Jeannette Whitton

Translocation is increasingly used as a measure to support the continued existence of rare and endangered plant species. However, historically translocations have a low rate of success, due in part to the lack of knowledge of species-specific habitat requirements. My research focused on the role of microsite features in determining the presence and translocation success of a globally vulnerable perennial plant variety, Oxytropis campestris var. davisii (Fabaceae). This variety is known only from British Columbia (BC) and Alberta (AB), Canada, with BC supporting most of the populations. My research tested the suitability of various microsite habitat types through experimental trials to acquire insight to inform a larger-scale translocation for this threatened plant variety. Firstly, I assessed the association of naturally occurring O. campestris var. davisii with microsite characteristics across three sites. Secondly, I used experimental approaches to investigate the role of microsites in determining translocation success at two life stages: the seedling stage (including germination) and the juvenile stage. Based on previous observations, I hypothesized that the presence of the microsites cobbles and litter (combined) and the microsite cobbles (alone) would serve as predictors for both presence of O. campestris var. davisii at occupied sites and survival of O. campestris var. davisii at recipient sites. Using a combination of generalized mixed linear and logistic models, I found that cobbles and litter (in combination) and cobbles (alone) were strong positive predictors of the presence of Oxytropis campestris var. davisii. I found that post-translocation survival varied by life stage and by microsite type, with higher survival in juvenile plants compared to seedlings. Cobbles and litter (independent of each other) positively predicted juvenile plant survival. There was no evidence to suggest an association between microsite type and seedling survival, perhaps due to low seedling emergence and survival. My study will help guide the development of protocols for translocating this variety and can also serve as a model for other species, for example, by showing how preliminary studies at different life stages can help managers learn the conditions that will favour survival at different life stages, and therefore increase the probability of translocation success.

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If we hope to mitigate the effects of the climate crisis, it is critical that we accurately represent the contributions of plants in global models and predictions. The need to link global cycles to biological processes that feed into these cycles involves making scaling assumptions. In the case of photosynthesis, most global models use parameters extrapolated from a handful of species. However, the variation in leaf form and function that we observe both within and across species makes one question the biological accuracy of this assumption. Despite advances in quantifying the differences between deeply divergent lineages, there is still a substantial gap in what we know about how C3 photosynthesis evolves both at very deep and very shallow evolutionary timescales. Filling this gap will allow us to better infer and incorporate photosynthetic behaviour in global models. Here we address two specific gaps: i) we assess the evolution of photosynthetic trait variation and ii) we evaluate the relationship between photosynthetic traits and a set of plant functional traits. These latter traits are often used as proxies for metabolic variation even though we don’t know how metabolic and morphological features are coupled through their evolutionary trajectories. We collected data for a phylogenetically structured sample of 106 species growing in a common environment, sampling metabolic and functional traits from the same individuals. Using estimates of phylogenetic half-life, we find significant phylogenetic structure in both metabolic and morphological traits, but the evolution of metabolic traits is much more constrained than that of morphology. We also ask whether changes across traits are coupled, and find that even when there are present day trait correlations, most traits do not seem to share correlated evolutionary history. Our finding of substantial interspecific variation in photosynthetic traits is not captured in current global ecosystem models; further, using functional trait variation as a proxy does not adequately represent this variation. Future work would benefit from using some element of evolutionary history or species identity in modeling photosynthetic behaviour.

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Mushrooms of some Galerina species equal the most poisonous Amanita species in their concentrations of deadly amanitin toxins. Although individual Galerina mushrooms are small, eating about ten would risk delivering a lethal dose of amanitins to a child. Understanding which species of Galerina pose an acute poisoning risk requires a better understanding of species boundaries within the genus, as well broad sampling for the presence of amatoxins. I analyzed 61 Galerina and eight outgroup specimens for the presence of amatoxins using HPLC/LC-MS. I then used multi-locus DNA data (ITS, LSU and RPB2) from a broad sampling of Galerina and outgroup taxa to generate a constraint tree, to which 322 Galerina ITS sequences from herbarium specimens at UBC, from A.H. Smith’s type material (University of Michigan) and from Genbank were added. I mapped toxin analysis data onto the resulting phylogeny, which indicated that amatoxin-production in BC Galerina is restricted to two species, G. venenata and G. castaneipes. These two species, along with two other reportedly toxic species (G. aff. marginata and G. sulciceps) and seven other species whose toxin production status remains unknown form a broad clade referred to as the G. marginata complex. Phylogenetic and toxin data suggest that the sister clade to the G. marginata complex (G. badipes) does not produce toxins, implying that the origin of amatoxin production in Galerina is somewhere within the G. marginata complex. Additionally, phylogenetic data also supports past evidence that members of the genus Gymnopilus are nested within the ‘Mycenopsis’ lineage of Galerina. The results provide the first comprehensive look at toxin production in Galerina, as well as the first report of additional toxin-producing species in North America. Using the molecular data from this study to update specimen names in herbarium collections and online databases will reduce downstream confusion resulting from inaccurate identifications or misapplied names. Doing so will contribute to ongoing efforts to update of field guides and other resources that list poisonous and edible mushrooms, allowing amateur mycologists, foragers and healthcare professionals to gain a better understanding of which Galerina pose a poisoning risk.

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Much is known about plant-environment associations, but we are far from able to predict community species composition under a given set of environmental conditions. Recent research using functional traits suggests niche-based processes are vital in structuring communities, though the generality of results across different ecosystems is unknown. I investigated community trait distribution along environmental gradients in sub-Arctic roadsides-- communities which represent novel ecosystems in which to apply trait-based analysis, and which allow for the comparison of ecological strategies and trait distribution of native and exotic species. While these environments have features specific to northern latitudes, they also broadly represent global roadside environments and their important role in the establishment and spread of exotic species. Invasive exotic species present a pervasive threat to global diversity, and understanding mechanisms of assembly, coexistence and strategies of native and exotic roadside communities can improve our ability to predict invasive species' behaviour. I measured species abundance and three functional traits in 42 roadside plots in the Yukon Territory and compared community traits across elevation, latitude and age of road. Across all species, abundance-weighted community height was negatively correlated with elevation and positively correlated with latitude. Native and exotic species tracked environment differently, however, and exotic species showed correlations between height and road age and between specific leaf area (SLA) and latitude that were not present among native species. A comparison of mean trait values of native and exotic species irrespective of environment revealed specific leaf area (SLA) was greater in exotic species than native species. In addition, I used three null models to test for habitat filtering and competitive exclusion, two important niche-based assembly processes. Ranges of trait values across plots were smaller than expected and trait values more evenly spaced compared to random samples from the regional species pool, suggesting both habitat filtering and competitive exclusion (limiting similarity) shape these disturbance communities. Both processes were found to also affect both presence/absence and abundance of species. Understanding mechanisms of community assembly along roadsides and the characterization of native and exotic community constituents will have important implications for development of conservation management strategies.

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Townsendia hookeri (Asteraceae) plants can reproduce sexually or via apomixis (i.e. asexual reproduction through seeds), and the breeding system is tightly linked with ploidy level, so that sexual outcrossers are exclusively diploid while apomictic plants are polyploid. The species grows from central Colorado to British Columbia, with a disjunct distribution in Yukon Territory. Outside Yukon, sexual populations are restricted to the southernmost portion of the range (Colorado and southern Wyoming) and apomictic populations occur from Wyoming to Canada, a pattern consistent with geographical parthenogenesis. The major objective of this study was to expand our understanding of the factors that have shaped and maintain this distribution, conferring an apparent advantage to apomictic lineages over their sexual progenitors. Having documented that polyploid plants retain the ability to produce some functional pollen, I hypothesized that if sexual forms spread into an apomictic population, and thus receive mostly heterospecific pollen, they would have reduced reproductive success, because the progeny sired in sexual-asexual crosses are predicted to be weak or inviable, and to include hybrid apomicts. This asymmetric reproductive interference could help explain why diploids have failed to spread into the territory dominated by apomicts. To test this hypothesis I performed a cross-pollination experiment in the field. I showed that diploid and polyploid cytotypes have comparable reproductive success (at least, in the area where the experiment was conducted), and I also confirmed that diploids are outcrossers while polyploids are apomictic. The crossing experiment indicates that, despite its low viability, pollen produced by apomicts can fertilize and negatively affect diploid seed parents. As predicted, when sexual plants received heterospecific rather than conspecific pollen, seed set and germination rate were reduced, and seedlings had a lower survival rate. Flow cytometric analysis of offspring from sexual-asexual crosses revealed the presence of putative euploid (diploid, triploid and tetraploid) as well as aneuploid cytotypes. Based on ploidy level it is reasonable to expect that polyploid hybrids inherited apomictic genes and that at least some of them might be fully apomictic.

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Despite the classic place that the North American Crepis (Asteraceae) agamic complex holds in evolutionary literature, few of the hypotheses about the group presented by Babcock and Stebbins 1938 monograph have been tested. In particular, they hypothesized that the seven sexual diploids had strong interfertility barriers that prevented the formation of diploid hybrids. Here I present an analysis of two previously unrecognized diploid morphotypes, which belong to an unresolved clade with Crepis pleurocarpa and Crepis occidentalis based on plastid DNA variation. Morphological traits suggest that both morphotypes may be the product of diploid x diploid hybridization. I gathered nuclear SNP markers using genotyping by sequencing to assess the origins of these two lineages. I constructed a de novo assembly of the nuclear genome of Crepis monticola to serve as a reference for SNP discovery. Analysis of contig length,number, and coverage indicate that the nuclear genome of Crepis is highly repetitive and shares features in common with other plant genomes that make angiosperm genomes challenging to work with. This complexity, as well as technical challenges likely due to partial enzymatic digestion of genomic DNA during GBS library preparation, resulted in only 19 SNPs passing the quality filters. Nonetheless, these 19 markers were used to provide a preliminary assessment of the origins of novel morphotypes. A signal of mixed ancestry was found for one of these morphotypes with the majority of their genome being distinct from both C. occidentalis subsp. occidentalis and C. pleurocarpa. The second morphotype is of non-mixed ancestry most closely resembling Crepis occidentalis. In a separate study, I provide a draft assembly of the Crepis monticola chloroplast genome. I show that gene order and content are unchanged from other members of Asteraceae with the exception of the rpl16 gene, which retains an intron that is reported as lost multiple times in Asteraceae. Results of a preliminary data analysis detailing the presence or absence of the first exon of rpl16 in published Asteraceae plastome sequences indicates that most of these supposed losses are errors, pointing to the need for careful examination of plastome assemblies gathered from databases.

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