Kijima A, Fujio Y
Department of Fishery Science, Faculty of Agriculture, Tohoku University, Sendai, Japan.
Prog Clin Biol Res. 1990;344:177-206.
Genetic differentiation and genetic variability were estimated from data on electrophoretically detectable isozymic loci in 12 species of marine teleosts belonging to 10 families of six orders, this study permitted conclusions concerning population structures within the species of marine teleosts. As a result the 12 species could be grouped into two classes, one of which showed higher genetic diversity and included the species inhabiting coastal areas; the other showed lower genetic diversity and included the species inhabiting offshore areas and spawning free pelagic eggs. Class I and Class II could be further divided into two groups (I-1 and I-2, and II-1 and II-2) on the basis of the level of average heterozygosity. Based on the above classification and ecological characteristics, the degree of genetic differentiation may be defined mainly by the level of mixing of eggs and by fry migration, and only to a small extent by adult migration between localities. The degree of average heterozygosity should be a measure of effective population size of the breeding units within the species but not of the whole species. Putting together the above facts, six types of population structure have been proposed for marine teleosts as follows: Species in type I-1 have formed some large populations with large breeding units in offshore areas; Type I-2-1, species have formed a large number of breeding populations with relatively large effective sizes of breeding units in the coastal areas or rivers where they were hatched, even though the species may have migrated over a wide pelagic area during their juvenile to adult stages. The species in type I-2-2 would have formed a number of local subpopulations with large to intermediate breeding units in the coastal areas they inhabit. Type I-2-3 species have formed two or more completely isolated local races (or subspecies) with relatively large breeding units, but with a low level of genetic differentiation within each local race. The species in Type II-1 would have formed a single large population consisting of a few breeding units with large effective sizes in offshore areas around Japan. Type II-2 species would have formed one large population consisting of a large number of breeding units with small effective sizes in wide offshore areas around Japan.
根据6个目10个科的12种海洋硬骨鱼电泳可检测同工酶位点的数据，对其遗传分化和遗传变异性进行了估计，本研究得出了有关海洋硬骨鱼种群结构的结论。结果，这12个物种可分为两类，其中一类显示出较高的遗传多样性，包括栖息在沿海地区的物种；另一类显示出较低的遗传多样性，包括栖息在近海区域并产漂浮性鱼卵的物种。根据平均杂合度水平，I类和II类可进一步分为两组（I-1和I-2，以及II-1和II-2）。基于上述分类和生态特征，遗传分化程度可能主要由鱼卵混合水平和幼鱼洄游决定，仅在很小程度上由成体在不同地点间的洄游决定。平均杂合度应是衡量物种内繁殖单位有效种群大小的指标，而非整个物种的指标。综合上述事实，为海洋硬骨鱼提出了六种种群结构类型如下：I-1型物种在近海区域形成了一些具有大型繁殖单位的大种群；I-2-1型物种在其孵化的沿海地区或河流中形成了大量繁殖种群，繁殖单位的有效大小相对较大，尽管这些物种在幼体到成体阶段可能在广阔的远洋区域洄游。I-2-2型物种在其栖息的沿海地区形成了许多具有大型到中型繁殖单位的地方亚种群。I-2-3型物种形成了两个或更多完全隔离的地方种群（或亚种），繁殖单位相对较大，但每个地方种群内的遗传分化水平较低。II-1型物种在日本周围的近海区域形成了由几个有效大小较大的繁殖单位组成的单一大型种群。II-2型物种在日本周围广阔的近海区域形成了由大量有效大小较小的繁殖单位组成的一个大型种群。
