Link flexibility: evidence for environment-dependent adaptive foraging in a food web time-series

Abstract

Temporal variability in the distribution of feeding links in a food web can be an important stabilising factor for these complex systems. Adaptive foraging and prey choice have been hypothesised to cause this link flexibility as organisms adjust their behaviour to variation in the prey community. Here, we analyse a 10-year time series of monthly aphid-parasitoid-secondary parasitoid networks and show that interaction strengths for polyphagous secondary parasitoids are generally biased towards the larger host species within their fundamental niche; however, in months of higher competition for hosts, size-based biases are reduced. The results corroborate a previous hypothesis stating that host-selectivity of parasitoids should be correlated to the relative likelihood of egg-limitation vs time-limitation. Our results evince adaptation of foraging behaviour to varying conditions affects the distribution of host-parasitoid link-strengths, where link-rewiring may be integral to stability in complex communities.