Department of Forest Genetics, Dendrology and Botany, Faculty of Forestry, University of Zagreb, Zagreb, Croatia.
INRAE, Univ. Bordeaux, BIOGECO, Cestas, France.
Mol Ecol. 2020 Jul;29(13):2359-2378. doi: 10.1111/mec.15492. Epub 2020 Jun 21.
Populations residing near species' low-latitude range margins (LLMs) often occur in warmer and drier environments than those in the core range. Thus, their genetic composition could be shaped by climatic drivers that differ from those occurring at higher latitudes, resulting in potentially adaptive variants of conservation value. Such variants could facilitate the adaptation of populations from other portions of the geographical range to similar future conditions anticipated under ongoing climate change. However, very few studies have assessed standing genetic variation at potentially adaptive loci in natural LLM populations. We investigated standing genetic variation at single nucleotide polymorphisms (SNPs) located within 117 candidate genes and its links to putative climatic selection pressures across 19 pedunculate oak (Quercus robur L.) populations distributed along a regional climatic gradient near the species' southern range margin in southeastern Europe. These populations are restricted to floodplain forests along large lowland rivers, whose hydric regime is undergoing significant shifts under modern rapid climate change. The populations showed very weak geographical structure, suggesting extensive genetic connectivity and gene flow or shared ancestry. We identified eight (6.2%) positive F -outlier loci, and genotype-environment association analyses revealed consistent associations between SNP allele frequencies and several climatic variables linked to water availability. A total of 61 associations involving 37 SNPs (28.5%) from 35 annotated genes provided important insights into putative functional mechanisms in our system. Our findings provide empirical support for the role of LLM populations as sources of potentially adaptive variation that could enhance species' resilience to climate change-related pressures.
居住在物种低纬度范围边缘（LLM）附近的种群通常处于比核心范围更温暖和干燥的环境中。因此，它们的遗传组成可能受到与高纬度地区不同的气候驱动因素的影响，从而产生具有保护价值的潜在适应性变体。这些变体可以促进地理分布范围内其他种群对正在发生的气候变化下预期的类似未来条件的适应。然而，很少有研究评估过自然 LLM 种群中潜在适应性基因座的遗传变异。我们在 19 个欧洲东南部的栓皮栎（Quercus robur L.）种群中，调查了位于 117 个候选基因内的单核苷酸多态性（SNP）的遗传变异及其与假定气候选择压力的关系。这些种群局限于大河低地的洪泛森林，其水系统在现代快速气候变化下正在发生重大变化。这些种群的地理结构非常弱，表明存在广泛的遗传连通性和基因流或共同的祖先。我们确定了 8 个（6.2%）正 F -outlier 基因座，基因型-环境关联分析揭示了 SNP 等位基因频率与几个与水分可用性相关的气候变量之间的一致关联。总共涉及 35 个注释基因中的 37 个 SNP（28.5%）的 61 个关联为我们的系统提供了潜在功能机制的重要见解。我们的研究结果为 LLM 种群作为潜在适应性变异的来源提供了经验支持，这可能增强物种对气候变化相关压力的适应能力。
