Prolactin is often referred to as the “parental hormone” because there is a clear and well-established role for this hormone in maintaining parental behavior in many animals. Yet, there is a seasonal prolactin peak in avian obligate brood parasites, which are birds that leave their eggs in nests of different species rather than build their own nest, incubate their own eggs and feed their own newborns. Elevated prolactin in species that provide no help to their offspring indicates that circulating prolactin levels may be insufficient or misleading in assessing how levels of this hormone motivate parental care. The studies will examine the disconnect between prolactin and parental care in avian brood parasites. The aim of these studies is to identify the molecular and neurophysiological building blocks of parental behavior and how modification in these building blocks result in striking transformations in parental care. Additionally, these studies investigate consequences of altering prolactin receptor on parental behaviors using modern gene manipulation approaches that increase prolactin receptor abundance in the brain of nest parasites and decrease prolactin receptor abundance in non-parasitic birds. Citizen scientists will participate in the field components of these studies, including students from programs promoting interaction of girls with female scientists so that they may view science careers as realistic options. Robotic birds used in the research will also be a component of summer research camps that will introduce high school students to biological experiments using robotics. Cutting-edge gene manipulation approaches will provide hands-on experience for undergraduate students in lab courses.

Parental care is critical for survival of offspring in many species. Yet, there are profound differences in parental care across species, sexes and individuals. These comparative studies take advantage of natural variation in parental care to identify the neurobiological- and molecular-basis of brood parasitic behavior in birds. Avian obligate brood parasites evade providing parental care to offspring by laying eggs in nests of other species, which releases the parasite from parental tasks but ensures that parasitic offspring receive necessary provisioning until they are independent. Some brood parasitic species, however, display seasonal surges in prolactin, a hormone well-established as the “parental hormone”. These studies include a blend of field and laboratory studies aimed at understanding the disconnect between prolactin and parental care in brood parasitic species. These aims track prolactin-dependent physiology and behavior across development in two closely related species with stark differences in parental care and identify whether prolactin physiology exhibits convergent features across phylogenetically distantly related brood parasitic species. The prolactin-related physiology to be investigated includes circulating prolactin, prolactin receptor isoforms and prolactin-regulated intracellular messenger systems, specifically the janus kinase/signal transducers and activators of transcription (i.e. JAK/STAT pathway). Prolactin-dependent behavioral responses to robotic nestlings will be investigated across development and breeding status as well as in transgenic parasitic and non-parasitic birds with altered prolactin receptors using adeno-associated virus and RNAi approaches. These studies will provide a long overdue mechanistic perspective to understanding the evolution of brood parasitism and provide insight into possible neurobiological mechanisms associated with novel behavioral phenotypes.

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.

National Science Foundation (NSF)
Division of Integrative Organismal Systems (IOS)
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Jodie Jawor
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Hofstra University
United States
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