Garcia-Rodriguez A I, Bowen B W, Domning D, Mignucci-Giannoni A, Marmontel M, Montoya-Ospina A, Morales-Vela B, Rudin M, Bonde R K, McGuire P M
U.S.G.S., Biological Resources Division, Sirenia Project, Gainesville, FL 32601, USA.
Mol Ecol. 1998 Sep;7(9):1137-49. doi: 10.1046/j.1365-294x.1998.00430.x.
To resolve the population genetic structure and phylogeography of the West Indian manatee (Trichechus manatus), mitochondrial (mt) DNA control region sequences were compared among eight locations across the western Atlantic region. Fifteen haplotypes were identified among 86 individuals from Florida, Puerto Rico, the Dominican Republic, Mexico, Columbia, Venezuela, Guyana and Brazil. Despite the manatee's ability to move thousands of kilometers along continental margins, strong population separations between most locations were demonstrated with significant haplotype frequency shifts. These findings are consistent with tagging studies which indicate that stretches of open water and unsuitable coastal habitats constitute substantial barriers to gene flow and colonization. Low levels of genetic diversity within Florida and Brazilian samples might be explained by recent colonization into high latitudes or bottleneck effects. Three distinctive mtDNA lineages were observed in an intraspecific phylogeny of T. manatus, corresponding approximately to: (i) Florida and the West Indies; (ii) the Gulf of Mexico to the Caribbean rivers of South America; and (iii) the northeast Atlantic coast of South America. These lineages, which are not concordant with previous subspecies designations, are separated by sequence divergence estimates of d = 0.04-0.07, approximately the same level of divergence observed between T. manatus and the Amazonian manatee (T. inunguis, n = 16). Three individuals from Guyana, identified as T. manatus, had mtDNA haplotypes which are affiliated with the endemic Amazon form T. inunguis. The three primary T. manatus lineages and the T. inunguis lineage may represent relatively deep phylogeographic partitions which have been bridged recently due to changes in habitat availability (after the Wisconsin glacial period, 10 000 B P), natural colonization, and human-mediated transplantation.
为了解西印度海牛（Trichechus manatus）的种群遗传结构和系统地理学，对西大西洋地区8个地点的线粒体（mt）DNA控制区序列进行了比较。在来自佛罗里达、波多黎各、多米尼加共和国、墨西哥、哥伦比亚、委内瑞拉、圭亚那和巴西的86个个体中鉴定出了15种单倍型。尽管海牛有能力沿着大陆边缘移动数千公里，但大多数地点之间仍存在强烈的种群隔离，单倍型频率发生了显著变化。这些发现与标记研究一致，标记研究表明开阔水域和不合适的沿海栖息地构成了基因流动和定居的重大障碍。佛罗里达和巴西样本中遗传多样性水平较低，可能是由于最近向高纬度地区的殖民或瓶颈效应所致。在海牛的种内系统发育中观察到三个独特的mtDNA谱系，大致对应于：（i）佛罗里达和西印度群岛；（ii）墨西哥湾到南美洲的加勒比河流域；（iii）南美洲东北大西洋海岸。这些谱系与先前的亚种划分不一致，它们之间的序列分歧估计为d = 0.04 - 0.07，这与海牛和亚马逊海牛（T. inunguis，n = 16）之间观察到的分歧水平大致相同。来自圭亚那的三个被鉴定为海牛的个体，其mtDNA单倍型与特有的亚马逊海牛T. inunguis相关。海牛的三个主要谱系和T. inunguis谱系可能代表了相对较深的系统地理分区，由于栖息地可用性的变化（在威斯康星冰川期之后，公元前10000年）、自然殖民和人类介导的移植，这些分区最近才被连接起来。
