Body size and lifespan are condition dependent in the mealworm beetle, Tenebrio molitor, but not sexually-selected traits
condition dependence, sexual selection, direct benefits, pheromones, lifespan, Tenebrio molitor
Traits under strong directional selection are predicted to be condition dependent, and thus increase in development when an organism acquires more resources. This prediction has been tested for a variety of traits, particularly those under precopulatory sexual selection. However, few studies compare the condition dependence of a variety of phenotypic traits, potentially subject to different selective forces. Here we examine the condition dependence of several important life history traits, including those under both pre- and postcopulatory sexual selection, in the mealworm beetle, Tenebrio molitor. We manipulated condition by randomly assigning larvae to one of: high-, medium- or low-quality diets. For males reared on the three diets we measured: a) adult body size and lifespan, b) pheromone attractiveness, c) weight of their ejaculate transferred to females, and d) fecundity of their female mates. Males raised on a high-diet were larger and lived longer than males raised on medium- and low-diets. Although females were significantly attracted to male pheromones, there were no significant differences amongst condition treatments in male attractiveness, nor ejaculate transfer. Furthermore, mates’ fecundity was also not affected by male condition. We discuss these results considering previous work on trade-offs and condition dependence of life history traits.
McConnell, M. W. & Judge, K. A. (2018). Body size and lifespan are condition dependent in the mealworm beetle, Tenebrio molitor, but not sexually-selected traits. Behavioral Ecology and Sociobiology, 72(32). https://doi.org/10.1007/s00265-018-2444-3
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