Johnson Mireille B, Clifford Stephen L, Goossens Benoît, Nyakaana Silvester, Curran Bryan, White Lee Jt, Wickings E Jean, Bruford Michael W
Centre International de Recherches Médicales de Franceville (CIRMF), BP 769, Franceville, Gabon.
BMC Evol Biol. 2007 Dec 19;7:244. doi: 10.1186/1471-2148-7-244.
Previous phylogenetic analyses of African elephants have included limited numbers of forest elephant samples. A large-scale assessment of mitochondrial DNA diversity in forest elephant populations here reveals a more complex evolutionary history in African elephants as a whole than two-taxon models assume.
We analysed hypervariable region 1 of the mitochondrial control region for 71 new central African forest elephants and the mitochondrial cytochrome b gene from 28 new samples and compare these sequences to other African elephant data. We find that central African forest elephant populations fall into at least two lineages and that west African elephants (both forest and savannah) share their mitochondrial history almost exclusively with central African forest elephants. We also find that central African forest populations show lower genetic diversity than those in savannahs, and infer a recent population expansion.
Our data do not support the separation of African elephants into two evolutionary lineages. The demographic history of African elephants seems more complex, with a combination of multiple refugial mitochondrial lineages and recurrent hybridization among them rendering a simple forest/savannah elephant split inapplicable to modern African elephant populations.
先前对非洲象的系统发育分析所纳入的森林象样本数量有限。本文对森林象种群线粒体DNA多样性进行的大规模评估揭示，非洲象作为一个整体，其进化史比二分法模型所假设的更为复杂。
我们分析了71头新的中非森林象线粒体控制区高变区1以及28个新样本的线粒体细胞色素b基因，并将这些序列与其他非洲象数据进行比较。我们发现，中非森林象种群至少分为两个谱系，西非象（包括森林象和草原象）几乎完全与中非森林象共享其线粒体历史。我们还发现，中非森林象种群的遗传多样性低于草原象种群，并推断其近期种群有所扩张。
我们的数据不支持将非洲象分为两个进化谱系。非洲象的种群历史似乎更为复杂，多个避难所线粒体谱系并存且其间反复杂交，使得简单地将非洲象分为森林象和草原象并不适用于现代非洲象种群。
