Wishing you had more science in your life?
For the month of May, CSEE will be premiering the five fantastic winners of the Excellence in PhD Research Award, with a 30-min research talk by them every Friday. Talks will streamed LIVE on Youtube starting at 4pm ET and you’ll have a chance to ask questions for a live Q/A session afterwards.
Full schedule below:
May 1, 4pm ET – Quinn Webber
May 8, 4pm ET – Anne McLeod
May 15, 4pm ET – Sarah Amundrud
May 22, 4pm ET – Ruth Rivkin
May 29, 4pm ET – Ken Thompson
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CSEE Excellence in PhD Research Award Talk
May 1st, 4pm ET
My core narrative as a PhD student has been to link animal social behaviour and space use. Animal social behaviour, habitat selection, and movement are inherently linked through density dependence and their effects on fitness. Using caribou (Rangifer tarandus) as a model system, I empirically tested these processes across scales and contexts. First, I tested whether social network position and habitat specialization are predictors of fitness in and vary as a function of population density. Second, I tested whether social group size varies as a function of population density. Third, I tested whether collective movement affects habitat selection. I found that social network position and group size are density-dependent, while habitat specialists tend to have higher fitness than generalists, but there was no effect of sociality on fitness. I found that individuals foraged alone, but moved together, highlighting that collective movement occurs between, but not within, foraging patches. The impact of my work is the establishment of the idea that social behaviour, habitat selection, movement, and population density are inter-related aspects of caribou socioecology. While much of my research is fundamental, caribou are federally threatened in Canada and my work has potential to inform caribou management.
Natural communities are undergoing accelerated changes due to human pressures such as habitat fragmentation, over-harvesting, and species invasions. Here, I use bioinformatics and mathematical models to examine the environmental and ecological drivers of food-web structure and dynamics. First, I use a spatially expansive food-web to examine drivers of spatial turnover in food-web interactions across an environmental gradient. I demonstrate that predicting local realizations of community structure is very difficult, but critical since environmental perturbations occur at the local scale. Then, I integrate empirical data and mathematical models to explore the consequences of different structural metrics, including omnivory, on food-web stability and persistence. I demonstrate that the importance of omnivory depends on both the type of omnivory and the food-web within which it appears. Finally, I derive a novel multi-trophic metacommunity model which demonstrate how movement is a product of both a species’ ability to move and the landscape across which it moves. Treating patch connectivity as a species’ specific property can change our conclusions about multi-patch stability. Overall, my thesis integrates data and theory to test the impacts of environmental gradients and change on food webs and provide testable predictions to guide future research in spatial food web ecology.
Species distributions and the composition of ecological communities result from the interplay of three constraints: physical barriers to dispersal, species-specific environmental requirements, and species interactions. While the relative importance of these factors is known to depend on spatial scale, the effects of climate change on the interplay of abiotic and biotic constraints are still poorly understood. I combined manipulative experiments, observational surveys along environmental gradients, and species distribution models to explore the relative importance of abiotic and biotic constraints on aquatic invertebrate communities inside bromeliad plants across a range of spatial scales: the geographic scale (Central and South America), the landscape scale (elevational gradients in Costa Rica), and the local scale (the bromeliad system). While species interactions were the main drivers of community change at the local scale, biotic effects were not important in driving species distributions at the large geographic scale. Notably, the relative importance of abiotic and biotic processes at the landscape scale depended on environmental context, an important insight given that environmental conditions are already shifting as a result of climate change. This hierarchical set of studies demonstrates the scale-dependence of the interplay of abiotic and biotic processes in affecting species distributions and community assemblages, as well as the potential role of environmental context at the intermediate scale of the landscape.May 22nd, 4pm ET
Urban habitats are more fragmented and degraded than nonurban habitats, which can impact both the ecology and evolution of species interactions. Species interaction may be particularly sensitive to urbanization because the species involved may be responding to urbanization separately, and together through effects on the strength of and direction of the interaction. We studied the effects of urbanization on a mutualistic interaction and an antagonistic interaction. We measured reproductive success of Brassica rapa plants across 30 experimental sites in Toronto, ON, and tracked within-site pollen dispersal and pollinator community variation among these sites. We found that urbanization influences plants reproductive success, but whether the effects on fitness were positive or negative depended on season and pollinator dispersal. We also studied the interaction between Darwin’s finches and Tirbulus cistoides in towns on three Galapagos Islands. We tested the effects of urbanization on seed predation rates, selection on mericarp size and defense traits, and ground finch community composition across 40 sites per island. Predation rates were elevated in urban sites, which corresponded to stronger selection on mericarp morphology and altered ground finch communities due to urbanization. Together, our results demonstrate the sensitivity of the ecology and evolution of species interactions to urbanization.
In my talk, I’ll describe the progress I made during my Ph.D. to ‘push the peanut forward’ in arriving at generalities about the mechanisms of natural and sexual selection that act on hybrids in nature. Because the phenotype of otherwise viable and fertile hybrids determines their fate, we must document patterns and test theoretical predictions to better understand the mechanisms of so-called ‘extrinsic’ post-zygotic isolation and its importance for speciation. I’ll discuss the results of a systematic literature review where I find that hybrid traits are typically more dominant than intermediate, resulting in hybrids that are often quite ‘mismatched’ for divergent parental traits. Using recombinant hybrid sunflowers grown in a common field environment, I experimentally demonstrate negative fitness consequences of trait mismatches in the field. I’ll then talk about some preliminary results from ongoing work illustrating the extent to which mismatched traits are expressed in first-generation vs. segregating (backcross and F2) hybrids. Finally, I’ll conclude with a brief summary of an ongoing field experiment in threespine stickleback testing whether parallel phenotypic evolution is an engine of speciation in nature