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Signal use in poeciliid fishes
Abstract
Evaluation of conspecifics is often facilitated by signals. I examined the use of two morphological features as signals in poeciliid fishes. The first set of experiments addressed the evolution and the maintenance of the sword, a composite trait on males of some poeciliid fishes. The sword has already been shown to be used by females in evaluating prospective mates. In Chapter 2, I tested the importance of sword length and body size in male-male competition in green swordtails, Xiphophorus helleri. Body size, measured by lateral area, was correlated with contest success. In a manipulative test, controlling for the importance of size, males with longer artificial swords were significantly more likely to win contests than expected by chance. In Chapter Three, I present the results of two tests showing that winning males might experience increased mating success by restricting access to females. Thus, the role of the sword in competitive interactions can have evolutionary consequences. Chapter 4 shows that artificially sworded males of Priapella olmecae (with the ancestral condition of swordlessness) experienced increased success when matched with similarly sized males with clear attachments. These data suggest that the bias for the sworded condition in males arose prior to the sword. Chapter Five addresses the importance of a female trait as a signal. Female green swordtails possess a brood patch, an obligate feature that varies with reproductive condition. This might function as a signal of receptivity to reduce the risks associated with courtship when not receptive and increase female sampling size of prospective mates when females are receptive. Males courted females with artificially enhanced brood patches significantly more often than they court females from a control group. These data show that this feature can serve as a signal, and be adaptive to females in a number of ways. Additional work with these fishes can address, more specifically, the adaptive value of both swords and brood patches.
Subject Area
Ecology
Recommended Citation
Benson, Kari E, "Signal use in poeciliid fishes" (1998). ETD collection for University of Nebraska-Lincoln. AAI9902947.
https://digitalcommons.unl.edu/dissertations/AAI9902947