Trade-off between warning signal efficacy and mating success in the wood tiger moth

Abstract

The coloration of species can have multiple functions, such as predator avoidance and sexual signalling, that directly affect fitness. As selection should favour traits that positively affect fitness, the genes underlying the trait should reach fixation, thereby preventing the evolution of polymorphisms. This is particularly true for aposematic species that rely on coloration as a warning signal to advertise their unprofitability to predators. Nonetheless, there are numerous examples of aposematic species showing remarkable colour polymorphisms. We examined whether colour polymorphism in the wood tiger moth is maintained by trade-offs between different functions of coloration. In Finland, males of this species have two distinct colour morphs: white and yellow. The efficacy of the warning signal of these morphs was tested by offering them to blue tits in the laboratory. Birds hesitated significantly longer to attack yellow than white males. In a field experiment, the survival of the yellow males was also higher than white males. However, mating experiments in the laboratory revealed that yellow males had lower mating success than white males. Our results offer an explanation for the maintenance of polymorphism via trade-off between survival selection and mating success.

Not all colors are equal: predation and color polytypism in the aposematic poison frog Oophaga pumilio

“…Understanding warning signal diversity in aposematic organisms continues to be a main focus in evolutionary biology as a way of studying natural selection and interactions among selective forces (Nokelainen et al 2012). Our findings support the hypothesis that predation is a selective force acting on the observed polytypism in Oophaga pumilio, and substantiate recent work suggesting that coloration functions as an honest signal toward predators (see Maan and Cummings 2012).…”

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

“…Paradoxically, withinpopulation variation exists in some aposematic species [5,6]. Despite studies suggesting a natural-sexual selection interaction as a cause [5,7], the mechanisms by which within-population variation is maintained, and its ecological and behavioural correlates, are poorly understood. Attempts to explain the maintenance of variable aposematic signals have primarily addressed among-population variation [8,9] or involved laboratory studies with artificial prey or computer games.…”

“…Because this relies on predators learning and remembering the relationship between colour patterns and unprofitability, selection should favour colour patterns with little or no variation [2]; patterns with low variation are easier to learn [2,3] and remember [4]. Paradoxically, withinpopulation variation exists in some aposematic species [5,6]. Despite studies suggesting a natural-sexual selection interaction as a cause [5,7], the mechanisms by which within-population variation is maintained, and its ecological and behavioural correlates, are poorly understood.…”

Influences of geographic differentiation in the forewing warning signal of the wood tiger moth in Alaska

“…One mechanistic explanation for the increased predation risk of more melanized individuals is that the amount of color (yellow or white) decreases as the proportion of the hindwing covered by melanin increases. Nokelainen et al (2012) showed that both yellow and white pigments in the hindwings of male P. plantaginis serve as warning signals, even though yellow males were avoided more by avian predators than white males. Larger warning signals increase detection by predators (Bohlin et al 2008, Lindstedt et al 2008, which should enhance signal recognition and avoidance by predators (Lindström et al 1999a.…”