Bottlenecks and multiple introductions: population genetics of the vector of avian malaria in Hawaii

Avian malaria has had a profound impact on the demographics and behaviour o f Hawaiian forest birds since its vector, Culex quinquefasciatus the southe rn house mosquito, was first introduced to Hawaii around 1830. In order to understand the dynamics of the disease in Hawaii and gain insights into the evolution of vector-mediated parasite-host interactions in general we stud ied the population genetics of Cx. Quinquefasciatus in the Hawaiian Islands . We used both microsatellite and mitochondrial loci. Not surprisingly we f ound that mosquitoes in Midway, a small island in the Western group, are qu ite distinct from the populations in the main Hawaiian Islands. However, we also found that in general mosquito populations are relatively isolated ev en among the main islands, in particular between Hawaii (the Big Island) an d the remaining Hawaiian Islands. We found evidence of bottlenecks among po pulations within the Big Island and an excess of alleles in Maul, the site of the original introduction. The mitochondrial diversity was typically low but higher than expected. The current distribution of mitochondrial haplot ypes combined with the microsatellite information lead us to conclude that there have been several introductions and to speculate on some processes th at may be responsible for the current population genetics of vectors of avi an malaria in Hawaii.