Bell Museum of Natural History, University of Minnesota, St Paul, MN 55108, USA.
BMC Evol Biol. 2010 Mar 10;10:71. doi: 10.1186/1471-2148-10-71.
The subtropical island of Taiwan is an area of high endemism and a complex topographic environment. Phylogeographic studies indicate that vicariance caused by Taiwan's mountains has subdivided many taxa into genetic phylogroups. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the evolutionary history of an endemic montane bird, Steere's Liocichla (Liocichla steerii), fit the general vicariant paradigm for a montane organism.
We found that while mountains appear to channel gene flow they are not a significant barrier for Steere's Liocichla. Recent demographic expansion was evident, and genetic diversity was relatively high across the island, suggesting expansion from multiple areas rather than a few isolated refugia. Ecological niche modeling corroborated the molecular results and suggested that populations of Steere's Liocichla are connected by climatically suitable habitat and that there was less suitable habitat during the Last Glacial Maximum.
Genetic and ecological niche modeling data corroborate a single history--Steere's Liocichla was at lower density during the Last Glacial Maximum and has subsequently expanded in population density. We suggest that such a range-wide density expansion might be an overlooked cause for the genetic patterns of demographic expansion that are regularly reported. We find significant differences among some populations in FST indices and an admixture analysis. Though both of these results are often used to suggest conservation action, we affirm that statistically significant results are not necessarily biologically meaningful and we urge caution when interpreting highly polymorphic data such as microsatellites.
台湾是一个亚热带岛屿，拥有高度的特有现象和复杂的地形环境。系统地理学研究表明，台湾山脉造成的地理隔离使许多分类单元分化成不同的遗传谱系。本研究运用线粒体 DNA 序列和核微卫星标记来检验特有山地鸟类 Steere's Liocichla（Steere's 鹪鹩莺）的进化历史是否符合山地生物的普遍隔离分化模式。
尽管山脉似乎限制了基因流，但它们并不是 Steere's Liocichla 的一个显著障碍。近期的种群扩张是明显的，整个岛屿的遗传多样性相对较高，这表明扩张来自多个地区，而不是少数孤立的避难所。生态位模型的结果与分子结果一致，表明 Steere's Liocichla 的种群通过气候适宜的生境连接在一起，而在末次冰期最大盛期，生境适宜性较低。
遗传和生态位模型数据证实了一个单一的历史——Steere's Liocichla 在末次冰期最大盛期的密度较低，随后种群密度增加。我们认为，这种广泛范围内的种群密度扩张可能是经常报道的种群扩张遗传模式的一个被忽视的原因。我们发现一些种群之间在 FST 指数和混合分析方面存在显著差异。尽管这两个结果通常被用来暗示保护行动，但我们肯定统计学上显著的结果不一定具有生物学意义，当解释高度多态性的数据（如微卫星）时，我们应谨慎行事。
