Nicolas V, Bryja J, Akpatou B, Konecny A, Lecompte E, Colyn M, Lalis A, Couloux A, Denys C, Granjon L
Muséum National d'Histoire Naturelle, Département de Systématique et Evolution, UMR 5202, Laboratoire Mammifères et Oiseaux, 57 rue Cuvier, CP 51, 75005 Paris, France.
Mol Ecol. 2008 Dec;17(23):5118-34. doi: 10.1111/j.1365-294X.2008.03974.x.
Two sibling species of the rodent genus Praomys occur in West African forests: P. tullbergi and P. rostratus. By sampling across their geographical ranges (459 individuals from 77 localities), we test the hypothesis that climatic oscillations during the Quaternary made an impact on the observed pattern of cytochrome b sequence variation. We show that, although these two species have parapatric geographical distributions, their phylogeographical histories are dissimilar, which could be related to their distinct ecological requirements. Since the arid phases of the Pleistocene were characterized by isolated forest patches, and intervening wetter periods by forest expansion, these changes in forest cover may be the common mechanism responsible for the observed phylogeographical patterns in both of these species. For example, in both species, most clades had either allopatric or parapatric geographical distributions; however, genetic diversity was much lower in P. tullbergi than in P. rostratus. The genetic pattern of P. tullbergi fits the refuge hypothesis, indicating that a very small number of populations survived in distinct forest blocks during the arid phases, then expanded again with forest recovery. In contrast, a number of populations of P. rostratus appear to have survived during the dry periods in more fragmented forest habitats, with varying levels of gene flow between these patches depending on climatic conditions and forest extent. In addition, historical variations of the West African hydrographic network could also have contributed to the pattern of genetic differentiation observed in both species.
图氏柔毛鼠（Praomys tullbergi）和罗氏柔毛鼠（Praomys rostratus）。通过在它们的地理分布范围内进行采样（来自77个地点的459个个体），我们检验了这样一个假设，即第四纪期间的气候振荡对观察到的细胞色素b序列变异模式产生了影响。我们发现，尽管这两个物种具有邻域地理分布，但它们的系统地理学历史却不相同，这可能与它们不同的生态需求有关。由于更新世的干旱阶段以孤立的森林斑块为特征，而其间的湿润期以森林扩张为特征，这些森林覆盖的变化可能是导致这两个物种观察到的系统地理学模式的共同机制。例如，在这两个物种中，大多数分支都具有异域或邻域地理分布；然而，图氏柔毛鼠的遗传多样性远低于罗氏柔毛鼠。图氏柔毛鼠的遗传模式符合避难所假说，表明在干旱阶段，极少数种群在不同的森林斑块中幸存下来，然后随着森林的恢复再次扩张。相比之下，罗氏柔毛鼠的一些种群似乎在干旱时期在更破碎的森林栖息地中幸存下来，这些斑块之间的基因流动水平因气候条件和森林范围而异。此外，西非水文网络的历史变化也可能促成了在这两个物种中观察到的遗传分化模式。
