Relative species abundance successfully predicts nestedness and interaction frequency of monthly pollination networks in an alpine meadow

Plant-pollinator networks have been repeatedly reported as cumulative ones
that are described with >1 years observations. However, such
cumulative networks are composed of pairwise interactions recorded at
different periods, and thus may not be able to reflect the reality of
species interactions in nature (e.g., early-flowering plants typically do
not compete for shared pollinators with late-flowering plants, but they
are assumed to do so in accumulated networks). Here, we examine the
monthly sampling structure of an alpine plant-pollinator bipartite network
over a two-year period to determine whether relative species abundance and
species traits better explain the network structure of monthly networks
than yearly ones. Although community composition and species abundance
varied from one month to another, the monthly networks (as well as the
yearly networks described with annual pooled data) had a highly nested
structure, in which specialists directly interact with generalist
partners. Moreover, relative species abundance predicted the nestedness in
both the monthly and yearly networks and accounted for a statistically
significant percentage of the variation (i.e., 20%-44%) in the pairwise
interactions of monthly networks, but not yearly networks. The combination
of relative species abundance and species traits (but not species traits
only) showed a similar prediction power in terms of both network
nestedness and pairwise interaction frequencies. Considering the
previously recognized structural pattern and associated mechanisms of
plant-pollinator networks, we propose that relative species abundance may
be an important factor influencing both nestedness and interaction
frequency of pollination networks.