Population genomic structure and hybridization of Glaucous Gull (Larus hyperboreus) in the Canadian Arctic
Presented by: Emma Lachance Linklater
October 22nd at 12:30pm – 1:30pm EST
Climate change poses a significant threat to the future of Arctic ecosystems. To effectively conserve Arctic species, genetically differentiated populations must be defined for genetic variation to be appropriately managed. This project examines population genomic differentiation in Glaucous Gull (Larus hyperboreus) – a circumpolar Arctic species – and assesses hybridization between Glaucous Gull and three closely-related species. Glaucous Gull is a valuable species, both biologically and culturally. As apex predators, Glaucous Gulls develop high levels of toxins in their tissue and are, therefore, excellent bioindicators of the long-range transport of contaminants in the Arctic. Glaucous Gulls also hybridize with other white-headed gull species where breeding ranges overlap. Although the IUCN currently lists Glaucous Gull as Least Concern, declines have been reported across their range in Arctic Canada. Currently no finescale population genetic information exists for this species, and management units have not been delineated. Double digest restriction-site associated DNA sequencing was conducted on 62 Glaucous Gull, 18 American Herring Gull (L. smithsonianus), 6 European Herring Gull (L. argentatus), and 15 Glaucous-winged Gull (L. glaucescens) sampled across the North American and European Arctic. Despite the geographic distance between sampling locations, STRUCTURE and discriminant analysis of principal components (DAPC) suggest only weak population differentiation between European and Canadian colonies of Glaucous Gull. Interspecific analyses using 2145 loci show that Glaucous Gull and Glaucous-winged Gull are genetically distinct species but that Glaucous Gull and the two species of Herring Gull are only weakly differentiated. Several sampled individuals may represent hybrids between Glaucous Gull and other species. Detailed information on population genetic structure and hybridization will help conservation practitioners effectively manage the long-term persistence of Glaucous Gull populations. Proactive management strategies for this species will benefit both Glaucous Gull and the entire Arctic ecosystem.
Testing for convergent evolution in semi-aquatic Anolis lizards
Oct. 15th at 12:30 – 1:30pm ET
Anolis lizards are a textbook example of convergent evolution. Independent anole lineages on each of the Greater Antillean islands have converged on the same six ‘ecomorphs’, categories encompassing morphology, ecology, performance, and behaviour. However, the majority of anole species, including those found on continental Central and South America, do not fit neatly into these categories. Of these ‘non-ecomorph’ anoles, there are twelve species which are always found within metres of neotropical streams, swim and dive to escape predators, and consume aquatic prey. Given the prevalence of convergence in anoles, we might expect these semi-aquatic species (that include 6 phylogenetically independent lineages) to exhibit broadscale convergence; yet previous work did not find evidence of morphological similarity between these lizards. To determine if semi-aquatic anoles should be considered a new ecomorph, I conducted a comprehensive study of their morphology, swimming performance, and underwater behaviours. In addition to finding multi-modal evidence of convergence, we also discovered a novel convergent respiratory behaviour that we have called ‘rebreathing’.
Making sound decisions: Singing mice as integrative models for adaptive display
Presented by: Dr. Steve Phelps from the University of Texas
October 8th 12:30-1:30pm ET
By their very nature, animal displays are among the most conspicuous of all behaviors. They are designed to be noticed, but not without cost. The trade-offs between costs and benefits of conspicuous displays are influenced by state variables, like an individual’s reproductive status or energy balance; contextual variables, like the presence or absence of a given audience; and idiosyncratic contingencies that are unique to the ecological circumstances of an individual and must be learned through experience. While such trade-offs have been well explored theoretically, we know surprisingly little about the mechanisms by which animals match display effort to such diverse concerns. Work with singing mice illustrates some of the many neural and hormonal mechanisms by which these considerations are balanced against one another to optimize display effort.
Models of adaptation to climate change with complex life histories
Climate warming has been the epitome of rapid global environmental changes induced by anthropogenic activities. The need to predict species responses to these challenges has been a strong motivation to develop the theory of adaptation to rapid and ongoing environmental changes. Early theory provided strong conceptual insights based on simple models, notably assuming non-overlapping generations. However, many organisms, some of major conservation or agronomic interest, have complex life histories structured in different ages and stages. I will present some of the work we have done to integrate life history in models of adaptation to changing environments. These models strongly emphasize the link between ecological and evolutionary dynamics. We demonstrate in particular how changing environments can trigger eco-evolutionary feedback loops with major consequences both on life history and on the fate of populations.
“Now, here, you see, it takes all the running you can do to keep in the same place. If you want to get somewhere else, you must run at least twice as fast!”
Direct and indirect effects of host food quality on host life history, host susceptibility to parasitism, and parasitoid life history
Thursday September 24th from 12:30-1:30 pm
Ecological communities are complex, comprising species and environmental factors that are so entangled in their effects on one another that ecologists and evolutionary biologists will forever be mystified by how they are assembled and function. Against such complexity, we have come to understand that autotrophic resources can have large cascading impacts on higher trophic levels via direct interactions (the effect of one species or environmental factor on another). However, because of indirect interactions (between species or environmental factors that are mediated through direct interactions with other species or factors), the relationships and dynamics we expect in natural communities are often not observed. In this thesis, I investigate how food resources directly impact consumer life histories and how this direct interaction indirectly impacts tertiary consumers in an experimental resource-host-parasitoid community. I address the direct and indirect effects of host food quality on primary and secondary consumer life histories in two highly replicated experimental life history assays. In the first assay, I ask whether variation in host life history traits in response to food quality is consistent within and across stages of host development. Importantly, throughout juvenile development, many organisms develop through several stages of growth that can have different interactions with their environment. For example, some parasitoids typically attack larger instars, whereas larval insect predators typically attack smaller instars. Interestingly, most studies lump all juvenile stages together, which ignores these ecological changes over juvenile development. Using a cross-sectional experimental approach combined with a stage-structured population model to estimate instar specific host vital rates, I show that food quality effects on host vital rates, growth and development are not consistent throughout ontogeny, suggesting host food quality may cascade to impact host susceptibility to parasitism and parasitoid life histories. In the second study, I ask whether host food quality indirectly cascades to impact host susceptibility to parasitism and parasitoid life histories. Using a similar cross-sectional approach, I show host food quality indirectly impacts host susceptibility to parasitism but has little to no effect on parasitoid life histories. Overall, my research shows that, despite large effects on host life histories, host food quality effects are markedly reduced in parasitoids in this system, emphasizing the need to consider specific species life histories when characterizing resource-host-parasitoid community relationships and dynamics, and whether or not resources cascade to impact higher trophic consumers.
How to make Ecology Less White: Responding to the #BlackInTheIvory and the Truth and Reconciliation Commission’s Calls to Action.
Thursday, Sept 17
12:30 – 1:30pm ET
A panel of ecologists will share their experiences in ecology and conservation as underrepresented visible minorities. They will speak about barriers they faced in education and in their careers and lead a discussion about ways those barriers can be broken down. We look forward to seeing you there!
Jacqueline L. Scott is a PhD student at OISE, University of Toronto. Her research focus is on how to make outdoor recreation and environmental discourse more welcoming for Black people. Twitter: @BlackOutdoors1
Peter Soroye is a PhD student at the University of Ottawa where he currently studies the effects of climate change and land use change on pollinators. Peter is an avid contributor and proponent of community science programs like eButterfly and iNaturalist, and has also studied these programs and their ability to inform global change and conservation research. Throughout his graduate studies Peter has also maintained a focus on public science communication, and has volunteered at and organized events for science communication initiatives like Let’s Talk Science and Science Slam Canada. Outside of the lab Peter is a keen camper, hiker, and outdoors-person, and an amateur photographer of butterflies, bees, birds, and any other wildlife he can aim his camera at.
Jessica Winters is a 24-year old Inuit artist from the Inuit region of Nunatsiavut, in Labrador. Her attempts to translate the traditional values of stewardship and sustainability lead her to pursue a undergraduate degree in ecology & conservation. Full-time she works as the Community Energy Lead for the Nunatsiavut Government and part-time as a project scientist for an underwater acoustics company. Jessica also has much experience working with Youth, science outreach, and cruise ship eco-tourism. As an indigenous person from a rural northern community, Jessica has experienced first hand how alienating academic science can be, and hopes to help bridge the gap between western science and indigenous ways of learning, observing and knowing.
DawnBazely has been a biology professor at York University, Toronto since 1990. She wears many academic hats but is a grass biologist at heart. Dawn cut her field work teeth in the sub-arctic salt marshes west of Cape Churchill forty years ago, where she spent five years becoming a world expert on goose poop at Queen’s University’s Camp Finney. Dawn is a long-time advocate for excellence in science communication, citizen science and women in science. In 2014, Dawn was singled out by the Globe and Mail as York University’s “Hotshot Professor” in their Universities Report. In 2017, she received the title of University Professor and the York University Sustainability Leadership award.
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Sociality across multiple foraging contexts in a colonial seabird
Abstract: Animals in groups experience both costs and benefits from social associations. Colonial species such as seabirds, live in a particularly complex social environment presenting significant opportunity for intraspecific social interactions. Access to social information, particularly in terms of social foraging, has frequently been proposed as an important factor driving coloniality. However, due to the vast size of many seabird colonies and long distances covered during foraging, it has previously been difficult to examine the scale of such foraging aggregations and the individual factors that drive social behaviours. By simultaneously tracking 85% of the breeding population of a colony of Australasian gannets (Morus serrator) I quantify the importance of sociality across multiple contexts associated with foraging. I demonstrate that individuals associate at the colony at a frequency greater than expected by chance, and that this coordination at the colony provides foraging information as co-departing individuals share more similar initial foraging locations. Using multi-layer social network analysis, I further demonstrate that individuals vary consistently in their sociality across foraging states (colony departure, commuting, foraging and colony return), but show individual flexibility in their social associations. This study also highlights the context-dependent nature of social foraging decisions, as the use of social foraging behaviour differed with habitat choice. Lastly, I examine social foraging decisions during commuting (following) and foraging (patch joining) in the context of a producer-scrounger foraging game. I provide evidence that use of exploitative foraging strategies varies with time and space during foraging, which are expected to relate to foraging motivation and scrounging opportunity.
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.