Quinn T P, Unwin M J, Kinnison M T
School of Fisheries, University of Washington, Seattle 98195, USA.
Evolution. 2000 Aug;54(4):1372-85. doi: 10.1111/j.0014-3820.2000.tb00569.x.
The timing of migration and breeding are key life-history traits; they are not only adaptations of populations to their environments, but can serve to increase reproductive isolation, facilitating further divergence among populations. As part of a study of divergence of chinook salmon, Oncorhynchus tshawytscha, populations, established in New Zealand from a common source in the early 1900s, we tested the hypotheses that the timing of migration and breeding are under genetic control and that the populations genetically differ in these traits despite phenotypic overlap in timing in the wild. Representatives of families from two populations were collected within a day or two of each other, reared in a common environment, and then released to sea from each of two different rivers, while other family representatives were retained in fresh water to maturity. The date of maturation of fish held in fresh water and the dates of return from the ocean and maturation of fish released to sea all showed significant differences between the two populations and among families within populations. The very high heritabilities and genetic correlations estimated for migration and maturation date indicated that these traits would respond rapidly to selection. Combined with the results of related studies on these chinook salmon populations, it appears that spawning time may not only evolve during the initial phases of divergence, but it may play an important role in accelerating divergence in other traits.
洄游和繁殖的时间是关键的生活史特征；它们不仅是种群对环境的适应，而且可以增加生殖隔离，促进种群间的进一步分化。作为对奇努克鲑（Oncorhynchus tshawytscha）种群分化研究的一部分，这些种群于20世纪初从一个共同来源引入新西兰，我们检验了以下假设：洄游和繁殖的时间受基因控制，并且尽管在野外这些特征的表型存在重叠，但不同种群在这些特征上存在基因差异。来自两个种群的家族代表在彼此相隔一两天的时间内被采集，在共同环境中饲养，然后从两条不同的河流中分别放流到海里，而其他家族代表则留在淡水中直至成熟。在淡水中饲养的鱼的成熟日期以及放流到海里的鱼从海洋返回和成熟的日期，在两个种群之间以及种群内的家族之间都显示出显著差异。对洄游和成熟日期估计的非常高的遗传力和遗传相关性表明，这些特征对选择会迅速做出反应。结合对这些奇努克鲑种群的相关研究结果，似乎产卵时间不仅可能在分化的初始阶段发生进化，而且可能在加速其他特征的分化中发挥重要作用。
