A time-calibrated phylogenetic approach to assessing the phylogeography, colonization history and phenotypic evolution of snakes in the Japanese Izu Islands
A time-calibrated phylogenetic approach to assessing the phylogeography, colonization history and phenotypic evolution of snakes in the Japanese Izu Islands
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DOI：
10.1111/j.1365-2699.2010.02403.x
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发表时间：
2011-02-01
影响因子：
3.9
通讯作者：
Hasegawa, Masami
中科院分区：
文献类型：
--
作者：
Kuriyama, Takeo;Brandley, Matthew C.;Hasegawa, Masami
目的通过对分布有限的陆栖脊椎动物--日本四纹锦蛇（Elaphe quadrivirgata）的地理分布和殖民历史的研究，揭示大陆种群入侵日本伊豆群岛的次数、这些殖民者的大陆来源以及殖民的时间尺度。我们将这些结果与过去的研究结果进行比较，试图揭示一般的地理模式。此外，我们简要地检查殖民历史的意义时，评估的身体大小和黑化的伊豆岛E的演变。位置的伊豆群岛（大岛，丰岛，新岛，志根，Kozu，Tadjun和Mikura），一个火山群岛太平洋沿岸的日本中部。MethodsWe获得的线粒体细胞色素B基因（1117碱基对）的DNA序列从373个个体的蛇采样从7个伊豆群岛和25个大陆的地方。我们采用分区贝叶斯系统发育分析假设一个宽松的分子钟，估计现存的单倍型之间的系统发育关系，并给出一个明确的时间尺度的分支分歧，殖民历史和身体大小的进化克里思。此外，我们采用基于模型的地理分析来计算最小次数E。quadrivirgata殖民的伊豆Islands.ResultsWe发现的证据表明，三个独立的地区的伊豆群岛已独立于大陆的祖先在过去的0.58-0.20马。伊豆半岛加上大岛和三仓都是独立于居住在日本东部大陆的血统的殖民地。丰岛、新岛、志根、小津和多津人口都来自日本西部大陆的单一殖民地。大岛已受到三个或可能四个colonization.Main conclusionsThese结果支持的假设，即极端的身体大小差异岛屿种群的这种鼠蛇在原地进化。此外，事实上，居住在大岛的矮，黑种群来自多个大陆殖民事件的证据是一个非常强大的自然选择压力，导致这种独特的形态的快速进化。这些结果与理论预测，自然选择的压力应该发挥作用减少岛屿靠近大陆和/或受到频繁或最近的移民。
AimWe infer the biogeography and colonization history of a dispersal-limited terrestrial vertebrate, the Japanese four-lined ratsnake (Elaphe quadrivirgata), to reveal the number of times mainland populations have invaded the Izu Archipelago of Japan, the mainland sources of these colonists, and the time-scale of colonization. We compare these results with those of past studies in an attempt to uncover general biogeographical patterns. Moreover, we briefly examine the significance of colonization history when evaluating the evolution of body size and melanism of the Izu Island E. quadrivirgata populations.LocationThe Izu Islands (Oshima, Toshima, Niijima, Shikine, Kozu, Tadanae and Mikura), a volcanic archipelago off the Pacific coast of central Japan.MethodsWe obtained DNA sequences of the mitochondrial cytochrome b gene (1117 base pairs) from 373 individual snakes sampled from seven of the Izu Islands and 25 mainland localities. We employed partitioned Bayesian phylogenetic analyses assuming a relaxed molecular clock to estimate phylogenetic relationships among extant haplotypes and to give an explicit temporal scale to the timing of clade divergence, colonization history and tempo of body-size evolution. Moreover, we employed model-based biogeographical analysis to calculate the minimum number of times E. quadrivirgata colonized the Izu Islands.ResultsWe found evidence that three separate regions of the Izu Archipelago have been colonized independently from mainland ancestors within the past 0.58-0.20 Ma. The Izu Peninsula plus Oshima and Mikura were both colonized independently from lineages inhabiting eastern mainland Japan. The Toshima, Niijima, Shikine, Kozu and Tadanae populations all derive from a single colonization from western mainland Japan. Oshima has been subject to three or possibly four colonizations.Main conclusionsThese results support the hypothesis that the extreme body-size disparity among island populations of this ratsnake evolved in situ. Moreover, the fact that the dwarf, melanistic population inhabiting Oshima descends from multiple mainland colonization events is evidence of an extremely strong natural selection pressure resulting in the rapid evolution of this unique morphology. These results contrast with theoretical predictions that natural selection pressures should play a decreased role on islands close to the mainland and/or subject to frequent or recent immigration.