Choosiness as a component of life history strategies in cabbage white butterflies

Abstract

Many animals are choosy when selecting resources such as mates, food, or sites to lay eggs. For animals that lay eggs and do not subsequently care for their young, choosing the best sites for their eggs can greatly increase the survival and health of their offspring. Given these benefits, it is surprising that there is variation in choosiness; not all animals are choosy when laying eggs. Behaviors can be costly if they require energy and exhibit trade-offs with other traits that also require energy. I applied this idea to choosiness during oviposition, testing the hypothesis that animals are not choosy when being choosy is costly. In cabbage white butterflies, I demonstrated variation in choosiness and a trade-off between choosiness and fecundity, suggesting that being choosy is costly. If energetic costs determine degree of choosiness, then manipulating energy from food should lead to variation in choosiness. I manipulated food availability directly by varying nutrition and indirectly by varying butterfly density and thus potential competition for food. Density did not affect choosiness or other traits, but nutrition did. Poor adult nutrition led to lower levels of choosiness and lower fecundity but no changes in other traits. Thus, poor nutrition may decrease investment in multiple traits, including choosiness, rather than causing adaptive shifts in life history with increased investment in some traits. My results suggest that choosiness is energetically costly, but only direct cues about energy availability affect choosiness. These findings have implications for the health of butterflies and other pollinators.