Sánchez-Ramírez Santiago, Tulloss Rodham E, Guzmán-Dávalos Laura, Cifuentes-Blanco Joaquín, Valenzuela Ricardo, Estrada-Torres Arturo, Ruán-Soto Felipe, Díaz-Moreno Raúl, Hernández-Rico Nallely, Torres-Gómez Mariano, León Hugo, Moncalvo Jean-Marc
Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada.
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, ON, M5S 3B2, Canada.
Mol Ecol. 2015 Dec;24(23):5938-56. doi: 10.1111/mec.13413. Epub 2015 Nov 20.
Some of the effects of past climate dynamics on plant and animal diversity make-up have been relatively well studied, but to less extent in fungi. Pleistocene refugia are thought to harbour high biological diversity (i.e. phylogenetic lineages and genetic diversity), mainly as a product of increased reproductive isolation and allele conservation. In addition, high extinction rates and genetic erosion are expected in previously glaciated regions. Some of the consequences of past climate dynamics might involve changes in range and population size that can result in divergence and incipient or cryptic speciation. Many of these dynamic processes and patterns can be inferred through phylogenetic and coalescent methods. In this study, we first delimit species within a group of closely related edible ectomycorrhizal Amanita from North America (the American Caesar's mushrooms species complex) using multilocus coalescent-based approaches; and then address questions related to effects of Pleistocene climate change on the diversity and genetics of the group. Our study includes extensive geographical sampling throughout the distribution range, and DNA sequences from three nuclear protein-coding genes. Results reveal cryptic diversity and high speciation rates in refugia. Population sizes and expansions seem to be larger at midrange latitudes (Mexican highlands and SE USA). Range shifts are proportional to population size expansions, which were overall more common during the Pleistocene. This study documents responses to past climate change in fungi and also highlights the applicability of the multispecies coalescent in comparative phylogeographical analyses and diversity assessments that include ancestral species.
过去气候动态对动植物多样性构成的一些影响已得到较为充分的研究，但对真菌的研究程度较低。更新世避难所被认为拥有高度的生物多样性（即系统发育谱系和遗传多样性），这主要是生殖隔离增加和等位基因保存的结果。此外，预计在先前冰川覆盖的地区会有较高的灭绝率和遗传侵蚀。过去气候动态的一些后果可能包括分布范围和种群规模的变化，这可能导致分化以及初始或隐性物种形成。其中许多动态过程和模式可以通过系统发育和溯祖方法推断出来。在本研究中，我们首先使用基于多位点溯祖的方法，在一组来自北美的密切相关的可食用外生菌根鹅膏菌（美洲凯撒蘑菇物种复合体）中界定物种；然后探讨与更新世气候变化对该类群的多样性和遗传学的影响相关的问题。我们的研究包括在整个分布范围内进行广泛的地理采样，以及来自三个核蛋白编码基因的DNA序列。结果揭示了避难所中的隐性多样性和高物种形成率。中纬度地区（墨西哥高地和美国东南部）的种群规模和扩张似乎更大。分布范围的变化与种群规模的扩张成正比，总体而言，这些变化在更新世更为常见。这项研究记录了真菌对过去气候变化的响应，同时也突出了多物种溯祖在包括祖先物种的比较系统地理学分析和多样性评估中的适用性。
