Amphibians are a key group in historical   biogeography because they are often thought to be unable to disperse over   saltwater barriers (Duellman & Trueb 1986; Meirte 1999; Bossuyt &   Milinkovitch 2001; Inger & Voris 2001; Brown & Guttman 2002). They   are well known to be extremely sensitive to osmotic stress and do not survive   in salt water, although some species of frogs tolerate or partially inhabit   brackish water (Balinsky 1981). Therefore, amphibians are considered to be   excellent models for vicariance scenarios as explanation for general   biogeographic patterns, and major biogeographic hypotheses have been influenced   by the occurrence of endemic amphibians on islands or continents (Duellman   & Trueb 1986; Richards & Moore 1996; Worthy et al. 1999; Bossuyt   & Milinkovitch 2001; Brown & Guttman 2002). One important argument   for such interpretations, ever since Darwin (1859), has been that heretoforth   no endemic amphibians were known from oceanic islands. By contrast, reptiles   are present on many islands and some are known to be excellent over-water   dispersers (Censky et al. 1998; Arnold 2000; Schoener et al. 2001).

两栖动物是历史生物地理学中的一个关键类群，因为它们通常被认为无法跨越海水屏障扩散（Duellman &   Trueb 1986; Meirte 1999; Bossuyt & Milinkovitch 2001; Inger & Voris   2001; Brown & Guttman 2002）。众所周知，尽管有些两栖种类的青蛙能够忍受或有时栖息在微咸水中（Balinsky 1981），它们对渗透压力极为敏感，不能在盐水中生存。因此，两栖动物被认为是解释岛屿或大陆特有两栖动物出现的影响因素的一般生物地理学模式的较优可选模型（Duellman & Trueb 1986; Richards & Moore 1996; Worthy et   al. 1999; Bossuyt & Milinkovitch 2001; Brown & Guttman 2002）。自达尔文（1859年）以来，对这种解释的一个重要论据就是迄今为止还没有发现来自海洋岛屿的特有两栖动物。相比之下，爬行动物出现在许多岛屿上，其中一些是众所周知的优秀的跨水域扩散者（Censky et al. 1998; Arnold 2000; Schoener et al. 2001）。