Year: 2012
Type: dissertation
Abstract: ABSTRACT \nEnvironmentally-induced stereotypic behaviour (SB) results from the chronic impact of \ncaptivity on brain development and function and, consequently, on behaviour. My study \nsought to determine group- and individual-level predictors and correlates of SB in the striped \nmouse, Rhabdomys dilectus, and to identify the mechanisms underlying the stereotypic \nphenotype. This aim was addressed by collecting cross-sectional and longitudinal behavioural \nand physiological data from a combination of wild-caught (WC) and captive-born (CB) \nstriped mice born and reared in different social and environmental conditions. First, I \nexamined the group-level effects of rearing conditions. Results confirmed the genetic \ncontribution to SB performance in striped mice, and furthermore indicated that (1) striped \nmice weaned at or later than their natural weaning age are less likely to develop SB than \nstriped mice weaned prematurely; (2) striped mice reared biparentally showed significantly \nless SB as adults than striped mice reared by their mothers alone; (3) striped mice raised from \nweaning in enriched conditions were four times less likely than standard-housed individuals \nto develop SB, an effect which endured after enriched-housed striped mice were transferred \nto standard housing; and (4) birth origin predicts the emergence of SB in striped mice, with \nthose WC individuals trapped as adults being relatively protected from the development of \nSB compared with both WC individuals trapped as juveniles and CB striped mice. I also \nshowed that (1) WC striped mice were more fearful and less active than CB animals, but that \nthese traits did not covary with SB, and (2) WC striped mice were less perseverative and \nbehaviourally more flexible than CB animals, traits that did covary with SB. Second, I \ncharacterized the developmental trajectory of SB in a large group of CB, standard-housed \nstriped mice, and then investigated potential individual-level predictors, mediators, and \ncorrelates of SB in these animals. Measures of perseveration, activity, and anxiety/fearfulness \nassessed in juveniles before the development of SB did not predict which animals later \ndeveloped SB, but stereotypic adults were more active and more perseverative than nonstereotypic \nindividuals. Whilst preweaning developmental maturity did not predict which \nstriped mice later developed SB, striped mice showing accelerated development in the \npreweaning period were likely to show SB at an earlier age, at a higher frequency, and \npotentially with reduced variability, effects which persisted into adulthood. In conclusion, my \nstudy shows that more naturalistic rearing environments reduce the incidence of SB, an effect \nmediated by genetic factors and possibly also by experience-dependent alterations in \nforebrain function. However, further work is necessary to explore whether the association \nbetween forebrain function and SB expression in striped mice is causal because, whilst \nenvironments which decrease perseverative tendencies also reduce SB, I found no evidence \nthat such tendencies predict which striped mice later develop SB.
Author: Megan A. Jones
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2286860700