Response to selection and evolvability of invasive populations
Response to selection and evolvability of invasive populations
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DOI：
10.1007/s10709-006-9013-9
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发表时间：
2007-02-01
期刊：
影响因子：
1.5
通讯作者：
Chang, Yu-Mei
中科院分区：
文献类型：
--
作者：
Lee, Carol Eunmi;Remfert, Jane Louise;Chang, Yu-Mei
虽然自然选择在某些情况下可能会促进入侵进入新的栖息地，但对入侵种群的选择反应的直接测量却很少。本研究利用桡足动物Eurytemora affinis研究了对盐度变化的选择反应。这种桡足动物在北半球多次独立地从含盐栖息地入侵淡水。在实验室中测量了来自北美圣劳伦斯流域的盐源和淡水入侵种群对恒定中等盐度（5 PSU）的选择响应。这些种群在三种条件下饲养：(1)本地盐度（0或15 PSU）至少两代，(2)5 PSU两代，(3)5 PSU六代。从这三种条件下饲养的种群中取出的全同胞卵卵被分成四种盐度（0、5、15和25 PSU），以确定生存和发育时间的反应标准。三种饲养条件下的生存和发育时间差异被视为选择反应。5 PSU的选择导致了咸水种群和淡水种群对淡水（0 PSU）的耐受性显著下降。然而，咸水种群和淡水种群在淡水耐受性方面的进化差异仍然存在。咸水种群和淡水种群在高盐度（25 PSU）耐受性方面趋于一致，淡水种群数量增加，咸水种群数量减少。在5 PSU的选择下，开发时间不会发生很大的变化。在三种饲养条件下，淡水种群均表现出幼虫发育迟缓和幼鱼发育加快的特点。本研究结果表明，盐碱地和淡水种群对适应相关特征的选择都表现出显著的反应，这对入侵新栖息地至关重要。
While natural selection might in some cases facilitate invasions into novel habitats, few direct measurements of selection response exist for invasive populations. This study examined selection response to changes in salinity using the copepod Eurytemora affinis. This copepod has invaded fresh water from saline habitats multiple times independently throughout the Northern Hemisphere. Selection response to a constant intermediate salinity (5 PSU) was measured in the laboratory for saline source and freshwater invading populations from the St. Lawrence drainage (North America). These populations were reared under three conditions: (1) native salinities (0 or 15 PSU) for at least two generations, (2) 5 PSU for two generations, and (3) 5 PSU for six generations. Full-sib clutches taken from populations reared under these three conditions were split across four salinities (0, 5, 15, and 25 PSU) to determine reaction norms for survival and development time. Contrasts in survival and development time across the three rearing conditions were treated as the selection response. Selection at 5 PSU resulted in a significant decline in freshwater (0 PSU) tolerance for both the saline and freshwater populations. Yet, evolutionary differences in freshwater tolerance persisted between the saline and freshwater populations. The saline and freshwater populations converged in their high-salinity (25 PSU) tolerance, with an increase in the freshwater population and decline in the saline population. Development time did not shift greatly in response to selection at 5 PSU. For all three rearing conditions, the freshwater population exhibited retarded larval development and accelerated juvenile development relative to the saline population. Results from this study indicate that both the saline and freshwater populations exhibit significant responses to selection for a fitness-related trait critical for invasions into a novel habitat.