Systematics of Seychellean Caecilians (Amphibia:Gymnophiona)

塞舌尔蚓螈系统学（两栖类：Gymnophiona）

• 批准号: 8817453
• 负责人: Ronald Nussbaum
• 金额: $ 23.44万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-03-15 至 1993-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8817453&HistoricalAwards=false
• 关键词: Systematics; Seychellean; Caecilians; Amphibia; Gymnophiona

The research is aimed at studying the evolutionary relationships among several populations and species of caecilians in the Seychelles Archipelago, western Indian Ocean. Caecilians are small, legless, largely burrowing amphibians restricted to the tropics. The granitic islands of the Seychelles are the mountaintop remnants of a partially submerged microcontinent. About 18,000 years ago when world sea-levels were lower, the Seychellean microcontinent (129,560 km2) was fully emergent. With postglacial warming of the earth, sea-levels rose, and, about 10,000 years ago, the Seychellean microcontinent was fragmented into an archipelago. At the same time, the species that occurred on the microcontinent were fragmented into island populations. Since fragmentation, there has been no gene flow (interbreeding) between these island populations in species like caecilians, which are intolerant of salt water and lack means of dispersal across marine barriers. The fragmentation of species' ranges occurred in parallel, so that several species share the same fragmentation history. The situation described above is well-suited for the study of a variety of evolutionary phenomena. The major goals of the research are to (1) determine the evolutionary relationships of the species and populations by comparing anatomical and biochemical characters; (2) determine the influence of interrupted gene exchange on the divergence of populations; (3) determine the relationship between island separation time and molecular divergence compared to anatomical divergence; (4)determine whether patterns of genetic divergence are similar across species suggesting uniform rates of evolution; and (5) test recently developed models of gene flow using a multispecies approach with different degrees of dispersibility among species.

该研究旨在研究进化 几个无尾目种群和种之间的关系 在西印度洋的塞舌尔群岛。 无足目 是小型无腿的穴居两栖动物， 热带地区 塞舌尔群岛的花岗岩岛屿是 部分淹没的微大陆的遗迹。 约1.8万 几年前，当世界海平面较低时， 微大陆（129，560平方公里）完全形成。 与 冰后期地球变暖，海平面上升， 一万年前，塞舌尔微大陆支离破碎 变成一个群岛 与此同时， 分散成岛屿种群 自分裂以来，没有基因流动（杂交） 在这些岛屿种群中， 它们不耐盐水，缺乏传播手段， 穿越海洋屏障 物种分布区的破碎化 同时发生，所以几个物种共享相同的 碎片化历史。 上述情况非常适合研究 一系列进化现象。 的主要目标 研究的目的是（1）确定进化关系， 通过比较解剖学和 生化特性;（2）确定影响 （3）基因交换中断对群体分化的影响; 确定孤岛分离时间与 与解剖学差异相比的分子差异; （4）确定遗传分歧的模式是否相似 在物种之间，表明进化的速度是一致的;（5） 测试最近开发的模型基因流使用多物种 不同物种之间的差异程度不同。