EEB Seminar: April 17th

Dr. Shannon McCauley will talk on

Assessing the interactions between local and regional processes in freshwater metacommunities

at 12:30 in the EEB lounge (BioSciences 4338)

The structure of ecological communities can be affected by both local processes occurring within habitats and by regional processes including the connectivity between habitats, shaped by both landscape structure and species dispersal. I will discuss how habitat connectivity and differences in species’ dispersal behaviour affect the distributions of dragonfly species across a landscape and how dispersal behaviour can shape species ranges across much larger (continental) scales. Local and regional processes do not, however, exist in isolation from each other and can interact in ways that have implications for populations and communities. I will also discuss results from work in dragonflies and other semi-aquatic insects that provide insights into some of the ways these interactions may develop including context-dependent dispersal and individual variation in dispersal behaviour. While we are just beginning to understand the connections between local and regional processes and how they modify each other, recognizing the linkages between processes at these different scales is yielding insights missed by a focus on processes only occurring at a single scale.

a marked dragonfly

Dr. Shannon McCauley is an Assistant Professor at the University of Toronto, Missassauga. She is a freshwater ecologist interested in the processes that shape ecological communities across different spatial scales. For example, how do predator-prey interactions shape local communities? How do dispersal abilities of organisms shape community composition and species distributions? And how do these processes (predation and dispersal) interact to influence community structure? Shannon addresses these question using a diversity of approaches from extensive spatial and temporal surveys of aquatic communities to experiments that range from mesocosm-level to landscape-level manipulations.

Everyone is welcome to attend
Coffee and treats available at the seminar

EEB Seminar: April 10th

Dr. Hugh Henry will talk on

Production and nutrient cycling in temperate ecosystems: how winter climate matters

at 12:30 in the EEB lounge (BioSciences 4338)

Climate exerts strong controls over plant growth and nutrient cycling, but the mechanisms underlying climate responses have mainly been studied over the growing season. However, winter processes can also play an important role in driving ecosystem responses, and northern temperate regions in particular are sensitive to variability in winter climate. I examined projections of soil freezing responses to climate change using a variety of modeling, observational and hindcasting approaches. Overall, despite a general pattern of a decreased numbers of days of frozen soil and decreased numbers of days with snow on the ground, projected responses of soil freezing dynamics to climate change have been regional in nature, and many northern temperate regions are expected experience an increased number of soil freeze thaw cycles as a result of reduced snow cover. The responses of plants and nitrogen dynamics to changes in soil freezing are sensitive to the timing, frequency, length and severity of soil freezing. I have conducted a range of laboratory, mesocosm and field experiments to examine the important thresholds inherent in these responses, and to assess how freezing damage may interact with increases in atmospheric N deposition over the next century.

one of Hugh's warming experiments

Dr. Hugh Henry is an associate professor at Western University. He completed his Master’s at Queen’s (with Lonnie Aarssen) and his PhD at the University of Toronto (with Robert Jefferies). Hugh is broadly interested in nutrient cycling, plant physiology, and global climate change, and how these factors affect plants and micro organisms at the individual, community and ecosystem level. Current research in the Henry lab examines nitrogen (N) uptake during winter (when N uptake is assumed to be unimportant) and during late fall and early spring when freeze-thaw cycles and water runoff create dynamic transitions in the nitrogen cycle. To explore these ideas, Hugh uses large-scale experiments that simulate climate warming, laboratory techniques, and theoretical modeling. His work has taken place in sunny California, snowy Ontario, and salt marshes in the Arctic.

Everyone is welcome to attend
Coffee and treats available at the seminar

EEB Seminar: April 3rd

Kristina Arseneau will talk on

Acidification & Climate Warming: Understanding Biological Recovery in Multiple Stressor Environments

at 12:30 in the EEB lounge (BioSciences 4338)

Lakes in North America and Europe are undergoing chemical recovery from acidification and there is consequently a pressing research need to define recovery targets for acidified sites. Researchers attempting to designate such targets are hampered by two issues: 1) a lack of long-term monitoring data; and, 2) the influence of multiple stressors on recovering lakes. This project highlights how pairing a regional reference site approach with paleolimnological techniques can overcome these two problems. Using a set of stringent selection criteria, 31 minimally-disturbed reference lakes protected from acidification, eutrophication, road salt seepage, and introduced piscivores were identified out of 1,469 Adirondack lakes (NY, USA). Paleolimnological techniques revealed that the species assemblages of the reference lakes have undergone a significant change in species composition since before 1900, including increases in warm-water species, large colonial algae, and algal taxa that can cause taste and odour issues in lakes. A subsequent series of case studies which paired reference lakes with acidified lakes revealed that though the acid-impacted lakes were undergoing recovery, they showed similar species shifts to those documented in the reference lakes. These shifting baselines make a return to pre-disturbance state an unreasonable recovery goal for acidified Adirondack lakes. Rather, recovery is likely to be a moving target as novel stressors like climate warming move both reference sites and recovering sites towards novel species assemblages with unknown ecological consequences.

Kristina Arseneau is currently finishing her Ph.D. at Queen’s, where she works in the Paleoecological Environmental Assessment and Research Laboratory with Dr. Brian F. Cumming. Kristina is interested in using paleolimnological techniques to understand biological recovery from acidification and specifically how we can understand and frame biological recovery in multiple stressor environments. Kristina’s fieldwork took place in the Adirondack Park in New York, where she and her field crews hiked in to more than 30 different lakes, dodging moose, overly ambitious beavers, and pathologically curious deer along the way.

Everyone is welcome to attend
Coffee and treats available at the seminar

EEB Seminar: March 27th

Catherine Duguay will talk on

Genetic architecture and sexual conflict in the life-history of Drosophila

at 12:30 in the EEB lounge (BioSciences 4338)

While males and females of a species ‘share’ homologous traits with a common genetic basis, sex-specific selection on these traits can shift the sexes away from their phenotypic optima, inhibiting the evolution of sexual dimorphism. This mode of sexually antagonistic coevolution is known as intralocus sexual conflict (IaSC). As IaSC has been a historically overlooked problem, many outstanding questions remain. For example, what is its contribution in maintaining genetic variation for fitness in populations? What characters underlie this variation in fitness? How does the selection history of the population influence the standing genetic variation? I used the model organism Drosophila melanogaster to attempt to resolve some of these questions. The first part of my Master’s project involved assessing the detectability of sexually antagonistic alleles in populations at different stages of adaptation to the lab. The second part of my Master’s project involved breaking down juvenile fitness into its trait components, such as growth and various morphological metrics, and examining the juvenile stage for antagonism with adult fitness effects. While the first part of my thesis proved inconclusive, the second part revealed a surprising source of sexual conflict in pre-adult stages of D. melanogaster.

Catherine Duguay is a Masters student at Queen’s University working with Adam Chippindale. Catherine is interested in genomic conflict between the sexes. How can males and females of the same species share the majority of their genome, yet have dramatically different strategies for increasing their fitness? Part of her Master’s research involves breeding Drosophilia from different populations to see if divergent sexual selection may function as an isolating mechanism. Catherine did her Bachelors at Western University and a thesis project (with Nusha Keyghobadi) on habitat fragmentation and its consequences to genetic diversity by examining the genetic structure of Wood Frogs in logged and intact forests. Catherine grew up in Quebec City then moved to Fairbanks Alaska, land of the midnight sun, where she lived for four years before returning to Canada.

Everyone is welcome to attend
Coffee and treats available at the seminar

EEB Seminar: March 20th

Dr. Steve Lougheed will provide…

Musings from Australia

at 12:30 in the EEB lounge (BioSciences 4338)

This week EEB is a little different. Steve, recently returned from Australia, will be supplying everyone with plenty of pictures, stories, and life lessons from his travels. So come out, we’ll ply you with good food and strong coffee, and then regale you with stories thick with adventure and mystery. Everyone is welcome to attend!

a snake, a spider, and a professor walk into a bar...

Dr. Lougheed is an Associate Professor in the Department of Biology at Queen’s University and is the Director of the Queen’s University Biological Station. His research focuses on understanding the origins of biodiversity and he uses a variety of genetic, experimental, and comparative techniques to tackle this topic. He has worked extensively with birds, frogs, snakes, and other squamate reptiles. He is a passionate teacher and teaches several courses both in the field and classroom; field-course locations include: east Africa, Argentina, Costa Rica, and the Queen’s University Biological Station, to name a few. Steve is a naturalist and researcher par excellence. He is currently on sabbatical, and recently returned from Australia, but has kindly agreed to share some of his stunning Australian photos and travel adventures with us.

EEB Seminar: March 13th

Clay Cressler will talk on

Adaptive genome evolution in salamanders: a phylogenetic perspective

at 12:30 in the EEB lounge (BioSciences 4338)

Salamanders have the largest and most variable genome sizes of all of the vertebrates, and the largest among all animals other than lungfishes. Additionally, there is a wide range of metamorphic strategies across the order, from the standard metamorphosis characteristic of frogs, to neoteny, where somatic development is slowed to the point that individuals sexually mature with most juvenile morphological traits intact, to direct development, where individuals bypass the larval stage and hatch as fully-formed, miniature adults. Among the direct-developing salamanders (plethodontids), there has been a subsequent regaining of metamorphosis. Because of the negative correlation between genome size and development rate (because cell division is slower the larger the genome), we expect that metamorphosis imposes constraints on genome size evolution. The variation in metamorphic strategies coupled with variation in genome sizes in salamanders provides an excellent opportunity to test this hypothesis. I briefly discuss the importance of incorporating phylogenetic information into such a test, and describe a method of phylogenetic comparative analysis that allows users to compare the strength of evidence for several competing adaptive and non-adaptive hypotheses. I apply that method to the salamander genome size dataset and find evidence for adaptive evolution of genome size, with smaller genomes associated with metamorphosis compared to direct development and neoteny. These results suggest that adaptive evolution may play an important role in limiting genome size in salamanders, even as non-adaptive processes (mutation and drift) may play a role in expanding genome size upper bounds.

a salamander!

Dr. Clay Cressler is an NSF Postdoctoral Fellow in the department of Biology at Queen’s University. For his PhD, Clay examined how behavioral and life-history traits are expected to evolve under the joint selection pressures of predation and starvation; this work was done with Dr. Aaron King at the University of Michigan. Clay’s current research investigates host-parasite interactions and how differential investment, by the host, into resource acquisition and allocation can shape ecological and evolutionary dynamics of host-parasite systems. This is an exciting approach because it incorporates energetics into our understanding of host-parasite dynamics and because it has important implications to understanding the evolution of and managing for diseases.

Everyone is welcome to attend
Coffee and treats available at the seminar

EEB Seminar: March 6th

Maren Vitousek will talk on

Sex, stress, and success: investigating the evolutionary causes and consequences of variation in the acute stress response

at 12:30 in the EEB lounge (BioSciences 4338)

From taking shelter in extreme weather, to reducing parental behavior in the presence of predators, to coping with injury, the ways in which organisms respond to stressors can influence their likelihood of survival and reproduction. Glucocorticoid hormones play a central role in orchestrating the behavioral and physiological response to stressful events in vertebrates. However, mounting a stress response imposes a trade-off: while elements of this response are often crucial to coping with immediate challenges, even relatively brief increases in glucocorticoids can impair the expression of a multitude of processes important for reproduction and longer-term fitness. Variation in glucocorticoid signals has thus been proposed as both a mediator of life-history trade-offs, and a target of selection. Using research in Galapagos marine iguanas and two species of swallows (Hirundininae) I will discuss the relationships between individual variation in the acute stress response and behavior, reproductive success, and survival. For selection to shape these traits they must have a heritable component; I will also present the first estimates of the heritability of circulating glucocorticoids in a natural population, and discuss the implications of these findings for the evolution of hormone signal systems.

barn swallows - photo by Matt Wilkins

Dr. Maren Vitousek is a Senior Research Associate in the Department of Neurobiology and Behavior at Cornell University. She completed her Masters and PhD at Princeton University where she worked with Martin Wikelski. Maren’s research interests lie at the intersection of behavior and endocrinology to understand how organisms cope with and respond to stressors in their environment. Current research in her lab investigates individual-level responses to stressful events, understanding the role of hormones in shaping life-history variation across vertebrates, and the costs of sexual signaling and signal assessment. Maren has worked extensively on Galapagos Marine Iguana’s and was a scientific consultant for David Attenborough’s Galapagos 3D.

Everyone is welcome to attend
Coffee and treats available at the seminar