The Breeding Habits And Population Status Of Hynobius Chinensis

Under the influences of climate changes and human activities,the amphibian population is increasingly declining;thus,its effective protection is a common task today.However,if we cannot fully understand the species habits and living conditions,we would not establish a targeted protection plan.Hynobius chinensis belongs to Amphibian,Urodela,Hynobiidae,hynobius,which is endemic to China and only distributed in Changyang,Yichang,Hubei Province.Due to the fact that rare research has been done on it,the basic biological information and the population status of the H.chinensis is yet unclear.H.chinensis has been listed as an endangered species by IUCN,which indicates that it is urgent to fully understand and to strengthen its protection.Reproduction is an important part of the life history.Studying breeding habits and population status of species can help to make protective measurements.Therefore,we studied the breeding habits and population census of H.chinensis in Changyang region from November 15th,2015 to April 05th,2016,and analyzed the population status H.chinensis.In this study,we treated the breeding sites of H.chinensis as observing sites,the breeding habits of the H.chinensis was studied in perspective of the breeding sites characteristics,breeding migration,reproductive behavior,egg and egg sacs characteristics.We found that:1)H.chinensis usually breed in lentic and permanent ponds;2)H.chinensis displayed breeding migration behaviors during breeding season.According to our field investigation,we found that the breeding migration of H.chinensis started from November 15th,2015 to March 29th,2016.There were differences in the breeding migration behaviors between males and females.Males moved into the breeding pond a month earlier than females and moved out at the end of breeding season,while the females moved into the breeding pond when they were about to spawn and left the pond soon after spawning.Larger individuals moved into breeding sites earlier than smaller individuals;3)H.chinensis presented external fertilization.Numerous males formed a mating ball to fertilize the eggs during reproduction because of the limitation of eggs;4)The breeding season lasted from December 27th,2015 to March 25th,2016,during which the females spawned a pair of sacs that were attached to branches or water plants.Each pair of egg sacs contained 141.21±26.60 eggs(66-189,n=61),and the egg size was 2.61±0.14 mm(2.4-2.8 mm,n=500).The H.chinensis yearly spawned a pair of egg sacs,and the number of egg sacs was equivalent to the number of breeding females.The sex ratio was 1:1.258 and there were 172 egg sacs in the 2015-2016 breeding season.Based on the sex ratio and number of egg sacs,we estimated that the population of H.chinensis had 388 individuals.Additionally,118 toe samples of H.chinensis were collected,and the genetic diversity of H.chinensis was analyzed using seven microsatellite loci.The results showed that:1)A total of 15 alleles were identified from 118 individuals based on seven microsatellite loci.The mean observed heterozygosity(Ho)was 0.41,the mean expected heterozygosity(He)was 0.38 and the mean polymorphic information content(PIC)was 0.3;2)H.chinensis had experienced a significant population bottleneck;3)The effective population size of H.chinensis was estimated as 36.1;4)The inbreeding coefficient(Fis)was-0.06,indicating that there was relatively low levels of inbreeding.In summary,we concluded that the population number,genetic diversity and effective population size of H.chinensis are extremely low,so the corresponding protective measures should be taken immediately.According to the breeding habits and population status,we suggested adopting the following measures:prohibit agricultural cultivation around the breeding sites at the radius of 500m range to protect the habitat,construct breeding sites to improve the amouts,exchange egg sacs among breeding sites to promote gene flow and establish protected areas to strengthen protection.