PREMISE Past climate fluctuations during the Holocene and Pleistocene shaped the distribution of several plant species in temperate areas over the world. Wild maize, commonly known as teosinte, is a good system to evaluate the effects of historical climate fluctuations on genetic diversity due to its wide distribution in Mexico with contrasting environmental conditions. We explored the influence of contemporary factors and historical environmental shifts on genetic diversity, including present and three historical periods using neutral markers. METHODS We used 22 nuclear microsatellite loci to examine the genetic diversity of 14 populations of Zea mays subsp. parviglumis and 15 populations of Zea mays subsp. mexicana (527 individuals total). We implemented genetic structure analyses to evaluate genetic differentiation between and within subspecies. We applied coalescent-based demographic analysis and species distribution modeling to evaluate the effects of historical environmental shifts. RESULTS We found 355 alleles in total for the two subspecies and variable levels of diversity in each (Z. mays subsp. parviglumis expected heterozygosity HE = 0.3646-0.7699; Z. mays subsp. mexicana HE = 0.5885-0.7671). We detected significant genetic structure among populations (DEST = 0.4332) with significant heterozygote deficiency (FIS = 0.1796), and variable selfing rates (sg2 = 0.0-0.3090). The Bayesian assignment analysis differentiated four genetic groups. Demographic and species distribution modeling analysis suggested that environmental shifts were influential in the amount of genetic diversity. CONCLUSIONS Our analyses suggest that the current genetic diversity in teosinte is shaped by factors such as local adaptation and genetic isolation, along with historical environmental fluctuations.

中文翻译：

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环境、当地适应和过去气候波动对墨西哥野生玉米两个亚种遗传多样性数量和分布的影响

前提 全新世和更新世过去的气候波动塑造了世界温带地区几种植物物种的分布。野生玉米，俗称 teosinte，是评估历史气候波动对遗传多样性影响的一个很好的系统，因为它在墨西哥广泛分布，环境条件不同。我们使用中性标记探讨了当代因素和历史环境变化对遗传多样性的影响，包括现在和三个历史时期。方法 我们使用 22 个核微卫星位点来检查 14 个玉米亚种种群的遗传多样性。parviglumis 和 Zea mays subsp. 的 15 个种群。墨西哥（共 527 人）。我们实施了遗传结构分析来评估亚种之间和亚种内的遗传分化。我们应用基于聚结的人口统计分析和物种分布模型来评估历史环境变化的影响。结果 我们发现两个亚种共有 355 个等位基因，每个亚种的多样性水平不同（Z. mays subsp. parviglumis 预期杂合性 HE = 0.3646-0.7699；Z. mays subsp. mexicana HE = 0.5885-0.7671）。我们检测到具有显着杂合子缺陷 (FIS = 0.1796) 和可变自交率 (sg2 = 0.0-0.3090) 的种群 (DEST = 0.4332) 之间的显着遗传结构。贝叶斯分配分析区分了四个遗传组。人口统计学和物种分布模型分析表明，环境变化对遗传多样性的数量有影响。