Oliver Jeffrey C, Shapiro Arthur M
Interdisciplinary Program in Insect Science and Department of Entomology, University of Arizona, Tucson, AZ 85721, USA.
Mol Ecol. 2007 Oct;16(20):4308-20. doi: 10.1111/j.1365-294X.2007.03494.x. Epub 2007 Sep 10.
Species exist as biological entities with patterns of discontinuous phenotypic variation. However, the distinctness of taxa is called into question when morphological intermediates exist in areas of sympatry, reflecting either gene flow among variants of a species or hybridization between different species. Studying the partitioning of genetic variation provides a means to discern between the two possibilities. We used genetic and morphometric approaches to investigate the degree of isolation among the three members of the Lycaena xanthoides species group. Lycaena xanthoides, L. editha, and L. dione are predominantly allopatric and have been treated both as three separate species and as a single polytypic species. Using 618 bp of the mitochondrial gene COII, we found little phylogenetic resolution, but significant among-taxa genetic variance partitioning. Divergence among these taxa has been relatively recent, as evidenced by relatively low pairwise sequence divergence. Also, the existence of two well-supported clades within L. xanthoides sensu stricto, concordant with the Transverse Ranges of southern California, indicates divergence within this taxon, and a possible cryptic species. Significant morphological differentiation between L. editha and L. xanthoides supports the hypothesis that these taxa represent separate gene pools. Populations occurring in a narrow zone where the two species' ranges approach are characterized by intermediate morphology, suggesting incomplete morphological divergence or recent hybridization. These findings highlight the utility of genetic data in inferring species boundaries and the identification of cryptic lineages.
物种作为具有不连续表型变异模式的生物实体而存在。然而，当在同域分布区域存在形态学中间类型时，分类单元的独特性就会受到质疑，这反映了一个物种的变体之间的基因流动或不同物种之间的杂交。研究遗传变异的分配提供了一种辨别这两种可能性的方法。我们使用遗传和形态测量方法来研究黄带灰蝶物种组三个成员之间的隔离程度。黄带灰蝶、伊迪丝灰蝶和狄俄涅灰蝶主要是异域分布的，它们既被视为三个独立的物种，也被视为一个单一的多型物种。利用线粒体基因COII的618个碱基对，我们发现系统发育分辨率较低，但分类单元间的遗传方差分配显著。这些分类单元之间的分化相对较新，相对较低的两两序列差异证明了这一点。此外，在狭义的黄带灰蝶中存在两个得到充分支持的分支，与南加州的横向山脉一致，这表明该分类单元内存在分化，以及可能存在隐存种。伊迪丝灰蝶和黄带灰蝶之间显著的形态分化支持了这些分类单元代表不同基因库的假设。在两个物种分布范围接近的狭窄区域出现的种群具有中间形态特征，这表明形态分化不完全或近期发生了杂交。这些发现突出了遗传数据在推断物种边界和识别隐存谱系方面的作用。
