A thesis submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg in fulfillment of the requirement for the degree of Doctor of
Philosophy
JOHANNESBURG
January 1996 / I investigated some evolutionary implications of female mate choice in a feral
population of guppies (Poecllia reticultuai. I performed correlative and manipulative
experiments to establish the relationship between female mate choice and other
sexually selective forces including iutermale aggression and sneak copulation, and
the exaggerated secondary sex characters (ornaments) of male guppies. Orange
(carotenoid) ornamentation is the best predictor of male attractiveness and mating
success, a relationship which held under manipulation. Black (melanin) is sometimes
correlated with male mating success. Mnnipulatiug the black area of males reveals
that it is important to male attractiveness, and this appears to be in the form of a
signal amplifier of male orangeness. This is the fi.st experimental evidence for a
visual signal amplifier. For both orange and black areas, the relationship between
absolute area and fluctuating asymmetry is positive and significant, suggesting that
neither is n signal of male condition. These results arc Interpreted in the context of
theories of the evolution of multiple male ornaments. Females are able to express
their preference for orange with the first mature male they ever encounter, uuggestlng
an important role for genetic determination in female preferences. This is
corroborated by high repeatability of female mate choice behaviour. Experience
modifies a female's preferences as she is able to adjust her response to a male in
relation to the ornamentation of (at least) the previous male she saw. Mate copying
has no mensurable effect on the outcome of female mate choice decisions. / MT2016
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/21433 |
| Date | January 1996 |
| Creators | Brooks, Robert Clinton |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (120 leaves), application/pdf |
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