Predation risk is associated with the geographic variation of a sexually selected trait in a viviparous fish (Xenotoca variata)

Abstract

Male secondary sexual traits may increase the risk of predation because mating signals make them conspicuous to predators and hamper evasive manoeuvres. Males of Xenotoca variata, a viviparous freshwater fish, show on their flanks bright and colourful spots (speckles), the number of which varies geographically. In this study, the association of this variation with the presence of the piscivorous snake Thamnophis melanogaster, which co-occurs with X . variata, was investigated. A test was also done to establish whether the snake distinguishes between male fish with contrasting numbers of speckles and if the perception of speckles is influenced by water turbidity. The amount of speckling and the prevalence of snakes in key localities was assessed by using one-way mirrors, and the effect of speckles on the predatory responsiveness of snakes was evaluated by presenting them with pairs of male fish in clear and in turbid water. In localities where snakes were infrequent there was a tendency for male fish to have many speckles. The snakes preferentially approached the males with more speckles than the males with fewer speckles. The direction of the preference did not change with the conditions of the water, but the magnitude was stronger in clear water than in turbid water. The snakes also approached first the males with more speckles. These findings indicate that predation risk by T. melanogaster may select against speckles and produce population differentiation.

Male-biased predation of a cave fish by a giant water bug

“…Sex-biased predation is usually associated with intrinsic differences in morphology or behavior between sexes; for example, many predators prefer males with flamboyant ornamentation or conspicuous courtship displays as prey (Burk 1982;Endler 1987;Magnhagen 1991;Macías Garcia et al 1994, 1998Godin and McDonough 2003;Moyaho et al 2004). In this study, it seems that behavioral differences between the sexes could indirectly lead to higher vulnerability of males to predation.…”

Patterns of speciation in endemic Mexican Goodeid fish: sexual conflict or early radiation?

“…Sexual dimorphism in fin size is related to complex male courtship behaviour, with less dimorphic species having more simple courtship (Fitzsimons, 1972; Macías Garcia, Unpublished). There are substantial population differences in sexual dimorphism in a few species (Fitzsimons 1972; Macías Garcia, Unpublished), which appears to reflect local differences in the outcome of sexual conflict over matings under differing ecological conditions (Macías Garcia, 1994; Moyaho et al. , 2004).…”

“…Sexual dimorphism in fin size is related to complex male courtship behaviour, with less dimorphic species having more simple courtship (Fitzsimons, 1972;Macías Garcia, Unpublished). There are substantial population differences in sexual dimorphism in a few species (Fitzsimons 1972;Macías Garcia, Unpublished), which appears to reflect local differences in the outcome of sexual conflict over matings under differing ecological conditions (Macías Moyaho et al, 2004). Thus it is highly likely that variation in sexual dimorphism between species reflects the extent to which female choice dominates the mating system, with the more dimorphic species being those in which female preference is more important to the outcome of mating attempts.…”

Linking stream ecology with morphological variability in a native freshwater fish from semi‐arid Australia

“…The sexes are often exposed to different levels of predation risk, for example, because bright colors that attract females also increase the males’ conspicuousness to visual predators (Godin and McDonough ; Moyaho et al. ). Male rainbowfish tend to be more brightly colored than females (Young et al.…”

“…); predation and sex (predators may preferentially target one of the sexes; Godin and McDonough ; Moyaho et al. ); and water flow and habitat complexity (water flow is affected by habitat; Kilsby and Walker ). All models were compared to a null model, which contained only the random effect.…”