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COLONISATION OF THE LAND: A CASE STUDY IN GASTROPODA

土地殖民化：腹足类动物案例研究

基本信息

批准号：
12440140
负责人：
CHIBA Satoshi
金额：
$ 9.92万
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：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

1. Vertical zonation in the intertidal snail Batillaria cumingi, was studied to examine ecological cause of colonization of land in marine gastropoda. The snails found in the highest part of the muddy shore possessed a larger shell with a longer spire than the snails from the lower tidal sites. Based on observations in the laboratory, the former prefers to stay above water to a greater extent than the latter, which corresponds to the difference in their intertidal heights. Among snails transplanted from the upper and lower tidal sites to the position boundary, most moved back to their original sites. Although further genetic analyses are needed, the above results suggest that the preferences for height and air-exposed/submerged condition on a tidal area are diversified within the populations of B. cumingi. This raises the possibility that the vertical zonation in the distribution of Batillaria species has arisen by diversification of habitat preference within populations.2. To estimate patterns of adaptive radiation in Neritopsine gastropoda, mplecular phylogenetic analysis using 28SrRNA sequences was conducted. This group was diversified into marine, flesh water and terrestrial habitat. The inferred phylogenetic relationsip suggests that colonization from marine to ground occur independently at least two times in different lineages and at different times. The ancestral lineages of the terrestrial group are living in marine cave at present. In addition, the colonization from marine to ground occurred through under ground water.3. The rates of molecular evolution were compared by examining nuclear 28SrRNA and mtchondrial DNA sequences in marine and land gastropoda. High evolutionary rates were observed in both 28SrRNA and mtDNA sequences, and thus, colonization of the land follow acceleration in molecular evolution.

1. 研究了潮间带蜗牛 Batillaria cumingi 的垂直分区，以探讨海洋腹足动物陆地定殖的生态原因。在泥泞海岸最高处发现的蜗牛比潮汐较低地点的蜗牛拥有更大的壳和更长的尖顶。根据实验室的观察，前者比后者更愿意停留在水面之上，这与潮间带高度的差异相对应。从上下潮位移植到位置边界的螺类中，大部分又迁回了原来的位置。尽管还需要进一步的遗传分析，但上述结果表明，在潮汐区，B. cumingi 种群对高度和暴露于空气/淹没条件的偏好是多样化的。这提出了一种可能性，即蝙蝠螈物种分布的垂直分区是由于种群内栖息地偏好的多样化而产生的。2．为了估计 Neritopsine 腹足动物的适应性辐射模式，使用 28SrRNA 序列进行了分子系统发育分析。该群体多样化为海洋、肉水和陆地栖息地。推断的系统发育关系表明，从海洋到陆地的殖民在不同谱系和不同时间独立发生至少两次。陆地群体的祖先谱系目前生活在海洋洞穴中。此外，从海洋到地面的定殖也是通过地下水进行的。3．通过检查海洋和陆地腹足动物的核 28SrRNA 和线粒体 DNA 序列来比较分子进化速率。在 28SrRNA 和 mtDNA 序列中都观察到了高进化率，因此，土地的殖民化伴随着分子进化的加速。