Exploring the limits of trait-based ecology: Causes and consequences of phenotypic variation and integration across biological scales
April 15th 12:30-1:30pm ET
The popularity of the trait-based approach to ecology (i.e. functional ecology) is partly due to three important promises the approach makes: generality, predictability and integration across biological scales. The promises are based on explicit or implicit assumptions made by the approach, but they remain poorly tested. I present research centered on the themes of variation, covariation and biological scales that test some of these fundamental promises and assumption. Together, these studies explore when the trait-based approach works well and when it doesn’t.
Amy Forsythe (Queen’s University)
Ecological and evolutionary consequences of individual heterogeneity
April 1st 12:30-1:30pm ET
Among-individual variation in vital rates, such as mortality and birth rates, exists in nearly all populations. While traditional life-history theory predicts that such individual heterogeneity will manifest as trade-offs between individual vital rates, accumulating empirical evidence reveals that positive covariances among vital rates are also prevalent across a wide variety of taxa. Research further suggests that individual heterogeneity scales up to influence population dynamics, however little is known about the effects of different kinds of individual heterogeneity on ecological and evolutionary processes. Here, we synthesize the existing literature into a single and comparatively straightforward framework with explicit terminology and definitions. We then apply this conceptual framework to develop age-structured models that compare the ecological and evolutionary consequences of individual heterogeneity in which intrinsic vital rates are permanent throughout an individual’s life (“fixed condition”) or can change at any time (“dynamic condition”). We find that heterogeneity can affect mean fitness in ways that depend on the sign of the covariance among intrinsic survival probabilities and birth rates, where a positive covariance leads to greater mean fitness in populations with individual heterogeneity structured as fixed condition, while a negative covariance (trade-off) favours populations with dynamic condition. These results emphasize the importance of not only considering among-individual variation in vital rates, but also the structure of that variation (positive or negative covariance, fixed or dynamic condition), when making predictions about the ecological and evolutionary dynamics of populations.
Dr. Zeeshan Syed (Syracuse University)
Sperm-looping: A spermatogenic novelty
March 25th 12:30-1:30pm ET
Post copulatory sexual selection (PCSS) is often responsible for rapid coevolution of male and female reproductive traits, resulting in co-diversification of those traits traits among species. One of the more dramatic examples of such co-diversification is the evolution of sperm length and female seminal receptacle length across diverse taxa including Drosophila. The female reproductive tract is the selective environment for sperm where there’s a strong selection on sperm length for competitive fertilization success. However, the cost for producing long sperm is in increased investment in producing long testes, often leading to extended time to reach sexual maturity. All Drosophila species studied so far have testes longer than the sperm they manufacture.
We discovered an exception to this rule in the members of the willistoni and saltans species groups. They represent an independent evolutionary origin of long sperm and long SR. However, the males are able to produce long sperm in much shorter testis through the innovation of sperm looping. In this talk, I would discuss the evolutionary costs and adaptive benefits of this phenomenon that we have figured out so far, as well as some unanswered questions that we are currently trying to address.
Dr. Amanda Xuereb (Université Laval)
Dispersal, connectivity, and population genetic structure in the sea: insights from an exploited marine invertebrate and applications to spatial management
March 18th 12:30-1:30pm ET
Marine populations are typically characterized by weak genetic differentiation due to the potential for long-distance dispersal favouring high levels of gene flow. However, strong directional advection of water masses or retentive hydrodynamic forces can affect dispersal trajectories of marine organisms, thus influencing the degree of connectivity and genetic exchange among populations. We integrated genomic data derived from restriction site associated DNA sequencing (RAD-sequencing) with biophysical modelling of larval dispersal and use a spatial eigenfunction approach to infer the importance of ocean circulation as a driver of population genetic structure in a commercially harvested marine invertebrate in coastal British Columbia – the giant California sea cucumber (Parastichopus californicus). We demonstrated that ocean currents better predict patterns of genetic variation across space compared to geographic distance, and that directional processes play an important role in shaping spatial patterns of genetic structure, especially at relatively fine spatial scales. Our study emphasizes the importance of accounting for directional current flow in analyses of marine connectivity and contributes to the growing body of seascape genomics literature identifying significant population structure in marine systems despite the potential for widespread gene flow. Our findings have implications for designing reserve networks and for the spatial management of a commercially important species in the northeastern Pacific coastal region.
Dr. Christopher Schell (University of Washington, Tacoma)
Socio-eco-evo dynamics: Exploring how society shapes the biology of cities
March 11th 12:30-1:30pm ET
Urban ecosystems are intrinsically heterogenous, characterized by dynamic biotic and abiotic interactions that are not witnessed in non-urban environments. Urban flora and fauna experience a suite of novel disturbances and stressors that have led to remarkable phenotypic strategies and adaptations to cope with urban living. Despite recent groundbreaking discoveries and innovation in the fields of urban ecology and evolution, the drivers of urban heterogeneity that induce biological change are seldom articulated. The spatiotemporal distributions of urban organisms are directly affected by the uneven distribution of resources (e.g., refugia, food, water) across cities, all of which are connected to societal function and governance. Hence, to build a comprehensive understanding of urban systems and wildlife adaptation, we must integrate and reconcile how structural inequality – especially racism and classism – shape urban environmental mosaics. In this seminar talk, Dr. Chris Schell will discuss how structural and systemic inequalities, especially economic and racial inequality, shape ecological and evolutionary outcomes of wildlife. In doing so, he will discuss how leading with an environmental justice and activism framework in the natural sciences can promote conversation, sustainability, and resilience in a human-dominated world.
Dr. Emily Choy (McGill University)
Marine predators as sentinels of environmental change in Arctic ecosystems
March 4th 12:30-1:30pm ET
Arctic ecosystems are undergoing rapid change, and long-lived top predators are considered sentinels of the impacts of climate change on marine ecosystems. Beaufort Sea beluga whales (Delphinapterus leucas) and thick-billed murres (Uria lomvia) in northern Hudson Bay have experienced long-term shifts in prey species and declines in inferred growth rates, believed to be the result of environmental changes. In partnership with Inuvialuit communities, we examined inter-annual variation and environmental factors affecting prey, body condition, and physiology of Beaufort Sea beluga whales. Body condition of belugas was positively correlated with myoglobin, hemoglobin concentrations, and % hematocrit, with lower total body O2 stores in whales with lower body condition. The relationship between body condition and O2 storage capacity in whales may represent a positive feedback mechanism, in which environmental changes resulting in decreased body condition impair foraging ability. To examine the impacts of climate- induced prey shifts on the energetics of seabirds, heart rate was examined as a proxy for O2 consumption in murres and black-legged kittiwakes (Rissa tridactyla), and were calibrated with GPS-accelerometers to classify behaviours and activity rate. Finally, we examined the effects of Arctic warming on murre physiology. In response to increasing temperatures, murres exhibited limited heat tolerance and low ability to dissipate heat, with one of the lowest evaporative cooling efficiencies recorded in birds. These results highlight the various impacts of climate change on marine predators and their broader implications on Arctic ecosystems.
Daniel Gillis (University of Toronto)
Citizen science reveals songbird spring migration arrival time is advancing more for efficient fliers
February 25th 12:30-1:30pm ET
Shifting phenology in response to climate change has been documented for many taxa worldwide. Several migratory bird species are arriving at their breeding regions earlier, which can lead to trophic and climatic mismatches. This trend towards earlier arrival times contains considerable variation and the mechanisms behind differences in migration shifts are not clear. We hypothesized that greater flight efficiency may be associated with larger shifts, as better fliers may have more flexibility to respond to changing conditions during migration. We applied an updated modelling approach towards analyzing 18 years of eBird citizen science data to generate estimates of the mean arrival date for 29 common passerines migrating to northeast North America. We compared temporal shifts in mean arrival date with morphology parameters associated with flight efficiency and migratory distance. Our research highlights how traits can influence the ability of species to adjust phenology in response to climate change. Identifying possible targets for climate change-induced selection will facilitate conservation efforts for targeting species with traits that will be a detriment to novel climatic conditions. Increasing citizen science involvement provides the opportunity to test novel modelling techniques for generating geographically broad, long-term analyses of important ecological trends.
Dr. Lindsay Miles (University of Toronto)
Gene flow and genetic drift in urban environments
February 18th 12:30-1:30pm ET
We currently live in the Anthropocene, where humans have a drastic impact on ecosystems. One of the ways that we alter ecosystems is through urbanization, the building of cities. This new urban ecosystem has the potential to influence evolution for the many organisms living in or near cities. I study the non-adaptive evolutionary signatures of urbanization, how gene flow and genetic drift are impacted by urbanization. There are two competing models that predict how urbanization changes non-adaptive evolution, the urban fragmentation model and the urban facilitation model. While many organisms appear to experience the urban fragmentation model, which suggests overall negative impacts of urbanization, there are some species that experience urban facilitation. My research aims to predict which organisms are most likely experience fragmentation vs facilitation.
Dr. Geetha Thimmegowda (National Centre for Biological Sciences)
Theeffect of air pollution on insects
Feb 11th 12:30-1:30pm ET
While the impact of air pollution on human health is well studied, mechanistic impacts of air pollution on wild systems, including those providing essential ecosystem services, are largely unknown, but directly impact our health and well-being. India is the world’s largest fruit producer, second-most populous country, and contains 9 of the world’s 10 most polluted cities. Here, we sampled Giant Asian honey bees, Apis dorsata, at locations with varying air pollution levels in Bangalore, India. We observed significant correlations between increased respirable suspended particulate matter (RSPM) deposition and changes in bee survival, flower visitation, heart rate, hemocyte levels, and expression of genes related to lipid metabolism, stress, and immunity. Lab-reared Drosophila melanogaster exposed to these same sites also exhibited similar molecular and physiological differences. Our study offers a quantitative analysis on the current impacts of air pollution on insects and indicates the urgency for more nonhuman studies to accurately assess the effects of pollution on our natural world.
René S. Shahmohamadloo from Guelph University
The toxicology of microcystins in freshwater organisms of the Great Lakes
Feb 4th 12:30-1:30pm ET
Harmful algal blooms dominated by Microcystis aeruginosa are causing ecological and socio-economic disturbances to freshwater ecosystems, in particular the Great Lakes, through the production of microcystin toxins, which can cause disease-related effects in freshwater organisms. This presentation investigates the mechanisms of microcystin toxicity to freshwater organisms of the Great Lakes and assesses the human health risks from consuming fish exposed to cyanobacterial blooms. Using state-of-the-art, quantitative techniques (e.g., targeted and nontargeted LC-QTOF MS to measure microcystins in tissues and proteomics) I further describe, for the first time, toxicological impacts from microcystin exposure to pelagic and benthic invertebrates, as well as fish species humans enjoy including in their diets.