Allelopathy, Evolution and Plasticity in Garlic Mustard
Abstract: Invasive plants offer excellent opportunities to study evolutionary processes because they are released from selective pressures in the native range and experience novel selective pressures in the invasive range. In order for a species to become invasive, they must respond to these changes, either through evolution or through plasticity. The goal of my research is to identify traits that are adaptive and determine whether evolution or plasticity for these traits is facilitating the invasion process. Garlic Mustard (Alliaria petiolata) is a member of the Brassicaceae family, which was introduced into North America in the 19th century and has since spread across much of the continent. I used genotypes collected throughout the invasive range of A. petiolata and subjected these genotypes to relevant selective pressures to determine which traits may be adaptive, under selection, or exhibiting adaptive plasticity. The main focus of my research surrounds the evolution of glucosinolate and flavonoid compounds in A. petiolata, particularly regarding their role in intra- and interspecific competition.
Do species with strong apical dominance incur a cost in terms of suppressed potential fecundity or biomass?
Abstract: Plants typically allocate axillary meristems to one of three principal fates: branching / growth (G), reproduction (R), or inactivity (I). The latter is commonly enforced (temporarily or permanently) by ‘apical dominance’, promoting a growth form that favours vertical shoot extension — mediated by the effects of auxin produced in the shoot apical meristem. When the latter is removed however (e.g. by consumers), meristem allocation may change, thus affecting plant architecture, biomass accumulation, and/or reproductive effort. Fecundity and/or plant mass may consequently suffer (under-compensation), remain unaffected (compensation; tolerance), or may increase (overcompensation). The latter thus signifies a ‘cost of apical dominance’, but one that may be outweighed by several potential benefits from having apical dominance intact; e.g. tall stature and thus avoidance of shading effects from neighbouring plants. I removed the shoot apical meristem for replicate plants early in the growing season within natural populations of 22 herbaceous angiosperm species with a conspicuously vertical (‘main stem’) growth form, commonly found in eastern Ontario — to: (i) test for a cost of apical dominance; (ii) examine effects of removal on leaf size and leafing intensity (number of leaves per unit stem dry mass) ; and (iii) explore effects of between-species variation in leafing intensity on propensity for a cost of apical dominance. Clipped and unclipped (control) plants had their near neighbours removed, and were harvested after seasonal flowering production had virtually finished but before seed dispersal. Dry mass was measured separately for above-ground body size (vegetative stems), leaves, seeds, and fruit; and counts were recorded for each type of meristem, number of leaves, fruits, and seeds per plant. I predicted that: (i) species with a strong apically-dominant growth form would respond to shoot apical meristem removal with greater branching intensity, and thus over-compensation in terms of fecundity and/or biomass (displaying a cost for apical dominance); and (ii) overcompensation is enabled by production of more but smaller leaves, and hence with a larger bank of axillary meristems (per unit stem dry mass) available for deployment in branching and/or flower/fruit production. Widely variable compensatory capacities were recorded for the study species, suggesting probably effects of uncontrolled between-species variation in phenology, life history traits, and natural susceptibility to herbivory. I also found no significant between-species relationships for compensatory response versus mean leaf size or leafing intensity. Overall, the results point to species-specific treatment effects on meristem allocation patterns, and no generalized ‘cost of apical dominance’ in herbaceous plants.
Given the situation with COVID-19, the EEB seminar for this week is cancelled. Jenna, Mike and Richie’s seminars in the following weeks will be on Zoom or another online platform, with links emailed to the graduate/prof/staff email lists and also posted here.
Gene Flow and its Role in Evolution: Applied Evolutionary Ecology of Weed(s)
Abstract: The Campbell Lab studies how genetic diversity influences population demography? To advance this goal, we study plant populations and their genetic systems – i.e., the reproductive machinery and processes that influence gamete quality and quantity, gamete dispersal, mating, fecundity and, ultimately, inter-generational transmission. Reproductive processes are highly labile in plants and have immediate evolutionary and demographic effects. Recent Progress: In the last six years, we have made significant advances in our long-term goal through research in reproductive biology, evolutionary ecology, molecular ecology, agriculture, and conservation. In the last funding cycle, My NSERC-supported research explored evolutionary demography, the environmental sensitivity of introgression, pollen dispersal, and chemical ecology. We have published groundbreaking, comprehensive studies on the role of genetic diversity in population demography1–4, the sensitivity of introgression (and mating systems more broadly) to variation in environmental conditions5– 12, and the genetic and ecological consequences of crop-wild hybridization.13–15 Our approach is novel in its serious exploration of male and female function in plants, the interacting influence of hybridization and climate on reproductive success, and their ecological and evolutionary implications. We used field experiments (selective inclusion of genotypes, reciprocal transplants), as well as physiological and molecular tools to assess the fitness consequences of altered mating patterns of agricultural weeds and crops. My work has influenced management of rare species and regulation of crops with novel traits.
Abstract: In this seminar I will discuss the transition from genetic to genomic data sets and the challenges that has posed for conservation initiatives. I will then spotlight two case studies highlighting how genomic data and analyses can inform wildlife conservation and management, and more broadly provide a road-map for integrating genomic data into conservation biology.
Abstract: The recent kerfuffle about data fabrication by Jonathon Pruitt (Canada 150 Research Chair at McMaster University) has lit up Twitter with all kinds of nonsense and misconceptions about scientific misconduct. In this session, I will present ten things I have learned about scientific misconduct over the past 30 years—studying the phenomenon, not practicing it! I intend this to be more of a discussion than a formal seminar as I think there is lots to talk about here. So far 17 of Pruitt’s papers are on the rocky road to retraction, making this one of the most prominent case of scientific misconduct in the history of EEB. Actual misconduct, though is not quite as rare as it appears and I think scientists in general would benefit from appreciating what can, should and cannot be done about that. While I do not intend this to be a formal seminar, I will bring stacks of material that I have used in seminars and workshops about this topic in the past decade or so.