My dissertation focuses on the factors that influence variation in female
reproductive success in plethodontid salamanders and in toads. Variation in
reproductive success fuels evolutionary change. Although, females often have been
overlooked in studies of reproductive success due to perceived lower levels of
variation when compared to variation in male reproductive success, understanding
factors influencing variation in female reproductive success is critical for several
reasons. First, female reproduction is usually the limiting factor on population growth.
Second, the factors affecting female reproduction provide the impetus for current and
evolving patterns of sexual dimorphism. Lastly, male reproductive success inevitably
is determined by the reproductive success of the females with which they mate.
Recent theoretical developments of sexual conflict have contributed significantly to a
renewed emphasis on studies of female reproductive success.
Sexual conflict theory elucidates important factors, from the perspective of
females, affecting female behavior and reproductive success. Sexual conflict assumes
that a female will benefit, in terms of reproductive success and offspring viability,
when she is able to freely choose among males, unconstrained by social and
environmental factors. Female choice would be constrained if a non-preferred male
(i.e., one that would be rejected by a freely choosing female) coerced a female to mate
in order to increase his own mating success. The dynamics between discriminating
females and non-preferred males will lead to a coevolutionary "arms race", referred to
as sexual conflict. From this perspective, secondary male traits may not reflect their
intrinsic quality, but rather their ability to manipulate or coerce female mating
decisions. The current debate lies in the importance and pervasiveness of sexual
conflict.
To address the current view of sexual conflict, I investigated whether sexual
conflict plays a role in the mating systems of amphibians. In particular, my results
support the main assumption that females benefit from freely expressed female mate
choice in toads. In addition, I explored the potential influence of sexual conflict in
plethodontid salamanders. During mating trials, I documented novel female courtship
behaviors. I also examined the effects of male courtship pheromones on female
reproductive success to assess the potential role of male pheromones in sexual
conflict. My results suggest that sexual conflict also may be an important factor in
plethodontid mating systems. My investigations of sexual conflict theory have
provided new insights and novel predictions for understanding sexual selection and
sexual dimorphism. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29398 |
| Date | 08 April 2005 |
| Creators | Dyal, Leslie A. |
| Contributors | Houck, Lynne D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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