Novick Rachel Roth, Dick Christopher W, Lemes Maristerra R, Navarro Carlos, Caccone Adalgisa, Bermingham Eldredge
Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT 06511, USA.
Mol Ecol. 2003 Nov;12(11):2885-93. doi: 10.1046/j.1365-294x.2003.01951.x.
While microsatellites have been used to examine genetic structure in local populations of Neotropical trees, genetic studies based on such high-resolution markers have not been carried out for Mesoamerica as a whole. Here we assess the genetic structure of the Mesoamerican mahogany Swietenia macrophylla King (big-leaf mahogany), a Neotropical tree species recently listed as endangered in CITES which is commercially extinct through much of its native range. We used seven variable microsatellite loci to assess genetic diversity and population structure in eight naturally established mahogany populations from six Mesoamerican countries. Measures of genetic differentiation (FST and RST) indicated significant differences between most populations. Unrooted dendrograms based on genetic distances between populations provide evidence of strong phylogeographic structure in Mesoamerican mahogany. The two populations on the Pacific coasts of Costa Rica and Panama were genetically distant from all the others, and from one another. The remaining populations formed two clusters, one comprised of the northern populations of Mexico, Belize and Guatemala and the other containing the southern Atlantic populations of Nicaragua and Costa Rica. Significant correlation was found between geographical distance and all pairwise measures of genetic divergence, suggesting the importance of regional biogeography and isolation by distance in Mesoamerican mahogany. The results of this study demonstrate greater phylogeographic structure than has been found across Amazon basin S. macrophylla. Our findings suggest a relatively complex Mesoamerican biogeographic history and lead to the prediction that other Central American trees will show similar patterns of regional differentiation.
虽然微卫星已被用于研究新热带树木当地种群的遗传结构，但尚未对整个中美洲进行基于此类高分辨率标记的遗传研究。在此，我们评估了中美洲桃花心木大叶桃花心木（Swietenia macrophylla King）的遗传结构，这是一种新热带树种，最近在《濒危野生动植物种国际贸易公约》（CITES）中被列为濒危物种，在其大部分原生范围内已商业性灭绝。我们使用了七个可变微卫星位点来评估来自六个中美洲国家的八个自然形成的桃花心木种群的遗传多样性和种群结构。遗传分化指标（FST和RST）表明大多数种群之间存在显著差异。基于种群间遗传距离的无根树状图为中美洲桃花心木强大的系统地理学结构提供了证据。哥斯达黎加和巴拿马太平洋沿岸的两个种群在遗传上与所有其他种群以及彼此都有很大差异。其余种群形成了两个聚类，一个由墨西哥、伯利兹和危地马拉的北部种群组成，另一个包含尼加拉瓜和哥斯达黎加的南部大西洋种群。地理距离与所有成对遗传分化指标之间存在显著相关性，这表明区域生物地理学和距离隔离在中美洲桃花心木中的重要性。本研究结果表明，中美洲桃花心木的系统地理学结构比整个亚马逊盆地的大叶桃花心木更为复杂。我们的研究结果表明中美洲生物地理历史相对复杂，并预测其他中美洲树木将呈现类似的区域分化模式。
