The Relationship Between Extinction Risk And Life History In Global Amphibian

The reduction and extinction of amphibians have been a long-term concern for zoologists,and the rate of decline of amphibian species worldwide is alarming.Globally,nearly two-thirds of amphibians are threatened with extinction,the highest among all vertebrate populations.There is increasing evidence that the extinction risk of amphibians is taxonomically non-random and depends on biological,environmental and human factors.Therefore,identifying the key factors leading to species extinction is an important prerequisite for minimizing the loss of amphibians in the future and protecting them to the greatest extent.This thesis mainly takes 3 867 Anuran amphibians as the research object,and explores the extinction risk and life-history of amphibians worldwide(female body size,male body size,egg size,clutch size,egg placement,developmental patterns,parental care,habitat type and activity time),so as to understand the direct or indirect factors leading to the increased risk of amphibians extinction.We used PGLS(Phylogenetically controlled generalized least-squared)analysis method and Markov Chain Monte Carlo GLMMs analysis(hereinafter referred to as MCMCglmm analysis)method to respectively explore the relationship between lifehistory variables and species extinction risk.In order to consider the universality and specificity of the research results in different taxa,10 families of Anura were analyzed to explore the factors of affecting the extinction risk.The results showed that: 1)The extinction risk of 3876 amphibians was significantly negatively correlated with female body size,clutch size,activity time,and habitat type;it was significantly positively correlated with egg size,egg placement and parental care;There was no correlation between the extinction risk and male body size or developmental patterns;2)After controlling the effect of female body size,the egg size was significantly positively correlated with the risk of extinction,and clutch size was significantly negatively correlated with the risk of extinction;3)In the Bufonidae,male and female body size,egg size,clutch size,egg placement and parental care would all lead to the increase in the risk of extinction;4)In the Strabomantidae,only activity time was negatively correlated with the risk of extinction;5)There was a significant negative correlation between clutch size of the Hyperdiidae and its extinction risk;6)There was a correlation between the egg size,clutch size and habitat type of the Microhylidae and the extinction risk;7)All life-history factors in the Dendrobatidae had no correlation with the extinction risk;8)There was a significant negative correlation between clutch size in the Eleutherodactylidae and the risk of extinction;9)In the Mantellidae,there is a positive correlation between parental care and extinction risk;10)The development pattern,habitat type and clutch size in the Rhacophoridae were all related to the extinction risk;11)In the Ranidae,there was only a negative correlation between the activity time and extinction risk.12)The egg size in Hylidae family was significantly positively correlated with the risk of extinction.We used the path analysis method in 2782 species of Anura,looking for the relationship between both female body size,egg size,clutch size,and parental care and the risk of amphibian extinction.It turned out that amphibians affected the egg size and clutch size through female body size,which directly or indirectly increased the risk of their extinction.The smaller the body size was,the larger the egg size was,and the smaller clutch size in the nest was,the more likely to be extinct.Conservation work requires a substantial increase in international research on long-term monitoring of amphibian populations and the collection of lifehistory and ecological data to effectively alleviate the current collapse of amphibian biodiversity.