Genetic Differentiation Among Culex tarsalis Populations in Montana

Abstract

Undergraduate researchers at Carroll College have been working to detect West Nile virus in the mosquito Culex tarsalis, the primary vector for the disease in the state of Montana. The purpose of this research is to use West Nile positive detections along with ecological data to create a risk model for the state of Montana that could predict the likelihood of a West Nile outbreak. The research presented in this paper attempts to further the goal of the risk model by determining the degree of genetic differentiation among different mosquito populations in Montana. Determining the genetic relatedness of different populations may help to predict how West Nile virus spreads across the state. One hundred twenty four individuals from eleven different locations in Montana were analyzed using ISSR analysis. Analyses included population pairwise FST values, percent polymorphic loci, and sources of variation between populations, all of which were calculated using analysis of molecular variance (AMOVA). Results suggest that while different populations of Cx. tarsalis seem to be genetically different, there is no evidence of genetic structure across the Continental Divide. Therefore, it appears that the Continental Divide does not act as a barrier to gene flow. It could be that the Continental Divide does not prevent the movement of mosquitoes from eastern Montana to western Montana. However, due to the high degree of genetic variability within populations, it seems more likely that this method of analysis yielded too much variation for genetic structure to be detected on a statewide level.