Department of Biology, Duke University, Durham, NC 27708, USA.
CNRS, Université Paul Sabatier, IRD; UMR5174 EDB (Laboratoire Évolution & Diversité Biologique), 118 route de Narbonne, 31062 Toulouse, France.
Syst Biol. 2021 Feb 10;70(2):203-218. doi: 10.1093/sysbio/syaa053.
Mouse lemurs (Microcebus) are a radiation of morphologically cryptic primates distributed throughout Madagascar for which the number of recognized species has exploded in the past two decades. This taxonomic revision has prompted understandable concern that there has been substantial oversplitting in the mouse lemur clade. Here, we investigate mouse lemur diversity in a region in northeastern Madagascar with high levels of microendemism and predicted habitat loss. We analyzed RADseq data with multispecies coalescent (MSC) species delimitation methods for two pairs of sister lineages that include three named species and an undescribed lineage previously identified to have divergent mtDNA. Marked differences in effective population sizes, levels of gene flow, patterns of isolation-by-distance, and species delimitation results were found among the two pairs of lineages. Whereas all tests support the recognition of the presently undescribed lineage as a separate species, the species-level distinction of two previously described species, M. mittermeieri and M. lehilahytsara is not supported-a result that is particularly striking when using the genealogical discordance index (gdi). Nonsister lineages occur sympatrically in two of the localities sampled for this study, despite an estimated divergence time of less than 1 Ma. This suggests rapid evolution of reproductive isolation in the focal lineages and in the mouse lemur clade generally. The divergence time estimates reported here are based on the MSC calibrated with pedigree-based mutation rates and are considerably more recent than previously published fossil-calibrated relaxed-clock estimates. We discuss the possible explanations for this discrepancy, noting that there are theoretical justifications for preferring the MSC estimates in this case. [Cryptic species; effective population size; microendemism; multispecies coalescent; speciation; species delimitation.].
鼠狐猴（Microcebus）是形态上隐秘的灵长类动物的辐射群，分布于马达加斯加各地，在过去的二十年中，其被识别的物种数量呈爆炸式增长。这种分类修订引起了人们的担忧，即鼠狐猴分支中存在大量过度分裂的现象。在这里，我们在马达加斯加东北部一个具有高水平微地方性和预测生境丧失的地区调查了鼠狐猴的多样性。我们使用多物种合并（MSC）物种界定方法分析了 RADseq 数据，这些方法适用于包括三个命名物种和一个以前被鉴定为具有不同 mtDNA 的未描述谱系的两个姐妹谱系对。在这两个谱系对中，有效种群大小、基因流动水平、隔离距离模式和物种界定结果存在明显差异。虽然所有测试都支持将目前未被描述的谱系识别为一个独立的物种，但对两个以前描述过的物种（M. mittermeieri 和 M. lehilahytsara）的物种水平区分并不支持——当使用谱系不和谐指数（gdi）时，这一结果尤其引人注目。在本研究采样的两个地点，非姐妹谱系发生了同域，尽管估计的分化时间不到 1Ma。这表明在焦点谱系和鼠狐猴分支中，生殖隔离的快速进化。这里报告的分歧时间估计是基于 MSC 与基于系谱的突变率校准的，比以前发表的化石校准的松弛时钟估计要新得多。我们讨论了这种差异的可能解释，指出在这种情况下，有理论依据偏好 MSC 估计。[隐种；有效种群大小；微地方性；多物种合并；物种形成；物种界定。]
