Possible ‘silver-spoon’ effect on adult terrestrial jumping in the mangrove rivulus fish (Kryptolebias marmoratus) (Cyprinodontiformes: Rivulidae)

Abstract

Survival in complex environments is dependent on whole-animal performance, a target of natural and sexual selection. Variation in whole-animal performance among mature individuals can become broadened by phenotypic plasticity driven by early life experiences. Thus, detailing the environmental factors that contribute to phenotypic plasticity, and the associated phenotypic responses governed by those environmental factors, is essential if we are to understand the evolution of whole-animal performance. Here, using isogenic lines established from the hermaphroditic mangrove rivulus fish (Kryptolebias marmoratus) housed in a ‘common garden’, we investigate the link between variation in adult terrestrial jumping performance and early life experience (i.e. egg density). First, we hypothesize that individuals from different isogenic lineages should vary in jumping performance independent of egg density, suggesting a strict genetic source of variation. Second, we hypothesize that phenotypic plasticity should also introduce variation in adult jumping performance. Specifically, we expect that hatchlings incubated at higher egg densities in early development should adopt better jumping performances as adults, because higher egg density might be a cue for greater intraspecific competition upon hatching.