The roles of fluctuating selection and long-term diapause in microevolution of diapause timing in a freshwater copepod
The roles of fluctuating selection and long-term diapause in microevolution of diapause timing in a freshwater copepod
复制标题
DOI：
10.1111/j.1558-5646.1999.tb05337.x
复制
发表时间：
1999-02-01
期刊：
影响因子：
3.3
通讯作者：
Babaï, D
中科院分区：
文献类型：
--
作者：
Ellner, SP;Hairston, NG;Babaï, D
在自然的，未经操纵的野生种群的选择反应的直接观察是罕见的。存在的那些是由于正在进行的研究期间环境的重大变化造成的。选择反应应该是更常见的，更容易观察到在短寿命的生物体中，选择的方向每年都在变化。我们研究了如何波动的选择，并出现长期滞育的相互作用，引起持续的微进化变化超过8年的一个重要的生活史特征（滞育时间）在淡水哲水蚤桡足类Diaptomus sanguineus。从长期滞育的出现释放到没有经历最近一轮选择的种群谱系中，从而促进了允许连续选择反应的可遗传性状变异的维持。建立了一个机械选择模型的基础上，实地和实验室研究，以预测如何年际变化的捕食强度产生每年的平均滞育时间和净繁殖成功的替代性状值的变化。预测的选择反应和估计的影响出现滞育都显着相关，观察到的性状平均值的变化。一个线性模型相结合的选择反应和出现滞育解释了59%的方差在性状的平均值逐年变化。根据这个模型，强选择发生在大约一半的研究年份，平均每年的贡献性状的变化，选择和出现大致相等。因此，波动的自然选择和从长期滞育中的出现都会影响D.多血的波动选择在自然界中是普遍存在的，并可能提供机会，在其他人群中见证正在进行的自然选择没有定向趋势的平均表型。
Direct observations of selection response in natural, unmanipulated populations in the wild are rare. Those that exist have resulted from major changes in environment during an ongoing study. Selection response should be more common and more readily observable in short-lived organisms where the direction of selection changes from year to year. We examined how the interaction of fluctuating selection, and emergence from long-term diapause, caused ongoing microevolutionary change over eight years in an important life-history trait (diapause timing) in the freshwater calanoid copepod Diaptomus sanguineus. Emergence from long-term diapause releases into the population lineages that did not experience the most recent bout of selection, thereby promoting the maintenance of the heritable trait variation that allows continual selection response. A mechanistic selection model was created on the basis of field and laboratory studies to predict how interannual variations in predation intensity generate year-to-year changes in mean diapause timing and in net reproductive success for alternate trait values. The predicted selection response and the estimated effect of emergence from diapause were both significantly correlated with observed changes in trait mean. A linear model combining selection response and emergence from diapause explained 59% of the variance in year-to-year changes in trait mean. According to this model, strong selection occurred in about half of the years studied, and the average annual contributions to changes in trait mean from selection and emergence were roughly equal. Thus, both fluctuating natural selection and emergence from prolonged diapause affect the expression of diapause timing by D. sanguineus. Fluctuating selection is ubiquitous in nature and may provide opportunities in other populations to witness ongoing natural selection without directional trends in mean phenotype.