Please click the drop-pins below for the research project at each location, and scroll down for details on each project



Understanding the complexities of global change requires a variety of approaches. Our work combines select case studies along a latitudinal gradient from the High Arctic to the equator, with the development of new modelling and statistical approaches for disentangling the mechanisms driving change, for forecasting likely future impacts, and/or for suggesting suitable mitigation and management strategies. Current efforts primarily focus on global change impacts on large mammals and on global change impacts on parasitism and disease spread.

Recent modelling foci include

  • bioenergetics and population dynamics models for understanding climate change and land use change impacts on large mammals and their prey
  • thermal performance curves, the Metabolic Theory of Ecology, and life-cycle-based host-parasite models for understanding how temperature changes alter host-parasite systems
  • spatial host-parasite models for understanding how climate change and land use change alter the transmission of parasites across landscapes


Current biological systems of interest include (see map for more details)

  • Climate change impacts on Arctic mammals, especially polar bears
  • The role of climate change in recently observed range expansions of parasites of muskoxen and caribou
  • Winter ticks that appear to be expanding their ranges in Yukon and are infesting moose, elk, caribou, and deer
  • The deformity-causing frog parasite Ribeiroia ondatrae and how its distributions and spread are affected by climate and land use change
  • Worm parasites of jaguars, pumas, and ocelots, and how land use change is affecting the transmission of these parasites between domestic and wild animals


Research Projects

Climate change impacts on polar bears

Polar bears are vulnerable to climate change because they require sea ice as a platform for hunting seals. Longer ice-free periods mean longer fasts for polar bears in affected regions, leading to declines in body condition, and ultimately, declines in reproduction and survival. Our work uses models for the energy budgets and population dynamics of polar bears to understand how past, current, and future changes in sea ice affect the viability of polar bear populations.


Climate change and range-expanding lungworms of muskoxen and caribou

Several parasites and parasitic diseases are expected to expand their ranges polewards as climate change continues to warm the planet. One example is found on Victoria Island in the Canadian Arctic, where two lungworms of muskoxen and caribou have established about a decade ago and continued to expand their ranges northwards by several hundred kilometers since then. Our work, currently led by PhD student Alexander Nascou, combines physiological and population dynamics modelling with empirical data, collected by our collaborators at the Kutz Lab (University of Calgary), to disentangle the respective roles of climate change, host movement, and parasite life histories in shaping the observed parasite range expansions.


Parasitism, animal migrations, and global change

Animals migrate for various reasons, including to escape harsh climates and to track food resources. Animal migrations can also have substantial consequences for the health of a population and the spread of their parasites. Migrations might, for example, allow animals to escape their parasites by temporarily abandoning heavily infested habitats (e.g. breeding grounds), but can also spread parasites to currently unaffected areas. Our work, currently led by NSERC Postdoctoral Fellow Stephanie Peacock, seeks to disentangle the mechanisms that shape how parasites interact with migratory animals by developing and applying spatial host-parasite models to select case studies, such as the mass migrations of barrenground caribou in the Canadian Arctic.


Climate change and winter ticks in Yukon

Winter ticks (Dermacentor albipictus) are blood-feeding parasites that are commonly found on cervids such as moose, elk, caribou, and deer. Moose are particularly susceptible to severe tick infestations, which can lead to hair loss, anemia, poor body condition, and sometimes the death of the host. Although winter ticks are found throughout North America at latitudes below 60°N, they have only recently begun colonizing areas further north. In Yukon, winter ticks have likely arrived via translocated elk from Alberta, have since established in areas around Whitehorse, and are now also being detected in other parts of Yukon, perhaps as a consequence of climate change creating better tick habitats. Our work, currently led by PhD student Emily Chenery, combines citizen science, laboratory experiments, field sampling and population dynamics modelling to determine the current distribution and abundance of winter ticks in Yukon, their sensitivity to temperature and precipitation changes, their host preferences and dynamics of spread, their impacts on hosts, and possible mitigation and management strategies.


Global change and a malformation-causing parasite

Ribeiroia ondatrae is a parasitic flatworm that requires three hosts to complete its life cycle: first a snail, then an amphibian or fish, and finally a bird or a mammal. The parasite is best known for causing deformities in their frog hosts, such as additional limbs, and may therefore also be a conservation concern in addition to the many concerns already plaguing amphibians. Like all parasites exposed to the environment, R. ondatrae is sensitive to temperature changes but the complexity of its life cycle makes it difficult to determine how climate change will affect its distribution and impacts on hosts. Our work, currently led by PhD student Korryn Bodner and in collaboration with Pieter Johnson (University of Colorado Boulder) and Sara Paull (University of Colorado Denver) combines mechanistic host-parasite models with machine learning approaches to understand how climate change – along with land use change, pollution and other factors –  influences the parasite’s range, phenology, and its impacts on hosts.


Land use change impacts on parasitism

Land use change can alter the dynamics of host-parasite systems and disease spread in multifaceted ways. Habitat fragmentation, for example, can alter the spatial distribution of hosts and increase or decrease their densities above or below the threshold for epidemic outbreaks. Moreover, changes in landscape geometry also alter the configuration of contact lines and contact barriers between animal populations, thereby changing the probabilities of cross-species disease transmission and zoonotic outbreaks. Our work combines the development of new modelling approaches for how land use change impacts parasitism and disease spread, with camera trapping and parasitological work on the Osa Peninsula in southern Costa Rica where we test our ideas and hypotheses empirically. Here, we collaborate with the NGO Osa Conservation to understand how ongoing land conversions affect the viability of mammalian populations and the transmission of parasitic diseases among them. Current work by PhD student Juan Vargas focuses on determining whether domestic dogs may be functioning as a reservoir species from which parasitic disease is spilling over to ocelots and pumas.