Millie Smith, MSc Candidate, Plaxton Lab Phosphorylation of the cytosolic glucose-6-phosphate dehydrogenase isozyme AtG6PD6 in response to phosphate nutrition of the model plant Arabidopsis thaliana Glucose-6-phosphate dehydrogenase (G6PD) is a tightly regulated enzyme that catalyzes the first committed step of the oxidative pentose phosphate pathway (OPPP). The OPPP plays a pivotal role in generating reducing power in the form of NADPH, and carbon skeletons (e.g., ribose-5-P) needed for anabolism and cell growth. Our recent phosphoproteomics study discovered that the cytosolic G6PD isozyme, AtG6PD6, became hyperphosphorylated at multiple N-terminal residues 48 h following resupply of 2 mM phosphate (Pi) to Pi-starved (–Pi) Arabidopsis thaliana cell cultures. Although other phosphoproteomic studies have documented in vivo N-terminal phosphorylation of AtG6PD6 and its orthologs from other plant species, the functions and mechanisms of this phosphorylation event remain unknown. My research seeks to test the hypothesis that phosphorylation activates AtG6PD6 to enhance OPPP flux during the rapid resumption of cell growth that follows Pi resupply to –Pi Arabidopsis. Immunoblotting with a phosphosite-specific antibody confirmed that AtG6PD6 from Pi-resupplied, but not –Pi, Arabidopsis suspension cells and roots was phosphorylated at Ser18. This correlated with an increase in extractable G6PD activity following Pi-resupply to –Pi Arabidopsis seedlings (i.e., root extracts). Although the native enzyme is highly unstable in vitro, a partial purification of phosphorylated AtG6PD6 was achieved from Pi-replete suspension cells. The purified preparation was rapidly dephosphorylated by incubating with exogenous λ-phosphatase, and the kinetic properties were investigated. Assessing the interplay between Pi nutrition and cytosolic G6PD phosphorylation may contribute to our understanding of post-translational OPPP control in plants, while identifying targets for developing Pi-efficient crop varieties. Such cultivars are urgently needed to alleviate agriculture’s over-reliance on massive applications of non-renewable and polluting Pi fertilizers.
Kate Mitchell, MSc Candidate, Martin Lab The impact of wind turbines on the distribution of wintering and migrating raptors Renewable energy sources, such as wind power, are rapidly expanding as governments aim to fight climate change. However, wind turbines may negatively impact surrounding wildlife. Raptors are birds of prey, essential in maintaining their ecosystems. Raptor collisions with wind turbines are heavily studied, but the spatial displacement of these birds due to wind turbines has received less attention. Understanding collisions and displacement are both necessary to comprehend the overall effects of wind turbines on raptors. In this study, we used standardized surveys to record the presence, number, and location of wintering and migrating raptors on Amherst Island for three years before and after the wind turbines were built to assess whether the wind turbines have affected raptor distributions.
Tazi Rodrigues, MSc Candidate, Blanchfield Lab Patterns, consequences, and processes of mutualism evolution in the legume-rhizobium system Cooperation between species is widespread in nature yet the circumstances under which
mutualism evolves remain mysterious. My research uses the legume-rhizobium interaction to better understand patterns in mutualism evolution across geographic space, the ecological consequences of engaging in mutualism, and how mutualism evolves at a molecular level. Currently, our understanding of the legume-rhizobium interaction comes from a few well-studied temperate species. My research advances the field of legume-rhizobium research by sampling, sequencing, and analyzing non-model species from other parts of the globe, including the tropics. Legume-rhizobium interactions are greatly influenced by nutrient and partner availability in their habitat. I investigated changes in microbial community assembly on legumes across a large latitudinal gradient to understand how this interaction changes in temperate and tropical habitats. Although legumes hosted similar numbers of rhizobia partners across the range, tropical legumes associated with more non-rhizobia strains suggesting that tropical plants are less choosy of their symbiotic partners. There are many predicted benefits of being a less choosy host or generalist host to many symbiotic microbes. Using meta-analysis methods, I demonstrated that legume hosts that associate with many different rhizobial partners are more likely to find a compatible partner when introduced to a novel habitat. Generalist legumes establish in many new ranges and therefore experience greater ecological success compared to legume species that specialized on only a few rhizobia partners. It is unclear whether or how mutualism effects rates of molecular evolution. Most of the literature is focused on understanding how parasitic interactions are predicted to increase evolutionary rates in interacting species. I generated new sequence data from several non-model mutualistic species and found that mutualistic lineages in plants and rhizobia show elevated rates of molecular evolution. Therefore, mutualists may experience greater genetic change because they adapt to both a changing environment and symbiotic partners. 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.
Lisa Cicchetti, MSc Candidate Grogan Lab Evolved tolerance to road salt among wild populations of Daphnia Snowmelt and rain carry road salt from paved surfaces through the watershed via runoff and groundwater and increase the salinity of lakes, often measured as chloride concentration (Cl- mg/L). Salinization negatively impacts freshwater organisms, including Daphnia pulicaria, a ubiquitous crustacean zooplankton grazer that is integral to healthy ecosystems. Daphnia are sensitive to environmental changes, but studies have shown they are capable of rapid evolution. We investigated intraspecific variation in salt sensitivity among D. pulicaria collected from 10 lakes in southeastern Ontario to understand how wild Daphnia respond to salt pollution. Acclimation can also influence tolerance, so we tested the effect of acclimation on acute 48-hour salt tolerance for Daphnia grown at low (18 mg Cl-/L) and high (218 mg Cl-/L) Cl-. Our results indicate that acclimation to salt does not significantly impact tolerance. Our common garden experiments testing acute toxicity of salt on Daphnia from lakes ranging from <1 mg Cl-/L to 271 mg Cl-/L show a wide range of salt tolerances for wild Daphnia. Daphnia from Presqu’ile Bay, Lake Ontario (26.2 mg Cl-/L) and Lake Wilcox (194 mg Cl-/L) have higher salt tolerances of 2222 mg Cl-/L and 2344 mg Cl-/L, respectively, compared to Daphnia from unimpacted lakes (1277 – 1617 mg Cl-/L). This indicates that D. pulicaria may have adapted to localized road salt pollution. Understanding the factors contributing to robust tolerance to road salt will help inform decisions regarding freshwater ecosystem conservation.
Michael Vermeulen, PhD candidate Babak/Craig Lab The Vanishing Y: Exploring the role of mosaic loss of chromosome Y in neurodegeration and cancer As men age they experience a gradual loss of the Y chromosome (LOY) in their cells, specifically within immune cell-types. Recent, large-scale epidemiological surveys have found
approximately 70% of men older than 70 years of age have a detectable loss of their Y chromosome. Furthermore, a range of association studies have linked LOY to several age-related diseases including heart disease, Alzheimer’s, cancer, and macular degeneration. Also, we know that LOY is one of the most common chromosomal aberrations observed in male cancers (occurring in about ~28% of primary tumors). Despite the frequency of LOY and its association with disease, relatively little is known about its mechanisms and its role in disease pathology. Although recent mouse studies suggest LOY can directly cause disease, we still don’t know if it directly causes disease or is a passenger biomarker of degrading genomic instability. My Master’s research aimed to better understand LOY in brain tissue, with a specific interest in the cell-types LOY tends to accumulate in. We found that LOY is particularly common in the microglia, the main immune cell in the brain and a cell-type with important roles in neurodegerative processes. My PHD research investigates the role of LOY in cancer, and its potential use as a therapeutic target. We plan to use CRISPR-cas9 editing systems to engineer isogenic cell lines differing only by the presence of the Y chromosome. We will then test for LOY-specific genetic vulnerabilities using CRISPR loss-of-function screens with the goal of highlighting potential weaknesses in LOY cells that could be exploited as a cancer therapy. Investigating pollen capture, production, and size strategies in wind-pollinated flowering plants The flowering plants (angiosperms) have evolved a wide diversity of pollination strategies, from complex interactions with specialized animal pollinators to strategies that are entirely abiotic, relying on fluid currents like wind or water to transport pollen from stamen to stigma. Compared to animal pollination, abiotic strategies like wind pollination have long been considered inefficient, evolving when animal pollination becomes unreliable. Traits commonly associated with wind-pollinated plants are thought to reflect this apparent inefficiency and low probability of successful pollen transfer. Compared to animal-pollinated species, which tend to have large showy flowers design to attract animal pollinators, wind-pollinated plants tend to make many small, inconspicuous flowers that produce large volumes of pollen and often have just one ovule. These traits may represent a strategy to mitigate inevitable pollen losses – or they may represent innovative adaptations to maximize pollen capture in a unique pollination system. For example, packaging just one ovule per flower might not be because the probability of multiple grains landing on a given stigma is unusually low. Instead, having many small, relatively inexpensive flowers may allow wind-pollinated plants to maximize their pollen capture by maximizing the area they sample in space, at minimal floral costs. Similarly, pollen production strategies in wind pollinated plants may not simply reflect low probability of pollen capture by stigmas. Instead, these may be the result of a complex balance of selection on pollen size and number imposed by transport through wind and subsequent competition between pollen grains for limited ovules. In my research, I’m broadly interested in understanding the strategies wind-pollinated plants use to facilitate successful pollination from both male and female fitness perspectives, despite the inherent stochasticity in wind pollination.
Effects of turbidity and nutrients on zooplankton community structure: a mesocosm study Freshwater ecosystems make significant contributions to biodiversity and provide ecosystem services of value to humans. However, freshwater habitats are among the most threatened globally. Among the many ways that humans are altering freshwater ecosystems, elevated turbidity from suspended clay-sized sediments remains relatively under-explored, with much research limited to controlled single-species laboratory studies or community-level studies in oligotrophic environments. Sediments can adsorb nutrients and simultaneously deliver nutrients to freshwater systems, resulting in turbidity and nutrients simultaneously acting as stressors in lakes. Zooplankton play an important role in aquatic ecosystems, transferring energy from lower to higher trophic levels, and are excellent indicators of freshwater ecosystems. With the objective of exploring the causal relationships between turbidity and nutrients on zooplankton communities, I conducted a mesocosm experiment at the Queen’s University Biological Station. Using 60 mesocosms, I established two 30-increment turbidity gradients, one at ambient (mesotrophic-eutrophic) and one at high (eutrophic-hypereutrophic) nutrient levels. I stocked the mesocosms with a diverse zooplankton community and measured community-level responses (abundance, biomass, and diversity) after 6 weeks. I found no change in total zooplankton abundance or biomass, and no interaction between turbidity and nutrients. Rotifer abundance and biomass declined with turbidity, which correlated with a decline in the concentration of cryptophytes, a preferred food source for rotifers. Cladocera abundance increased with turbidity and there was no change in biomass, indicating compensatory responses within the cladocera community. Changes in the abundance of specific cladocera species further support the presence of compensatory dynamics in response to turbidity. In contrast with my findings, past laboratory studies and oligotrophic community studies found that turbidity had no impact on rotifer abundance and caused a decline in Cladocera abundance. In drawing different conclusions from previous studies, my research provides insights to how a highly diverse zooplankton community in nutrient-rich conditions respond to turbidity, and the potential for nutrients to alter the effects of turbidity on zooplankton communities.
Conner Elliot PhD Student, Tufts lab Biotelemetry provides new insights about the migration of adult walleye in Lake Ontario Walleye (Sander vitreus) populations throughout the Laurentian Great Lakes complete annual migrations between spawning and foraging habitats. Until recently, information regarding these migrations was collected using fisheries-dependent data, which can be biased based on fishing effort. Advances in tracking technology and electronic tagging techniques now provide the tools to collect fisheries-independent information about highly mobile species. This thesis examined the timing, extent, and patterns of migration for adult walleye that spawn in the Bay of Quinte and migrate through eastern Lake Ontario. The within-individual repeatability of these annual migrations was determined to be high at the temporal, spatial, and combined spatiotemporal levels. Tagging fish with a combination of acoustic transmitters and pop-off data storage tags (pDSTs) provided insights into the benefits and limitations of each method and identified a novel diving behaviour for this species. Combining the data from both methods provided an overview of the seasonal temperatures, depths, and activity levels experienced by these fish across an entire annual migration. There were sex-based differences in the timing, extent, area use, and vertical activity rates during the annual migration, as well as the number of dives per day during the summer. For most studies, acoustic transmitters can provide estimates of thermal and depth preferences, but they also have important limitations that were identified in this study. This thesis improves our understanding of migratory behaviour in freshwater fish, and the degree to which they are able to repeat these behaviours. It outlines the benefits and limitations of new methods that can be used to collect high-resolution data throughout the year. Future studies should examine the drivers behind these movements, and the mechanisms that these fish use to navigate across large inland waterbodies.
Xinyu Sun PhD Student, Arnott Lab Interactive effects of elevated salinity & heatwaves on freshwater zooplankton: From community ecology to individual physiology Freshwater ecosystems are being disturbed by multiple new and ongoing stressors that often occur simultaneously or asynchronously. Among those stressors, fluctuations in salinity levels and heatwaves that are becoming more frequent and intensified can individually and interactively impact freshwater organisms. However, we lack a good understanding of their joint impacts and how the temporal fluctuation of these stressors affects the impacts. To help fill this gap, I conducted experiments using freshwater zooplankton to investigate their interactive effects at community, population, and physiological levels. My results show that the joint effects of elevated salinity and heatwaves vary at different scales: antagonism (i.e., the joint effect is less than the sum of each individual effect) at the community level, mainly driven by species compositional changes; no interaction at the population level, caused by evolutionary changes; and synergism (i.e., the joint effect is greater than the sum of each individual effect) at the individual level, due to physiological responses. My results also suggest that the interactions between stressors change with different time intervals between them, because of the carry-over effect of the prior stressor or population and community recovery processes. My work contributes to the knowledge gap in the area of multiple-stressor interaction by showing the joint effects of elevated salinity and heatwave conditions at different levels of biological organization. The findings demonstrate that ecosystem management and restoration efforts that commonly just address the effect of a single stressor should consider prior stressor exposure, and the combined effects of two asynchronously occurring stressors can be more accurately predicted when accounting for the time intervals between the exposures. Moreover, the upscaling of lower-level (physiological and individual) results to the community or ecosystem level, which is sometimes used in the management of ecosystems, should be done with caution since there can be inconsistency in responses across ecological scales.
Aaron Dain MSc, Yakimowski Lab Phenotypic variation of a moderately salt tolerant sunflower (Helianthus annuus) and a halophytic sunflower (Helianthus paradoxus) under extreme environmental salinity Environmental salinity is a global phenomenon that is increasing with anthropogenic change. Salt is toxic to most plants, but less than 1% of plant species are considered highly salt tolerant. Helianthus annuus is considered a moderately salt tolerant glycophyte, although populations occur in the saline Great Salt Lake region of Utah. This raises the question: can populations of glycophytes in saline habitats locally adapt to more extreme salinity? Furthermore, is the range and upper limit of H. annuus within the range associated with its homoploid hybrid descendent, the halophyte H. paradoxus? To investigate variation in the relation between environmental salinity and phenotypic variation, we conducted a common-garden experiment using H. annuus seeds collected from 20 populations of the species’ range with varying concentrations of environmental salinity, and seeds collected from 5 populations of H. paradoxus. Seedlings were treated with control, moderate (field), and high (field x2) salinity treatment solutions mimicking the ionic composition of H. paradoxus habitat. Phenotypic traits related to salt tolerance (above- and below-ground biomass, plant height, and growth rate) of juvenile plants were measured and compared among populations and treatment groups. Quantitative soil salinity data was collected for ten of these populations, and used to investigate the relation between environmental salinity and salt tolerance. In the Great Salt Lake region soil salinity (% sodium) ranged from 1.3 to 37.9 (n = 26 populations); thus, high-saline sites exhibit salinity in the range associated with its halophytic relative H. paradoxus. Under non-saline conditions, H. annuus plants originating from non-saline habitats are larger than those originating from saline habitats. However, under field-like salinity, saline-originating H. annuus plants retain more biomass than non-saline originating plants. H. paradoxus plants are smaller than H. annuus under non-saline conditions but are larger under field-like salinity. This suggests biomass is shaped by environmental salinity. In comparison, growth rate and plant height do not significantly differ between saline- and non-saline H. annuus populations, and those from populations with the highest salinity grow more slowly than those from populations with lower salinity. Additionally, H. paradoxus plants grow more slowly than H. annuus plants. This suggests that plant height and growth rate are not shaped by environmental salinity in the same way, and that growth rate may not be selected for in saline habitats.
Damian Bourne MSc Student, Colautti Lab Morphometric variation in Ixodid ticks at an expanding range edge Ixodid ticks (Acari: Ixodidae) are important vectors of zoonotic disease that have devastating impacts on human health and well-being. Therefore, it is essential that effective monitoring protocols be put into place to map tick abundance and richness within certain areas. Although research into the most important tick species across Eastern, Ontario is abundant, up-to-date studies looking into the morphological features that contribute to observed diversity are lacking. Geometric morphometrics is a powerful tool that allows researchers to compare shape variation between groups. This study utilizes geometric morphometrics to survey important tick species within Eastern Ontario and explore the morphological diversity that defines them. A total of 518 ticks were sampled over a 6-year period representing two medically important species known to harbour harmful pathogens: D. variabilis and I. scapularis. Morphometrics utilizing principal component analyses of these two species found that the chosen common dorsal and ventral landmarks accurately categorized individuals by their respective species and sex. Furthermore, I. scapularis females showed significantly different morphologies across locations possibly representing diverse environmental pressures that need to be considered in management protocols. Supervised machine learning algorithms were also utilized and found that the selected landmarks accurately assigned individuals to their respective groups. Additionally, this analysis identified individuals with abnormal morphologies that may represent novel or cryptic species. Future research should combine both morphometric and genetic approaches to increase the robustness of species identification and provide additional evidence for tick diversity that may lead to better mitigation and management solutions for these critical vectors of zoonotic disease.
Christina Steinecke MSc Student, Friedman Lab Selection and genetic constraints on clonal investment in a perennial plant Many plant species can reproduce both clonally (for example, via stolons or corms) and sexually via flowers and seed. The question, then, is why some plants invest resources into both, and whether phenotypic and genetic correlations exist when investing in traits associated with one mode or the other. The relative importance of the two modes of reproduction likely vary in different ecological conditions, but to what extent can selection drive different investment strategies? A population’s ability to respond to selection on clonal investment might impact its capacity to respond to environmental change. Furthermore, genetic correlations between traits can either facilitate or constrain evolutionary responses depending on the direction and strength of selection. Here, we investigate the capacity for clonal investment to respond to high or low truncation selection in a perennial population of Mimulus guttatus. The aims of our research are to first quantify the magnitude of phenotypic responses to artificial selection on clonal growth, and then to identify traits that respond in concert due to underlying genetic correlations. To address these aims, we first established an outbred population from field collected seed in a greenhouse, and then imposed four generations of divergent, truncation selection on clonal growth for two replicate high lines, two low lines, and a control line. We used quantitative genetics and pedigree analyses to investigate additive genetic variance, heritability, and the response of clonal growth through time. We then investigated genetic correlations among life history traits measured throughout the life cycle to identify whether genetic constraints might constrain evolutionary trajectories. Our results showed that selection elicited the predicted divergent response in clonal growth; however, low-clonal lines respond more strongly to selection compared to high-clonal lines. Decreased clonal growth was also negatively correlated with a suite of traits including overall size, flower number, and flowering time. These findings suggest unequal additive genetic variance in the low-clonal and high-clonal lines, and indicate that populations have greater capacity to reduce clonality in the face of selection, and that increases in clonal investment might be more difficult. This study tests a classic, yet unresolved, evolutionary question and suggests populations harbour sufficient standing genetic variation to respond rapidly to selection but that the underlying genetic architecture and trait covariation could constrain evolutionary trajectories and adaptive divergence
Ruoqi Dou PhD, Monaghan Lab Investigating the role of subgroup IV calcium-dependent protein kinases (CDPKs) across the plant lineage Calcium-dependent protein kinases (CDPKs) are a unique family of integrated Ca2+-sense/response proteins with diverse functions in plants. In model plant Arabidopsis thaliana, there are 34 CDPK genes which can be clustered into four subgroups (I, II, III & IV). There are only 3 members in subgroup IV, with CPK28 being the most highly expressed among them. CPK28 is a major regulator of immune homeostasis and growth in multiple angiosperm plants including tomato, rice, cotton, and Arabidopsis. This project aims to investigate the conserved and/or diverged functions of subgroup IV CDPKs from extant lineages that represent crucial points over the evolutionary history of plants. Our results suggest that the function of subgroup IV CDPKs are well conserved across over 450 M years of evolution. By experimentally assessing whether functions of the subgroup IV CDPKs are conserved in plants with varying life history traits, I will be able to determine if these proteins play core roles in plants immune system, which holds promise for biotechnological applications by generating CDPK alleles that enhance plant microbial pathogens resistance without consequences to yield.
Nell Libera PhD, Smol Lab Lake ecosystem impacts from the fur farming industry in Nova Scotia, Canada Residents and environmental managers in Nova Scotia (NS), Canada, have attributed mink fur farms as a possible source of nutrient pollution that is causing algal blooms in regional lakes. However, water quality monitoring was only initiated in 2008, decades after the advent (ca. 1930s) and expansion (ca. 1970s) of the fur industry in NS. Further, multiple anthropogenic stressors, including climate change, acidification, brownification, and other land-use changes are likely contributing to ecosystem change. We analyzed the sediment archives of regional lakes to document the impacts of multiple stressors, and to better understand the environmental impacts of fur farming in NS. Our analyses included a detailed water chemistry survey, bioindicator analyses (diatoms and Cladocera), stable isotopes, and spectroscopic inferences of whole-lake primary production and organic carbon. Our data clearly implicate fur farms as a source of nutrient pollution. The most severe eutrophication impacts occurred in lakes where farms were closest to the shoreline. Some lakes were more resilient to eutrophication due to high colour and trace metal concentrations. This information can be used to inform management efforts in this region and in other lake ecosystems impacted by multiple stressors.
Lisa Han MSc, Yakimowski Lab Estimating the stability and heritability of resistance fueling copy number variation in glyphosate-resistant Amaranthus palmeri Copy number variation (CNV), especially when present in extrachromosomal fashion, provides unparalleled opportunity for speciation and adaptation. As observed in agricultural weed species, Amaranthus palmeri, CNV of the herbicide glyphosate’s target gene, EPSPS, has resulted in emergence of glyphosate-tolerant and resistant populations across the globe. The amplification of EPSPS copies in forms of extrachromosomal circular DNA (eccDNA) poses unique challenges when assessing the heritability of EPSPS CNV as its origin and the tethering mechanisms are still mostly unknown. I used 30 F0 pairs and 900 F1 individuals from glyphosate-resistant populations to examine the heritability of EPSPS CNV in relation to parental EPSPS CNV. The results display a shifting pattern in progeny CNV with increasing parental mean EPSPS copy number. Over 70% of progeny resulting from parental crosses of low-med CNV displayed an increase in EPSPS CNV in a single generation while the opposite pattern was observed in progeny resulting from high EPSPS CNV mean parental crosses. This result indicates a substantial decline in heritability after a threshold point of 48.8 mean parental EPSPS CNV. The weaker heritability of eccDNA gene copy number variation at high CNV suggests weak evolutionary potential of highly glyphosate resistant CNV individuals and may constrain the evolution of population EPSPS CNV mean.
Regan Cross PhD, Eckert Lab Long-term experimental analysis of ecological and evolutionary processes at a species’ range limit Why do species have stable range limits – and what happens if they break free? Many species’ geographic ranges have historically been stable in space, but they may shift as climate change alters habitats. My thesis first looks at why species have stable range limits; what prevents them from dispersing beyond their ranges and adapting to the new habitat? I briefly review the current state of the field of range limits and provide a novel long-term test of whether a species’ range is limited by its niche. Next, I examine a few things that might happen if species shift their ranges using a beyond-range transplant experiment with the best coastal dune plant, Camissoniopsis cheiranthifolia. First, I ask: are populations from the range center or edge better suited to establish in beyond-range habitat? And second: did populations adapt to beyond-range conditions over ten generations? Finally, I test whether local or genetically mixed populations perform best within the range, to inform conservation efforts to re-establish populations and restore habitats. Come to my talk to learn about the mechanisms stopping species from expanding their ranges, some of the ecological and evolutionary processes going on during range shifts, and which populations are best used for conservation efforts like assisted migration and habitat restoration! (The photo is me with my first flowering transplant in 2018.)
Dr. Anusha Shankar Lab of Ornithology at Cornell University Hot and cold hummingbirds: The ecology, physiology and genes of cold endotherms Information about Dr. Anusha Shankar here
Hummingbirds live fast. They have among the highest metabolic rates of all vertebrates, and must eat constantly to stay alive. I will talk about some of what I have learned about how they manage their energy budgets during the day, and how they allocate time and energy to different activities based on changes in their environment. At night, they save energy by entering the fascinating hibernation-like state of torpor. How do they manage to get so cold (~50°F/10°C) and slow their metabolism down as much as they do, and stay alive? This is what I am currently working on finding out. My work integrates methods and approaches from ecology, physiology and transcriptomics to understand how these tiny endotherms manage to survive in a variety of environmental conditions. Kapillesh Balasubramaniam MSc, Smol Lab Assessing the impacts of emerging anthropogenic stressors on lakes within the Rideau Canal system: A paleolimnological re-assessment Earlier diatom-based paleolimnological studies were conducted on a suite of diverse lakes (i.e., Lower Rideau L., Big Rideau L., Otter L., Upper Rideau L., Indian L., L. Opinicon) within the Rideau Canal system ~25-30 years ago and provided important information regarding the ecological impacts of canal construction (1827-1832). Following these early paleolimnological studies, the same lakes are now facing the potential impacts of newly emerging environmental stressors, particularly accelerated climate warming. Here, I revisited the same suite of lakes by conducting a series of paleolimnological analyses, focusing on recent changes in diatom assemblage composition, to assess the potential ecological impacts of newly emerging environmental stressors. Despite the substantial environmental impacts associated with canal construction, the highest rate of diatom compositional change across the suite of lakes only took place in the past ~25-30 years, which coincided mainly with an increase in planktonic diatom taxa. This recent shift in assemblage composition could not be explained by nutrient enrichment, as total phosphorus (TP) concentrations, measured since the 1980s, have significantly declined across the study lakes. The continued increase of planktonic taxa across the study lakes suggests the impact invasive zebra (ca. 1990) mussels in the Rideau Canal region appeared to have only been modest. Rather, these recent changes in diatom assemblage composition were strongly related to increasing regional air temperatures, as the conditions associated with warmer temperatures (i.e., longer, and stronger periods of thermal stratification, alterations to water-column mixing regimes, reduced ice cover duration) provide favorable conditions for extensive planktonic diatom growth. Lakes within the Rideau Canal system are changing rapidly in ecologically significant ways and will likely continue to do so as temperatures continue to rise.
Zoe Lai MSc Candidate, Regan Lab Exploring the cellular basis of environmental stress and plant development: Bioremediation potential of Senna and gene function in Populus As of 2021, the earth holds about 3.04 trillion trees. Plants account for 80% of the world’s total biomass. Trees, and plants in general, inherently play very important roles in our daily lives. My thesis examines the potential of a plant, Senna occidentalis, to phytoremediate arsenic- and cadmium-contaminated soils. Additionally, my thesis advances our understanding of leaf and stem development though the analysis of a mutant line of Populus tremula x Populus alba called shriveled leaf.
A new Genotyping-in-thousands by sequencing (GT-seq) panel for Canadian polar bears: population structure and sex-biased dispersal applications In the context of a rapidly warming arctic, effective management planning for polar bear (Ursus maritimus) subpopulations is limited by infrequent surveys and data deficits that preclude robust estimates of population trends. Genetic monitoring using non-invasively collected scat samples is an alternative that can mitigate some of the challenges associated with traditional monitoring (e.g. expensive, invasiveness) and provide opportunities for collaboration between Northern communities and Western scientists. Scat samples can provide numerous insights into individual- and population-level health, such as information on contaminants levels and diet. However, understanding this information relies on being able to reliably genetically identify individuals. To identify individual polar bears from non-invasive scat samples, we have developed and validated a new genomics method called Genotyping-in-Thousands by sequencing (GT-seq). We demonstrate that our new method can successfully genotype (>50% loci present) 62.9% and provide genetic identity for 80% of non-invasively collected fecal samples determined to contain polar bear DNA (i.e. from cells shed from the gut lining). Using an optimized, cost-efficient GT-seq panel of 324 Single Nucleotide Polymorphisms (SNPs), we are also able to comprehensively characterize polar bear population structure at similar levels to past studies that have used more invasive methods. Major contributors to contemporary population structure include dispersal (including sex-biased) and gene flow, yet few studies have been able to characterize sex-biased dispersal in Ursids. In my second data chapter, we aim to confirm sex-biased dispersal in polar bears using our new GT-seq assay and investigate density-dependent impacts on sex-biased dispersal through comparison of sex-biased dispersal patterns in subpopulations varying in bear density. This GT-seq test and the information it enables will provide the foundation of a non-invasive toolkit for polar bear monitoring and contribute to community-led programs - data from which can inform co-existence with polar bears, conservation, and policy decisions.
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