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Evolution in frontier environments

前沿环境的演变

基本信息

批准号：
15340174
负责人：
CHIBA Satoshi
金额：
$ 10.56万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Ecological and genetic process of adaptive radiation were examined using endemic land snail genus Mandarina of the oceanic Ogasawara Islands in the northwestern Pacific. Based on the habitat analysis, morphological analysis, and examination of the mitochondrial DNA sequence variations, we showed that hybridization between sympatric species occurred by alteration of habitat use due to environmental change. This suggests that speciation and adaptive radiation are still in progress in Mandarina. In addition, populations with unique shell morphologies were found in a hybrid zone constituted between morphologically closely related species. This suggests that hybridization is an important source of creating novel morphology and evolutionary novelty.Phylogenetic relationship among the species of the land snails Euhadra in the mainland of Japan was estimated on the basis of mitochondrial DNA sequences. Repeated expansion and immigration have occurred in Euhadra, associated with climatic change during the Pleistocene. Complex spatial structure in genetic variations was created by mixing and isolation that were accompanied with the climatic change.Relationship between intertidal gastropoda Batillaria cumingii and its parasites was examined on the basis of ecological, morphological and genetic (mitochondrial DNA and nuclear ITS gene) analysis. Genetic analysis revealed that these parasites include a large number of cryptic species. These species showed less geographical variations in genetic variations. On the other hands, Batillaria showed a high level of geographical variations in genetic components. Ecological speciation due to habitat shift would be a main cause of diversification of parasites in intertidal gastropoda.

以西北太平洋小笠原群岛特有陆地蜗牛属Mandarina为研究对象，对其适应辐射的生态和遗传过程进行了研究。基于生境分析、形态分析和线粒体DNA序列变异分析，我们认为同域物种间的杂交是由于环境变化导致的生境改变而发生的。这表明物种形成和适应性辐射仍在进行中。此外，在形态相近的种间杂交区发现了具有独特壳形态的居群。这表明杂交是创造新形态和进化新颖性的重要来源。基于线粒体DNA序列，对日本大陆陆地钉螺种间的系统发育关系进行了估计。与更新世期间的气候变化有关，在Euhadra发生了反复的扩张和移民。遗传变异的复杂空间结构是伴随着气候变化而产生的混合和隔离。通过生态学、形态学和遗传学（线粒体DNA和核its基因）分析，对潮间带腹足动物cumingii及其寄生虫的关系进行了研究。遗传分析表明，这些寄生虫包括大量的隐种。这些物种在遗传变异方面表现出较少的地理差异。另一方面，巴提拉属在遗传成分上表现出高度的地理差异。生境转移导致的生态物种形成是潮间带腹足动物寄生虫多样化的主要原因。