Williams Barry L
Department of Animal Biology, 515 Morrill Hall, 505 S. Goodwin Avenue, University of Illinois at Urbana, Urbana, IL 61801, U.S.A.
Conserv Biol. 2002 Feb;16(1):148-157. doi: 10.1046/j.1523-1739.2002.00147.x.
I investigated the phylogeography of mitochondrial DNA haplotypes in the regal fritillary ( Speyeria idalia ) to determine the conservation status of isolated populations in light of alternative definitions of species, subspecies, and evolutionarily significant units. A total of 1441 bases of partial cytochrome oxidase I and II genes were sequenced from 115 individuals in 18 populations located throughout the range of the species. A relatively disjunct population was differentiated with five synapomorphies, whereas all other populations had little haplotype variation and no apparent association between geographic and genetic distance. The divergence of the disjunct population may be due to either historical isolation among populations or extinction of intermediate populations within a cline. Genetic divergence due to the extinction of populations in fragmented habitat, termed "anthrovicariance," may be a generalizable phenomenon. Similar cases in insects have been described previously. If more cases can be elucidated, taxonomists will need to consider whether allopatry achieved through a natural vicariant event should be treated differently than that achieved via human-induced habitat loss. Mitochondrial DNA sequence divergence, along with ecological and natural-history data, suggest that the disjunct population of S. idalia is a distinct evolutionary lineage. Although taxonomic designation is not a simple task, the data indicate that the disjunct population is clearly of conservation concern.
我研究了帝王环蝶（Speyeria idalia）线粒体DNA单倍型的系统地理学，以便根据物种、亚种和进化显著单元的不同定义来确定孤立种群的保护状况。在该物种分布范围内的18个种群中，对115个个体的细胞色素氧化酶I和II基因的部分序列进行了测序，共1441个碱基。一个相对隔离的种群有五个共同衍征，而所有其他种群的单倍型变异很小，地理距离和遗传距离之间没有明显关联。这个隔离种群的分化可能是由于种群间的历史隔离或渐变群中中间种群的灭绝。由于破碎栖息地中种群灭绝导致的遗传分化，即“人类致变”，可能是一种普遍现象。此前已描述过昆虫中的类似案例。如果能阐明更多案例，分类学家将需要考虑通过自然隔离事件实现的异域性与通过人为导致的栖息地丧失实现的异域性是否应区别对待。线粒体DNA序列差异，以及生态和自然历史数据表明，帝王环蝶的隔离种群是一个独特的进化谱系。虽然分类指定并非易事，但数据表明这个隔离种群显然值得关注其保护问题。
