Male mate preference in the eastern mosquitofish (Gambusia holbrooki)
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Michael Mcmillan (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Katherine Bruce
Abstract: As a live-bearing fish, Gambusia holbrooki offers unique opportunities to study sexual
selection. While males of this species invest little time or energy per offspring, sexual selection
theory should predict that if a male is presented with two females of differing size, a preference
should be shown for the larger of the two females. Evolution should favor the choice of a larger
female because of increased brood size, better health, and ability to survive the environment.
Only two studies to date have looked at male mate preferences in Gambusia holbrooki, and the
results were mixed. In this study, to measure male preference a dichotomous choice test was
used with female fish of varying sizes placed in clear containers at opposite ends of an aquarium.
The elapsed time a free swimming male spent in “side time” (on same side of aquarium as either
female) and “proximity time” (within one male length) was recorded. Experiment 1 looked at
male preference for females differing in size by at least 5mm and found that males (n=12) spent
significantly more time in close proximity to larger (compared to smaller) females in the first 10
minutes of a 20-minute preference test. The males, however, did not show a significant
preference in side time. Experiment 2 sought to increase the size discrepancy between the two
females tested and included very large females, as they might provide a supernormal stimulus for
the male (n=9). However, the results of Experiment 2 showed no such preference in side time or
proximity time. Experiment 3 increased the number of subjects to 27 to provide a more
representative sample of female fish a male might encounter in the wild and added a social
interaction portion to the testing. Female size differential groupings were broken in to three
categories: Small (2-6mm), Medium (8-11mm), and Large (13-17mm). The results of this
experiment showed a significant preference for the larger females that was dependent upon the
size differential grouping, with proximity time in the medium grouping being most pronounced.
In the social interaction portion of the testing, a significant preference was found for larger
versus smaller females, but there was not a significant preference found between the size
groupings. As predicted by the sexual selection theory, the results of the aforementioned
experiments seem to indicate that a male mate preference for larger females does exist, but only
within certain parameters.
Male mate preference in the eastern mosquitofish (Gambusia holbrooki)
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Created on 1/1/2009
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Arts
- Language: English
- Date: 2009
- Keywords
- Courtship in animals , Eastern mosquitofish--Reproduction, Eastern mosquitofish--Research, Eastern mosquitofish--Sexual behavior
- Subjects
- Eastern mosquitofish -- Research
- Eastern mosquitofish -- Reproduction
- Courtship in animals
- Eastern mosquitofish -- Sexual behavior