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Title:Effect of selection for interspecific behavior on stress and conspecific behavior in tame and aggressive foxes
Author(s):Ford, Alexandra
Advisor(s):Kukekova, Anna
Contributor(s):Bahr, Janice; Stumpf, Rebecca
Department / Program:School of Integrative Biology
Discipline:Ecol, Evol, Conservation Biol
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:Domestication of a species is a process that involves the evolution of a species overtime, influenced by a combination of genetic mechanisms and environmental events. As a domestic phenotype begins to develop over generations, physiological, morphological, and behavioral changes start to appear, a phenomena known as “domestication syndrome”. Exploring the mechanisms behind these early changes observed during the process of domestication would allow for further understanding into the physiological and behavioral differences between domesticates and their ancestral counterpart. Two strains of foxes developed at the Russian Institute of Cytology and Genetics by selecting foxes solely for behavior, specifically for a friendly or aggressive response to humans, provide a unique model of long-term selection for specific behaviors that allows for detailed analysis of physiological and behavioral mechanisms responsible for changes in behavioral responses to humans observed in domesticated animals. One result of selection for tameness included a decrease in basal adrenocorticotropic hormone and cortisol levels in blood and overall less stress-sensitivity of tame compared to aggressive foxes. Our first aim was to develop and test a method for noninvasive measurement of fecal glucocorticoid metabolites (FGM) as a proxy for hypothalamic-pituitary-adrenal (HPA) axis activity in tame and aggressive foxes. Glucocorticoid measurement from fecal samples is a practice that has been validated in other canids, such as coyotes and dogs. Fecal samples were collected six month-old tame and aggressive male foxes to develop a profile of FGM present in fox feces in order to determine the most abundant glucocorticoid for analysis. Identification of the most abundant glucocorticoids in the fox feces was imperative to choosing the most appropriate antibody to conduct the analysis with an enzyme immunoassay (EIA). Proper validation of the EIA through parallelism and accuracy to ensure the precision with which the glucocorticoid concentrations were measured was executed. Our results showed that individual’s FGM concentrations vary from day to day and found lower FGM concentrations overall in tame versus aggressive foxes. High individual variation was observed, especially within the aggressive population, suggesting that changes in the environment on a daily basis may affect fox FGM concentrations. This is the first study measuring stress hormones through fecal glucocorticoid metabolite analysis in tame and aggressive fox populations. The validation of this technique should allow further investigation of HPA activity associated with selection for behavior. While we are aware of the immense differences in behavior between the two populations regarding their response to human interaction, whether the long-term selection for tame and aggressive behavior towards humans has an influence on conspecific behavior has yet to be addressed. Our second aim was to investigate how selection for tameness and aggression towards humans is related to concurrent behavioral changes observed in conspecifics in tame and aggressive foxes. Through development of an ethogram for a pair interaction in a three-cage apparatus we conducted extensive behavioral coding of video tape interactions between mixed (tame-aggressive) and same-type (tame-tame, aggressive-aggressive) dyads. We found that tame individuals spent more time together and were more likely to initiate interactions both with another tame fox and aggressive foxes. Aggressive foxes were more likely to show agonistic behaviors such as pawing and spent significantly less time exploring their enclosure compared to tame individuals. These results suggest that intense selection for human-directed behavior has an influence on how individuals behave towards conspecifics and led to consistent temperament changes in tame and aggressive foxes. To better understand the physiological and behavioral differences between tame and aggressive foxes, it was important to establish and validate an effective non-invasive method to measure fecal glucocorticoid metabolites. This will allow future investigation into the developmental differences between these two fox populations to determine how genetic and environmental components play a role in the onset of the fear response and HPA axis maturation and influence adult behavior. Investigating the social behavior of foxes from these two populations allowed us to understand how intense selection for human-directed behavior can influence conspecific behavior. Observing such similar behaviors in each populations when interacting in different social contexts compared to how they interact with humans indicates that certain behavioral traits are not as flexible as previously assumed.
Issue Date:2019-04-22
Rights Information:Copyright 2019 Alexandra Ford
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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