THE GENETIC-BASIS OF PHOTOPERIODISM AND ITS EVOLUTIONARY DIVERGENCE AMONG POPULATIONS OF THE PITCHER-PLANT MOSQUITO, WYEOMYIA-SMITHII
THE GENETIC-BASIS OF PHOTOPERIODISM AND ITS EVOLUTIONARY DIVERGENCE AMONG POPULATIONS OF THE PITCHER-PLANT MOSQUITO, WYEOMYIA-SMITHII
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DOI：
10.1086/285549
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发表时间：
1993-09-01
影响因子：
2.9
通讯作者：
HOLZAPFEL, CM
中科院分区：
文献类型：
--
作者：
HARD, JJ;BRADSHAW, WE;HOLZAPFEL, CM
我们测量了群体内的加性遗传方差和复合加性，显性和上位性效应，有助于区分两个南方（祖先）和四个逐步更多的北方（衍生）种群的猪笼草蚊子，Wyeomyia smithii之间的光周期反应。临界光周期及其加性遗传方差随纬度的增加而增加，但遗传力不随纬度的增加而增加。西太平洋向北辐散过程中临界光周期的方向选择。因此，史密斯并没有削弱这一性状背后的加性遗传变异。群体间杂交的联合尺度试验表明，上位性效应，尤其是加性×加性和显性×显性互作，在临界光周期上压倒了加性和显性的复合效应。大量上位性的存在表明，在W. smithii可能是导致衍生群体中逐渐增加的加性遗传方差释放的原因，尽管定向和稳定选择减少了它。如果上位性对其他物种群体的遗传分化有类似的贡献，那么，目前的适应性进化模型只考虑种群内的加性遗传变异和协变，在预测自然种群如何生活史上的差异。
We measured the additive genetic variance within populations and the composite additive, dominance, and epistatic effects contributing to differentiation of photoperiodic response between two southern (ancestral) and each of four progressively more northern (derived) populations of the pitcher-plant mosquito, Wyeomyia smithii. Critical photoperiod and its additive genetic variance but not its heritability increased with latitude. Directional selection on critical photoperiod during the northward divergence of W. smithii has therefore not eroded the additive genetic variance underlying this trait. Joint scaling tests of crosses between populations showed that epistatic effects, especially additive x additive and dominance x dominance interactions, overwhelm composite additive and dominance effects on critical photoperiod. The presence of substantial epistasis suggests that multiple founder events during the northward divergence of W. smithii may have been responsible for the release of progressively greater additive genetic variance in derived populations, despite directional and stabilizing selection to reduce it. If epistasis makes a similar contribution to the genetic differentiation of populations in other species, then current models of adaptive evolution that consider only additive genetic variation and covariation within populations may be of limited value in predicting how natural populations differentiate in life history.