Seutin Gilles, Klein Nedra K, Ricklefs Robert E, Bermingham Eldredge
Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama.
Museum of Zoology, University of Michigan, Ann Arbor, Michigan, 48109.
Evolution. 1994 Aug;48(4):1041-1061. doi: 10.1111/j.1558-5646.1994.tb05292.x.
We analyzed mitochondrial DNA (mtDNA) restriction-site variation in bananaquit (Coereba flaveola; Aves, Coerebinae) populations sampled on 12 Caribbean islands and at 5 continental localities in Central America and northern South America. Multiple fixed restriction-site differences genetically defined several regional bananaquit populations. An mtDNA clade representing all Jamaican bananaquits was the most divergent; the estimated average sequence divergence (d ) between Jamaican and all other mtDNA haplotypes surveyed was 0.027. Three groups of populations, representing Central America, northern South America, and the eastern Antilles (Puerto Rico to Grenada) were nearly equally differentiated among themselves (average d = 0.014), and may represent a single, recent range expansion. Within the eastern Antilles, three geographically restricted haplotype groups were identified: Puerto Rico, north-central Lesser Antilles (U.S. Virgin Islands to St. Lucia), and Grenada-St. Vincent. The evolutionary relationships of these groups were not clear. Genetic homogeneity of the island populations from the U.S. Virgin Islands to St. Lucia suggested a recent spread of a specific north-central Lesser Antillean haplotype through most of those islands. Haplotype variation across this region indicated that this spread may have occurred in two waves, first through the southernmost islands of St. Lucia, Martinique, and Dominica, and more recently from Guadeloupe to the north. The geographic distribution of mtDNA haplotypes, and of bananaquit populations, suggests periods of invasiveness followed by relative geographic quiescence. Although most genetic studies of bird populations have revealed homogeneity over large geographic areas, our findings provide a remarkable counterexample of strong geographic structuring of mtDNA variation over relatively small distances. Furthermore, although the mtDNA data were consistent with several subspecific distinctions, it was clear that named subspecies do not define equally differentiated evolutionary entities.
我们分析了在加勒比地区12个岛屿以及中美洲和南美洲北部5个大陆地点采集的香蕉鹎（Coereba flaveola；雀形目，香蕉鹎亚科）种群的线粒体DNA（mtDNA）限制性位点变异。多个固定的限制性位点差异从基因上定义了几个区域性的香蕉鹎种群。一个代表所有牙买加香蕉鹎的mtDNA进化枝差异最大；牙买加香蕉鹎与所有其他被调查的mtDNA单倍型之间的估计平均序列差异（d）为0.027。三组种群，分别代表中美洲、南美洲北部和安的列斯群岛东部（从波多黎各到格林纳达），它们之间的差异几乎相同（平均d = 0.014），可能代表一次单一的、近期的分布范围扩张。在安的列斯群岛东部，确定了三个地理分布受限的单倍型组：波多黎各、小安的列斯群岛中北部（美属维尔京群岛到圣卢西亚）以及格林纳达 - 圣文森特。这些组之间的进化关系并不明确。从美属维尔京群岛到圣卢西亚的岛屿种群的遗传同质性表明，一种特定的小安的列斯群岛中北部单倍型最近在这些岛屿的大部分地区扩散。该地区的单倍型变异表明，这种扩散可能分两波发生，首先通过最南端的圣卢西亚、马提尼克和多米尼克岛，最近则是从瓜德罗普向北扩散。mtDNA单倍型以及香蕉鹎种群的地理分布表明，存在入侵期，随后是相对的地理静止期。尽管大多数鸟类种群的遗传研究揭示了在大地理区域内的同质性，但我们的研究结果提供了一个显著的反例，即在相对较小的距离内mtDNA变异存在强烈的地理结构。此外，尽管mtDNA数据与几个亚种的区分一致，但很明显，已命名的亚种并不能定义同样分化的进化实体。
