Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794-5245, USA.
Mol Ecol. 2013 Sep;22(18):4681-94. doi: 10.1111/mec.12412. Epub 2013 Aug 5.
Speciation is often categorized based on geographic modes (allopatric, parapatric or sympatric). Although it is widely accepted that species can arise in allopatry and then later become sympatrically or parapatrically distributed, patterns in the opposite direction are also theoretically possible (e.g. sympatric lineages or ecotypes becoming parapatric), but such patterns have not been shown at a macrogeographic scale. Here, we analyse genetic, climatic, ecological and morphological data and show that two typically sympatric colour morphs of the salamander Plethodon cinereus (redback and leadback) appear to have become parapatrically distributed on Long Island, New York, with pure-redback populations in the west and pure-leadback populations in the east (and polymorphic populations in between and on the mainland). In addition, the pure-leadback populations in eastern Long Island are genetically, ecologically and morphologically divergent from both mainland and other Long Island populations, suggesting the possibility of incipient speciation. This parapatric separation seems to be related to the different ecological preferences of the two morphs, preferences which are present on the mainland and across Long Island. These results potentially support the idea that spatial segregation of sympatric ecotypes may sometimes play an important part in parapatric speciation.
物种形成通常基于地理模式（异域、邻域或同域）进行分类。虽然人们普遍认为，物种可以在异域发生，然后再成为同域或邻域分布，但理论上也可能出现相反的模式（例如同域谱系或生态型成为邻域），但这种模式在宏观地理尺度上尚未得到证实。在这里，我们分析了遗传、气候、生态和形态数据，结果表明，蝾螈 Plethodon cinereus 的两种典型同域色型（红背和铅背）似乎在纽约长岛呈现出邻域分布，西部是纯红背种群，东部是纯铅背种群（中间和大陆上是多态种群）。此外，长岛东部的纯铅背种群在遗传上、生态上和形态上与大陆和其他长岛种群存在分歧，这表明可能正在发生物种形成的初期阶段。这种邻域分离似乎与两种色型的不同生态偏好有关，这种偏好存在于大陆和长岛各地。这些结果可能支持这样一种观点，即同域生态型的空间隔离有时可能在邻域物种形成中发挥重要作用。
