Lozano-Jaramillo María, Rico-Guevara Alejandro, Cadena Carlos Daniel
Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia.
Department of Ecology & Evolutionary Biology, University of Connecticut, Storrs, Connecticut, United States of America.
PLoS One. 2014 Sep 24;9(9):e108345. doi: 10.1371/journal.pone.0108345. eCollection 2014.
Studies of the origin and maintenance of disjunct distributions are of special interest in biogeography. Disjunct distributions can arise following extinction of intermediate populations of a formerly continuous range and later maintained by climatic specialization. We tested hypotheses about how the currently disjunct distribution of the Blossomcrown (Anthocephala floriceps), a hummingbird species endemic to Colombia, arose and how is it maintained. By combining molecular data and models of potential historical distributions we evaluated: (1) the timing of separation between the two populations of the species, (2) whether the disjunct distribution could have arisen as a result of fragmentation of a formerly widespread range due to climatic changes, and (3) if the disjunct distribution might be currently maintained by specialization of each population to different climatic conditions. We found that the two populations are reciprocally monophyletic for mitochondrial and nuclear loci, and that their divergence occurred ca. 1.4 million years before present (95% credibility interval 0.7-2.1 mybp). Distribution models based on environmental data show that climate has likely not been suitable for a fully continuous range over the past 130,000 years, but the potential distribution 6,000 ybp was considerably larger than at present. Tests of climatic divergence suggest that significant niche divergence between populations is a likely explanation for the maintenance of their disjunct ranges. However, based on climate the current range of A. floriceps could potentially be much larger than it currently is, suggesting other ecological or historical factors have influenced it. Our results showing that the distribution of A. floriceps has been discontinous for a long period of time and that populations exhibit different climatic niches have taxonomic and conservation implications.
对间断分布的起源和维持的研究在生物地理学中具有特殊意义。间断分布可能在先前连续分布范围的中间种群灭绝后出现，随后通过气候特化得以维持。我们检验了关于哥伦比亚特有蜂鸟物种花冠蜂鸟（Anthocephala floriceps）当前间断分布的起源及维持方式的假设。通过结合分子数据和潜在历史分布模型，我们评估了：（1）该物种两个种群之间的分离时间；（2）间断分布是否可能是由于气候变化导致先前广泛分布范围破碎化的结果；（3）间断分布目前是否可能是由于每个种群对不同气候条件的特化而维持。我们发现，两个种群在线粒体和核基因座上相互单系，它们的分化发生在约140万年前（95%可信区间为0.7 - 2.1百万年前）。基于环境数据的分布模型表明，在过去13万年里气候可能一直不适合完全连续的分布范围，但6000年前的潜在分布范围比目前大得多。气候分化测试表明，种群之间显著的生态位分化可能是维持其间断分布范围的原因。然而，基于气候因素，花冠蜂鸟目前的分布范围可能比实际大得多，这表明还有其他生态或历史因素对其产生了影响。我们的结果表明，花冠蜂鸟的分布长期以来一直是间断的，且种群表现出不同的气候生态位，这对分类学和保护具有重要意义。
