EEB Seminar- October 19th

This week the department is pleased to welcome Gustavo Betini from the University of Guelph.

Eco-evolutionary dynamics in seasonal environments


Gustavo Betini is broadly trained in evolutionary ecology. He has done theory and experimental work on the consequences of seasonality, on migration and fear (yes fear!) using Drosophila, on songbird behavior in the field, and (currently) on consumer-resource interactions using Daphnia. He has chosen to talk about his Drosophila work, simulating distinct breeding and non-breeding seasons to examine the ecological consequences of seasonality and on interplay between fluctuations in density and life history trade-offs (i.e. eco-evolutionary dynamics).

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm. This week there will be a pizza lunch to follow in the EEB Lounge.


EEB Seminar- October 12th

This week the department is pleased to welcome Debbie Leigh from Queen’s University.

Bottlenecks, evolution and the behavior of selected variation

Debbie Leigh

Can recent adaptive responses be identified after a population crash? Moreover, can signals of selection be distinguished from allele frequency change due to drift? Our understanding of the on-going evolutionary processes through a population bottleneck is limited. Adaptation experiments and population genetic theory suggest that a bottleneck will have far reaching consequences on the potential for, rate, and direction of adaptation.  However our ability to characterise and explore these effects within naturally bottlenecked systems is often limited by the confounding effects of drift-driven false positive signals of selection.

Within this study we explored if signals selection could be accurately distinguished from drift across 23 bottlenecked and reintroduced populations of Swiss Alpine ibex (Capra ibex). To this end, a set of simulated neutral markers and adaptive markers contributing to a polygenic trait with a shifting local optimum, were generated under the reintroduction history. Through this approach we quantified the false and true positive rates of three different selection-detection softwares and found high detection-accuracy is achievable through overlapping outlier lists and incorporating environmental data in outlier detection. By employing this approach within the Alpine ibex RADseq SNP data, we identified a candidate adaptive response with moderate confidence in relation to the depth of winter snow, an environmental variable known to drive mortality events in the species. 

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm.

EEB Seminar- October 5th

This week the department is pleased to welcome Sapna Sharma from York University.

On thin ice: are lakes feeling the heat?

Sapna Sharma.jpeg

Lakes are warming around the world in response to a changing climate, including warmer water temperatures and shorter ice duration.  Historically Ontario lakes have been highly significant bellwethers, as they represent a northern or southern limit to many freshwater fish species.  This makes Ontario fish particularly vulnerable to climate change. Of particular interest are walleye and smallmouth bass.  Walleye, trout and smallmouth bass are all angler favourites. But as the feisty smallmouth continues its march northward in Ontario, it will put populations of trout and walleye at long-term risk.

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm. This week there will be a pizza lunch to follow in the EEB Lounge.


EEB Seminar- September 28th

This week the department is pleased to welcome Peter Kotanen from University of Toronto Mississauga.


Latitudinal and local variation in damage by above- and below- ground enemies of an invasive thistle

Non-native plants frequently escape their native-range natural enemies (herbivores and pathogens) while colonizing new geographic regions. However, once in a new region, these invaders often acquire new enemies recruited from native plants; as well, enemies from the invader’s original range may be accidentally or deliberately co-introduced. Even so, escape might continue to benefit such invaders as they repeatedly colonize new sites. In this talk, I’ll discuss some of our recent work on a Eurasian thistle, Cirsium arvense, which has widely invaded here in Ontario. We documented herbivore damage to C. arvense by sampling plants over a 800 km transect from agricultural southern to boreal northern Ontario. We also monitored colonization of artificial populations, and investigated soil feedback using inocula sampled at both local (inside/outside existing populations) and geographic scales. Results indicate that thistle populations host a diverse set of herbivores, but their impacts generally decline with latitude. Plants inoculated with northern soils outperformed those inoculated with southern soils, suggesting the reduction of pathogens at northern sites. At a local scale, artificial populations were colonized rapidly by herbivores, but even short (<100m) separation from other populations significantly slowed this process. Similarly, plants grown in soils inoculated with samples from outside thistle populations performed better than plants inoculated with soil from invaded areas only 50-100 metres away. These results indicate that C. arvense can temporarily escape many of its natural enemies by founding new populations. Plants near this thistle’s northern range margins may experience more lasting reductions in damage. Escape from enemies therefore may contribute to the success of this thistle both in local spread to new sites, and in expanding its future range.

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm. This week there will be a pizza lunch to follow in the EEB Lounge.

EEB Seminar- Sept. 21

This week the department welcomes Harris Ivens from Queen’s University:

As above so below? – Impacts of water limitation on growth and nutrient accumulation by a crop plant and its soil microbes across a fertility gradientHarris Ivens

Strategies to increase yields, fertilizer use efficiency, and drought stress tolerance in agricultural crops are urgently needed to meet future global food demands, especially in the context of a changing climate. Plants respond to water limitation by accumulating solutes, yet solute accumulation has not been well studied across fertilizer gradients. Conventional agricultural practice assumes that increasing fertilizer additions results in larger but chemically identical plants. However, a growing body of literature has demonstrated that increased nutrient availability results in ratio changes of organic (i.e. glucose, proline) to inorganic (i.e. NO3, PO4) solutes in sap pressed from leaves. Our study asks: Does the ratio of organic to inorganic solutes in leaf sap affect tolerance to reduced water availability? We used a greenhouse experiment to investigate the effects of three levels of nitrogen and potassium fertilizer (NK) additions on shoot growth, leaf sap composition, and soil microbial nutrient pools of replicate Collard greens (Brassica oleracea, n=9) before and after a water limitation treatment. Our results demonstrate that organic and inorganic solute concentrations in leaves and soil microbes were affected by the fertilizer addition and water limitation treatments, but these differences in solute concentrations did not affect the pattern of plant growth during the water limitation period. However, we found significant relationships among leaf sap, soil microbial biomass, and bulk soil nutrient pools that will contribute to the development of new crop assessment tools to increase precision in nitrogen fertilizer use and reduce harmful run-off, leaching, and gaseous nitrogen losses from agricultural lands.

This seminar will be held in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm.

EEB Seminar- Sept. 14

This week the department welcomes Dr. Pedro M. Antunes from Algoma University:

Functional ecology of the arbuscular mycorrhizal symbiosis – implications for below and above ground biodiversity in a changing world 

Pedro Antunes

Arbuscular mycorrhizal (AM) fungi are obligate symbionts capable of establishing mutually beneficial associations with the roots of most vascular plants. Until recently, very little was known about the functional ecology of AM communities in natural systems. However, technological developments together with novel theoretical frameworks are rapidly contributing to fill in this knowledge gap. Based on this, in this talk I will dissect the relationship between AM and plant community diversity paying attention to eco-evolutionary soil feedback mechanisms in the context of exotic species introductions. I will conclude with implications of these mechanisms for ecological succession.

This seminar will be held in Room 1102, Biosciences Complex, from 12:30-1:30pm. Free meet & greet pizza lunch after the seminar from 1:30-2:30PM in the 3rd floor lunch room (3406).


Departmental Seminar – 18 April

This week the Department welcomes Dr. Stephen Short from the Department of Biology, University of Toronto:

The Complex and Enigmatic World of Freshwater Algal Viruses


As well as being agents of infectious disease, it is now widely accepted that viruses are intimate partners in life that have shaped the evolution of cellular organisms and have played an ongoing role in Earth’s biogeochemistry. With respect to the latter, the discovery almost 30 years ago that viruses infected marine and freshwater primary producers, including species of eukaryotic algae, contributed to the emergence of virology as its own discipline within aquatic sciences. My research program is centered on freshwater algal viruses with the broad goal to understand how they influence aquatic primary production and food web processes. To that end, my students and I have explored freshwater algal virus ecology by studying their biodiversity and seasonal dynamics, persistence in the environment, and relative importance to phytoplankton mortality. We have learned that diverse algal viruses can be found in various freshwaters, but as in marine environments, freshwater algal virus communities are surprisingly dominated by a single group. We have also discovered that algal viruses can form seasonally persistent ‘seedbanks’, and some can overwinter in a frozen pond remaining infectious until their host abundances reach levels we presume are necessary for ongoing virus production. Additionally, the fact the we were able to detect diverse viruses in Lake Erie sediments suggests that sediments are an important refugium that could allow some phytoplankton virus to escape seasonal bottlenecks when they suffer high rates of destruction. With respect to our studies of virus-mediated mortality, we have developed experimental methods to examine phytoplankton mortality at a species, or taxon level. An unexpected finding from this work was the observation that in some cases, viruses appeared to counteract the effects of grazing mortality by stimulating an alga’s growth, perhaps through the liberation of resources from other lysed cells, or by reducing competition. Finally, an additional focal point of my research program is our isolation and ongoing characterization of a newly discovered algal virus. Molecular characterizations of this virus in the lab and field have revealed its complex evolutionary history as well as its puzzling ecological dynamics. Overall, my research has helped demonstrate that, despite their furtive nature and borderline status as ‘living’ microorganisms, freshwater algal viruses are critically important members of freshwater ecosystems.

This seminar will be held in Room 1102, Biosciences Complex, from 11:30-12:30pm. Free meet & greet pizza lunch after the seminar from 12:30-1:30PM in the 3rd floor lunch room (3406).