Zink Robert M
Museum of Natural Science, Louisiana State University, Baton Rouge, Louisiana, 70803.
Evolution. 1994 Feb;48(1):96-111. doi: 10.1111/j.1558-5646.1994.tb01297.x.
Geographic variation in mitochondrial DNA (mtDNA) restriction sites was studied in the fox sparrow (Passerella iliaca). Seventy-eight haplotypes were found. Haplotypes fall into four phylogeographic groups that correspond to groups defined by plumage characters. The geographic distribution of these four groups does not appear congruent with mtDNA patterns in other vertebrates. Within each group, there is little geographic variation in mtDNA restriction sites, although there is geographic variation in plumage coloration and body size. The evolution of mtDNA diversity in fox sparrows seems best explained by vicariant events rather than isolation by distance. The mtDNA evidence suggests that Passerella megarhyncha and Passerella schistacea, two nonsister taxa that occur in western North America, have independently undergone bottlenecks. Hybridization is limited between all pairs of taxa except P. megarhyncha and P. schistacea, where mtDNA evidence suggests a narrow contact zone along the interface of the Great Basin and Sierra Nevada/Cascades. Morphometric characters intergrade over a broader area, suggesting that different processes are responsible for the two gradients. The occurrence of limited backcrossing among taxa suggests that cytoplasmic-nuclear incompatibility is lacking. The number of biological species would range from one to four, depending on the degree of hybridization tolerated. The mtDNA and plumage characters suggest four phylogenetic species: P. iliaca, P. megarhyncha, P. unalaschcensis, and P. schistacea.
对狐色雀鹀（Passerella iliaca）线粒体DNA（mtDNA）限制性位点的地理变异进行了研究。共发现了78种单倍型。单倍型分为四个系统地理学组，这与根据羽色特征定义的组相对应。这四个组的地理分布似乎与其他脊椎动物的mtDNA模式不一致。在每个组内，mtDNA限制性位点几乎没有地理变异，尽管羽色和体型存在地理变异。狐色雀鹀mtDNA多样性的进化似乎最好用地理隔离事件来解释，而不是距离隔离。mtDNA证据表明，北美西部出现的两个非姐妹分类群——大喙雀鹀（Passerella megarhyncha）和岩色雀鹀（Passerella schistacea）——都独立经历了瓶颈效应。除了大喙雀鹀和岩色雀鹀外，所有分类群对之间的杂交都很有限，mtDNA证据表明，沿着大盆地与内华达山脉/喀斯喀特山脉交界处有一个狭窄的接触带。形态测量特征在更广泛的区域内渐变，这表明不同的过程导致了这两个梯度。分类群之间有限的回交现象表明不存在细胞质-细胞核不相容性。生物物种的数量将在一到四个之间，这取决于所能容忍的杂交程度。mtDNA和羽色特征表明有四个系统发育物种：狐色雀鹀、大喙雀鹀、阿留申雀鹀（P. unalaschcensis）和岩色雀鹀。
