Evolution and Environment Shape Cancer Across Species
Evolutionary theory explains why metazoan species are largely protected against the negative fitness effects of cancers. Nevertheless, cancer is observed across a range of species and sometimes at high prevalence. I present a simple model showing how life history traits (e.g., body size) are expected to co-evolve with anti-cancer mechanisms. The insights of this model form the basis for understanding cancer incidence and resistance mechanisms in different species and across different human tissues.
This week, we welcome our own Alexandra McClymont.
Abstract: Extensive road salt use across the Northern Hemisphere is causing long-term and substantial salinization in many freshwater systems, with significant consequences for aquatic organisms and communities. American and Canadian water quality guidelines for chloride are currently based on single-species studies conducted under laboratory conditions, which do not account for community interactions or the effects of additional stressors. Concurrent with salinization, lakes are warming due to climate change. Increasing water temperatures alter lake communities, and could exacerbate the effects of increasing chloride concentrations on aquatic biota. To determine the impacts of these stressors, we conducted a mesocosm experiment using pelagic plankton communities from a lake typical of the Canadian Shield. Our results show that plankton communities will be negatively affected by road salt pollution, even at low chloride concentrations. To ensure the preservation of freshwater systems, Canadian water quality guidelines should be modified to better protect these crucial populations.
Abstract: A species’ genetic structure results from interactions between genetic drift, natural selection and gene flow and, therefore, strongly depends on the species’ spatial distribution and can have a profound influence on the management of species at-risk. I will discuss two factors that may influence range wide genetic structure in the endangered coastal dune species Abronia umbellata; peripherality and hybridization. On one hand, peripheral populations may have low genetic variation, low fitness and be prone to extinction. Alternatively, they might be adapted to extreme range-edge environments and thus well-poised for range expansion during climate change, increasing their conservation value. This is extremely relevant to Canadian conservation where ~90% of “at-risk” species are at their northern range limit in southern Canada but much more common to the south. Hybridization from a closely related congener could provide beneficial alleles needed for adaptation to habitats beyond the range or result in demographic swamping, eliminating the rarer species. Hybridization could play an important role in a species’ genetic structure, but it is rarely studied in a single species across its entire range. The results from our study will contribute to the recovery strategy of this precarious species and help us move towards biologically informed strategies for managing species at-risk in Canada.
This week, we welcome our own Kelly Alexandra Estrada Piedrahita
Having spent the last seven years as the administrator of a wild animal rehabilitation centre in the Amazon region of Ecuador, what it means to work in the field of conservation has become a very complex question to me. There are many more players and factors involved in the rescue and release of an endangered yellow-bellied spider monkey or a lowland tapir than the animals themselves. I will be telling you the story of amaZOOnico – Selva Viva – an animal rescue project that champions the rights of wildlife to live a wild life in a country that is battling the illegal animal traffic trade on an international level. We will be exploring the questions of what it means to rehabilitate an animal, the complexities of foreign intervention in a local indigenous Quichua community, how demands and pressures on a global scale are affecting our rainforests, and a behind-the-scenes look at what it means to run a wildlife rescue in a remote location on a daily basis. Take a journey with me to discuss some of the struggles and joys in the jungles of South America.
This week, we welcome our own Regan Cross and Matt Macpherson.
Abstract: Populations of many snake species around the globe are in decline as a result of anthropogenic threats such as road mortality. To reduce road mortality, wildlife barrier fencing is often used, albeit with varying levels of success. Given how adept gray ratsnakes (Pantherophis spiloides) are at climbing and the relatively large size they reach, this Threatened species serves as a good system for testing mitigation fencing as they can act as an umbrella species for other, smaller Ontario snakes. In this experiment, the exclusion potential and behavioural response of gray ratsnakes to different types of barrier fencing were assessed. We expect fencing material, height, and/or shape to determine an individual’s success in climbing over it. Gray ratsnakes were tested in circular testing arenas 2m in diameter, and constructed of eight different combinations of fencing materials, heights, and shapes based on the recommendations of the OMNRF’s best management practices for reptiles and amphibians. The behavioural responses, such as success in climbing over the fencing, number of climbing attempts made, and time taken to escape were video-recorded for each snake. Morphometrics and ground temperature were also recorded, as these factors can also affect a snake’s climbing ability. For each of the fencing combinations a minimum of 10 trials were performed (88 trials in total). Preliminary results show that the snakes had the most success escaping from the 0.6 m tall vinyl sheet fencing with a lip (100% escaped), and the most difficulty escaping from the 1 m tall hardware cloth fencing with a lip (only 6.7% escaped). Our study will inform the use of barrier fencing to reduce snake road mortality, thus helping to conserve snake populations at risk and apportioning limited resources for conservation more effectively.
Abstract: Species should be able to continuously adapt to conditions at their geographic range edges and disperse into the habitat beyond, yet most do not. Experimental planting of species within and beyond their range directly tests the mechanisms causing stable range limits, however experimental populations are rarely followed for more than one generation, providing little insight into long-term demography and potential for local adaptation beyond the range. In 2005, we transplanted eight source populations of the Pacific coastal dune plant Camissoniopsis cheiranthifolia into four sites within and one site beyond its northern range limit. Fitness of beyond-range individuals was comparable to within-range populations, suggesting that the northern range edge is limited by dispersal rather than niche constraints. Compared to sites within the range, the beyond-range population experienced high seedling recruitment in the two seasons following the transplant. Approximately 12 generations after planting, beyond-range individuals remained as abundant and reproductively successful as within-range individuals, providing compelling support for a role of dispersal in limiting the northern range edge for this species. Long-term experiments such as this provide robust conclusions in the face of environmental stochasticity, and allow for a better understanding of how species respond to novel habitats.
mate recognition system is the foundation of biological speciation in anurans. Ecological
and sexual selection have been suggested as major causes of male call
evolution. It is generally assumed that a significant fraction of variation in
male advertisement call has an underlying genetic basis and that there is a link
between key call attributes and fitness, yet these remain key, largely unproved
assertions regarding call evolution, and many factors contribute to diversity
of calls within a male chorus. Anurans advertisement calls are important in
studies of behavior, sexual selection, speciation, and phenology. In all of
these, understanding, heritability is prerequisite to understanding
evolutionary patterns and potential responses to selection. However, very few
studies have quantified heritability of advertisement calls in wild populations
of anurans, nor incorporate all factors know to influence call variation. In
this study, I try to estimate the heritability of anuran call attributes within
a calling assemblage of a temperate treefrog, Pseudacris crucifer, and quantify the relative contributions of
different factors: body size, age, calling temperature, and genetics. I use sonographic
analysis to assess call variation, skeletochronology to estimate age, and single
nucleotide polymorphisms (SNPs) markers to estimate the relatedness of calling
males. I use the animal model to evaluate all factors that may affect calls. By
simultaneously investigating the genetic basis of advertisement call attributes
as well as the effects of environmental factors, we will gain a better
understanding of call evolution and the potential for selection to drive
Meeting our global population’s food needs has involved intensive mechanization and centralization of food production. While this industrialization has allowed farmers to provide food for a burgeoning population, it has fundamentally changed the life cycles of domesticated animals in ways that create new and unknown threats to global food security. In my research I build mathematical models aimed at answering the question: how do modern agricultural management practices impact infectious disease burden, the risk of disease outbreaks and pathogen evolution? In this talk I will focus on recent changes to the poultry and the honeybee industries.