John C. Wingfield - US grants

High-latitude environments impose constraints on breeding activities of migratory birds which necessitate adjustments to a much shorter season. Environmental constraints may have been met by adaptations of the endocrine system which serve to fine-tune breeding activities to suit arctic conditions. It is proposed that the endocrine systems of polar nesting birds display decreased sensitivity to stimuli that would result in rapid and disruptive elevations of hormones which could affect breeding or nesting activities at inappropriate times. The roles of two potentially antagonistic hormones will be examined: testosterone, which elicits territorial aggression; and corticosterone, which can act to inhibit reproductive activities including territorial aggression. The endocrine adaptations to be investigated in this research program may elucidate physiological mechanisms by which polar animals avoid delays and/or conflicting behaviors which might reduce chances for successful reproduction.

Vertebrates have diverse reproductive cycles spanning continua from brief to prolonged breeding seasons, and from precisely timed to opportunistic reproductive periods. Variations in the timing of gonadal maturation and onset of breeding require that individuals of a population or species adjust secretion of reproductive hormones in response to environmental signals. Dr. Wingfield proposes to develop a mathematical model to describe the type of breeding cycle for a given population. Of particular interest are the degrees of constancy and contingency within a particular breeding cycle. The more constancy within a cycle (e.g. the environment is in a state conducive to breeding most of the time), then less environmental information is required to regulate secretion of reproductive hormones and thus optimize breeding. As contingency in the cycle increases (e.g. the environment shows major changes in suitability for breeding within a year), more environmental cues are required to time onset of breeding. The PI has chosen several avian species, with varying degrees of constancy and contingency in their reproductive cycles, as tests of this model. The responses of each species to environmental signals known to influence reproductive function (e.g. annual change in daylength, temperature, availability of food) will be tested. Their effects on gonadal development, and secretion of reproductive hormones will be measured. Ultimately, the effects of these environmental cues on gene expression for hormones within the brain, that act as a link between the environmental and internal processes, will also be determined. The proposed research is designed to explore the possibility of a unifying theory that can be used to predict how all vertebrates (and perhaps all organisms) integrate signals from the environment in order to optimize reproduction. It may also be possible to use this model for processes other than reproduction (e.g. migration, growth etc.) The research will provide new insight into the mechanisms by which environmental signals are transduced into internal processes (such as hormone secretion) that regulate reproductive function. This may have considerable impact on our knowledge of reproduction in general, and could provide a firm base for approaching problems of how to breed and protect endangered species and populations.

Little is understood of how environmental and social factors, particularly territorial aggression, affect the breeding of migratory arctic birds. Relationships between reproduction and environmental induced stress, where they play an important adaptive role, are virtually unknown in high latitude species. Many species arrive in the arctic,establish territories and eventually feed their nestlings in a fraction of the time for temperate birds. Adherence to this rigorous schedule, pairs must ignore environmental conditions that would normally inhibit or delay breeding at temperate latitudes. Dr. Wingfield proposes that these constraints have been met by adaptations of the endocrine system in arctic birds. This study proposes to continue examining the relationship between two potentially antagonistic hormones: corticosterone, which directs behavior away from reproductive activities and towards survival activities and testosterone, which mediates the aggressive behavior associated with territoriality. In both hormone-behavior systems, Dr. Wingfield suggests that the endocrine responses of arctic-nesting birds will show decrease sensitivity to environmental stimuli, allowing more prolonged opportunities to breed. The endocrine adaptations to be investigated in this research program may elucidate physiological mechanisms by which polar animals avoid delays and/or conflicting behaviors which might reduce their chances for successful reproduction.

This award will support a two-year U.S.-Japan cooperative research project between Professor John Wingfield, Department of Zoology, University of Washington, and Professor Masaru Wada, Department of General Education, Tokyo Medical and Dental University. Dr. Wingfield studies the role of environmental factors in controlling the breeding cycle in birds. His present research involves assaying reproductive hormones in different species on birds under different environmental conditions. His project with Professor Wada involves collaboration to develop and apply cDNA probes for the reproductive hormones in chicken, since these probes will hybridize with the pituitary DNA of these birds. Avian reproductive cycles are diverse, spanning continuums from brief to essentially continuous breeding seasons, and from precisely timed to opportunistic reproductive periods. This collaborative effort will measure changes in gene expression for reproductive hormones in response to environmental signals. This will extend Dr. Wingfield's current research to test a constancy/contingency model of predictability as a potential unifying hypothesis to explain how birds, and perhaps other organisms, integrate environmental maturation under varying environmental conditions.

This is a Shannon Award providing partial support for research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. Further scientific data for the CRISP System are unavailable at this time.

Arctic breeding birds arrive on their nesting grounds at a time when weather conditions may still be extreme (low temperature, snow). However, the brief arctic summer requires that they begin nesting as early as possible to take advantage of the ephemeral abundance of food to feed young. Failure to adhere to this rigid schedule results in drastically reduced reproductive success. Hormone-behavior adaptations that maximize survival and reproductive success under the extreme conditions of the Arctic are the focus of this proposal. It has been shown that the interrelationships between testosterone and territorial aggression are diverse, especially as birds arrive on the arctic breeding grounds. In some species territoriality is extremely brief, following which birds apparently become refractory to the effects of testosterone. Others are territorial throughout the breeding season, but the dependence of these behaviors upon testosterone activation remains unclear. Aggressive behavior of between four and seven arctic breeding passerines displaying different types of territoriality will be compared. Temporal patterns of testosterone in relation to patterns of aggressive behavior and the effects of manipulating testosterone level will also be determined. Additionally, these species will be compared with their closest relatives breeding at mid-latitudes (i.e. matched pairwise comparisons to avoid confounding issues relating to phylogenetic relationships). In this way it is possible to determine the ecological bases of different types of territorial behavior and interrelationships with testosterone, as well as indicate potential specializations of arctic breeding birds. The same spectra of species in the Arctic and at mid-latitudes will be used to compare adrenocortical responses to stress. Extensive data now indicate that arctic birds modulate the secretion of corticosterone in response to a standardized capture stress protocol as a function of latitude and stage in the breeding cycle. This is thought to be an adaptation to allow onset of territorial behavior and breeding in the face of potentially stressful conditions. Both arctic and mid-latitude species will be compared. Behavioral and physiological responses to corticosterone treatment will be determined within these species comparisons to indicate how endocrine mechanisms may vary in relation to latitude and other ecological factors. Finally, laboratory experiments will assess the number and distribution of receptors for testosterone (and possible metabolites) and corticosterone in the central nervous system. This unique approach of field experiments to compare types of territorial behavior in arctic and mid-latitude passerines, effects of hormones and stress, and ultimately the related distribution of hormone receptors in the brain will not only pinpoint specific adaptations for birds breeding in the Arctic, but will have significance for the regulation of reproductive processes of vertebrates in general.

This study seeks to understand how variations in climatic conditions alter the reproductive cycles in three populations of white-crowned sparrows living in diverse habitats within a relatively small area of western Washington state. The research will integrate field and laboratory studies on reproductive function. Comparisons between populations will be made of behavior and reproductive state in the springtime and experimental manipulations of environmental cues suspected of signaling environmental change will be performed. The long range goal of the project is to determine the extent and function of pathways in the brain of these animals for environmental signals that regulate changes in appearance and behavior. Such information is critical to understand, in general, how animals react to their habitat to aid us in the future in solving problems associated with global warming and habitat destruction. Understanding the mechanisms by which vertebrates transform environmental information into morphological, physiological and behavioral adjustments may help us evaluate the extent to which species are able to adapt and how we may fare in a changing environment.

This study proposes to examine the hormone-behavior adaptations that maximize survival and reproductive success in birds breeding in the extreme conditions of the high Arctic. The focus will be on a typical high Arctic seabird, the Dovekie (Alle alle), and two typical arctic passerines, the Lapland Longspur (Calcarius lapponicus) and Snow Bunting (Plectrophenax nivalis). Temporal patterns of testosterone, breeding condition, and reproductive success will be studied, as well as adrenocortical responses to environmental stress. Field studies will be conducted in northern Greenland using Thule AFB as a logistical staging area. This will be the first study in the region using these techniques and and logistical capabilities. Because these techniques are inherently risky and the logistical demands are extreme, the PIs have chosen to submit a proposal of limited scope under the guidelines of the Small Grants for Exploratory Research (SGER) program.

We propose to investigate the environmenmtal control of breeding in populations of "crowned sparrows" of the genus Zonotrichia. We have identified key populations in Artic, mid-latitudes and equatorial regions that express the full spectrum of extreme inflexibility of timing (Artic) to almost complete flexibility and asynchrony (equatorial regions). Intermediate degrees of flexibility are found at mid-latitudes. We also have a large corpus of data from a population of Melospiza melodia in western Washington State that expresses a similar cline of reproductive flexibility showing most plasticity in mild, coastal habitats and least flexibility in high altitude habitats in the Cascade mountains. Field experiments will determine how flexible breeding seasons are within each habitat. Parallel laboratory experiments will explore further how environmental signals such as change in day length, temperature, food and water interact with social cues to regulate neuroendocrine and endocrine secretions that orchestrate reproductive development. The results will have practical application on how vertebrates may respond t global change in the near future.

Male birds participate in parental care more than males of any other vertebrate group. Thus, birds represent an extraordinary model to untangle the various factors that affect care of young. When breeding begins, males experience a rise in the hormone testosterone (T) that declines by the time young hatch. This pattern may represent a trade-off between T levels and expression of paternal care: experimentally, high levels of T are associated with reduced paternal care in favor of enhanced sexual behavior. In chestnut-collared longspurs (CCLO), experimentally increased T enhances sexual behavior before eggs hatch, but surprisingly, does not reduce care of nestlings. This study will test the hypothesis that this unusual insensitivity to T during the parental phase occurs because males are critical for nestling survival. By manipulating environmental and hormonal variables, this study will determine (1) if male care is essential, (2) if the environment drives male care, and (3) if elevated T affects nest defense in CCLO. Male care, though generally rare in nature, is prevalent in birds. Whether paternal care is driven by environmental factors or by internal cues, however, is unknown. This study will help to unravel the relative roles of hormones and environmental cues on the expression of paternal care. Determining the role of environmental factors in the apparent trade-off between T and paternal care is particularly important, because it can be applied to additional systems in which paternal care is critical for survival of young.

This research project involves field and laboratory studies on the physiological and behavioral adaptations of birds to the extreme conditions that prevail in Arctic environments. The study will focus on four bird species found at sites in Greenland and Alaska that represent a series of harsh polar conditions. The effect of different environments on breeding will be determined in order to examine the role of climate. Blood samples and steroid treatment will be used to test hypotheses about the role of environmental conditions on testosterone production and its effect on reproductive behavior during the breeding season. The results will be used to examine the potential effects of changing climate conditions, such as global warming, on the breeding behavior of birds that migrate into the Arctic.

DESCRIPTION (provided by applicant): A directly inhibitory neuropeptide for gonadotrophin release has, until recently, remained unknown. Last year, a novel neuropeptide was found specifically to inhibit pituitary gonadotrophin release in vitro. This peptide has now been named gonadotrophin inhibitory hormone (GnIH). A gonadotrophin inhibitory system is a novel concept for the environmental control of reproduction in any vertebrate. The overall aim of this application is to provide a thorough characterization of the biological activity of the GnIH peptide system. We propose to establish the site(s), nature and mode of action of this peptide system. With such fundamental information in hand, we can then determine whether this peptide system is an integral component of how the brain transduces environmental cues into signals that affect reproduction as a whole. We recognize that there is great potential from the discovery of this peptide system, but some groundwork needs to be performed upon which to build a research program. A thorough characterization and experimental demonstration that the GnIH system plays a fundamental role in the regulation of reproductive function, both biochemical and behavioral, needs to be mapped out. Specific aims are: 1) Based upon our preliminary immunocytochemistry (ICC) data, we will identify the central locations of synthesis and storage of GnIH peptides, using situ hybridization and ICC. 2) With preliminary data in hand, we will build upon on the effects of GnIH on gonadotrophin release in vivo by identifying its specificity of action, and by using established behavioral assays for its effects. This will be performed via central infusion and subsequent behavioral quantification. 3) The locations of action of the GnIH peptide will be identified using iodinated ligands for receptor autoradiography on neural tissues. Potential sex differences in receptor distribution will also be investigated. Receptor binding characteristics will be quantified using Scatchard analysis. The studies outlined in this application will provide a new level of understanding of the neural basis of reproduction that can then be applied to reproductive research in general.

DISSERTATION RESEARCH:
HORMONAL REGULATION OF IMMUNE FUNCTION
IN SEASONALLY-BREEDING BIRDS

Noah T. Owen-Ashley & John C. Wingfield

University of Washington, Seattle

The steroid hormone testosterone (T) is thought to have bidirectional effects on fitness in many vertebrates. T is important in orchestrating reproductive and aggressive behavior in males, and promoting the development of many secondary sex characters important for female choice. On the other hand, high levels of T are thought to suppress immune function. Many studies in birds have found that T suppresses some component(s) of the immune system, but it is not known if this mechanism occurs through direct or indirect pathways. The main goal of this research is to understand the contributions of these pathways in regulating T-induced immunosuppression in the Northwestern Song Sparrow (Melospiza melodia morphna) and the White-crowned Sparrow (Zonotrichia leucophrys). Experimental elevation of T in many bird species alters the levels of other hormones, such as corticosterone and estradiol, which also regulate immunity. Therefore, avian immune function may be altered through these intermediary hormones, rather than by testosterone directly. A suite of experiments will be conducted on both species involving the use of hormone implants and/or pharmacological blockers to tease apart these direct and indirect effects on physiological and behavioral immune function. These studies will provide new insights into hormonal regulation of immunity in seasonally-breeding birds, and reconcile existing theories which assume a direct role of T in regulating a tradeoff between immunocompetence and reproductive success in male vertebrates.

This proposal will investigate the environmental control of breeding in populations of "crowned sparrows" of the genus Zonotrichia. Key populations have been identified in Arctic, mid-latitudes and equatorial regions that express the full spectrum of extreme inflexibility of timing (Arctic) to varying degrees of flexibility and asynchrony at mid-latitudes and equatorial regions. Field experiments will determine how flexible breeding seasons are within each habitat. Particular emphasis will be placed on how social interactions within and between sexes contribute to the synchronization and temporal organization of the breeding cycle. Parallel laboratory experiments will explore further how environmental signals such as change in day length, temperature, food and water interact with social cues to regulate neuroendocrine and endocrine secretions that orchestrate reproductive function. Of particular importance are investigations of novel peptides in the hypothalamus that may provide pathways for these environmental signals. The results will have practical applications for how vertebrates may respond to global change in the near future, and will provide unique insight on how environmental control mechanisms evolved. Some populations may be able to adjust, whereas others may not, possibly indicating where future conservation efforts should be focused. The project will provide a framework for education at undergraduate and graduate levels, as well as for outreach to an ongoing project with a local high school.

Award Abstract

The symposium entitled: "EcoPhysiology and Conservation: The Contribution of Endocrinology and Immunology" sponsored by the Society of Integrative and Comparative Biology, examines the contributions that ecophysiologists are making to conservation biology. This symposium will focus on overviews of endocrinology and immunology with a special emphasis on endocrine disruptors in marine, aquatic and terrestrial invertebrates, which are important to environmental monitoring. New perspectives from the symposium will aid biologists in identifying stressed individuals, reproduction problems, source and sink populations, carrying capacity of specific sites, and landscape features that promote the survival of populations and new metrics to quantify ecosystem health. These perspectives will provide a mechanistic linkage across multiples levels of biological organization, centering on the individual organism. Resulting publications and a website from this symposium will launch a new direction in organismal physiology called Conservation Physiology. This field will draw attention to the role that physiologists can play in conservation biology, spur conservation biologists to revise their text books to incorporate physiological perspectives, encourage ecophysiologists to undertake conservation problems, and will also provide fresh examples and materials for undergraduate and graduate teaching. The combination of physiology and conservation biology in the new field of Conservation Physiology will have broad impacts on the fields of integrative and organismal biology.

Research Coordination Network: Integrating Ecology and Endocrinology in Avian Reproduction.
John C. Wingfield


This network will coordinate research activities of ecologists, and endocrinologists on a specific theme - reproduction in birds. Research will cover the full spectrum from field ecology to molecular mechanisms. A critical goal is to develop a framework whereby organismal biologists can communicate effectively with cell/molecular biologists (endocrinology) and bridge a conceptual rift that has been widening for several decades. Avian reproduction provides an ideal focus because of extensive literature from genes to ecosystems. The proposed collaboration and the resulting network will have direct application to programs integrating organisms and molecules throughout biological sciences.
The network will allow educational revision at K-12, undergraduate and graduate levels and will facilitate a truly integrative, biology curriculum including conservation biology. Activities will include workshops aimed at developing ecologically based studies at physiological, cell and molecular levels. Technical meetings will identify mechanisms that can be brought to bear on novel investigations including those with conservation emphasis. Laboratory exchange visits involving faculty and students will follow workshops. A web site will be developed to promote this new framework as well as collect databases that can be used for research analysis and education. Links to this web site will be made with other national and international groups so that network resources will be available to all of the scientific community, K-12 schools and the public at large. Faculty and student participants have been identified that represent diversity and more will be specifically invited to participate.

Global climate change is resulting in dramatic adjustments of migrations, breeding seasons and other aspects of the life cycle of organisms. Some populations flourish, others decline and yet others remain unchanged. Why this variation? A population of songbirds (White-crowned Sparrow, Zonotrichia leucophrys pugetensis) has recently been identified that has colonized urban habitat in Seattle as well as taken advantage of human disturbed areas in the Cascade Mountains of Washington State. These birds have settled in new habitat and their populations have expanded dramatically in the last twenty years. These populations are now in contact with alpine sub-species (Z.l. gambelii) that is not changing its range. Furthermore, there is a non-migratory, coastal sub-species (Z.l. nuttalli) that also is not changing its range. Accumulating data show that the sub-species that is changing its range is also changing hormone-behavior mechanisms to match the alpine sub-species. This includes the hormonal responses to stress. These responses are modulated up in the spring and down once nesting begins in the alpine and northern sub-species, but not modulated in the coastal sub-species (including the populations of Z.l. pugetensis in ancestral, coastal, habitat). Populations of Z.l. pugetensis that have colonized urban and alpine habitats now modulate their hormone responses to acute stress as do the northern and natural alpine sub-species. The current project will determine whether this is an epigenetic effect or rapid evolution of new traits. This will include potential epigenetic regulation of gene transcription in ancestral populations and pioneer populations of Z.l. pugetensis, compared with the sub-species Z.l. gambelii and Z.l. nuttalli that are not changing their ranges. This research will be a new blend of cell and molecular techniques in ecological settings in relation to global change. At least two graduate students will be involved in the field work and developing molecular methods for the epigenetic work. This project will likely become the focus for thesis research for these two students and undergraduate students will also join the project through this spring and summer.

The University of California Davis is awarded a grant to acquire and deploy specialized receiver/antenna units that will enable automated animal telemetry at the Quail Ridge Natural Reserve using the existing wireless communications towers. The project will also enhance the wireless communications at the UC Davis West Campus Reserve (Putah Creek) and establish a compatible telemetry receiver network at that site. The proposed system is compatible with a diverse range of available radio transmitter devices and will allow researchers visiting the sites to pursue continuous, real-time animal movement and physiological studies that would be technically difficult or impossible in settings without an extensive off-grid communications infrastructure. A key objective of the automated telemetry program at Quail Ridge will be the integration of animal movement information from the reserve into the NSF-funded Movebank database.

Automated animal telemetry systems provide an unparalleled opportunity to study animal movement, interaction, and physiology. With such systems, signals from tiny transmitters attached to individuals are detected by a network of receivers, which interpret signal strength and direction to determine real-time animal location and activity; the transmitters may also communicate physiological parameters such as body temperature and heart rate. Data collected by the network are then streamed to the web, where researchers, instructors and students have instant access. In spite of the enormous potential of automated telemetry networks, very few operational systems exist. The daunting investment necessary to establish such a system, given the challenges of constructing receiver towers, providing electric power, and building a functional communications network in a remote setting, has greatly limited their implementation.

Most vertebrates live more than one year and are subjected to varying degrees of seasonal changes in diverse habitats. Animals must also cope with unpredictable events that include stresses from severe weather events, predators and recently, human disturbance, pollution, global climate change etc. Changes in morphology, physiology and behavior that underlie coping mechanisms for predictable and unpredictable environmental changes are regulated by neuroendocrine and endocrine secretions that in turn are triggered by environmental signals. Except for effects of photoperiod, relatively little is known about how environmental signals are perceived and transduced into neuroendocrine secretions. This project is to determine how animals in their natural habitat perceive environmental cues and how this information is processed resulting in responses. The work will involve both field and laboratory approaches that also provide an ideal training opportunity for undergraduate and graduate students. Such an approach is timely given the impact of global change and how organisms in general may be able to cope. Fieldwork will address the degree of seasonality, behavioral modulation and responses to acute stresses in populations of songbirds at comparable latitudes and altitudes in North and South America. Laboratory studies will focus on mechanisms at cell and molecular levels. What environmental cues are important, how are they perceived and transduced into hormone secretions, and how do those hormones then act are the focus of this project. In addition, the PI has developed an environmental endocrinology course for undergraduate and graduate students (including international courses)and leads a NSF research coordination network.

As a consequence of global warming, arctic North America has been ?greening? over the past several decades, with increases in relative abundance and size of shrubs documented in numerous locations. Much of the research on this topic examines how this shift toward more woody species affects element cycling, particularly carbon, with potential feedbacks to the atmosphere regionally and globally. To date, the response of higher trophic levels to such shifts in vegetation in the Arctic has not been well studied. One group that has been almost completely ignored is migratory songbirds; they have a complex relationship with shrubs that provide both shelter and food, both of which are directly affected by weather patterns. This research will characterize the interactions between tundra vegetation and migratory songbirds in habitats that differ in shrub dominance for five consecutive growing seasons that will differ in timing and severity of weather events. The team will 1) identify and characterize interactions between shrub dominance and weather to determine how these affect food and shelter availability for migratory songbirds; 2) examine how reproductive success of populations of two songbird species responds to variation in both shrub dominance and timing of spring snowmelt, and; 3) measure how both variation in shrub dominance and timing of spring snowmelt affect composition and size of the entire songbird community. The multi-year approach will allow for examination of how interannual variability in arctic seasonality, particularly the timing of snowmelt, impacts songbird communities. Because the increasing shrub dominance is occurring too slowly for organisms to respond to during the time period of a grant, the researchers will examine habitat usage in open tundra plots, moderate shrub dominance plots, and high shrub dominance plots, at each of four study sites on the North Slope of Alaska. These include Atigun Valley, one of the first tundra stops made by migratory songbirds as they travel north, and at Toolik Lake, farther north, including two additional sites farther north to increase the spatial scale of sampling. In five project years, they will sample intensively at all four field sites to investigate spatial and temporal variation in plant resources, arthropod abundance, songbird community composition, and the arrival, settlement and reproductive success of two songbird species. During five years they hope to capture a range of interannual variability in weather, onset of spring snowmelt, and biotic responses to provide and understanding of current relationships and to predict how future changes in climate and vegetation may affect these organisms. They also intend to verify the use of remote techniques for monitoring bird community attributes via bioacoustic recordings for conducting automated bird community censuses.

Extreme weather events such as storms, are increasing in frequency, duration and intensity. Couple this with other global changes resulting from human disturbance and it is clear that mechanisms underlying organism-environment interactions in response to stressful environmental factors are key. These responses, often called the "stress response" help the animal cope through the modification of physiology and behaviour that promote survival. The focus here will be on the stress hormone responses, particularly from the adrenal gland, that are a highly adaptive suite of physiological and behavioral traits that are conserved across vertebrates including humans. A basic understanding of how seasonal modulations of the stress response works will allow us to predict how vertebrate organisms adjust their physiology and behaviour in response to an increasingly capricious environment as well as across a species' range with an emphasis on those populations that are on the limits of, or have pushed beyond, their geographic range. The PIs aim to educate K-12 students and teachers, while also reaching out to under-represented minorities (particularly Latinos in California) to enhance awareness, and conservation, of habitat for all organisms as well as birds. In these ways the work can be broadly disseminated to the public at large. In an era of dramatic environmental change, public awareness is critical and the broader impact activities will have far reaching influence.

Mechanisms underlying organism-environment interactions in response to perturbations of the environment are key for survival. The focus here will be on the hormonal response, particularly corticosteroids from the adrenal gland. The PIs have a good understanding of the responses to environmental stress in biomedical contexts, often under the chronic stress paradigm. However, these approaches do not mimic nature in which organisms experience seasonal cycles in environmental conditions and the stress response is modulated accordingly. Understanding how individuals push the boundaries of their coping strategies as well as geographic range is critical both from a basic science standpoint and for conservation. The proposed work will assess how the adrenocortical stress response is regulated using both laboratory and field studies to inform us of what brain centers are responsible for controlling seasonal fluctuation in the stress response. In addition, the focus will be on how the activity of these brain regions fluctuates across the annual cycle of environmental severity, and also across a species' range with an emphasis on those populations that are on the limits of, or have pushed beyond, their geographic range. A basic understanding of how the HPA axis works in species that undergo seasonal modulations in the stress response will also allow the PIs to predict how vertebrate organisms adjust their physiology and behavior in response to an increasingly capricious environment.