Rare genetic variation and balanced polymorphisms are important for survival in global change conditions
Rare genetic variation and balanced polymorphisms are important for survival in global change conditions
复制标题
DOI：
10.1098/rspb.2019.0943
复制
发表时间：
2019-06-04
影响因子：
4.7
通讯作者：
Pespeni, Melissa H.
中科院分区：
文献类型：
--
作者：
Brennan, Reid S.;Garrett, April D.;Pespeni, Melissa H.
长期遗传变异对极端环境条件下种群的持久性至关重要。虽然有些物种可能有能力适应预测的未来全球平均变化条件，但在极端事件中生存的能力在很大程度上是未知的。我们使用了单代选择实验，从野生捕获的成年人产生的数十万的Strongylocentrotus purpuratus海胆幼虫，以确定适应性遗传变异响应中度（pH 8.0）和极端（pH 7.5）低pH值条件。对幼虫池的基因组DNA进行测序，我们确定了每个pH条件下重复培养物中等位基因频率的一致变化，并观察到所选位点周围的连锁不平衡增加，揭示了重组常设遗传变异的选择。我们发现，基因座独特地响应于任一选择制度是在低起始等位基因频率，而响应于两种pH条件的变体（11.6%的选择的变体）开始在高频率。根据选择位点进行功能有关的能量，pH值的耐受性，细胞生长和肌动蛋白/细胞骨架动力学。这些结果突出表明，在未来条件下的持久性将需要两类遗传变异：常见的，pH值响应的变异保持平衡选择在异质环境中，和罕见的变异，特别是在极端条件下，必须保持大的人口规模。
Standing genetic variation is important for population persistence in extreme environmental conditions. While some species may have the capacity to adapt to predicted average future global change conditions, the ability to survive extreme events is largely unknown. We used single-generation selection experiments on hundreds of thousands of Strongylocentrotus purpuratus sea urchin larvae generated from wild-caught adults to identify adaptive genetic variation responsive to moderate (pH 8.0) and extreme (pH 7.5) low-pH conditions. Sequencing genomic DNA from pools of larvae, we identified consistent changes in allele frequencies across replicate cultures for each pH condition and observed increased linkage disequilibrium around selected loci, revealing selection on recombined standing genetic variation. We found that loci responding uniquely to either selection regime were at low starting allele frequencies while variants that responded to both pH conditions (11.6% of selected variants) started at high frequencies. Loci under selection performed functions related to energetics, pH tolerance, cell growth and actin/cytoskeleton dynamics. These results highlight that persistence in future conditions will require two classes of genetic variation: common, pH-responsive variants maintained by balancing selection in a heterogeneous environment, and rare variants, particularly for extreme conditions, that must be maintained by large population sizes.