The relationship between male ornamentation and swimming performance in the guppy, Poecilia reticulata

Abstract

The objective of this study was to determine if three male ornaments in the guppy (Poecilia reticulata) were reliable indicators of swimming performance. Tail shape and dorsal fin length were chosen because they are ornaments that are of primary importance in swimming, which is a major survival component of fitness in fish. The carotenoid pigments and especially their density are ornaments that are hypothesized to be long term indicators of male vigor. Carotenoid pigment density and swimming performance were significantly positively correlated, but there was no relationship between swimming performance and tail shape or dorsal fin length. These results indicate that density of carotenoid pigmentation may function as a male vigor indicator during mate choice. Tail shape and dorsal fin length are not related to swimming performance, and females probably could not use them as vigor indicators during mate choice. The results are discussed in terms of ornament function and adaptive and Fisherian hypotheses of female choice.