University of Alaska Museum, Fairbanks, AK, USA.
Biology Department, University of Kentucky, Lexington, KY, USA.
Mol Ecol. 2020 May;29(9):1717-1729. doi: 10.1111/mec.15433. Epub 2020 May 11.
Madagascar's shrew tenrecs (Mammalia: Tenrecidae; Microgale, Nesogale) represent an excellent system for studying speciation. Most species are endemic to the island's eastern humid forests, a region renowned for high levels of biodiversity and a high rate of in situ diversification. We set out to understand the speciation dynamics in a clade of recently described taxa: Microgale fotsifotsy and M. soricoides, which have nearly identical distributions in the moist evergreen forest, and M. nasoloi, which occurs in the western dry deciduous forest. A phylogenetic analysis using mitochondrial DNA data recovered two distinct clades of M. fotsifotsy: a south clade that is sister to, and broadly sympatric with, M. soricoides, and a north clade that is sister to the dry-forest and distantly allopatric species M. nasoloi. To better understand this result, we analysed cranioskeletal measurements and performed demographic analyses using nuclear sequence data from ultraconserved elements. Nuclear data did not support a sister relationship between M. soricoides and the south clade of M. fotsifotsy but did demonstrate introgression between these clades, which probably explains the discordance between nuclear and mitochondrial phylogenies. Demographic analyses also revealed the absence of gene flow between the north and south clades of M. fotsifotsy. Morphometric data revealed several major differences between M. soricoides and M. fotsifotsy, as well as more subtle differences between the two clades of M. fotsifotsy. In light of these results, we treat the south clade of M. fotsifotsy as a new candidate species. Our findings demonstrate the utility of integrating multiple data types to understand complex speciation histories, and contribute to a growing body of evidence that species diversity on Madagascar is underestimated.
马达加斯加的鼩形长尾狸（哺乳纲：鳞尾狸科；Microgale，Nesogale）是研究物种形成的绝佳系统。大多数物种是该岛东部湿润森林的特有种，该地区以生物多样性水平高和原地多样化速度快而闻名。我们旨在了解最近描述的分类群中的一个分支的物种形成动态：Microgale fotsifotsy 和 M. soricoides，它们在潮湿的常绿林中几乎有相同的分布，而 M. nasoloi 则分布在西部干燥的落叶林中。使用线粒体 DNA 数据进行的系统发育分析恢复了 M. fotsifotsy 的两个不同分支：一个是南部分支，与 M. soricoides 是姐妹关系，且广泛同域；另一个是北部分支，与干燥森林和遥远的异域物种 M. nasoloi 是姐妹关系。为了更好地理解这一结果，我们分析了颅骨骼测量值，并使用来自超保守元件的核序列数据进行了种群动态分析。核数据不支持 M. soricoides 与 M. fotsifotsy 的南部分支之间的姐妹关系，但确实表明这些分支之间存在基因渗透，这可能解释了核和线粒体系统发育之间的不匹配。种群动态分析还揭示了 M. fotsifotsy 的北部和南部分支之间不存在基因流。形态学数据揭示了 M. soricoides 和 M. fotsifotsy 之间的几个主要差异，以及 M. fotsifotsy 的两个分支之间更微妙的差异。鉴于这些结果，我们将 M. fotsifotsy 的南部分支视为一个新的候选种。我们的研究结果表明，整合多种数据类型来理解复杂的物种形成历史是有用的，并为越来越多的证据提供了依据，即马达加斯加的物种多样性被低估了。
