Timothy Greives, PhD - US grants

0852986
Greives

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.

This award will support a twenty-four-month research fellowship by Dr. Timothy J. Greives to work with Dr. Michaela Hau at Max Planck Institute for Ornithology in Germany and with Dr. Tom Hahn at the University of California, Davis in the US.

Seasonal cycles in reproductive activity are observed in virtually all animals, including birds. These cycles represent adaptations that ensure offspring production during favorable environmental conditions. In the temperate-zone, photoperiod (i.e., day-length) provides a ?noise-free? seasonal cue that does not vary from year to year for a given day. Hence, most species rely on photoperiod to determine the time of year. Seasonal changes in reproduction have even been demonstrated in species living in relatively stable habitats (i.e., the tropics), suggesting that selection favors a seasonal regulation of reproductive activity across latitudes. However, the nature of the selection pressures that shape gonadal cycles in vertebrates remains unknown. This has been due, in part, to methodological constraints limiting the ability to modify experimentally the timing of gonad activation in the field. This fellowship tests the hypothesis that the precise timing of reproduction has evolved in response to fitness costs associated with mistimed breeding events. The timing of gonadal activation is being advanced in free-living great tits through manipulation of perceived photoperiod using a miniature light emitting diode (LED) attached to the birds? head, providing photoperiodic stimulation prior to the start of normal gonadal development. Further, the effect of mistimed reproduction on novel neuropeptides (e.g., kisspeptin, gonadotropin-inhibitory hormone) is being examined; this will enable a better understanding of their specific roles in regulating vertebrate reproduction. In Experiment 1, behavior, reproductive success and survival rates are being documented in breeding pairs. In Experiment 2, neuroendocrine responses to precocious photoperiodic stimulation will be investigated using state-of-the-art techniques. The proposed experiments are the first to advance gonadal development using photoperiod manipulation in a free-living vertebrate to quantify resulting effects on fitness.

Understanding the selection pressures that act on mistimed seasonal processes will help to resolve the question of why most avian species, and a large number of vertebrates world-wide, exhibit pronounced cycles in gonad size. They will also provide a unique opportunity to elucidate mechanisms by which diverse environmental cues are integrated within the brain. The knowledge generated will be useful in understanding the underlying processes (both ultimate and proximate) shaping the ability of populations and species to respond to global climate change or spread to new habitats.

This research asks how animals know whether and when to migrate and when to breed. The focal animal is a songbird in which populations with separate breeding ranges winter together but differ in whether or not they migrate. When spring arrives the non-migrants begin to breed, while the non-migrants delay breeding despite living in the same environment. Research on the mechanisms that account for different responses to identical environments could help to explain how animals monitor the environment and adjust their physiology to their needs. The dark-eyed junco is a songbird and an ideal model to address these questions.

This project will investigate plasticity in hormone systems using hormonal "challenges" and pharmacological manipulations. It will also explore differences in gene expression between resident and migratory juncos from recently diverged populations (California) and longer diverged populations (in Virginia) that over-winter together but breed in different places at different times. The prediction is that migrants will differ from residents in their response to challenges and that recently diverged populations will differ less than populations that diverged longer ago. Another prediction is that gene expression in a common garden will differ between longer diverged populations as compared with recently diverged populations.

Broader impacts
The research will enhance understanding of why and how some animals are able to thrive in changing environments, while other animals' ranges retreat, and some species are lost. This research will provide numerous opportunities to train graduate and undergraduate students, and knowledge gained will be disseminated broadly. The project will enable promotion of a documentary film starring the study species and designed for use in high schools and public venues for adult learners.

Data Management.
Data supporting results in published papers will be made available on Genbank and/or Dryad. All data generated from this research will be archived in an online repository maintained by the Indiana University Library (https://scholarworks.iu.edu/dspace/handle/2022/7911).

Non-technical Description
Temperate and arctic regions experience dramatic variations in environmental conditions across the year. For animals to be able to successfully rear offspring in these environments, reproduction must be limited to a short window of time that ensures favorable conditions (i.e., mild temperatures and abundant food resources). While prior research has revealed how male animals prepare for mating, much less is known regarding how females precisely time reproduction (and thus, the time when offspring are born or hatch), even though it is female timing that ultimately dictates when rearing of offspring will occur. Traits expressed by an individual (i.e., phenotype) are shaped by interactions between an animal's genetics and the environment. This project will enable training at Columbia University and knowledge transfer of techniques and skills aimed at uncovering the genetic processes that are capable of responding to the environment and regulating expression of key genes to influence female reproductive timing decisions. This training and knowledge transfer will enhance the research capabilities of the PI's laboratory and facilitate future collaborations within the PI's home institution of North Dakota State University and beyond. Such knowledge will not only contribute to robust basic knowledge, but also has the potential to enhance animal livestock breeding programs (e.g., sheep, which are seasonal breeders) to enhance economic productivity.

Technical Description
An organism's phenotype is the result of interactions between its genome and the environment. Understanding the processes that influence an individual's evolutionary fitness (i.e. lifetime reproductive success) requires investigations of the molecular architecture that shape an individual's phenotype. One primary way whereby the environment can influence which genes are expressed (which gives rise to the phenotype) is via epigenetic modification. The ability of an individual to produce and successfully rear young directly dictates an individual?s evolutionary fitness. In animals inhabiting temperate or arctic clines, reproduction must be limited to a short window of time that ensures favorable conditions for rearing offspring. Seasonal epigenetic modification of the DNA regulating production of yolk-precursor proteins may enable appropriate annual responses, inhibiting production of yolk precursors when favorable conditions are experienced at inappropriate times of year (e.g., the late winter warm period) while enabling yolk precursor production when favorable conditions are experienced in the appropriate season. Utilizing a songbird model of seasonal breeding, the Dark-eyed Junco (Junco hyemalis), this proposal will test the novel hypothesis that methylation of DNA in the regulatory region of an important gene needed for yolking and final follicle maturation is seasonally modulated. This project will provide training and transfer of knowledge of the skills and tools utilized to uncover epigenetic modifications that may influence an individual's phenotype and fitness. The training received at Columbia University for methods of detecting methylation in the genome will allow our group to test the hypothesis that seasonal information influences epigenetic modulation of the promoter region of a gene the codes for a key yolk pre-cursor protein, vitellogenin (VTG).

The CHANGE program will provide mentored research experiences for post-baccalaureate participants, many of whom will be from groups traditionally underrepresented in the Life Sciences. Mentees will engage in research projects across biological levels (e.g., molecules, cells, tissues, whole organisms, populations) exploring how organisms respond to rapidly changing environments. It is imperative to train future generations of biologists to be able to easily work and collaborate across different biological levels to build capacity for future discovery. The CHANGE network includes diverse experts from academia, a non-governmental organization, government agencies and industry, as well as network members focused on enhancing professional development of trainees. CHANGE will recruit post-baccalaureates from diverse backgrounds in order to broaden participation in scientific research according to several geographically relevant themes; diverse partnering institutions (including tribal colleges) will also benefit from this process. <br/><br/>Most organisms respond to predictable environmental changes across the day and year. However, anthropogenic influences have led to an increase in unpredictable perturbations and altered the timing and occurrence of previously predictable daily and seasonal changes. While some individuals and populations of the same species are adjusting, others may not, and there is a growing appreciation that a comprehensive understanding of this variation in resilience requires an integrative approach. The mentored research conducted by participants in the CHANGE program will identify fundamental properties of robustness and resilience that enable certain populations or species to persist in response to rapid environmental change. The research will provide insight into increasingly relevant questions such as the following: (1) What is the ability to change as the climate changes?; (2) Does variation at critical levels or organization enable response to future change?; and (3) What responses enable adaptive change? The CHANGE program will employ evidence-based practices to create a community of practice, with intentional mentoring that enables a supportive, individualized learning and research environment. Through participation in the CHANGE program, participants will be prepared to become leaders in a rural, EPSCoR state and capable of tackling basic biological questions while engaging with questions of biological importance for the Upper Midwest on a changing planet. One unique goal of the CHANGE program is to systematically develop and disseminate an evidence-based model of mentoring post baccalaureates. In this way, our network will enhance national efforts to establish programs that are more inclusive of diverse populations.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.