How resource acquisition influences the detection of trade-offs.

Abstract

Trade-offs should be ubiquitous in nature. Yet, direct trade-offs between traits essential for fitness are challenging to detect. Recent theory suggests that population level variation in resource acquisition could play an important role in our ability to detect trade-offs. Here, we test experimentally the hypothesis that the detection of trade-offs depends on the underlying distribution of individuals with different resource acquisition in a population. Specifically, we re-sampled ecologically and experimentally relevant resource acquisition distributions from a population of male Australian field crickets (Teleogryllus oceanicus) subjected to a continuous range of diet manipulation. While we found evidence for trade-offs between different male fitness traits, the distribution of resource acquisition in the population had no systematic effect on the strength of these trade-offs. Interestingly, trade-offs were most pronounced between post-copulatory traits and immune function, but trade-offs involving pre-copulatory traits were relatively weak. Overall, our findings question the hypothesis that resource acquisition may influence our ability to detect trade-offs and instead suggest that other factors, like the hierarchical complexity of resource allocation, make detecting trade-offs so elusive.