Melo Warita A, Vieira Lucas D, Novaes Evandro, Bacon Christine D, Collevatti Rosane G
Laboratório de Genética & Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil.
Departamento de Biologia, Universidade Federal de Lavras, Lavras, Brazil.
Front Genet. 2020 Dec 23;11:596662. doi: 10.3389/fgene.2020.596662. eCollection 2020.
Despite the global importance of tropical ecosystems, few studies have identified how natural selection has shaped their megadiversity. Here, we test for the role of adaptation in the evolutionary success of the widespread, highly abundant Neotropical palm We used a genome scan framework, sampling 16,262 single-nucleotide polymorphisms (SNPs) with target sequence capture in 264 individuals from 22 populations in rainforest and savanna ecosystems. We identified outlier loci as well as signal of adaptation using Bayesian correlations of allele frequency with environmental variables and detected both selective sweeps and genetic hitchhiking events. Functional annotation of SNPs with selection footprints identified loci affecting genes related to adaptation to environmental stress, plant development, and primary metabolic processes. The strong differences in climatic and soil variables between ecosystems matched the high differentiation and low admixture in population Bayesian clustering. Further, we found only small differences in allele frequency distribution in loci putatively under selection among widespread populations from different ecosystems, with fixation of a single allele in most populations. Taken together, our results indicate that adaptive selective sweeps related to environmental stress shaped the spatial pattern of genetic diversity in , leading to high similarity in allele frequency among populations from different ecosystems.
尽管热带生态系统具有全球重要性，但很少有研究确定自然选择是如何塑造其巨大多样性的。在这里，我们测试了适应性在分布广泛、数量众多的新热带棕榈进化成功中的作用。我们使用了基因组扫描框架，通过目标序列捕获对来自雨林和稀树草原生态系统中22个种群的264个个体的16262个单核苷酸多态性（SNP）进行了采样。我们利用等位基因频率与环境变量的贝叶斯相关性确定了异常位点以及适应性信号，并检测到了选择性清除和遗传搭便车事件。对具有选择足迹的SNP进行功能注释，确定了影响与环境胁迫适应、植物发育和初级代谢过程相关基因的位点。生态系统之间气候和土壤变量的强烈差异与群体贝叶斯聚类中的高分化和低混合相匹配。此外，我们发现来自不同生态系统的广泛分布种群中，假定处于选择状态的位点的等位基因频率分布只有很小的差异，大多数种群中单个等位基因固定。综合来看，我们的结果表明，与环境胁迫相关的适应性选择性清除塑造了 的遗传多样性空间格局，导致来自不同生态系统的种群之间等位基因频率高度相似。
