The temporal and spatial scale of microevolution: fine-scale colour pattern variation in the Lake Erie watersnake, Nerodia sipedon insularum
The temporal and spatial scale of microevolution: fine-scale colour pattern variation in the Lake Erie watersnake, Nerodia sipedon insularum
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微进化的时间和空间尺度：伊利湖水蛇 Nerodia sipedon insularum 的精细尺度颜色图案变化
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
R. King
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文献类型：
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作者：
J. Ray;R. King
问：微进化的时空尺度是什么？假设：自然选择和基因流动的共同作用导致了遗传性状在精细空间和地理尺度上的变异。生物：伊利湖水蛇，Nerodia sipedon insularum。野外地点：伊利湖西部的美国和加拿大岛屿。方法：我们使用自1980年以来进行的几乎每年一次的人口普查数据、博物馆标本和已发表的资料，测试了岛屿内、岛屿间和随时间的颜色图案频率变化。我们比较了一个假定的主要颜色模式位点的FST和等位酶位点的FST，以确定空间变异是否偶然超过预期。我们根据假设的颜色图案等位基因的时间频率变化计算有效种群大小（Ne），以确定时间变化是否超过偶然预期（Ne显著小于∞）。结论：岛屿内或距离较近的岛屿之间的变形频率差异不显著。从1980年到现在，在遥远的岛屿之间和采样周期之间，变形频率有时确实存在显著差异，但并不超过偶然预期。相比之下，在历史（1961年之前）和最近（1980-2003年）样本之间，形态频率发生了显著变化。可能的机制包括选择强度的变化（由于捕食者组合和视觉环境的变化）和基因流动速率的变化（由于岛屿水蛇种群规模的变化）。
Question: What is the temporal and spatial scale of microevolution? Hypotheses: The combined effects of natural selection and gene flow result in variation in heritable traits on fine spatial and geographic scales. Organism: The Lake Erie watersnake, Nerodia sipedon insularum. Field site: US and Canadian islands in western Lake Erie. Methods: We tested for variation in colour pattern frequency within islands, among islands, and over time using data from nearly annual censuses conducted since 1980, museum specimens, and published sources. We compared FST for a presumptive major colour pattern locus to FST for allozyme loci to determine whether spatial variation exceeded that expected by chance. We computed effective population size (Ne) based on temporal frequency changes in presumptive colour pattern alleles to determine whether temporal variation exceeded that expected by chance (Ne significantly less than ∞). Conclusions: Morph frequencies did not differ significantly within islands or between islands separated by short distances. Morph frequencies did sometimes differ significantly among distant islands and among sampling periods from 1980 to the present, but no more than expected by chance. In contrast, a marked change in morph frequency occurred between historic (prior to 1961) and recent (1980–2003) samples. Possible mechanisms include changes in the strength of selection (due to changes in predator assemblages and visual environments) and rates of gene flow (due to changes in island watersnake population size).