Mouline Karine, Granjon Laurent, Galan Maxime, Tatard Caroline, Abdoullaye Doukary, Ag Atteyine Solimane, Duplantier Jean-Marc, Cosson Jean-François
IRD, Laboratoire de Mammalogie, Centre de Biologie et Gestion des Populations (CBGP), BP 2528, Bamako, Mali.
Mol Ecol. 2008 Feb;17(4):1036-53. doi: 10.1111/j.1365-294X.2007.03610.x.
The multimammate rat Mastomys huberti is a Sahelian species restricted to West Africa. Throughout its distribution area, the species is associated with humid habitats, flood plains and ponds, which make its current distribution highly fragmented. Knowing that humid and dry climatic phases regularly alternated along the Quaternary in West Africa, it can be postulated that the evolutionary history of the species and its genetic variation largely reflect these climatic oscillations. We used mitochondrial cytochrome b sequences to investigate the phylogenetic relationships of M. huberti populations across the totality of the species' geographical range (Mali, Senegal, Guinea and Mauritania). We found that cytochrome b sequence variation is partitioned into four divergent clades (mean Kimura 2-parameter genetic distances varying from 0.57 to 3.08%) corresponding to distinct geographical regions. We dated the separation events of these clades between 0.93 and 0.17 million years ago, suggesting that M. huberti history was strongly influenced by the Quaternary climatic variations and related hydrographic network changes. Relationships between lineages and the partitioning of genetic diversity suggest the occurrence of two refuges along the Atlantic coast during arid periods. Moreover, the species' current range results from a stepwise colonization from west to east. M. huberti colonized recently the Inner Delta of Niger River in Mali, probably during a humid episode some 0.6 million years ago. Demographically stable and highly diversified populations were found in South Senegal and Guinea while populations in North Senegal and in Mali experienced low numbers followed by a demographic expansion during the African Humid Period (c. 14 800-5500 bp). During the last arid period (c. 23 000-18 000 years ago), Malian populations found refuge in the northern parts of the Inner Delta of the Niger River, then expended to the southern parts of the delta and along the course of the Niger River downstream Tombouctou. More recently, M. huberti would have rapidly expanded into irrigated areas along the Senegal River and along the Canal du Sahel, Mali, reflecting the invasive and the pest character of this species.
多乳鼠（Mastomys huberti）是一种分布于萨赫勒地区的西非物种。在其整个分布区域内，该物种与湿润栖息地、洪泛平原和池塘相关联，这使得其当前分布高度碎片化。鉴于西非在第四纪期间湿润和干燥气候阶段 regularly alternated（此处原文有误，应是alternated regularly，交替出现），可以推测该物种的进化历史及其遗传变异在很大程度上反映了这些气候振荡。我们使用线粒体细胞色素b序列来研究多乳鼠种群在整个物种地理范围内（马里、塞内加尔、几内亚和毛里塔尼亚）的系统发育关系。我们发现细胞色素b序列变异被划分为四个不同的进化枝（平均Kimura 2参数遗传距离在0.57%至3.08%之间），对应于不同的地理区域。我们确定这些进化枝的分离事件发生在93万至17万年前，这表明多乳鼠的历史受到第四纪气候变化及相关水文网络变化的强烈影响。谱系之间的关系以及遗传多样性的划分表明，在干旱时期，沿着大西洋海岸存在两个避难所。此外，该物种当前的分布范围是由从西向东的逐步殖民形成的。多乳鼠最近在马里的尼日尔河内陆三角洲定居，可能是在约60万年前的一个湿润时期。在塞内加尔南部和几内亚发现了人口统计学上稳定且高度多样化的种群，而塞内加尔北部和马里的种群数量较少，随后在非洲湿润期（约14800 - 5500年前）经历了人口扩张。在最后一个干旱期（约23000 - 18000年前），马里的种群在尼日尔河内陆三角洲北部找到了避难所，然后扩展到三角洲南部以及沿着尼日尔河下游通布图的河道。最近，多乳鼠迅速扩展到塞内加尔河沿岸以及马里的萨赫勒运河沿岸的灌溉区域，这反映了该物种的入侵性和害虫特性。
