Gimnig J E, Reisen W K, Eldridge B F, Nixon K C, Schutz S J
Department of Entomology, University of California, Davis 95616, USA.
J Med Entomol. 1999 Jan;36(1):23-9. doi: 10.1093/jmedent/36.1.23.
The genetic structure of 11 populations of Culex tarsalis Coquillett from California and 1 population from Nevada was examined at 18 loci using polyacrylamide gel electrophoresis. Six populations from northern and southern California were sampled repeatedly to determine if the genetic structure of Cx. tarsalis changes seasonally. Significant differences in allele frequencies at 13 different loci were seen in 3 populations over time as determined by contingency chi-square tests. Nei's genetic distance coefficients among different sampling dates was consistently < 0.025. The number of alleles per locus in these populations ranged from 1.6 to 2.7, whereas the average heterozygosity ranged from 0.086 to 0.228. No single locus was found to vary in a consistent pattern within all populations that were sampled repeatedly. These results indicate that Cx. tarsalis populations are genetically stable over time and that temporal variation is due to fluctuations in population size or immigration of genetically distinct individuals. In contrast, Cx. tarsalis did exhibit some differences in genetic structure that were related to geographical features including the Sierra Nevada and the Tehachapi Mountains of southern California. Genetically differentiated populations occurred in Nevada, southern and northeastern California, and the Central Valley of California. Little differentiation was observed among populations located in the Central Valley of California and those located at high elevations in the Sierra Nevada. Thus, in the populations examined, mountain ranges or arid conditions that limit the number of larval development sites appeared to be important barriers to the dispersal of Cx. tarsalis.
利用聚丙烯酰胺凝胶电泳技术，在18个基因座上研究了来自加利福尼亚州的11个致倦库蚊种群和内华达州的1个致倦库蚊种群的遗传结构。对来自加利福尼亚州北部和南部的6个种群进行了重复采样，以确定致倦库蚊的遗传结构是否随季节变化。通过列联卡方检验确定，随着时间的推移，在3个种群的13个不同基因座上观察到等位基因频率存在显著差异。不同采样日期之间的内氏遗传距离系数始终<0.025。这些种群中每个基因座的等位基因数量在1.6至2.7之间，而平均杂合度在0.086至0.228之间。在所有重复采样的种群中，没有发现单个基因座以一致的模式发生变化。这些结果表明，致倦库蚊种群在时间上遗传稳定，时间变化是由于种群大小的波动或遗传上不同个体的迁入。相比之下，致倦库蚊在遗传结构上确实表现出一些与地理特征相关的差异，包括内华达山脉和南加利福尼亚的 Tehachapi 山脉。在内华达州、加利福尼亚州南部和东北部以及加利福尼亚州中央谷地出现了遗传分化的种群。在加利福尼亚州中央谷地的种群和内华达山脉高海拔地区的种群之间观察到的分化很小。因此，在所研究的种群中，限制幼虫发育地点数量的山脉或干旱条件似乎是致倦库蚊扩散的重要障碍。
