Date

2014

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Integrative Biology

First Adviser

Itzkowitz, Murray

Other advisers/committee members

Godwin, John; Nyby, John; Swann, Jennifer; Wisenden, Brian

Abstract

The overall goal of this research was to provide further understanding of the mechanisms involved in pair bonding in the monogamous convict cichlid. This project tested the influences of different aspects of social environment on subsequent reproductive behaviors. The effects of social experience, dominance and the role of visual and water-borne cues on pair bond formation as well as hormonal correlates of social experience were evaluated. The hypothesis tested in the first experiment was that prior experience in a mixed-sex group or dominance status affects subsequent pair formation or spawning. Individuals from mixed-sex groups paired with a novel fish more frequently than fish from single-sex groups, although dominance did not influence pair formation and spawning occurred infrequently. Behaviors in groups or pairs did not predict reproductive outcomes. To test the idea that hormones better explain the reproductive outcome of single- versus mixed-sex groups, 11-ketotestosterone (11-KT), 13,14-dihydro-15-keto prostaglandin F2α (PGF2α metabolite), and follicle-stimulating hormone (FSH) were measured. The hypothesis was that reproductive hormone levels would differ according to whether subjects had prior social experience with the opposite sex. 11-KT varied widely across males and was correlated with chasing behavior, but did not differ by social experience or dominance status. PGF2α metabolite did not differ among females as a function of prior social experience. FSH was elevated in subordinate males in single-sex groups only, and a similar trend in females was not statistically significant. The third experiment tested the hypothesis that visual and chemical cues influence pair bonding. Visual cues from the opposite sex did not influence pair bonding; pairs formed frequently among all the groups. Males exposed to female chemosensory cues paired significantly less frequently than males exposed to male chemosensory cues, but there was no difference between the female groups. The difference in males might be related to group aggression as opposed to negative effects of female chemical cues on male behavior. Overall, results from these experiments indicate that being in mixed-sex groups facilitates pair formation, although the mechanism remains unclear. There was no relationship between dominance and pair formation. However, effects of dominance might be masked by the artificial laboratory environment in which pairs were assessed; individuals were removed from groups to evaluate pair formation. These results suggest that social environment influences pair formation in convict cichlids in a context-dependent way although how hormones contribute remains unclear.

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