横断山区华西蟾蜍群体遗传学与谱系地理学研究

Population genetic structures and phylogenetic relationships are fundamental traits and of central importance to evolutionary biology in animals which are affected by some factors such as mutation, migration, selection and genetic drift. It is important to study the population genetic structures and phylogenetic relationships for species conservation because genetic structure and diversity directly affect on population size. Hence, population genetic structures and phylogenetic relationships can produce important effects in the evolutionary and ecological process resulting from natural selection which benefits to breeding behaviour and speciation in nature. Previous results from our studies have been shown that population genetic structures and phylogenetic relationships of the Andrew’s toad, Bufo andrewsi, a species widely distributed in the Hengduan mountains in western China, exhibits significant variation in genetic structures among populations and some of this variation can be explained by environmental factors (i.e. altitude, temperature and rainfall). Therefore, we propose two hypotheses: (1) there are geographic variations in population genetic structures of B. andrewsi populations, and altitude, temperature and rainfall can explain these variations; (2) quaternary glaciation and interglacial period affect the current spatial pattern of B. andrewsi across populations. In order to test two hypotheses, we plan to use genetic analysis methods to study geographic variations in genetic structures and phylogenetic relationships in B. andrewsi populations distributed in different latitude and altitude in seven National Nature Reserves at the Hengduan Mountains in western China. Our aims are: (1) to test whether geographic variations in population genetic structures and phylogenetic relationships occur in B. andrewsi across populations, and how do vary; (2) what are the proximate factors affecting geographic variations in population genetic structures and phylogenetic relationships in B. andrewsi among popualtions; (3) to test whether the current spatial pattern in B. andrewsi populations is related to the history of geological events, and the quaternary glaciation and interglacial period are mainly factors affecting the current spatial pattern in B. andrewsi across populations. According to results of testing two hypotheses, we will gain insight into the molecular mechanisms of geographic variations in both genetic structures and phylogenetic relationships and the current spatial pattern in B. andrewsi in the Hengduan Mountains.

群体遗传结构和谱系关系能够对自然选择等重要的生态和进化过程产生深远影响，并在物种的保护中发挥了重要的作用，至今依然是进化生物学研究的热点课题。我们前期研究发现，华西蟾蜍的遗传结构的地理变异与海拔和温度有关，且现有分布格局与历史地质事件有关。为此，我们假设：海拔、温度和降雨量是导致华西蟾蜍遗传结构地理变异的重要环境因素以及第四纪冰期是导致其现有分布格局的主要因素。为检验该假设，本项目拟以横断山区七个自然保护区华西蟾蜍不同地理种群为研究对象，采用遗传分析方法，比较研究华西蟾蜍：（1）是否存在遗传结构的地理变异？如果存在，那么不同地理种群遗传结构怎样变化？（2）影响种群遗传结构地理变异的因素有哪些？以及（3）第四纪冰期是否是导致华西蟾蜍不同种群现有分布格局的主要因素？通过对华西蟾蜍遗传结构和现有分布格局假设的验证，揭示华西蟾蜍遗传结构地理变异及现有分布格局的机理。

群体遗传结构和谱系关系能够对自然选择等重要的生态和进化过程产生深远影响，并在物种的保护中发挥了重要的作用，至今依然是进化生物学研究的热点课题。我们前期研究发现，华西蟾蜍的遗传结构的地理变异与海拔和温度有关，且现有分布格局与历史地质事件有关。为此，我们假设：海拔、温度和降雨量是导致华西蟾蜍遗传结构地理变异的重要环境因素以及第四纪冰期是导致其现有分布格局的主要因素。为检验该假设，本项目拟以横断山区七个自然保护区华西蟾蜍不同地理种群为研究对象，采用遗传分析方法，比较研究华西蟾蜍：（1）是否存在遗传结构的地理变异？如果存在，那么不同地理种群遗传结构怎样变化？（2）影响种群遗传结构地理变异的因素有哪些？以及（3）第四纪冰期是否是导致华西蟾蜍不同种群现有分布格局的主要因素？通过对华西蟾蜍遗传结构和现有分布格局假设的验证，揭示华西蟾蜍遗传结构地理变异及现有分布格局的机理。通过对项目的研究，我们发现：（1）华西蟾蜍种群存在明显的遗传变异，其变异程度随地理距离增加而增加；（2）环境的温度、降雨量是影响华西蟾蜍种群遗传差异的主要影响因素；（3）第四纪冰期是导致横断山区华西蟾蜍不同种群现有分布格局的主要因素，研究结果为华西蟾蜍的保护提供了理论依据。相应的成果在Diversity and Distributions, Molecular Ecology Resources, Animal Biology及Asian Herpetological Research等期刊上发表，此外，关于华西蟾蜍不同地理种群分布格局及物种保护的论文正在撰写，准备在Conservation Biology期刊上投稿，项目执行期间培养博士研究生1名，硕士研究生4名。