4000 years of phenotypic change in an island bird: Heterogeneity of selection over three microevolutionary timescales
4000 years of phenotypic change in an island bird: Heterogeneity of selection over three microevolutionary timescales
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DOI：
10.1111/j.1558-5646.2008.00437.x
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发表时间：
2008-09-01
期刊：
影响因子：
3.3
通讯作者：
Owens, Ian P. F.
中科院分区：
文献类型：
--
作者：
Clegg, Sonya M.;Frentiu, Francesca D.;Owens, Ian P. F.
岛屿种群显着的表型变化通常归因于自然选择，但在长期选择机制中重建异质性仍然是一个挑战。我们研究了为殖民新环境的物种提出的分歧情景，包括定向选择，快速转向新的最佳状态以及随后的稳定。我们使用来自岛鸟 Zosterops Lateris Chlocephalus 三个时间尺度的形态学数据，为这种进化模型提供了一些最初的经验证据。在与大陆分离后不到四千年的时间里，体型发生了大幅增加，并且可能在殖民后不到 500 代的时间内实现了。近四年来，形态性状的大小发生了波动，但没有表现出显着的方向性趋势，表明维持了相对稳定的表型。最后，对当代选择梯度的估计表明方向选择普遍较弱。这些结果提供了对长期自然状况中异质性的罕见描述，并警告说，由于即使在短时间内也缺乏稳定性，当前选择的观察在推断过去适应机制方面的价值可能有限。
Pronounced phenotypic shifts in island populations are typically attributed to natural selection, but reconstructing heterogeneity in long-term selective regimes remains a challenge. We examined a scenario of divergence proposed for species colonizing a new environment, involving directional selection with a rapid shift to a new optimum and subsequent stabilization. We provide some of the first empirical evidence for this model of evolution using morphological data from three timescales in an island bird, Zosterops lateralis chlorocephalus. In less than four millennia since separation from its mainland counterpart, a substantial increase in body size has occurred and was probably achieved in fewer than 500 generations after colonization. Over four recent decades, morphological traits have fluctuated in size but showed no significant directional trends, suggesting maintenance of a relatively stable phenotype. Finally, estimates of contemporary selection gradients indicated generally weak directional selection. These results provide a rare description of heterogeneity in long-term natural regimes, and caution that observations of current selection may be of limited value in inferring mechanisms of past adaptation due to a lack of constancy even over short time-frames.