Electronic Theses and Dissertations

Identifier

4876

Date

2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Biology

Committee Member

Duane D McKenna

Committee Member

Matthew J Parris

Abstract

Developing young are exposed to many factors that influence behavior and physiology. During development, circulating hormones, such as the metabolic hormone corticosterone (CORT) can have organizational effects on the central nervous system that may determine a fixed adult behavioral and physiological phenotype. The main objectives of this research were to determine whether environmental and physiological factors 1) influence variation in nestling behavior and physiology and 2) contribute to the development of the adult physiological and behavioral phenotype in a free-living avian model, the Florida scrub-jay (Aphelocoma coerulescens). I investigated the short-term effects of CORT exposure on growth and begging behavior by manipulating CORT levels in nestlings by feeding individuals a CORT-injected waxworm. I determined that exposure to increased CORT did not alter begging rate of the treated individual relative to its siblings, but instead increased the begging rate of all nestlings within a treatment nest whether they received the treatment or not. I then investigated whether nestling CORT levels were altered by parental provisioning and found that nestlings that were fed more frequently and more recently prior to sampling collection had higher CORT. To determine whether developmental CORTexposure had long-term effects on neophobia and stress responsiveness at one year-of-age, Itested all individuals to assess their degree of neophobia by placing a novel object in their home territory and recording their behavior. I also trapped and collected blood samples from all individuals to determine their degree of stress responsiveness to a standardized capture and restraint test. My results revealed that CORT-treated individuals had lower baseline CORT levels, but higher stress responsiveness at one year-of-age. Treatment had no detectable effect on neophobia. I also determined that there exists a relationship between begging behavior and an individual's future physiological stress response. Together, these results indicate that many factors during development may influence the behavior and CORTlevels of individual nestlings, including adult provisioning and sibling interactions. Further, these developmental experiences may have long-term effects on the physiological stress response of Florida scrub-jays. Increased understanding of the long-term impacts of early experience on an animal may faciliate future conservation efforts of many species.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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