Bowie Rauri C K, Fjeldså Jon, Hackett Shannon J, Crowe Timothy M
Percy FitzPatrick Institute (DST/NRF Centre of Excellence), University of Cape Town, Private Bag Rondebosch, 7701, South Africa.
Mol Phylogenet Evol. 2004 Oct;33(1):56-74. doi: 10.1016/j.ympev.2004.04.013.
This study constitutes the first investigation of the phylogeographic structure of a forest bird distributed throughout the montane and lowland forest biomes of Africa. The key objective was to investigate the importance of Pleistocene climatic cycles on avian diversification across Africa. The Olive Sunbird is a relatively large polytypic sunbird widely distributed throughout evergreen, montane and coastal forests in Africa. Recently, it was split into two species, the Eastern Olive Sunbird (Nectarinia olivacea) and the Western Olive Sunbird (Nectarinia obscura), based on morphological grounds. Analyses of a 395bp fragment of the mtDNA NADH subunit 3 gene with flanking tRNA sequences, from 196 individuals of N. olivacea and 86 from N. obscura indicate that genetic divergence levels are low (1.0-2.4%) across some 9000km, from Ghana in the northwest of Africa to KwaZulu-Natal in eastern South Africa. Neither currently recognized Olive Sunbird species were monophyletic using either parsimony or likelihood tree-building methods. Phi(ST) values suggested that there was less variation partitioned among species than between most neighboring regions. Genetic diversity within the N. olivacea/obscura complex was dominated by three star-like phylogenies linked to each other by a single mutational step and two subnetworks (IV and V) separated from the core star-like phylogenies (subnetworks I, II, and III) by five to six mutational steps. The dominant evolutionary mechanism shaping genetic variation within the N. olivacea/obscura complex as identified by nested-clade analyses, appears to be one of range expansion possibly out of East Africa associated with a period of forest expansion during the mid-Pleistocene, some 1.1-0.7 million years ago. Mismatch profiles suggested that secondary contact has occurred between eastern and western lineages within the Ufipa Escarpment and possibly Zimbabwe, as well as between eastern lineages in the Kenyan Highlands and northern Eastern Arc Mts.
本研究首次对一种分布于非洲山地和低地森林生物群落的森林鸟类进行了系统发育地理学结构调查。关键目标是探究更新世气候周期对非洲鸟类多样化的重要性。橄榄太阳鸟是一种相对较大的多型太阳鸟，广泛分布于非洲的常绿、山地和沿海森林。最近，基于形态学依据，它被分为两个物种，即东部橄榄太阳鸟（Nectarinia olivacea）和西部橄榄太阳鸟（Nectarinia obscura）。对196只橄榄太阳鸟和86只暗背太阳鸟的线粒体DNA烟酰胺腺嘌呤二核苷酸亚基3基因的395bp片段及其侧翼tRNA序列进行分析，结果表明，从非洲西北部的加纳到南非东部的夸祖鲁 - 纳塔尔，约9000公里的范围内，遗传分化水平较低（1.0 - 2.4%）。使用简约法或似然树构建方法时，目前认可的两种橄榄太阳鸟物种均非单系类群。Phi(ST)值表明，物种间的变异分配比大多数相邻区域间的变异分配要少。橄榄太阳鸟/暗背太阳鸟复合体中的遗传多样性由三个星状系统发育树主导，它们通过单个突变步骤相互连接，还有两个子网（IV和V），与核心星状系统发育树（子网I、II和III）相隔五到六个突变步骤。通过嵌套分支分析确定，塑造橄榄太阳鸟/暗背太阳鸟复合体中遗传变异的主要进化机制似乎是范围扩张，可能是从中更新世（约110万至70万年前）森林扩张时期的东非向外扩张。失配分布图表明东部和西部谱系在乌菲帕悬崖以及可能在津巴布韦之间发生了二次接触，同时肯尼亚高地和东弧山脉北部的东部谱系之间也发生了二次接触。
