Stadelmann B, Lin L-K, Kunz T H, Ruedi M
Department of Mammalogy and Ornithology, Natural History Museum, P.O. Box 6434, 1211 Geneva 6, Switzerland.
Mol Phylogenet Evol. 2007 Apr;43(1):32-48. doi: 10.1016/j.ympev.2006.06.019. Epub 2006 Jul 14.
Recent studies have shown that species in the genus Myotis have evolved a number of convergent morphological traits, many of which are more related to their mode of food procurement than to their phylogeny. Surprisingly, the biogeographic origins of these species are a much better predictor of phylogenetic relationships, than their morphology. In particular, a monophyletic clade that includes all New World species was apparent, but only a third of the 38 species have been analysed. In order to better understand the evolution of this clade, we present phylogenetic reconstructions of 17 Nearctic and 13 Neotropical species of Myotis compared to a number of Old World congeners. These reconstructions are based on mitochondrial cytochrome b (1140 bp), and nuclear Rag 2 genes (1148 bp). Monophyly of the New World clade is strongly supported in all analyses. Two Palaearctic sister species, one from the west (M. brandtii) and one from the east (M. gracilis), are embedded within the New World clade, suggesting that they either moved across the Bering Strait, or that they descended from the same ancestor that reached the New World. An emerging feature of these phylogenetic reconstructions is that limited faunal exchanges have occurred, including between the North and South American continents, further emphasizing the importance of biogeography in the radiation of Myotis. A fossil-calibrated, relaxed molecular-clock model was used to estimate the divergence time of New World lineages to 12.2+/-2.0 MYA. Early diversification of New World Myotis coincides with the sharp global cooling of the Middle Miocene. Radiation of the temperate-adapted Myotis may have been triggered by these climatic changes. The relative paucity of species currently found in South America might result from a combination of factors including the early presence of competitors better adapted to tropical habitats.
最近的研究表明，鼠耳蝠属的物种已经进化出了许多趋同的形态特征，其中许多特征与其食物获取方式的关系比与系统发育的关系更为密切。令人惊讶的是，这些物种的生物地理起源比其形态更能准确预测系统发育关系。特别是，一个包含所有新大陆物种的单系类群很明显，但在38个物种中，只有三分之一进行了分析。为了更好地理解这个类群的进化，我们展示了17种新北界和13种新热带界鼠耳蝠物种与一些旧大陆同属物种相比的系统发育重建。这些重建基于线粒体细胞色素b（1140 bp）和核Rag 2基因（1148 bp）。在所有分析中，新大陆类群的单系性都得到了有力支持。两个古北界姐妹物种，一个来自西部（布氏鼠耳蝠），一个来自东部（纤细鼠耳蝠），嵌入在新大陆类群中，这表明它们要么是穿越白令海峡迁移过去的，要么是来自到达新大陆的同一个祖先。这些系统发育重建的一个新特点是，包括北美和南美大陆之间在内，发生的动物区系交流有限，这进一步强调了生物地理学在鼠耳蝠辐射中的重要性。一个经过化石校准的宽松分子钟模型被用来估计新大陆谱系的分歧时间为1220±200万年前。新大陆鼠耳蝠的早期分化与中新世中期全球急剧变冷相吻合。适应温带的鼠耳蝠的辐射可能是由这些气候变化引发的。目前在南美洲发现的物种相对较少，可能是多种因素共同作用的结果，包括早期存在更适应热带栖息地的竞争者。
