This research investigates factors affecting variation in life-history traits across the life cycle of a medically important mosquito, Aedes albopictus. First, to evaluate ecological differences between Ae. albopictus and Ae. japonicus, I compared their larval foraging behavior. Based on results from a previous competition experiment, I predicted that Ae. albopictus would be a more active forager than Ae. japonicus. However, Ae. japonicus exhibited greater activity than Ae. albopictus, suggesting that more active foraging does not connote superior competitive ability.
In addition, I performed common-garden and line-cross experiments in order to examine the genetic differentiation of fitness for Ae. albopictus at three spatial scales. I found that North American populations had lower fitness than populations from outside North America. Population crosses resulted in significant heterosis and outbreeding depression of hybrids, but the results did not depend on the geographic distance separating populations. My results imply a role for local genetic drift affecting the lifehistory differentiation of Ae. albopictus populations.
Local genetic drift is known to influence genetic differentiation among populations for a variety of vector species. Next, I created inbred Ae. albopictus lines to test the boundary conditions under which local genetic drift might affect pathogen susceptibility. I predicted that inbreeding would significantly decrease life history traits and increase susceptibility to infection by the model pathogen, Plasmodium gallinaceum. Inbred mosquitoes had significantly reduced larval survivorship and female adult longevity, but I found no effect of inbreeding on susceptibility to infection.
Finally, I compared egg volume of populations from across a latitudinal gradient in the native (Japan) and invasive (US) range of Ae. albopictus. Egg size clines are frequently observed in insect populations, so I predicted that egg size would increase with population latitude for both native and invasive populations. I measured egg size for 11 populations from Japan and the US over the same approximate latitudinal range. However, I did not find a cline of increasing egg size correlated with increasing latitude for Ae. albopictus in either country. Overall, these results provide valuable insight regarding ecological and evolutionary processes during the invasion and range expansion of Ae. albopictus in North America.
|Advisor:||Armbruster, Peter A.|
|Commitee:||Lehmann, Tovi, Weiss, Martha R., Wimp, Gina M.|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 71/01, Dissertation Abstracts International|
|Keywords:||Aedea albopictus, Inbreeding depression, Invasive species, Larval forgaing behavior, Latitudinal clines, Pathogen susceptibility, Population structure, Tiger mosquito|
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