Department of Biology and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.
PLoS One. 2013 Jul 23;8(7):e69245. doi: 10.1371/journal.pone.0069245. Print 2013.
The increase in species diversity from the Poles to the Equator is a major biogeographic pattern, but the mechanisms underlying it remain obscure. Our aim is to contribute to their clarification by describing the latitudinal gradients in species richness and in evolutionary age of species of New World bats, and testing if those patterns may be explained by the niche conservatism hypothesis. Maps of species ranges were used to estimate species richness in a 100 x 100 km grid. Root distances in a molecular phylogeny were used as a proxy for the age of species, and the mean root distance of the species in each cell of the grid was estimated. Generalised additive models were used to relate latitude with both species richness and mean root distance. This was done for each of the three most specious bat families and for all Chiroptera combined. Species richness increases towards the Equator in the whole of the Chiroptera and in the Phyllostomidae and Molossidae, families that radiated in the tropics, but the opposite trend is observed in the Vespertilionidae, which has a presumed temperate origin. In the whole of the Chiroptera, and in the three main families, there were more basal species in the higher latitudes, and more derived species in tropical areas. In general, our results were not consistent with the predictions of niche conservatism. Tropical niche conservatism seems to keep bat clades of tropical origin from colonizing temperate zones, as they lack adaptations to survive cold winters, such as the capacity to hibernate. However, the lower diversity of Vespertilionidae in the Neotropics is better explained by competition with a diverse pre-existing community of bats than by niche conservatism.
从极地到赤道，物种多样性的增加是一个主要的生物地理模式，但支撑它的机制仍然不清楚。我们的目标是通过描述新世界蝙蝠物种丰富度和物种进化年龄的纬度梯度，并检验这些模式是否可以用生态位保守性假说来解释，从而为其阐明做出贡献。使用物种分布范围图来估计 100x100km 网格中的物种丰富度。分子系统发育中的根距离被用作物种年龄的代理，并估计网格中每个单元格中物种的平均根距离。广义加性模型用于将纬度与物种丰富度和平均根距离相关联。这是为三个最丰富的蝙蝠科和所有翼手目动物分别进行的。在整个翼手目动物和在辐射热带的 Phyllostomidae 和 Molossidae 中，物种丰富度向赤道方向增加，但在 Vespertilionidae 中观察到相反的趋势，Vespertilionidae 被认为起源于温带。在整个翼手目动物和三个主要科中，高纬度地区有更多的基础物种，热带地区有更多的衍生物种。一般来说，我们的结果与生态位保守性的预测不一致。热带生态位保守性似乎阻止了热带起源的蝙蝠进化枝在温带地区殖民，因为它们缺乏适应寒冷冬季的能力，例如冬眠的能力。然而，新热带地区 Vespertilionidae 的多样性较低，这与其说是生态位保守性的结果，不如说是与先前存在的蝙蝠多样性竞争的结果。
