Charlotte Ngo MSc Student, Yakimowski Lab Investigating the evolutionary origin(s) of EPSPS copy number variation in Amaranthus palmeri Agricultural use of herbicides has led to the repeated evolution of herbicide resistance in numerous agricultural weeds, posing significant challenges for food production and agriculture sustainability worldwide. The development of herbicide resistance over contemporary timescales has provided us with a unique opportunity to investigate the origins of this adaptation - has herbicide resistance arisen from de novo mutations or from standing genetic variation? Amaranthus palmeri (A. palmeri), a major agricultural weed originating from southwestern United States and Mexico, has been expanding northward, recently was detected in Canada. Many A. palmeri populations exhibit resistance to glyphosate, a common herbicide, primarily through EPSPS gene copy number variation. Yet it remains unclear whether such variation predated the commercialization of glyphosate in 1974. This project aims to answer an important evolutionary question concerning glyphosate resistance in A. palmeri - did the copy number variation of EPSPS exist as standing genetic variation, or did it evolve rapidly in response to glyphosate selection pressure? To investigate the origins of glyphosate resistance, I collected historic samples from the United States and Mexico from herbaria across the United States, spanning three different time periods (pre-1974, between 1974 and 1995, and post-1995), representing a broad geographic distribution. I extracted leaf tissue samples using a modified CTAB protocol, followed by quantification of EPSPS gene copy number using digital drop PCR (ddPCR). The project unveiled intriguing evolutionary patterns that can be explored further through genomic analyses of whole genomes. Given the expanding range of A. palmeri across North America, understanding the evolutionary mechanisms of herbicide resistance is imperative for unraveling the spread of not only A. palmeri but also other weed species. Moreover, the utilization of historical samples in this research serves as an exemplar for studying rapid adaptation to human-induced environmental changes.
Mia Akbar MSc Student, Colautti Lab Examining phenological trade-offs under biotic and abiotic selection in Lythrum salicaria Studies measuring phenotypic selection on day of first flower or “flowering time” in natural populations commonly observe directional selection for early flowering. Paradoxically, phenological responses to climate change are highly variable and do not demonstrate a unilateral shift to earlier flowering time. The timing of flowering is only one part of the overall “flowering schedule” and may trade-off with other adaptive aspects such as duration and peak flowering time, offering one potential resolution to this apparent contradiction. Furthermore, variation in growing conditions across years may maintain variation in the flowering time phenotype and offer an additional explanation for the lack of evolution in response to selection for earlier flowering. Focusing on the North American invasive plant Lythrum salicaria, I use common garden experiments to investigate whether flowering time correlates with other characteristics of the flowering schedule, how variation in annual growing conditions and insect herbivory have the potential to alter the strength of selection on flowering time and whether these relationships differ by latitude of origin. I discovered that detailed metrics of the flowering schedule vary along a latitudinal gradient and that responses to insect herbivory were highly variable across years of the experiment, demonstrating two potential mechanisms that contribute to the “paradox of evolutionary stasis” in the flowering time trait.
Dr. Steven Brady Professor, Southern Connecticut State University Boulevard of broken frogs: The perils of polluted ponds and life beside the road Human impacts on wild populations are numerous and extensive, degrading habitats and causing population declines across taxa. Residing perhaps in the shadows of climate change, roads and their many contaminants remain a widespread but often overlooked threat to biota, fragmenting landscapes and delivering suites of pollutants to adjacent habitats. In the snowbelt region of North America, deicing salts – used to melt snow and ice on roads and other impervious surfaces – is causing the salinization of many freshwater habitats. There, these added salts join a bevy of other runoff pollutants that threaten environmental health. Simultaneously, roads and their pollutants can act as agents of natural selection. Increasingly, it is becoming clear that road salt and other pollutants are driving population divergence across contemporary timescales. However, the capacity for local populations to adapt to these stressors remains unclear. Here, we consider the effects of road adjacency and road salt exposure on a pair of amphibian species, the spotted salamander (Ambystoma maculatum) and the wood frog (Rana sylvatica), which are found throughout much of North America. At the population level, these two species of spring-breeding amphibians exhibit contrasting responses to polluted roadside ponds. Spotted salamanders show evidence for local adaptation to roadside habitats. Wood frogs present a complex suite of maladaptive traits expressed during aquatic life stages but adaptive traits in terrestrial life stages. For instance, embryonic survival is relatively low for roadside populations yet adults from these populations have increased fecundity and locomotion. Further, recent evidence suggests that temperature has an exacerbating effect on salt toxicity, especially for roadside populations, and that a pair of genes might underlie the differential sensitivity found between populations. Together, this work indicates that exposure to pollution can have complex transgenerational effects, both adaptive and maladaptive, and that life history tradeoffs and potentially negative pleiotropy might mediate these outcomes.
Alex Row MSc Student, Tufts Lab Spatial Ecology of Smallmouth Bass (Micropterus dolomieu) in the St. Lawrence River Smallmouth Bass (Micropterus dolomieu) are an important top predator in many freshwater ecosystems in North America. They are also one of the most popular species for recreational anglers. Although there is a lot of research describing the ecology of Smallmouth Bass, most studies have been carried out on populations in relatively small inland lakes and rivers. At present, much less is known about the ecology of this species in aquatic ecosystems at the scale of the Great Lakes and St Lawrence River, which have very different physical attributes and food webs. In recent years, Smallmouth Bass populations in the Great Lakes and St Lawrence River have also been experiencing intense pressure from competitive fishing events (bass tournaments), as well as invasive nest predators (Round Gobies). Since management and conservation efforts are most effective when there is a strong foundation of biological information, there is an urgent need for more information about the ecology of Smallmouth Bass in these unique aquatic ecosytems. On this background, this study uses acoustic telemetry to describe the spatial ecology of Smallmouth Bass in an area where Lake Ontario flows into the St Lawrence River. The annual movements and home ranges reported in this study may be the largest described for this species. The results of this thesis also provide important considerations for assessing, managing, and conserving this population of Smallmouth Bass.
Jamie Would MSc Student, Smol Lab Tracking long-term changes in climate and salinity using cladoceran and other markers from saline lakes in Yukon In the Canadian sub-Arctic, inland saline (athalassic) lakes are rare, as they are typically only found in temperate or equatorial regions with arid climates. These lakes, characterized by unusually high salinities and shallow, closed-basin morphometries, are especially sensitive to climate change as salinity increases markedly with increased evaporation. However, due to their remote location, little is known about the ecology of northern athalassic lake systems and their responses to climate warming. Here, we used paleolimnological approaches to reconstruct multi-trophic level responses to climate warming using biological, chemical and physical information preserved in dated lake sediments. Siliceous algae indicated increasing salinity since the early 1900s, closely tied to rising air temperatures. Cladoceran (commonly known as water fleas) microfossils, representing intermediate-trophic levels, tracked declines in species diversity with increasing salinity. Interestingly, a major lake drawdown (for road maintenance) between 1948 and the mid-1970s did not affect cladoceran assemblage composition (but did result in a change in diatom composition), allowing us to independently separate the effects of lake salinization and water level changes. This research sheds light on the impact of climate-induced salinization on northern lake ecosystems and also demonstrates the value of cladoceran microfossils as paleolimnological indicators of salinity.
Dr. Celia Symons Professor, University of California - Irving Species interactions in a changing world As the global climate becomes increasingly extreme and variable, society relies on stable ecosystem functioning for irreplaceable resources and services. To understand what nature will look like in a warmer and more variable future, we must be able to forecast how the climate shapes the strength of negative (predation, competition) and positive (facilitation) species interactions. We have good predictions of how climate will change through time, but we have less understanding of how climate change will cause perturbations across ecological networks via changes in species interactions. Species interactions are more fragile than species themselves because they don’t just require the species to be there, they depend on how species behave, their nutritional requirements, and their phenologies. My research group runs a long-term study of lakes in California’s Sierra Nevada Mountains to address the sensitivity of species interactions to spatial and temporal climate variation. Since 2013, we have conducted annual surveys of ecosystem structure, including biomass and community composition of pelagic producers and primary consumers, benthic invertebrates and chemistry in 21 lakes varying in elevation between 2000 and 3200m. Our 11-year survey includes both the wettest and second driest years of the past century, an indication that extreme conditions are occurring more frequently. Our study indicates that climate can magnify or dampen the influence of both bottom-up and top-down perturbations from pollution and non-native species introductions on aquatic ecosystem structure and function.
Austin Macklem MSc Student, Aristizabal Lab Uncovering the functional consequences of cancer associated histone H2B mutations In eukaryotes DNA is wrapped into chromatin, a nucleoprotein structure that controls DNA-templated processes like DNA replication, transcription and DNA repair. Nucleosomes are the basic unit of chromatin and consist of 146 base pairs of DNA wrapped around two copies of histone H2A, H2B, H3, H4. The increased availability of cancer genomics datasets has revealed a large repertoire of mutations on histone genes and shown that these occur frequently in cancer patients. Although, the significance of the large histone gene mutational landscape remains understudied, some of these mutations (H3K27M, H3K36M and H3G34R) have been shown to drive oncogenesis and are now used as biomarkers of specific tumor types. My project aims to advance our understanding of the functional consequences of cancer-associated histone mutations using Saccharomyces cerevisiae as a model system. To this end, we have mined The Cancer Genome Atlas (TCGA) and identified cancer-associated mutations on histone H2B, a histone that remains poorly characterized with regards to cancer-associated histone mutations. Focusing on mutations that fall on residues conserved between yeast and humans, I have generated a panel of strains carrying only mutant or mutant and wild type version of H2B. These strains will be examined for effects on growth, chromatin structure and function in vivo.
Graydon Gillies MSc Student, Eckert Lab Metapopulation structure and dynamics may maintain a species’ range edge Species range limits may be enforced by various evolutionary and ecological processes.
It is thought that many range limits are imposed by low fitness beyond a species’ range or the inability to disperse to suitable habitat beyond the range. However, transplant experiments and geographic surveys often find that these hypotheses fail to adequately explain species ranges, requiring the use of a more comprehensive framework. The metapopulation-hypothesis outlines how changes in habitat patch colonization rates, extinction rates, and habitat availability may cause metapopulation collapse and the generation of an abrupt range limit. Using coastal dune plant Camissoniopsis cheiranthifolia, I evaluated the metapopulation-hypothesis by conducting a multi-year survey across the species’ northern range. I found that patch structure, including the frequency, size, isolation, and quality of patches, changes towards the northern range edge. Furthermore, I found that colonization rates and habitat availability decline towards the range edge, while extinction rates increase non-significantly. With this survey, I provide the first empirical estimates of metapopulation parameters towards a species’ range edge and demonstrate that metapopulation dynamics may contribute to the maintenance of species’ range limits. Dr. Anje Geitmann Professor, McGill University Multi-scale control of structural functionality in plants Plant tissues display structural organization that is intimately related with the specific tissue's functionality. A unique functionality in plants is organ motion. Although plants are not exactly known to move much, many species actuallly have the ability to orient or fold their leaves in order to optimize photosynthesis or ward off herbivores. Leaf actuation is executed by pulvini—joint-like motor organs that operate like hydraulically powered hinges. In the mimosa leaf, pulvini are incorporated at multiple locations in the compound leaf allowing it to rapidly and efficiently fold upon touch. To understand the mechanical principles underlying the execution of the rapid motion, we investigated pulvinus structure at tissue and cell scales. We found that circumferential hoop reinforcements present at various length scales optimize the translation of hydraulic changes into motion. Specialized cell wall structures and epidermis morphologies direct tissue swelling into directed organ shape changes. These findings provide insight into the role of cell wall structure in plant motor strategies, underscore the hierarchical, emergent nature of biomechanical systems, and highlight design principles that can inform the development of biologically inspired soft actuators.
Faiqa Amin MSc Student, Monaghan Lab Phosphorylation of the Arabidopsis thaliana E3 ubiquitin ligase ATL6 by the Ca2+-dependent protein kinase CPK4 Post-translational modifications (PTMs) such as reversible phosphorylation integrate signalling and gene expression with cellular metabolic networks and represent some of the earliest responses of plant cells to (a)biotic stress that rapidly controls the functions of many proteins. Ca2+ -dependent protein kinases (CPKs) transduce Ca2+ signals via the catalytic activity of their kinase domain to phosphorylate specific residues of target proteins. Our research discovered that the Arabidopsis CPK isozyme CPK4 phosphorylates the E3 ubiquitin ligase ARABIDOPSIS TÓXICOS EN LEVADURA 6 (ATL6) at multiple residues including Ser278. ATL6 is a positive regulator of immune signalling as it polyubiquitinates CPK28, leading to its proteasomal degradation and subsequent activation of pathogen defense responses. Rabbit polyclonal antibodies were raised against purified, heterologously expressed ATL6 (anti-ATL6), whereas anti-(phosphoSer278-specific) antiserum (anti-pSer278) was raised against a synthetic ATL6 phosphopeptide. These antibodies will augment various biochemical and genetic tools that are being integrated to investigate the functional relationship of CPK4 and ATL6 during Arabidopsis stress signaling. For example, immunoblot time-course assays using anti-pSer278 have established the ATP- & Ca2+ -dependent phosphorylation of ATL6 at Ser278 by CPK4. In vitro E3 ubiquitin ligase assays are being developed to test the hypothesis that CPK4-mediated phosphorylation enhances ATL6’s ability to polyubiquitinate CPK28. Overall, This work will provide an insightful understanding of the role of AtATL6 in biotic or (a)biotic stress responses.
Jules Petrenko MSc Student, Bonier Lab Do urban environments ameliorate range-limiting challenges for urban-tolerant species? Species’ distributions are constrained by challenges which usually increase in severity approaching the range edge. While urban environments might generally be expected to exacerbate such range-limiting challenges, some urban-tolerant species take advantage of the opportunities provided by cities, and persist in urban areas. For these urban-tolerant species, cities might ameliorate range-limiting challenges; however, no direct tests of this hypothesis exist. To test how urban environments affect urban-tolerant species’ distributions, I will compare the relative abundance of North American, urban-tolerant bird species across their distributions in both urban and nonurban habitats. I will use a large community science dataset (eBird Status & Trends Products) to quantify the relative abundance of each species in approaching climatic and geographic range edges of its distribution, in urban compared to nonurban habitats. If cities do ameliorate range-limiting challenges, then species abundance will decline less approaching the range edge in urban habitat, relative to nonurban habitat. Alternatively, if cities do not affect or exacerbate range-limiting challenges, then species abundance will decline at a similar rate or even more steeply approaching the range edge in urban habitat, relative to nonurban habitat. By examining whether relative abundance differs in urban compared to nonurban habitats at the range edge, I will identify whether urban environments provide enough advantages for urban-tolerant species to support persistence among range-limiting challenges. This insight into the effects of urban environments on range limits can increase our understanding of how anthropogenic environments influence species’ distributions.
Harshavardhan Thyagarajan PhD Candidate, Chippindale Lab Intralocus sexual conflict explored through male-limited selection in Drosophila melanogaster Intralocus sexual conflict (IaSC) arises from the opposing forces of sex-specific selection pressures and positive genetic trait correlations between sexes, impacting the evolutionary genetics of sexually reproducing populations. This conflict is implicated in maintaining genetic variance for fitness, shaping trait dimorphism and influencing sex-biased gene expression. However, direct tests of its contributions remain limited and challenging. Here, I present findings from a sex-limited selection experiment using Drosophila melanogaster haplotypes, artificially ‘resolving’ IaSC under male-limited (ML) selection without opposing female fitness selection. I estimate heritable variance for fitness in selected and matched control (MC) lines. In alignment with theory, I observed increased estimates of male fitness and a sharp decline in heritable variance for the same in selected lines. Surprisingly however, I found no significant improvement in selected male fitness compared to controls under generic test conditions, challenging both the findings about genetic variance, and assumptions about ubiquity of IaSC in D melanogaster lab populations. Female fitness of selected haplotypes declined as predicted. Upon further investigation, this system reveals substantial impact of selection from unforeseen sources, likely obscuring our ability to identify adaptive responses to a release from IaSC. I demonstrate evidence of local adaptation to a novel environment of sexual selection and compensatory adaptations in a new genetic background, in the form of nuclear recovery from mother’s curse and adaptations to unique Y chromosomes. These results highlight the complexity of selection experiment design, raising concerns about the generality and accuracy of previous findings.
Dr. Paul Grogan Professor, Queen's University What can Biology tell us about our future? Science is the human-constructed process aimed at understanding phenomena in nature, and hence developing sufficient knowledge to be able to make rational, evidence-based predictions. The human species currently finds itself in a severely threatening environmental and social sustainability crisis. What can the science of Biology tell us about our future?
This seminar will focus on applying core foundational biological principles to understanding our civilisation’s current position and future trajectory, and on suggesting appropriate responses that are coupled with an over-arching strategy to help us cope with the profound realities of our fundamental existential predicament. In short, it will attempt to put the science of biology in its larger context to address the following questions: i) Why are we in the current sustainability crisis, and what does the ultimate underlying answer mean for our future?; and ii) How can we best respond to, and cope with, the fundamental existential realisations that arise from acknowledging that answer? Addressing these questions has been a long personal journey for me, and I am looking forward to presenting my latest attempts at answers to the Department – (i.e. to my community of friends and colleagues that have deep and wide expertise in Biology). My central goal in leading this seminar is to get your feedback, and I look forward to a lively and insightful discussion. Nick Smith MSc Student, diCenzo Lab Characterizing bifunctional sugar-processing enzymes from thermophilic bacteria Nucleotide sugars are the donor substrates for glycosyltransferase enzymes, which are widely studied throughout biochemistry, medicine, and glycobiology. However, nucleotide sugars are prohibitively expensive, prompting the development of in-lab chemoenzymatic synthesis protocols to circumvent this cost. One such example is the usage of the bifunctional Fucokinase/GDP-fucose pyrophosphorylase enzyme from Bacteroides fragilis (BfFKP) to catalyze the production of the costly compound GDP-Fucose. The BfFKP enzyme contains a C-terminal Fucokinase domain and an N-terminal GDP-Fucose pyrophosphorylase domain that catalyze sequential steps in the GDP-Fucose synthesis pathway. As a result, this bifunctional protein is used in “one-pot” syntheses, resulting in appreciable amounts of GDP-Fucose for a fraction of the commercial cost. Since the discovery of the BfFKP enzyme, studies have mainly focused on using this enzyme rather than sourcing novel FKP proteins, despite an enormous sequence space of putative FKP orthologs. To address this lack of knowledge, a sequence similarity network (SSN) was used to identify putative bifunctional FKP enzymes. To test the hypothesis that FKP enzymes from thermophilic organisms would exhibit altered properties and/or activities, an uncharacterized FKP sequence from the thermophile Thermophagus xiamenesis (i.e., TxFKP) was selected. I recombinantly overexpressed both the TxFKP and BfFKP enzymes in Escherichia coli and purified the proteins using Immobilized Metal Ion Affinity Chromatography. To compare thermostability between the two enzymes, I used Thermal Shift Assays to approximate their melting temperatures (Tm). Unexpectedly, both proteins demonstrated biphasic melt curves, suggesting that the enzymatic domains are modular enough to unfold at separate temperatures in vitro. In addition, I performed kinetic analyses of the Fucokinase domains of both enzymes, revealing key differences and similarities between the two. These results will shed light on the variance of properties within a fascinating group of biocatalytic tools.
Dr. Tanja Slotte Professor, Stockholm University Genomic analyses of distyly in Linum reveal convergent evolution at the molecular level Supergenes govern multi-trait balanced polymorphisms in a wide range of systems, yet our understanding of their origins and evolution remains incomplete. The reciprocal placement of stigmas and anthers in pin and thrum floral morphs of distylous species constitutes an iconic example of a balanced polymorphism governed by a supergene, the distyly S-locus. Recent studies have shown that the Primula and Turnera distyly supergenes are both hemizygous in thrums, but it remains unknown if hemizygosity is pervasive among distyly S-loci. As hemizygosity has major consequences for supergene evolution and loss, clarifying whether this genetic architecture is shared among distylous species is critical. We aimed to characterize the genetic architecture and evolution of the distyly supergene in Linum by generating a chromosome-level genome assembly of Linum tenue, followed by the identification of the S-locus using population genomic data. We show that hemizygosity and thrum-specific expression of S-linked genes, including a pistil-expressed candidate gene for style length, are major features of the Linum S-locus. Structural variation is likely instrumental for recombination suppression, and although the non-recombining dominant haplotype has accumulated transposable elements, S-linked genes are not under relaxed purifying selection. Genomic analyses of additional distylous Linum species identify shared presence-absence variation at the S-locus, indicating that hemizygosity in thrums is a general feature of Linum S-loci. Finally, we investigate the genetic causes and genomic consequences of breakdown of distyly, resulting in homostylous species with elevated levels of self-fertilization. Our findings reveal remarkable convergence in the genetic architecture and evolution of independently derived distyly supergenes, and shed new light on the evolution and loss of an iconic floral polymorphism.
MSc Student, Aristizabal Lab Characterizing the effects of human cancer-associated histone H2AZ mutations using S. cerevisiae Nucleosomes, the building blocks of chromatin, are composed of 146 base pairs of DNA wrapped around an octamer of histone proteins (typically two copies of H2A, H2B, H3, and H4). Chromatin, the packing structure by which DNA is condensed into chromosomes, is dynamic and can be altered in several ways, including: (1) the sliding, eviction, and deposition of nucleosomes, (2) the addition of posttranslational modifications (PTMs) to histone proteins and (3) the incorporation of histone variants in place of canonical counterparts. A wide range of mutations on histone-encoding genes have been identified among publicly available whole-exome sequencing data from human cancer patients. Some of these mutations have been demonstrated to disrupt the histone octamer, alter higher order chromatin structure, and affect histone tail dynamics, DNA accessibility and transcription factor binding. Although most of these mutations remain to be studied, some, termed “oncohistones,” have been shown to drive cancer development and are correlated with poor disease prognosis. My project seeks to advance our understanding of the effect(s) of these cancer-associated missense mutations to the histone H2A variant, H2A.Z, using budding yeast (Saccharomyces cerevisiae) as a model system. H2A.Z is implicated in a wide range of molecular processes, including transcriptional regulation, DNA replication, cell cycle progression, and DNA damage repair. It is also highly conserved from yeast to humans. Focusing on cancer-associated mutations that map to identical residues between yeast and humans, we have generated a library of 21 mutations which will be screened for effects on cellular growth, chromatin dynamics, and gene expression. This work will improve our understanding of the various mechanisms by which cancer-associated mutations affect genome function, providing some clues as to how they may contribute to cancer development and progression.
MSc Student, Snedden Lab Arabidopsis CML13 and CML14 Interact with Myosins and Function as Plant-Specific Myosin Light Chains Calcium ions (Ca2+) are widely present as secondary messengers in eukaryotes. Ca2+-signals are interpreted by Ca2+-binding proteins called sensors, which then regulate various responses. Apart from the highly conserved calmodulin (CaM), plants possess a distinct family of CaM-like proteins (CMLs) that function as Ca2+-sensors. CMLs primarily consist of Ca2+-binding EF-hands and lack any other functional domains. They are believed to act as sensor-relays by undergoing conformational changes induced by Ca2+ and interacting with target proteins. Among the 50 CMLs found in Arabidopsis, AtCML13/14 are particularly intriguing due to their unique biochemical properties and high expression levels in vivo. To investigate the function of CML13/14, we screened a yeast two-hybrid library to identify potential interacting proteins. Our screen led to the discovery of three unrelated families of putative targets: IQ67 domain proteins (IQDs; microtubule scaffolds), CAMTAs (transcription factors), and myosins (motor proteins). These proteins possess a structural characteristic known as tandem IQ-motifs, which are a special type of CaM-binding domain. Through in vitro and in vivo protein-interaction assays, we found evidence suggesting that CML13, CML14, and CaM are the primary interactors of these targets via their IQ domains within the CML family. Focusing on myosins as representative targets of CML13/14, we utilized confocal microscopy, in vitro kinetic assays, and in vitro binding tests to demonstrate that these CMLs act as novel myosin light chains. To gain further insights into their functions in vivo, we employed an inducible RNAi system to specifically silence either CML13 or CML14 in Arabidopsis. The resulting phenotypes were pleiotropic, indicating that these CMLs play crucial roles in development by regulating cytoskeletal function through their interactions with myosins and IQDs. In summary, our data suggests that CML13/14 are important regulators in various biological processes. They modulate cytoskeletal activity via their association with myosins and IQDs, while potentially influencing gene expression through interactions with CAMTAs.
Associate Dean, Serving and Engaging Society Assistant Professor, Departments of Community Health and Epidemiology and Continuing Professional Development and Medical Education Research Scholar, Health Law Institute Dalhousie University Faculty of Medicine Rethinking EDIA in 2024 By the end of this session participants will:
PhD Student, Regan Lab Surveying the Hormonome of Hazelnut Flower Dormancy Hazelnut is an emerging crop in Ontario but elite, European cultivars must adapt to Ontario winters to support local demand. Hazelnut is a winter flowering tree, meaning flowers begin their development in the summer, go dormant over the winter, and bloom in the spring. Brief, early, warm spells are typical of Ontario winters and can signal hazelnut’s male flowers (catkins) to bloom prematurely. Premature bloom makes catkins especially vulnerable to incoming cold weather, damaging pollen and reducing nut yield. To help establish hazelnut as a reliable crop in Ontario, premature catkin bloom must be prevented. Plant hormones are known to regulate flower dormancy and hormones have been manipulated to delay bloom in select crops. This study has surveyed the endogenous levels of canonical plant hormones and their metabolites (the hormonome) of catkins from early, mid, and late-season blooming hazelnut cultivars across a full season of dormancy. This hormonome is the first of its kind within deciduous woody perennials and provides a valuable resource for those studying flower dormancy in fruit crops. Preliminary analysis shows increased ethylene precursor levels in the early blooming cultivar, revealing a potential target pathway for the manipulation of catkin bloom.
Associate Department Head and Associate Professor; Director of Olga Lakela Herbarium, University of Minnesota Duluth Evaluating a drought-driven model for the evolution of obligate asexual reproduction Obligate apomixis -- asexual reproduction by seed, spore, or egg -- has evolved repeatedly across the tree of life, in diverse organisms ranging from animals (such as reptiles, insects, and fishes) to angiosperms and other plants. Despite its many origins, and the intriguing ecological and evolutionary parallels among them, little is known regarding the causes and long-term consequences of this heritable reproductive syndrome. Some studies suggest that drought, or periodic water limitation, could be key to driving the repeated evolution of obligate apomixis. To evaluate the drought hypothesis, my lab is uniting genomic, spatial, environmental, and life history data (across multiple evolutionary and ecological scales), leveraging ferns as a model system. Current estimates indicate that 10–30% of ferns exhibit obligate apomixis, which has evolved repeatedly in xeric and monsoonal environments around the world. Dry environments impose major constraints on plant life histories and the fern life cycle is especially vulnerable. This study is focused primarily on North American desert ferns and integrates reproductive traits (karyotype, gametophyte development, and spore size/number), climate and microhabitat, and phylogenomic data to specifically ask: Does environmental niche predict obligate apomixis or its constituent traits in desert ferns of North America? This work aims to also bridge generational gaps in technical expertise among next-generation researchers for a variety of cutting-edge and classical approaches, thereby stimulating interdisciplinary student-driven research that emphasizes the value and relevance of museum specimens for addressing fundamental biological questions.
Julia Paton, MSc Candidate, Smol Lab Long-term changes in lake ecosystems linked to smelter emissions on the Atikameksheng Anishnawbek First Nations Reserve Mining operations in Sudbury, Ontario, may have caused acidification, metal contamination, and other disturbances on lakes on the Atikameksheng Anishinabek First Nation (AAFN) Reserve. Despite the societal importance of the Reserve’s many lakes, little direct long-term limnological data are available. Here we use paleolimnology and a multi-proxy approach to reconstruct the potential long-term effects of mining operations on water quality and aquatic biota.
Whitefish Lake is a relatively shallow lake that is situated adjacent to the Sacred Lands of the AAFN community and located approximately 15 km southwest of the Vale Copper Cliff Complex. A sediment core was retrieved in September 2022, radioactively dated, and analyzed for geochemistry. Sedimentary geochemical data reconstructions show increased metal inputs linked to mining operations, with arsenic and copper reaching probable effects levels during peak mining emissions, circa 1960s. Further, the sediment chlorophyll a concentration profile records changes similar to mining-impacted lakes of the Sudbury region. Meanwhile, diatom assemblages show only subtle changes in response to mining, indicating that there was no biological evidence of acidification. Round Lake is a relatively deep lake, located approximately 20 km southwest of the Vale Copper Cliff Complex and less than 5 km west of the abandoned Long Lake Gold Mine, which contains over 163,000 m3 of mining tailings. A sediment core was retrieved in September 2022, radioactively dated, and analyzed for geochemistry. Geochemical reconstructions show increased metal inputs linked to mining operations, with arsenic, cadmium, copper, lead, and zinc reaching probable effects levels during peak mining emissions, circa 1960s. Interestingly, and in contrast to Whitefish Lake, Round Lake’s sedimentary chlorophyll a concentration profile showed no change with the onset of mining. The largest shift in biological data shows a striking change in diatom assemblages post-mining; however, these changes were not linked to acidification. This research offers a unique opportunity to collaborate with Indigenous communities and apply western scientific approaches to provide data critical to proper lake management and ultimately protect the societal value of aquatic ecosystems within the Atikameksheng Anishinabek First Nation community. Evan Jones, MSc Candidate, Smol Lab Tracking the long-term limnological impacts of silver mining near Keno City on the traditional territory of the First Nation of Na-Cho Nyäk Dun (Yukon, subarctic Canada) Mining in Northern Canada has caused many major environmental problems; however, historical data are often non-existent. Here, a multi-proxy (metals, bioindicators, pigments) paleolimnological approach is used to reconstruct the historical impacts of mining activity near Keno City, on the traditional land of the First Nation of Na-Cho Nyäk Dun in central Yukon (Canada). Silver was discovered in the Keno region in the early 1900s and intensive mining has taken place ever since.
Christal Lake, a shallow water body, lies near many historical and current mines, and was once the site of a processing mill. A sediment core was retrieved from Christal Lake in September 2022. Geochemical data from the dated sediment core were used to reconstruct metal inputs linked to the mining activity. The largest shift in biological indicators was a striking decline in sedimentary chlorophyll-a concentrations, indicating declining algal populations. Meanwhile, subfossil diatom assemblages only changed subtly in response to mining. There was no biological evidence of acidification, likely due to the neutralizing effect of the carbonate-rich catchment. The Hanson lakes are situated ~10 km from Keno City and are outside the Christal Lake watershed. These lakes are being studied to determine the potential extent of aerial deposition of mining contaminants. A sediment core was retrieved from a basin in the Hanson lakes system in October 2023. Preliminary results indicate that, despite proximity to mines, it is climate that is the major driver of ecological change in this system. Collectively, the data from these two sites help document the long-term impacts of silver mining in this subarctic environment. Dr. Patricia Gillis, Research Scientist, Environment and Climate Change Canada Are Clams Actually Happy? Using Freshwater Mussel Ecotoxicology to Determine What Threatens an Imperiled Group Native freshwater mussels (Unionidae) are an ecologically important group, although their complex lifecycle leaves them vulnerable to a range of hazards. Over 70% of North American mussel species are either endangered, threatened, or in decline and poor water quality is considered to be one of the key contributors to their global decline. Canada’s Recovery Strategies for freshwater mussel Species at Risk recognize that poor water quality can affect conservation efforts and pose a risk to recovery. However, the identification and remediation of specific threats presents a challenge when extrapolating from single contaminant lab-based bioassays to the health of native mussel populations, especially in areas with complex mixtures of anthropogenic inputs. With the goal of broadening our understanding of which contaminants pose a risk to mussels, laboratory studies with a range of chemicals have been undertaken in parallel with wild mussel health and population assessments in anthropogenically-impacted habitats. This seminar will illustrate the joys and challenges of working with this complex canary by providing examples of studies that combine lab and field investigations. The first example is centered on the heightened sensitivity of early life stage mussels to salt and the threat that road salt-laden winter road runoff poses to mussels. The second example demonstrates how urban influences, including municipal wastewater effluent negatively impact freshwater mussels across multiple levels of biological organization. A final example will touch on the ‘Clam Project’, an Indigenous Community led investigation of freshwater mussels in Alberta’s Oil Sands Region.
Yael Lewis, MSc Candidate, Orihel Lab The effects of microplastics on zooplankton and emerging insect communities in a littoral limnocorral experiment Although microplastics research has rapidly accelerated in the last few years, our understanding of their effects on freshwater invertebrates, particularly under environmentally relevant conditions, remains limited. Using in-situ limnocorrals at the International Institute for Sustainable Development – Experimental Lakes Area (IISD-ELA), we investigated the effects of a microplastic mixture on zooplankton and emerging insect communities. We installed 12 open-bottom limnocorrals in the littoral zone of a boreal lake in June of 2022 and added an environmentally relevant range of microplastic concentrations in a regression-based design. Our microplastic mixture consisted of distinctively coloured polystyrene, polyethylene, and polyethylene terephthalate fragments in equal parts by count, manufactured with common plastic additives. I sampled the zooplankton and emerging insect communities pre-addition and every week thereafter for the 8-week duration of the experiment. To evaluate possible longer-term effects, I sampled the emerging insect community again in May of 2023 over the partially enclosed bases of the limnocorrals. I assessed the relationship between nominal microplastic concentration and the abundance and community composition of zooplankton and insects. Microplastic concentration was negatively related to total zooplankton abundance at weeks 1 and 5 post-addition and drove changes in community composition at week one. Evidence for microplastic effects on the emerging insect community was more limited – microplastic concentration was negatively related to insect emergence only at week 2, and the total seasonal emergence exhibited only a weak relationship with microplastic concentration. There were no effects of microplastic on insect community composition. I anticipate my results will inform policy regarding ecological risk thresholds for microplastics in freshwater ecosystems.
Dr. Ian Richter, Postdoctoral Fellow, Blanchfield Lab, Queen's University Using the metabolic theory of ecology and size spectrum modelling to develop predictive stream fish productivity models Secondary production is indicative of the amount of energy available to higher trophic levels and can provide valuable insight into the dynamics of energy transfer within an ecosystem. Fish production incorporates a wide range of key response metrics such as abundance, biomass, growth, and reproduction, into one quantitative metric but requires resource-intensive data for empirical estimation. An alternative approach to evaluating the distribution and transfer of energy within aquatic ecosystems is size spectrum modelling which is reflects the negative scaling relationship between abundance and body size. While many studies have investigated fish productivity, few have evaluated different methods of estimating production or investigated the key drivers of productivity in riverine ecosystems. In this presentation, I present my research that focuses on investigating different approaches to predict the biomass production of stream fish assemblages using the metabolic theory of ecology and size spectrum modeling. More specifically, I test whether the metabolic theory of ecology and published standard production models can provide precise estimates of total stream fish productivity, investigate how a combination of abiotic and biotic variables are related to stream fish productivity in wadeable Ontario streams, and evaluate the effects of stream classification, spatial scale, and sampling design on the key parameters of riverine size spectrum models. Overall, this research demonstrates that published standard fish production models can be used to estimate productivity, that productivity is better predicted by biotic than abiotic variables, and that size spectra models at broad spatial scales can be used to investigate the movement of energy at higher trophic levels in river ecosystems. My research furthers our knowledge on the biomass production of stream fish communities and can serve a wide range of applications, including conservation and management efforts surrounding stream fish communities.
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