Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases, 3150 Rampart Road, Fort Collins, CO 80521, USA.
J Med Entomol. 2010 Sep;47(5):805-13. doi: 10.1603/me10031.
Aboveground and belowground populations of the mosquito Culex pipiens L. are traditionally classified as form pipiens and form molestus, respectively, and gene flow between forms is thought to be limited. Relatively few f. molestus populations have been found in the United States, which has hindered their study in North America. In this study, we used microsatellites to characterize a newly discovered population of f. molestus in Chicago, IL, and compared levels of genetic diversity and differentiation in aboveground and belowground populations from Chicago and New York City, NY. Levels of genetic diversity, as measured by expected heterozygosity and allelic richness, were markedly lower in both f. molestus populations. Allele frequencies were distinctly different between the two f. molestus populations, and some alleles were present in one belowground population and not the other. Pairwise F(ST) values between populations indicated that f. molestus populations were highly divergent from each other, as well as from their associated aboveground populations. Cluster analysis suggested the most likely number of groups was three, with the four f. pipiens populations in one cluster, and each of the f. molestus populations in its own cluster. Admixture analysis detected a low number of hybrids, 8%, between forms. We also tested the efficacy of two assays purported to distinguish between the forms, the CQ11 assay and a restriction fragment-length polymorphism assay of the COI gene, and found neither assay reliable in this regard. Our findings support the hypothesis that f. molestus populations in Chicago and New York City arose from local aboveground populations.
传统上，蚊子 Culex pipiens L. 的地上和地下种群分别被分类为 pipiens 型和 molestus 型，并且认为两种形式之间的基因流动是有限的。在美国相对较少发现 f. molestus 种群，这阻碍了它们在北美的研究。在这项研究中，我们使用微卫星来描述在伊利诺伊州芝加哥新发现的 f. molestus 种群，并比较了来自芝加哥和纽约市的地上和地下种群的遗传多样性和分化水平。遗传多样性水平，如预期杂合度和等位基因丰富度所衡量的，在两种 f. molestus 种群中都明显较低。两种 f. molestus 种群之间的等位基因频率明显不同，有些等位基因存在于一个地下种群中而不存在于另一个种群中。种群之间的成对 F(ST) 值表明，f. molestus 种群彼此之间以及与它们相关的地上种群之间高度分化。聚类分析表明，最有可能的群体数量是三个，四个 f. pipiens 种群在一个聚类中，每个 f. molestus 种群在自己的聚类中。混合分析检测到两种形式之间的低数量杂种，为 8%。我们还测试了两种据称可区分两种形式的检测方法的功效，CQ11 检测法和 COI 基因的限制性片段长度多态性检测法，发现这两种检测法在这方面都不可靠。我们的研究结果支持了这样一种假设，即芝加哥和纽约市的 f. molestus 种群是由当地的地上种群产生的。
