Sherise Vialva MSc Candidate, Colautti Lab Exploring co-occurrence patterns and the impact of Climate Change on the Competitive Dynamics between Alliaria petiolata and Vincetoxicum rossicum My research looks at the interaction between two invasive plant species, Alliaria petiolata and Vincetoxicum rossicum, and how co-occurrence and competition may be affected by climate change. I conducted a field survey across Southern Ontario to determine if these species naturally co-occur and what environmental conditions possibly lead to one dominating over the other.
The results from the field survey found that both species naturally co-occur, leading me to conduct a field experiment to further investigate their interactions. The objective of this experiment was to examine how climate change may affect the interactions between Alliaria petiolata and Vincetoxicum rossicum. And to determine how this change could impact the abundance of both species, as well as their ability to spread in the future. My results suggest that climate warming may increase the fitness for both species, which may lead to greater spread and abundance in the future. However, this benefit from warming appears to be greater for each species when they are grown alone rather than together. This suggests that the presence of one species negatively affects the other. More research is needed to understand how these interactions will impact native plant communities. And on developing management strategies to better control the future spread of both species in a warmer climate. Allochronic speciation with gene flow? Genomics of parallel breeding time divergence among storm-petrels (Hydrobatidae) Parallel evolution, in which similar phenotypes arise among independent lineages, provides strong insights into the mechanisms and constraints on evolution. However, whether the same genomic regions underly the evolution of parallel traits is often unclear. Storm-petrels (Procellariiformes: Hydrobatidae), a cosmopolitan family of island-breeding seabirds, provide a useful case study for parallel evolution. Several sister races of storm-petrels have independently diverged in breeding season – an example of parallel allochronic divergence. I am using low-coverage whole-genome sequencing to disentangle the origins of repeated breeding time switches in storm-petrels. I am examining allochronic sister races in the band-rumped storm-petrel species complex (Hydrobates spp.), as well as an allochronic species pair from Guadalupe Island, Mexico: Townsend’s (H. socorroensis) and Ainley’s storm-petrels (H. cheimomnestes). Firstly, I am using outlier analyses to determine whether the same genomic regions differentiate sympatric population pairs. Secondly, I am assessing the role of adaptive introgression in promoting parallel evolution and inspecting the overlaps between introgressed regions and genomic outliers. Preliminary results confirm that allochronic populations arose in parallel across the breeding range. Moreover, the identification of outliers and evidence for widespread introgression among seasonal populations suggest that gene flow may have facilitated parallel divergence in the storm-petrels. The use of annotated genome databases will complement these results by matching potential gene functions to the outliers, which will further improve our understanding of the drivers of population divergence and adaptation.
Patterning the meristems - the development and evolution of the floral ground plan Despite the seemingly infinite morphological diversity, all flowers are highly organized structures. The overall pattern, or the floral ground plan, is determined at the earliest developmental stage in making a flower by the floral meristem. Knowledge of how different floral ground plans are established and evolved is critical for our understanding of flower diversification as well as genetic engineering of crop species. Although comparative analyses have revealed many evolutionary trends in the floral ground plan during angiosperm diversification, the molecular mechanisms underlying these evolutionary transitions remain largely known. Using Aquilegia and Mimulus, two charismatic emerging model systems for evo-devo studies, I demonstrate how developing new model systems can help us understand key aspects of the floral ground plan that cannot be addressed by previously established model systems.
Beetlejuice, Beetlejuice, Beetlejuice: The role of antimicrobial secretions in competition in the burying beetle, Nicrophorus orbicollis An organism’s ability to survive and reproduce is often related to its ability to compete for resources. Competition can be intense for organisms that rely on temporally or spatially limited or unpredictable resources. Carrion is often both limited and unpredictable, and is particularly valuable because it is nutrient rich. Animals that use carrion face intense competition from microbes, which can make the carcass unpalatable or inhospitable. I investigated adaptations to competition with microbes in the burying beetle, Nicrophorus orbicollis. Burying beetles require vertebrate carcasses to reproduce, and use anal secretions containing antimicrobial components and beneficial gut microbes to protect a carcass during breeding. Anal secretions can delay carcass decay and prevent pathogenic competitor microbes from colonizing the carcass during larval rearing. However, the proximate mechanisms by which these antimicrobial effects occur, whether through endogenous immune defenses of the beetle and/or direct competition between gut and carcass microbes, remains unknown. Fungal gut symbionts from the genus Yarrowia might play a critical role in competition with harmful carrion consuming microbes, and until now the direct effects of fungal gut symbionts on competition between burying beetles and carcass microbes have not been tested. I determined the competitive consequences of experimentally disrupting fungal symbionts from the gut microbiome of N. orbicollis by measuring treatment effects on carcass preparation behaviours, anal secretion antimicrobial potency, and carcass decomposition rate. Results demonstrate the importance of the gut microbiome in behavioural plasticity, but suggest that fungal microbial symbionts might not contribute to the antibiotic properties of anal secretions, or impact the rate of carcass decomposition. Our findings contribute to our understanding of symbiotic relationships with gut microbes, and the complex strategies some organisms use to compete for scarce resources.
Machine learning and genomics: Using neural networks for population assignment of a threatened seabird Population genomics is aiding researchers in uncovering more information about non-model organisms, and has aided in the development of species and population-specific conservation plans. For many species, effective conservation remains difficult due to low population genetic structure and difficulty in accurately assessing potential threats. The Leach’s storm-petrel (Hydrobates leucorhous) is a migratory pelagic seabird that breeds in large colonies throughout the North Pacific and Atlantic Oceans. In the past 50 years, Atlantic populations have declined by an estimated 54%. Several potential threats, ranging from offshore structures to increased predation from gulls, have been identified, however determining the impact of these widely distributed threats on specific colonies remains difficult due to the species low genetic structure and migratory behaviour. Where previous population assignment studies on this species have failed, I aim to use a combination of genomic data and novel machine learning methods to investigate the genetic structure of Atlantic Leach’s Storm-Petrels and assign individuals of unknown origin to their respective breeding colonies. Using DNA collected from over 300 individuals from 11 different populations, as well as 84 deceased individuals of unknown origin, I attempted to use the novel neural network popfinder to generate colony of origin predictions and determine what threats appear to be the most pertinent to specific colonies.
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