Study On The Reproductive Ecology And Habitat Selection Of Two Species Of Urodela In Changbai Mountain

Changbai Mountain is a known and rare symptric region of Salamandrella keyserlingii and Hynobius leechii.In this study,from April to May,2017 and 2018,two species of urodela?Salamandrella keyserlingii and Hynobius leechii?in Changbai Mountain are chosen to be the research objects,the breeding period,sexual dimorphism,oviposition habits and characteristics of egg bags were investigated and measured.Furthermore,the differences of habitat utilization characteristics between two species of urodela spawning sites and oviposition sites were compared and analyzed.It provides a theoretical basis for species differentiation and conservation of symptric distribution.The main researches result in the following aspects:1.There was overlap in spawning time between the two species of urodela from mid-April to early May,but Salamandrella keyserlingii started to be active about 3 days earlier than Hynobius leechii.2.A total of 260 pairs of eggs bags of Salamandrella keyserlingii and 162 pairs of eggs bags of Hynobius leechii were observed.The attachment of eggs bag of Salamandrella keyserlingii is mainly aquatic,accounting for 66.15%of the total,while that of Hynobius leechii is mainly deadwood,accounting for 71.60%of the total.The egg bag length and egg diameter of Salamandrella keyserlingii were significantly smaller than that of Hynobius leechii,while the egg bag diameter and egg number were significantly larger than that of Hynobius leechii.3.The snout-vent length?SVL?was significantly different between the male and female in Salamandrella keyserlingii(F_1,59=25.796,P<0.01).The heteromorphism was that the head length and diameter of eye females were larger than that of males,while the head width,tail height and tail length of males were larger than that of females.The average head length ratio of females to males was 1.089,and the SDI was 0.08.The snout-vent length?SVL?was significantly different between the male and female in Hynobius leechii(F_1,59=25.796,P<0.01).The heteromorphism was that the head length and length of foreleg females were longer than that of males,while the tail height of males was higher than that of females.The average head length ratio of females to males was 1.066.and the SDI was 0.04.4.A total of 13 spawning sites of two species of urodela were found,of which the number of spawning sites of Salamandrella keyserlingii was large,6 were distributed in a wide range of 619 to 739 m;the number of spawning sites of Hynobius leechii was small,3 were distributed in a concentrated range of 662 to 692 m;and there were 4common spawning sites with a distribution range of 658 to 692 m.The average altitude of spawning sites of Salamandrella keyserlingii was lower,658.00±17.63 m,while that of Hynobius leechii was higher,680.67±9.40 m.The average altitude of coexisting spawning sites was between them 678.75±7.89 m.5.There are no significant differences in the spawning sites habitat factors,but there are significant differences in the oviposition sites microhabitat such as depth of oviposition,water temperature and sundries coverage ration.Salamandrella keyserlingii oviposition sites were shallower the depth of oviposition,had higher the water temperature,had higher the sundries coverage ration than were Hynobius leechii oviposition sites.It can be seen that the habitat separation of the spawning sites is the main reason for the coexistence of the two sympatric species.