As climate change and habitat alteration proceed at unprecedented rates, studying animal behavior and physiology, especially in relation to environmental change, is important for the conservation of biodiversity, in part because wild animals play vital roles in ecosystems. For example, migratory animals, such as songbirds, may play a critically important role in the spread, transmission, virulence, and evolution of infectious diseases that affect human and animal health. Dr. Ellen Ketterson, Distinguished Professor of Biology and Gender Studies at Indiana University, studies songbirds in the wild to understand animals’ responses to environmental change. Along with Dr. Jonathan Atwell and Dr. Adam Fudickar, senior scientists who provide expertise in neuroendocrine techniques and emerging tools in migration biology, Dr. Ketterson’s team brings greater knowledge to the organismal and evolutionary mechanisms that underlie behavioral and physiological shifts in response to climate change and urbanization.

Dr. Ketterson’s research is a collective effort, capitalizing on emerging technologies in electronics miniaturization, computing, biogeochemistry, genomics, transcriptomics, and informatics, in order to study the interplay between migration, seasonal timing, disease, and climate change, across the continent-wide range of a common backyard songbird, the Dark-eyed Junco. Important subjects in scientific research for nearly a century, juncos are distributed across North America, but from place to place they exhibit stunning variation in feather plumage coloration, migratory behaviors, and seasonal physiology. Because they are common and abundant, yet diverse and widely distributed, juncos provide an ideal study model to evaluate generally how variable and changing environments are altering the biology of wild species.

A documentary film, Ordinary Extraordinary Junco, which highlights the importance of the junco in scientific research, focusing especially on Dr. Ketterson’s research program, can be viewed at: www.juncoproject.org.

Current projects include:

• Animal Migration and Infectious Disease: Given their wide geographic distributions and annual journeys across diverse habitats, migratory animals likely play a disproportionately important role in the emergence, spread, transmission, and virulence of infectious diseases, with potentially huge impacts on human and animal health. Yet to date, remarkably little research has examined the interplay between migration and disease, a critical topic, especially as global climate change is altering the distributions and behaviors of both migratory hosts and zoonotic pathogens. Until recently studying the movements of free-living animals has been extremely time-consuming, expensive, and nearly impossible—especially for the thousands of small-bodied birds, for which tracking devices (e.g. GPS tags) are too large. Thus, even the most basic aspects of geographic connectivity (i.e. links between breeding and wintering grounds), distances travelled, migratory routes of travel, or the seasonal timing of migration have remained entirely uncharacterized for most animals. However, the synergistic implementation of emerging technologies, including tiny light-level geolocators, stable isotopes, and cost-effective high-throughput genomic sequencing are finally allowing scientists to connect breeding and wintering habitats and assess the timing and routes of migratory journeys for small animals. Drs. Ketterson, Atwell, and Fudickar hope to take advantage of these emerging technologies, as well as cutting-edge genetic methods in disease diagnostics, to study the relationship between migration and disease ecology at an unprecedented geographic and temporal scale. Their studies will characterize migratory behavior and the prevalence, diversity, and virulence of malarial parasites for thousands of individuals across North America.
• Behavioral and physiological responses to environmental change: As climate change and habitat alteration proceed at unprecedented rates, organisms are faced with the challenge to adapt or face extinction. Accordingly, biological processes are rapidly changing, with cascading effects through ecosystems. As examples, in the northern hemisphere wildlife species are shifting their distributions northward, reducing (or ceasing altogether) their migratory journeys, and breeding earlier each year in relation to warming global temperatures. In urban and suburban habits, animals are becoming more bold, altering their breeding schedules, and changing their physiology and immunity in response to the novel conditions associated with city life. Understanding the organismal and evolutionary mechanisms underlying such changes has become a critical aspect of both biodiversity conservation and public health.

                 Drs. Ketterson’s team is addressing this knowledge gap by examining the integrated roles of sensory systems, neural and hormonal processes, and gene expression profiles in facilitating responses to changing environments. Studies to date include evaluations of divergence in seasonal timing and migratory strategies in eastern Dark-eyed Junco populations, as well as hormonal and behavioral divergence in urban birds adapted to the constant disturbances and stresses of urban living, including frequent and unpredictable disturbances by people, vehicles, noise and light pollution, and novel communities of predators and parasites. For example, Dr. Atwell studied juncos, not previously known not to breed or live in the city, that started to breed on the rambunctious campus of University of California, San Diego in the 1980s. Dr. Fudickar’s recent work has characterized changes in hormonal and gene expression profiles that underlie shifts in seasonal timing in response to environmental cues. In order to see how the biology of birds change or “evolve” in response to the environment, Drs. Ketterson and Atwell continue to refine tools and approaches that will help track adaptation and diversification at multiple levels of the organism—from genes to tissues to behaviors.

• Testosterone and Aging: Over more than 30 years, Dr. Ketterson has established herself as a leading expert on the organismal and evolutionary importance of testosterone, the steroid hormone that underlies a host of behavioral and physiological processes in vertebrate animals, including humans. Her groundbreaking, long-term field experiments demonstrated previously undocumented ways in which testosterone facilitates tradeoffs among aggression, parental behavior, stress, immunity, and, ultimately, survival—studies that elucidated testosterone’s vital role in both males and females.

                 Most recently, Dr. Ketterson’s team has begun studying the role of testosterone in male aging. Because testosterone increases metabolism, it has been suggested to play a role in cellular aging through telomere loss—yet this predication has yet to be thoroughly investigated. The gold standard in aging research is to follow individuals over their lifetimes, and because Dr. Ketterson’s lab has studied natural and experimentally-augmented testosterone levels in marked birds in the field for several decades, they are perfectly positioned to use both existing and future datasets to determine generally whether individuals with higher testosterone levels age faster than usual.