The ecological niche and population history shape mosquito population genetics: a case study from Caribbean islands

Background: Despite their medical and veterinary importance, little is known about the general patterns in genetic population structure of mosquitoes. The scarce information that is available comes from a small subsample of cosmopolitan (and often pathogen-transmitting) species. This greatly hampers our ability to generalise previously described patterns of variation in mosquito population genetics to global mosquito biodiversity. This study aimed to explore variation in population genetics of species from a wide range of ecological niches and how variation in these patterns relates to species-specific ecologies and population history, using the mosquito fauna of the Caribbean islands of Aruba, Curaçao, and Bonaire as a case study. Methods: Mitochondrial COII sequences were obtained from 258 mosquito specimens belonging to six species, occurring on all three islands. Sequences were used in phylogenetic analysis and haplotype network analysis to assess the genetic variation between mosquito populations of each of the six ecologically diverse species, which vary in both their population history and ecological niche. Results: Both the genetic diversity and population genetic structure were found to differ strongly between sets of species, leading to a subdivision into three species groups: i) non-native species with low genetic diversity across all three investigated islands; ii) locally native species with high genetic diversity and closely related haplotypes occurring on different islands; iii) locally native species with high genetic diversity and locally restricted haplotypes. Conclusions: Our results show that the population genetics of non-native and native species strongly differ, likely as a result of population history. Furthermore, the results suggest that native populations may display distinct population genetic structure, which is likely related to differences in their ecology and dispersal capacity. Based on these results, we hypothesize that similar contrasts in mosquito population genetics along historical and ecological axes may be present worldwide.