Hybrid networks reveal contrasting effects of agricultural intensification on antagonistic and mutualistic motifs

1. Anthropogenic-driven perturbations such as agricultural intensification
can affect simultaneously and distinctly several species groups and
ecosystem functions. Unveiling these concurrent effects on interdependent
species groups connected by different types of ecological interactions is
a key challenge for ecologists. To this endeavor, hybrid ecological
networks arise as a promising tool. 2. In this study, we used bee trap
nests to sample hybrid networks that combined mutualistic and antagonistic
interactions to explore agricultural intensification effects on the
representation of network motifs (i.e., subnetworks showing different
interaction types between a small number of species). Also, we assessed
the variability of network motif’s frequencies on farms under similar
management regimes and the dissimilarity between farms under different
ones. For this, we implemented a novel approach, calculating network
functional spaces based on probability density estimates of network
motif’s frequencies, using network motifs as traits. 3. Results showed
that environmentally-friendly practices maximize the representation of
mutualistic (cavity nesting bees-plants) and predation (wasps-prey and
bees/wasps-antagonists) motifs. In contrast, intensive agriculture favored
generalist and intraguild predation interactions. Lastly, the frequency of
motifs representing antagonistic interactions was more inconsistent and
unpredictable across sites than mutualistic motifs, especially on
intensified farms. 4. Our novel approach, dissecting hybrid networks into
their motifs and analyzing the functional space defined by these, reported
detailed and contrasting effects of agricultural intensification on
network motifs that represent the mutualistic and antagonistic
interactions in this system.