Research
- Demographic pathways of range expansion
- Genetic consequences of range expansion
- DEI in Canadian Science
Demographic pathways of range expansion
In order to study genetic consequences of species geographic range expansion (e.g., decreased genetic diversity, increased genetic load, local adaptation, mating system and life-history shifts), it is important to resolve the underlying demographic pathways of range expansion. I am using the native alpine plant Erythranthe lewisii—previously Northern Mimulus lewisii and commonly known as pink monkeyflower—as a focal species to study the demographic pathways of range expansion at contrasting spatiotemporal scales.
Alpine glacier recession pathway fieldwork. (Left) View of Black Tusk in Garibaldi Provincial Park, BC. (Middle) Erythranthe lewisii growing in an older alpine recession pathway zone. (Right) Sampling E. lewisii leaf tissue at the edge of Helm Glacier.
I am studying colonization dynamics of E. lewisii along alpine glacier recession pathways (since the end of the Little Ice Age ~150 years ago) in Garibaldi Provincial Park, BC and across its entire latitudinal range in Northwestern North America (which spans the Coast, Cascade, and Rocky Mountain ranges) since the end of the Pleistocene Ice Age (~20 000 years ago) to test whether current and competing range expansion hypotheses apply to the process of primary succession across shorter, smaller elevational ranges and longer, larger latitudinal scales.
Range wide sampling fieldwork. (Left) Range-wide geographic distribution of E. lewisii from iNaturalist. (Middle-left) Flowering and fruiting E. lewisii at Mount Hood, OR. (Middle-right) Erythranthe lewisii habitat at Mount Stearn, AB. (Right) Searching for E. lewisii along the Jarbidge River, Jarbidge, NV.
Genetic consequences of range expansion
Empirical
Current eco-evolutionary theory predicts shifts in plant mating system type as a result of range expansion to achieve reproductive assurance, where the ability to self-fertilize or reproduce clonally provides a means to successfully reproduce in a new environment that is potentially devoid of conspecifics and/or pollinators. I am testing the effect of range expansion on mating system evolution and will use my phylogeographic results across the latitudinal range of E. lewisii as a framework to test whether spatial patterns in mating system in E. lewisii (e.g., autonomous selfing rate vs. propensity for clonal growth) are related to historical pathways of range expansion.
To test spatial patterns in reproductive assurance, I sampled mature E. lewisii fruits from across its entire geographic range and conducted a common garden greenhouse experiment to investigate spatial patterns in population-level autonomous selfing rate. Some photos from my greenhouse experiment (left to right) working in the greenhouse with my labmate, Takuji Usui, E. lewisii flowering, flood benches covered in tulle to exclude any potential pollinators.
Theoretical
Contemporary models of expansion load have only explored the effects of density-independent selection on relative reductions in edge population fitness, however, the demographic pathways of range expansion underlying the process of allele surfing create conditions where density-dependent selection is relevant. In collaboration with Ailene Macpherson at SFU, I am using simulation modelling to investigate the genetic consequences of density-dependent selection on life-history traits during range expansion. Our eco-evo range expansion model explores a more nuanced set of assumptions underlying expansion load theory, and broadens the potential processes included in existing theoretical frameworks that likely occur during range expansion in nature.DEI in Canadian Science: Gender & Career Stage
We investigated potential barriers to successful scientific funding outcomes for women and/or early career scientists. Using publicly available data from the NSERC Database, we explored interactions between gender and career stage on grant writing (word use) and funding success in the 2016 Discovery Grant competition.
We did not detect significant influence of gender on word use or grant value, but we detected a strong main effect of career stage and gender across all NSERC categories on funding success. Career stage was the most important predictor of award value and rejection rates were higher for women (40 percent) than men (33 percent) at early career stages. We shared our results with NSERC, to draw their attention to existing discrepancies between early career researchers and to improve future grant evaluation policies.