Prey evolution on the time scale of predator-prey dynamics revealed by allele-specific quantitative PCR
Prey evolution on the time scale of predator-prey dynamics revealed by allele-specific quantitative PCR
复制标题
DOI：
10.1073/pnas.0600434103
复制
发表时间：
2006-07-11
影响因子：
11.1
通讯作者：
Yoshida, Takehito
中科院分区：
文献类型：
--
作者：
Meyer, Justin R.;Ellner, Stephen P.;Yoshida, Takehito
利用轮虫-藻类微宇宙，我们跟踪了生态捕食者-猎物动态中随时间变化的自然选择所导致的快速进化。我们以前证明了轮虫藻类实验室微观世界中的捕食者-猎物振荡被猎物内的遗传变异的存在定性地改变。在这项研究中，藻类基因频率的变化是从它们对种群动态的影响中推断出来的，但没有直接观察到。在这里，我们记录在这个系统中的快速猎物进化，直接观察小球藻基因型频率的变化，这些藻类和他们的消费者，萼花臂尾轮虫，随着时间的推移而变化的丰度。我们分离了一组藻类克隆，我们可以区分使用微卫星DNA标记，并开发了等位基因特异性定量PCR技术（AsQ-PCR），以定量的频率对混合培养的克隆。我们发现，这些基因型中的两个表现出健身权衡，其中一个是更耐捕食（更耐消化），和其他限制氮浓度下有更快的人口增长。一个完全指定的轮虫藻类种群和进化动力学的数学模型预测，这两个克隆将经历一个单一的振荡，克隆频率随后渐近固定的更耐克隆，而不是经常性的振荡以前观察到的其他藻类克隆。我们使用AsQ-PCR证实了这一预测：上级竞争对手占主导地位的最初，但随着轮虫密度的增加，更捕食者抗性克隆占主导地位。
Using rotifer-algal microcosms, we tracked rapid evolution resulting from temporally changing natural selection in ecological predator-prey dynamics. We previously demonstrated that predator-prey oscillations in rotifer-algal laboratory microcosms are qualitatively altered by the presence of genetic variation within the prey. In that study, changes in algal gene frequencies were inferred from their effects on population dynamics but not observed directly. Here, we document rapid prey evolution in this system by directly observing changes in Chlorella vulgaris genotype frequencies as the abundances of these algae and their consumer, Brachionus calyciflorus, change through time. We isolated a group of algal clones that we could distinguish by using microsatellite-DNA markers, and developed an allele-specific quantitative PCR technique (AsQ-PCR) to quantify the frequencies of pairs of clones in mixed culture. We showed that two of these genotypes exhibited a fitness tradeoff in which one was more resistant to predation (more digestion-resistant), and the other had faster population growth under limiting nitrogen concentrations. A fully specified mathematical model for the rotifer-algal population and evolutionary dynamics predicted that these two clones would undergo a single oscillation in clonal frequencies followed by asymptotic fixation of the more resistant clone, rather than the recurrent oscillations previously observed with other algal clones. We used AsQ-PCR to confirm this prediction: the superior competitor dominated initially, but as rotifer densities increased, the more predator-resistant clone predominated.