Past Research Projects
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Phenotypic response to thermal stress in two complexes of Pacific rockfishes
Supervised by Dr. Katie E. Lotterhos, Northeastern University
Sea-surface temperature (SST) is increasing at an unprecedented rate under climate change and predicting species responses to these changes remains an important biological challenge. In species with pelagic larvae, successful recruitment events can often be correlated with SST. Many rockfish species recruit to the same coastal habitats, but show variation in the timing of recruitment, which additionally corresponds to different oceanographic conditions. On the West Coast of Vancouver Island two species complex exist that recruit to the same habitat, but at different times of year under different oceanographic conditions. The BY
complex comprised of black rockfish (Sebastes melanops) and yellowtail rockfish (S. flavidus) recruit early in the summer and display high recruitment success during years marked by strong upwelling. The CQ complex comprised of copper rockfish (S. caurinus) and quillback rockfish (S. maliger) recruit later in the summer and show high recruitment success during years marked by prolonged downwelling. Using these two complexes of Pacific rockfishes, we set out to determine whether we find variation in performance between these species complexes in activity, growth and mortality rates in response to temperature, 2) whether peak performance corresponds to the thermal regime at the time of settlement of each complex and 3) whether the range in temperatures that each complex can tolerate will overlap with expected temperature increases for this region.
Inversion invasions! Understanding the conditions in which inversion polymorphisms arise and persist in populations undergoing environmental adaptation
Supervised by Dr. Katie E. Lotterhos, Northeastern University Marine Science Center
Collaboration with Dr. Benjamin Haller
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Inversion polymorphisms have been implicated in the evolution of coexisting phenotypes and behaviors in a number of species. Within Atlantic cod, some studies have implicated inversions polymorphisms in the evolution of the migratory and stationary ecotypes found throughout their distributional range. Although theory has suggested that a reason that inversions evolve is due to the reduction in recombination between alleles captured within an inversion, little work has explored the range in conditions (e.g. levels of migration & selection, genomic redundancy, inversion size, etc.) necessary for inversions to arise and persist in a population.
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Using evolutionary simulations built using the SLiM evolutionary software, we tested a range of parameters in a two population model undergoing stabilizing selection on a single trait to better understand when inversions arise and how often they persist in a population. Using these models, we also evaluated whether inversions are more likely to persist if they capture already established adaptive mutations or if they arise neutral and accumulate mutations over time. Finally, because we still do not fully understand how well our current statistical methods perform when identifying structural rearrangements linked to adaptation, our work tested whether genome scan methods can identify neutral vs. adaptive inversion polymorphisms in the genome.
SLiM
Population Genetic Structure of a Nuisance Green Algae Cladophora spp.
Supervised by Dr. Filipe Alberto, University of Wisconsin-Milwaukee
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Although native to Lake Michigan and its tributaries, Cladophora populations have grown exponentially due to the increased clarity of the lake resulting from the quagga mussel invasion. Due to a lack of population genetic research on Cladophora in the Great Lakes, my project started with the design and optimization of
microsatellite loci for the assessment of population structure and gene flow along Lake Michigan’s west coast. Data gathered from this project has shed light on two unexpected, but interesting results. First, we found location-specific morphological differences and location-specific failure of PCR primers to amplify genetic markers. This result suggested there may be multiple distinct species in the Lake Michigan watershed. Second, we found amplification of more than two alleles in some individuals. If the possibility of sample contamination by another individual can be ruled out, this result suggests that Cladophora may be polyploidy.
Change in the Optical Properties of Lake Michigan due to an Invasive Mussel
Supervised by Drs. Carmen Aguilar, Russell Cuhel, Istvan Lauko, and Gabriella Pintar
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The quagga mussel (Dreissena bugensis) arrived in Lake Michigan in the ballast waters of trans-oceanic ships that came from the Caspian Sea. These invasive mussels were able to outcompete the already established
zebra mussels (Dreissena polymorpha) and thrive in the deep, cold waters. Current estimations have put their numbers at over one hundred trillion along the lakebed and their impacts have been widespread affecting the lake's food web, clarity, and nutrient abundance. I studied the impacts that these mussels are having on light attenuation in the lake. My research was added to a 19-year light measurement dataset collected by the PI's of my project. After doing a large scale data analysis, we found that there was a significant increase in the depth of 1% light penetration providing evidence for increased clarity of Lake Michigan due to the quagga mussels.
