The Evolutionary Consequences of the Transition to Non-Blood-Feeding in the Pitcher Plant Mosquito Wyeomyia-Smithii
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The pitcher plant mosquito Wyeomyia smithii maintains a broad geographic range from the Gulf of Mexico to central Canada, and throughout its range is genetically and phenotypically variable, though fully interfertile. Many of the traits that vary across the broad range of this mosquito owe their diversity to selection on populations, which maximize fitness in the unique environment in which each populations finds itself. While a diversity of traits vary by latitude and merit the interest of evolutionary biologists, including critical photoperiod, voltinism, and thermal tolerance, of interest in the following thesis is the variation in blood-feeding propensity within this single species of mosquito. In no other mosquito species are some populations obligate non-biters while in other populations willingly hematophagous. This thesis explores the evolutionary transition from biting to non-biting in the pitcher plant mosquito at multiple levels of biological integration, starting first by establishing a heritable basis for the transition, then moving to the fitness and life historical consequences of both the natural system and of a line artificially selected in the lab. The latter half of this thesis moves on to probe the genetic architecture underlying the shift in phenotype and ends after examining the transition to non-biting at the level of the gene using an RNA-sequencing experiment. The results stemming from this thesis are thoroughly discussed: in short, we find that fitness differs between biting and non-biting populations, that complex genetic architectures underlie the transition to non-biting in nature, but not under artificial selection, and finally, that many candidate loci are differentially regulated in biting populations relative to non-biting populations and that these loci most often cluster with metabolic biological pathways.