| In this dissertation, I examined mate choice and mating systems in fishes. I tested for female mate choice of size and/or coloration in orangethroat darters, Etheostoma spectabile. Neither size nor breeding color correlated with spawning success of males under natural field conditions. No preference was detected for large versus small males when females were presented experimentally with a simultaneous choice. Similarly, females also displayed no preference for bright males. This provides an example of a sexually dimorphic species with no evident female preference for large male size or bright coloration.; I modified Parker's (1983) mate choice model to examine the potential for mate choice by male orangethroat darter's preference based on female size. The male threshold for rejection of mating partners occurred at extremely low female fecundities. Indeed, it is not possible for females to deposit the predicted minimum number of eggs (female size was converted to eggs) for rejection, so males were predicted to accept any female, to reject none. In my experiment, males did not show any preference for larger females as measured by number of matings or time until mating, consistent with predictions from application of Parker's (1983) model.; I tested the ability of probability of sperm competition, male guarding, and male-male contest to predict SSD in North American freshwater minnows, after controlling for phylogenetic effects by an independent contrasts method. With 58 species only male territorial guarding was significant; guarding was associated with increasing male-biased size dimorphism. When tested at the genus level, male territorial guarding and male-male contest were significant in the model, with male-male contests also favoring larger male size. Probability of sperm competition varied with SSD in a manner concordant with Parker's prediction, in that changes from states in which sperm competition were present (and male territorial guarding absent) to those in which it was absent (and male territorial guarding present) were associated with changes from monomorphism to male-biased dimorphism. |
