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Dryad

Data to: Carotenoids-based reddish pelvic spines in non-reproducing female and male sticklebacks (Gasterosteus aculeatus) – signalling social dominance?

Data files

Aug 08, 2022 version files 58.14 KB

Abstract

Conspicuous ornaments are often considered a result of evolution by sexual selection. According to the social selection hypothesis, such conspicuous traits may also evolve as badges of status associated with increased boldness or aggression towards conspecifics in conflicts about ecological resources. This study tested predictions from the social selection hypothesis to explain evolution of conspicuous red colour of the pelvic spines of the three-spine stickleback (Gasterosteus aculeatus). Wild non-reproducing sticklebacks were presented to pairs of dummies which differed at their pelvic spines, having either (i) normal sized grey or red pelvic spines, or (ii) normal sized grey or large red pelvic spines. The experimental tank was illuminated by white or green light, since green light impedes the sticklebacks’ ability to detect red colour. The dummies moved slowly around in circles at each end of the experimental tank. We quantified the parameters (i) which of the two dummies was visited first, (ii) time taken before the first visit to a dummy, (iii) distribution of the focal sticklebacks in the two zones close to each of the two dummies and in the neutral zone of the tank, (iv) close to which of the two dummies did the focal fish eat its first food-piece, and (v) time spent until the first piece of food was eaten. This was carried out for 22 females and 29 males sticklebacks. The results suggested no effect of the colour or size of the dummies’ pelvic spines, on none of the five behavioural parameters. Moreover, neither the colour of the pelvic spines of the focal sticklebacks themselves (as opposed to redness of the dummies’ spines) or their body length was associated with behaviour towards the dummies. Thus, this study did not support predictions from the social selection hypothesis to explain evolution of red pelvic spines in sticklebacks.