Research Projects

Our research examines patterns and drivers of host-pathogen interactions across multiple scales, from within-host processes to community-level dynamics. We apply field, experimental, molecular, modeling, and comparative approaches to diverse study systems, including insect pathogens, avian diseases, bat viruses and mammal parasites. Specific themes we address include: (1) animal movement and infectious disease dynamics, (2) resource subsidies and wildlife health in human-modified landscapes, (3) monarch butterfly conservation and responses to global change, and (4) macroecology of infectious diseases and global patterns of parasitism. Major projects underway by lab members are summarized below:

Current projects

Animal movement and infectious disease dynamics

Seasonal long-distance migration occurs in many animal systems, from birds to marine species, terrestrial mammal and insects. Our work linking migrations to infectious disease dynamics has emphasized that even though animal migration is often assumed to enhance the spread of infectious disease, there are several ways that migration can have the opposite effect and actually lower pathogen risk. Specific projects include:

Large-scale patterns of association between migration and disease in ungulates (Claire Teitelbaum)
Mechanistic drivers of migration-disease associations in theoretical models and empirical work in monarchs (Sonia Altizer)
The effects of shifts from migratory to resident behavior on infectious disease dynamics (Cecilia Sanchez, Sonia Altizer, Ania Majewska)
Nomadic movement patterns, resources and disease (Claire Teitelbaum)

An important part of this work has been the creation and expansion of a citizen science program (2006-present) to monitor infections in wild monarch populations: Project Monarch Health, www.monarchparasites.org

Macroecology of infectious diseases and global patterns of parasitism

This work aims to connect hypotheses that explain pathogen transmission in single-host-single-parasite interactions to understand pathogen diversity at much larger spatial and taxonomic scales. Some of this work involves collaborations supported by a Research Coordination Network grant from the NSF EEID panel (2013-2018). Current projects include:

Determinants of parasite sharing and specificity (Maria Luisa Muller Theissen, Tj Odom, Sonia Altizer)
Animal threat status and infectious disease risk (Sonia Altizer)
Host range and specificity of milkweed butterfly parasites (Maria Luisa Muller Theissen, Paola Barriga)
Migration and infectious disease in ungulates (Claire Teitelbaum)

Resource subsidies and wildlife health in human-modified landscapes

A major interest of lab members examines how anthropogenic change affects infectious disease dynamics in wildlife populations. Urbanization and other land-use changes can affect infectious disease via changes in feeding and movement behavior, stress levels and immune function, habitat use and intraspecific contact. Current projects include:

Urbanization and flying foxes in Australia (Cecilia Sanchez)
Resource subsidies in urban parks: impacts on Florida white ibis and their pathogens (Cali Wilson, Claire Teitelbaum)
Wildlife tourism and human feeding of wildlife in nature reserves: ringtails and rock squirrels in ZNP (Anna Willoughby)
Human-planted gardens, pollinators, and disease (Ania Majewska)
Livestock-rearing and vampire bats (Dan Becker)

Monarch butterfly conservation and responses to global change

Monarch butterflies are globally-distributed, iconic insects famous for undertaking a two-way migration in parts of North America. Migratory monarchs have undergone alarming declines at their wintering sites in Mexico, prompting research to examine mechanistic drivers of population and movement dynamics, and potential causes of declines. Projects include:

Effects of climate change on population viability of monarchs: nectar availability/resource abundance (Isabella Ragonese, Ashley Ballew, Sonia Altizer)
Environmental transmission dynamics of parasite infection in monarchs (Dara Satterfield, Ania Majewska, Cecilia Sanchez)
Continent-wide data analysis and modeling of monarch population viability (Paola Barriga, Ania Majewska, Sonia Altizer)
Native plant restoration for monarchs (Ania Majewska, Dara Satterfield, Hayley Schroeder)
Neonicotinoid pesticide impacts on monarchs (Cody Prouty)

Past projects

Social and mating behavior and infectious disease dynamics

In exploring another type of animal behavior, we have examined the roles of social and mating behavior in infectious disease spread in birds, primates and other mammal species. Earlier comparative work tested whether group size and mating systems predicted variation in primate infectious diseases, including STDs. We also examine the association between seasonal flocking behavior of House Finches and annual outbreaks of a bacterial eye disease (mycoplasmal conjunctivitis). More recently, we've used social network approaches to empirically quantify social contacts in wild apes, and merged these contact networks with epidemic models to predict outbreak size and the efficacy of control strategies. A key result was that control strategies targeted towards animals that are central to the network could avoid outbreaks with a third fewer vaccines than random vaccination. Another recent project took a comparative approach in mammals to show that interspecific variation in the strength of sexual selection explains more immunogenetic variation at the MHC across large numbers of wild mammals than does variation in parasite risk.

Evolution of host defenses and pathogen virulence

Several lab members are interested in the evolution of host resistance and pathogen virulence in natural populations. Much of this work has focused on the monarch-protozan interaction, and combined field collections of wild host and pathogen genotypes with laboratory experiments. Work in collaboration with students and postdocs showed high levels of variation in parasite virulence within and among populations and provided some of the first solid empirical evidence that optimal intermediate pathogen virulence can be driven by tradeoffs between within-host replication increasing transmission on the one hand, but cutting short the infectious period on the other hand. Our work also provided support for genetic variation in host resistance and underlying effects of environmental stressors and for effects of age, sex and parasite infection on host immune defense. We found strong evidence for genotype-specific interactions between monarchs and parasites that could ultimately impede selection on host resistance or pathogen virulence in wild populations. More recent work examines how resource limitation and long-distance migratory behavior affect immune defense and pathogen resistance in monarchs, take an ecoimmunological perspective.

Geographic variation in monarch butterflies

Monarch butterflies populate islands and continents worldwide, including North America, South and Central America, Caribbean and Pacific Islands, and Australia. Monarchs in these populations are exposed to different climates, host plant species, and natural enemies, and experience different levels of geographic isolation and migratory strategies. Divergent selective forces may have affected traits associated with monarch flight ability, including wing size and shape, and monarch responses to different host plant species and performance in different thermal regimes. We have examined geographic variation in phenotypic traits of monarch butterflies from different populations, and have collaborated with other researchers who are using molecular markers to examine monarch evolutionary genetics.