Genetic diversity and population divergences of an indigenous tree (Coffea mauritiana) in Reunion Island: role of climatic and geographical factors
Genetic diversity and population divergences of an indigenous tree (Coffea mauritiana) in Reunion Island: role of climatic and geographical factors
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DOI：
10.1038/s41437-018-0168-9
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发表时间：
2019-06-01
期刊：
影响因子：
3.8
通讯作者：
Lashermes, Philippe
中科院分区：
文献类型：
--
作者：
Garot, Edith;Joet, Thierry;Lashermes, Philippe
海洋岛屿通常被认为是研究进化和物种形成的天然实验室。与物种生物学相关的岛屿的进化特性为研究地理和气候在推动种群分化中的作用提供了独特的场景。然而，很少有研究涉及这个问题，在海洋小岛屿与异质气候。毛里求斯咖啡广泛分布于留尼汪岛森林中，是一个有趣的模式案例，在小空间尺度上调查岛屿内的分化模式。本研究对中国对虾的遗传多样性和群体分化进行了研究。使用SNP标记从留尼汪岛34个地点的323个个体中获得。利用冗余分析，我们进一步评估了地理和气候因素对形成种群间遗传分化的贡献。遗传多样性分析表明，加入聚类根据源人口，与区域集群进一步分组。各区域集群之间的遗传关系突出表明，该岛两侧最近出现了逐步殖民化的扩张进程。源种群间的分化主要是由地理距离和气候异质性的共同作用驱动的。地理隔离的模式是根据该物种的扩散特性，而环境隔离主要是由异质性降雨模式，可能与种群之间的异步开花解释。这些发现推进了我们对留尼汪岛原生物种遗传多样性模式和种群分化因素的了解，也将有效地指导森林保护管理。
Oceanic islands are commonly considered as natural laboratories for studies on evolution and speciation. The evolutionary specificities of islands associated with species biology provide unique scenarios to study the role of geography and climate in driving population divergence. However, few studies have addressed this subject in small oceanic islands with heterogeneous climates. Being widely distributed in Reunion Island forest, Coffea mauritiana represents an interesting model case for investigating patterns of within-island differentiation at small spatial scale. In this study, we examined the genetic diversity and population divergences of C. mauritiana using SNP markers obtained from 323 individuals across 34 locations in Reunion Island. Using redundancy analysis, we further evaluated the contribution of geographic and climatic factors to shaping genetic divergence among populations. Genetic diversity analyses revealed that accessions clustered according to the source population, with further grouping in regional clusters. Genetic relationships among the regional clusters underlined a recent process of expansion in the form of step-by-step colonization on both sides of the island. Divergence among source populations was mostly driven by the joint effect of geographic distance and climatic heterogeneity. The pattern of isolation-by-geography was in accordance with the dispersal characteristics of the species, while isolation-by-environment was mostly explained by the heterogeneous rainfall patterns, probably associated with an asynchronous flowering among populations. These findings advance our knowledge on the patterns of genetic diversity and factors of population differentiation of species native to Reunion Island, and will also usefully guide forest management for conservation.