THE POPULATION-GENETICS OF REINFORCING SELECTION
THE POPULATION-GENETICS OF REINFORCING SELECTION
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DOI：
10.1007/bf00123305
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发表时间：
1983-01-01
期刊：
影响因子：
1.5
通讯作者：
LAMBERT, DM
中科院分区：
文献类型：
--
作者：
HARPER, AA;LAMBERT, DM
破坏性选择实验在两个分化种群之间产生不利杂交的一个常见结果是同性交配的增加。当经典的选择实验被重新设计时，这里报告的实验得出了另一个结果。在这些改良的实验中，交配种群[2个黑腹果蝇突变株]的基因型频率不是人为地维持在胎次，而是由上一代的后代比例决定的。在这些选择系中，除了同性婚姻增加之外，还证明了另一个结果。在对杂合子的高选择系数下，观察到一个纯合子的消除和另一个的固定。在杂合子劣势的选择过程中，没有一个选择系能够同时维持2个分化群体。在这一群体遗传过程中，需要大量的世代选择来增加两个群体之间的差异。相比之下，导致纯合子固定或消除的基因频率的不稳定性是极其迅速的。重复经典实验，21代选择后，分化没有增加。对于较低的选择系数，高水平的渗入是明显的，因此两个群体的遗传独特性随着时间的推移而降低。这是在对杂合子的选择下不稳定平衡的问题之外。这两个方面都很重要，但在讨论其含义的物种形成模型的实验证据中没有考虑到。
A common outcome of disruptive selection experiments between 2 differentiated populations which produce disadvantageous hybrids is an increase in homogamy. Experiments reported here result in another outcome when classical selection experiments are redesigned. In these modified experiments, frequencies of genotypes in the mating populations [2 mutant strains of Drosophila melanogaster] were not artificially maintained at parity but were instead determined from progeny proportions in the previous generation. In these selection lines another outcome, apart from an increase in homogamy, was demonstrated. Under a high selection coefficient against heterozygotes, elimination of a homozygote and the corresponding fixation of the other was observed. No selection line demonstrated the maintenance of 2 differentiated populations concurrently with the selection process of heterozygote disadvantage. A high number of generations of selection under this population genetical process is necessary to increase differences between 2 populations. The instability of gene frequencies which results in fixation or elimination of a homozygote is extremely rapid by comparison. Classical experiments were repeated and after 21 generations of selection there was no increase in divergence. For lower selection coefficients, high levels of introgressions are apparent, and hence the genetical distinctness of the 2 populations decreases over time. This is in addition to the problem of an unstable equilibrium under selection against heterozygotes. Both aspects are important but not previously considered in experimental evidence for speciation models for which their implications are discussed.