Examination of boldness traits in sexual and asexual mollies (Poecilia latipinna, P. formosa)
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Considering the high costs of sexual reproduction (e.g., the production of males), its maintenance and predominance throughout the Animal Kingdom remain elusive. Especially the mechanisms allowing for a stable coexistence of closely related sexual and asexual species are still subject to a lively debate. Asexuals should rapidly outnumber sexuals due to higher population growth rates, unless they face some disadvantages. Here, we investigate potential differences in feeding behavior in a system of sexual (sailfin mollies, Poecilia latipinna) and coexisting gynogenetic fishes (Amazon mollies, Poecilia formosa). In two different experiments, we tested for differences in behavioral traits associated with boldness. Bold individuals take higher risks for gains in resources, so shyer individuals should be less competitive. Our study was motivated by the recent finding that P. formosa are less likely to be preyed upon by piscine predators than P. latipinna. We asked whether this result is indicative of low boldness in P. formosa. However, no differences between the two species were detectible in our behavioral experiments measuring (a) time to emerge from shelter to explore a novel environment, (b) latency time until feeding in a novel environment, and (c) recovery time until feeding restarted after a simulated predator attack. Furthermore, different boldness measures were not correlated with each other within individuals.
KeywordsAggressive behavior Amazon molly Behavioral syndromes Competition Foraging Maintenance of sex Poeciliidae
We would like to thank Kirk Winemiller (Texas A&M University) for kindly providing laboratory facilities. We also like to thank Dylan Thompson for assistance with computer-generated images to illustrate the experimental tanks. M. Ziege kindly provided the drawings of a sailfin and an Amazon molly. Financial support came from the German Academic Exchange Service (DAAD) and the German Society for Ichthyology (to K. S.), the Hermann-Willkomm Foundation (to M. P.), as well as the Swiss National Science Foundation (to M. T.). The Texas Parks and Wildlife Department kindly issued permits for collecting fish (SPR-1008-340).
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