Fitness landscapes reveal context-dependent benefits of oviposition behaviour

Resource choice behaviour has enormous fitness consequences and can drive
niche expansion. However, individual behavioural choices are often
mediated by context, determined by past experience. Do such
context-dependent behaviours reflect maladaptive variation, or are they
locally adaptive? Using Tribolium castaneum (the red flour beetle), we
demonstrate that context-dependent oviposition behaviour reflects
distinct, context-specific local fitness peaks. We measured offspring
fitness to generate fitness landscapes as a function of all possible
oviposition behaviours (i.e., combinations of fecundity and resource
preference) in a habitat containing optimal and suboptimal resource
patches. We did this by experimentally manipulating female egg allocation
across patches, which allowed us to assess behaviours not typically
observed in the laboratory. We found that females from different age and
competition contexts exhibit distinct behaviours which optimize different
fitness components, linked in a tradeoff. With prior exposure to strong
competition and increasing age, females produce few but fast-developing
offspring that are advantageous under high resource competition. In
contrast, young naïve females produce significantly more (but
slower-developing) offspring, which is beneficial under weak competition.
Systematically mapping complete context-dependent fitness landscapes is
thus critical to infer behavioural optimality and offers predictive power
in novel contexts.