Department of Biological Sciences and Museum, Texas Tech University, Lubbock, TX 79409, USA.
Proc Natl Acad Sci U S A. 2010 Jun 22;107(25):11447-52. doi: 10.1073/pnas.1000133107. Epub 2010 Jun 2.
Most diploid species arise from single-species ancestors. Hybrid origins of new species are uncommon (except among polyploids) and are documented infrequently in animals. Examples of natural hybridization leading to speciation in mammals are exceedingly rare. Here, we show a Caribbean species of bat (Artibeus schwartzi) has a nuclear genome derived from two nonsister but congeneric species (A. jamaicensis and A. planirostris) and a mitochondrial genome that is from a third extinct or uncharacterized congener. Artibeus schwartzi is self-sustaining, morphologically distinct, and exists in near geographic isolation of its known parent species. Island effects (i.e., area, reduced habitat variability, and geographic isolation) likely have restricted gene flow from parental species into the Caribbean populations of this hybrid lineage, thus contributing to local adaptation and isolation of this newly produced taxon. We hypothesize differential rates of the development of reproductive isolation within the genus and estimate that 2.5 million years was an insufficient amount of time for the development of postzygotic isolation among the three species that hybridized to produce A. schwartzi. Reticulated evolution thus has resulted in a genomic combination from three evolutionary lineages and a transgressive phenotype that is distinct from all other known species of Artibeus. The data herein further demonstrate the phenomenon of speciation by hybridization in mammals is possible in nature.
大多数二倍体物种都源自单一种群的祖先。新物种的杂交起源并不常见（多倍体物种除外），并且在动物中也很少有记录。在哺乳动物中，自然杂交导致物种形成的例子极为罕见。在这里，我们展示了一种加勒比蝙蝠（Artibeus schwartzi）的核基因组来自两个非姐妹但同属的物种（A. jamaicensis 和 A. planirostris），而线粒体基因组则来自第三个已灭绝或未被描述的同属物种。Artibeus schwartzi 是自我维持的，形态上有明显的区别，并且与其已知的亲种在近地理隔离的情况下存在。岛屿效应（即面积、栖息地可变性减少和地理隔离）可能限制了来自亲种的基因流进入加勒比地区的这种杂交谱系，从而促进了这个新产生的分类群的局部适应和隔离。我们假设在属内生殖隔离的发展速度存在差异，并估计在三种杂交产生 A. schwartzi 的物种中，250 万年的时间不足以形成合子后隔离。因此，网状进化导致了来自三个进化谱系的基因组组合和一种与所有其他已知 Artibeus 物种都不同的过度表现型。本文中的数据进一步证明了在哺乳动物中，通过杂交进行物种形成的现象在自然界中是可能的。
