Browsing by Author "Villalobos, Soraya"

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    Biological Constraints Determining Specialization in Canadian Plant-Pollinator Communities
    (2018-04-16) Villalobos, Soraya; Vamosi, Jana C.; Cartar, Ralph; Kevan, Peter G.; Johnson, Steig E.; Samuel, Marcus A.
    The overall objective of the research reported in this dissertation was to investigate biological factors underlying ecological specialization in Canadian plant-pollinator communities. Using a combination of fieldwork and the analysis of previously collected data, my research determined that landscape degradation led to observed local-scale differences in the prevalence of ecologically specialized clades of plants and pollinators in Canadian ecosystems. Through ecological and phylogenetic community analysis, I found that the alteration in community composition increases the prevalence of zygomorphic clades in the more degraded zones. Thus, plant community composition in disturbed areas favours the persistence of ecologically specialized groups (notably nitrogen fixers) that may enhance soil conditions. The prevalence of particular clades of pollinators in the two different habitats across Canada is partly due to the environmental tolerances of certain pollinator clades. Bombus clade comprised a higher proportion of prairie bees, whereas assemblages in Garry oak sites exhibited higher representation from solitary bees (e.g., Osmia, Andrena, Ceratina). Likewise, pollinator traits associated with areas that had more precipitations was soil nesting and traits related to areas that exhibited high temperatures were cavity-nesting. I identified specific cases of reciprocal specialization in plant-pollinator interactions as well as selective environmental occupancy of ecologically specialized clades. These findings can inform conservation efforts to maintain adequate pollination services to plant communities. Although disturbance interactions remained consistent in the number of reciprocal specialization cases, I hypothesize plant-pollinator interactions in prairie grassland systems in Alberta exhibit more interesting cases of specialization than previously thought.
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    Specialization in plant–pollinator networks: insights from local-scale interactions in Glenbow Ranch Provincial Park in Alberta, Canada
    (2019-09-06) Villalobos, Soraya; Sevenello-Montagner, José M; Vamosi, Jana C
    Abstract Background The occurrence and frequency of plant–pollinator interactions are acknowledged to be a function of multiple factors, including the spatio-temporal distribution of species. The study of pollination specialization by examining network properties and more recently incorporating predictors of pairwise interactions is emerging as a useful framework, yet integrated datasets combining network structure, habitat disturbance, and phylogenetic information are still scarce. Results We found that plant–pollinator interactions in a grassland ecosystem in the foothills of the Rocky Mountains are not randomly distributed and that high levels of reciprocal specialization are generated by biological constraints, such as floral symmetry, pollinator size and pollinator sociality, because these traits lead to morphological or phenological mismatching between interacting species. We also detected that landscape degradation was associated with differences in the network topology, but the interaction webs still maintained a consistently higher number of reciprocal specialization cases than expected. Evidence for the reciprocal evolutionary dependence in visitors (e.g., related pollinators visiting related plants) were weak in this study system, however we identified key species joining clustered units. Conclusions Our results indicate that the conserved links with keystone species may provide the foundation for generating local reciprocal specialization. From the general topology of the networks, plant–pollinators interactions in sites with disturbance consisted of generalized nodes connecting modules (i.e., hub and numerous connectors). Vice versa, interactions in less disturbed sites consisted of more specialized and symmetrical connections.