Anthropocene determinants of diversity in island anole lizards
The central aim of my research is to understand how ecological and evolutionary factors combine to determine biodiversity patterns over large spatial and temporal scales. To do this, I use radiations of Anolis lizards on Caribbean islands as a natural experiment to test hypotheses about macroevolution, biogeography, and community ecology. In this seminar, I will ask how biogeographic patterns and community structure, both of which bear strong signatures of macroevolutionary history, are being reshaped by human activities in the Anthropocene. Specifically, I will ask how classic biogeographic factors (e.g., island area and isolation) and economic trade combine to predict species richness in invaded island faunas, and how natural climate gradients and recent land use patterns jointly predict the assembly of local communities within islands.
How changing biodiversity in the Canadian Arctic is affecting seabirds: from pathogens to predators, bacteria to bears
We often view the Arctic as a pristine wilderness largely free of environmental threats. Times are changing. I’ll provide a few examples of changing conditions currently affecting eider duck populations in Arctic Canada: harvest, emerging diseases, and changing predatory regimes. Infectious disease is a potentially important driver of wildlife population dynamics although the demographic effects of disease in free-ranging hosts have proven difficult to quantify. Avian cholera is a highly virulent disease of birds that has circulated among common eider populations in Europe and North America for several decades. The disease has recently appeared in the Canadian Arctic where high annual mortality, coupled with near total reproductive failure on affected colonies, has raised fears over local extirpation and severe population decline. In this study, our group used data from a marked population of northern common eiders (S. m. borealis) to estimate vital rates before and during a multi-year cholera outbreak. Nesting success remains below replacement level and there has been no evidence for population recovery. Climate change can also influence species directly by modifying their physical environment or indirectly by altering interactions among organisms. Changes affecting the ecology of top predators are a particular concern because variation in predator behaviour has the potential to restructure food webs and lead to cascading ecological impacts on prey populations. Polar bears (Ursus maritimus) are a top predator in the circumpolar Arctic and are adapted to use sea ice as a platform to hunt seals. Advancement in the timing of sea ice break-up in the spring has recently reduced the access of seals to bears, and has been associated with increased bear predation of eider eggs on islands in summer. The proportion of days on which bears are present on eider duck colonies before their median annual laying date has more than doubled during the past two decades. Nest success has also declined raising concern about the long-term viability of ground-nesting bird populations such as eiders that are unaccustomed to such intensive depredation by bears.
The evolutionary ecology of alternative reproductive tactics in Chinook Salmon
Until recently, sexual selection theory assumed most taxa were monogamous and selection was thought to operate mainly via processes prior to copulation, namely mate choice (typically females choosing amongst males) and competition for mates (typically among males). However, genetic and behavioural studies have shown that sexual promiscuity is common among most taxa. Multiple mating by females creates the potential for sexual selection to continue post-copulation via; (i) the competition between sperm of different males for the fertilization of ova (sperm competition) and (ii) the differential use of sperm from one male over another, with a presumed genetic benefit to offspring fitness (cryptic female choice). As a result, reproductive fitness is now understood to be determined by the complex interactions of male and female traits (at the phenotypic/genotypic level) during episodes of selection pre- and post-copulation. In this seminar I will outline some of the recent research our lab has conducted to better understand pre- and post-spawning sexual selection among alternative male reproductive tactics of Chinook salmon and outline areas where we are pursuing new research using behavioural, physiological, proteomic and transcriptomic approaches to better understand sexual selection and the evolutionary ecology of alternative reproductive tactics.
Eco-evolutionary impacts of land use on freshwater communities
My work focuses on eco-evolutionary dynamics in human-altered environments, asking whether changes in intraspecific variation and contemporary evolution caused by anthropogenic stressors can influence population, community, and ecosystem-level processes. This talk will describe two projects in which we (tried to!) link human-induced phenotypic change to ecological processes. Both projects focus on aquatic communities impacted by land use intensification: the first project asks if stream invertebrates and fishes can adapt to watershed deforestation in an African biodiversity hotspot, while the second project tests the theory of ‘evolutionary rescue’ in pond mesocosms facing pesticide pollution.
Welcome to our second semester of EEB Seminars! This week we’ll hear from our own John Smol.
A crisis in science literacy: Does our reluctance to engage the public make academics complicit?
I believe we are facing a developing crisis in science literacy and communication and, by extension, how poorly science is used to formulate evidence-based policy. My general concern is that science, at the very least, is being under-used by politicians, policymakers, and the public-at-large. At worst, science is being misinterpreted, misrepresented, and misused. I believe that we, as academics, are partly to blame for this situation. My focus will be on environmental science, using primarily Canadian examples, although I believe many of my concerns are applicable to other disciplines and regions. I will argue that the onus falls increasingly on academic scientists to provide information transfer in effective ways. Equally important, we must correct misconceptions concerning “how science is done.” If facts and information are not prized and communicated, then ideology will trump evidence. And if you don’t value truth, then you don’t value democracy.
Daphnia vertical position and implications for the impact of the invasive Spiny Water Flea, Bythotrephes longimanus, on plankton communities
The introduction of the Spiny Water Flea (Bythotrephes longimanus) in North American lakes has reduced zooplankton abundance and diversity, especially for cladocerans such as Daphnia. Studies have shown that in some invaded lakes Daphnia occupy a deeper vertical in the water column during the day, thereby reducing overlap with Bythotrephes, a visual predator restricted to shallow, light penetrating regions. However, Daphnia daytime vertical position is also influenced by a number of factors including resource availability and UV exposure. The goal of my PhD research was to assess if abiotic factors influence Daphnia vertical position response to Bythotrephes and determine if differences in Daphnia vertical position influence the impact of this predator on plankton communities. My results suggest that Daphnia vertical position in invaded lakes is influenced by water clarity and that Daphnia vertical position mediates Bythotrephes impact on plankton communities.
Besides climate, soils are the major driver of terrestrial plant diversity. In this talk, I will present results from our long-term research program about edaphic drivers of plant taxonomic and functional diversity. Much of our field-based research was conducted along long-term soil chronosequences in south-western Australia. These chronosequences are of particular interest because they occur in a global biodiversity hotspot and provide exceptionally strong natural gradient of soil nutrient availability. Our field studies have allowed us to make important new discoveries about the ecological importance of plant-soil interactions in driving plant biodiversity patterns across soil fertility gradients.