Department of Biological Sciences, 107 Life Sciences Building, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Evolution. 2010 Dec;64(12):3380-97. doi: 10.1111/j.1558-5646.2010.01071.x.
Mitochondrial and nuclear sequence data should recover historical demographic events at different temporal scales due to differences in their effective population sizes and substitution rates. This expectation was tested for two closely related coral reef fish, the tube blennies Acanthemblemaria aspera and A. spinosa. These two have similar life histories and dispersal potentials, and co-occur throughout the Caribbean. Sequence data for one mitochondrial and two nuclear markers were collected for 168 individuals across the species' Caribbean ranges. Although both species shared a similar pattern of genetic subdivision, A. spinosa had 20-25 times greater nucleotide sequence divergence among populations than A. aspera at all three markers. Substitution rates estimated using a relaxed clock approach revealed that mitochondrial COI is evolving at 11.2% pairwise sequence divergence per million years. This rapid mitochondrial rate had obscured the signal of old population expansions for both species, which were only recovered using the more slowly evolving nuclear markers. However, the rapid COI rate allowed the recovery of a recent expansion in A. aspera corresponding to a period of increased habitat availability. Only by combining both nuclear and mitochondrial data were we able to recover the complex demographic history of these fish.
线粒体和核序列数据应该能够在不同的时间尺度上恢复历史人口动态，这是由于它们的有效种群大小和替代率的差异。这一预期在两种密切相关的珊瑚礁鱼类中得到了检验，即管鼻鱼 Acanthemblemaria aspera 和 A. spinosa。这两种鱼具有相似的生活史和扩散潜力，并且在整个加勒比地区共存。为了研究这两种鱼，我们在其加勒比地区的范围内收集了 168 个个体的一个线粒体和两个核标记的序列数据。尽管这两个物种具有相似的遗传分化模式，但在所有三个标记中，A. spinosa 的种群间核苷酸序列差异比 A. aspera 大 20-25 倍。使用松弛时钟方法估计的替代率表明，线粒体 COI 每百万年的序列差异进化率为 11.2%。这种快速的线粒体进化率掩盖了这两个物种的古老种群扩张的信号，只有使用进化速度较慢的核标记才能恢复这些信号。然而，快速的 COI 进化率使我们能够恢复 A. aspera 的近期扩张，这与栖息地可用性增加的时期相对应。只有结合核和线粒体数据，我们才能恢复这些鱼类的复杂人口历史。
