,000.Small numbers likely within this population also winter in South Korea.These results provide our first basic understanding of the winter distribution of Chinese-and Japanese-wintering populations in relation to their breeding areas,confirming the need to coordinate future research and monitoring in the two flyways as well as the need for more information on Bewick's Swans wintering in South Korea.(2)Clarified population status and genetic diversity of four populations of Bewick's Swans in Eurasia:the Northwest European population,included birds bred in Russia-European tundra,wintered in northwestern Europe,the population numbers is estimated as c.20,148 with decrease trend;the Caspian population,included birds bred in Yamal,wintered in Caspian sea,Black sea and Evros Delta in Greece,the population numbers is estimated as c.3,000 with increase trend;the Chinese population included birds bred between Yamal Peninsula and Svyatoy Nos Cape,wintered in China,the population numbers is estimated as c.65,000 with decrease trend;and Japanese population included birds bred between nearby Indigirka River and Chaun Delta,wintered in Japan,the the population numbers is estimated as c.40,000 with increase trend.Five hundred and eighty-six individuals with different genotypes were identified from 824 feather samples from 8 geographic groups.From the results of the mitochondrial control region,among the wintering populations,the genetic diversity of Chaun and European groups were the lowest,while Yamal,Greece,Chinese groups were the highest.From the results of microsatellite data,the heterozygosity of the eight geographic groups is similar.Both mitochondrial and microsatellite markers showed that the Chaun and Japanese populations are genetically different from other geographic populations and have similar genetic structures,while other populations have similar structures,this result was consistent with the flyway structure.The haplotype network using the mitochondrial control region did not show obvious geographical pattern.No population expansion and bottleneck events of the Bewick's Swan were detected based on the current molecular markers.In this study,the two flyways of Bewick's Swans in East Asia were determined for the first time,and we also estimated the population status and genetic diversity of Bewick's Swans in Eurasia.The results provide important scientific basis for the conservation and management of this species.