Evolutionary and ecological processes influence a plant-bumble bee network

Species interactions, such as those between plants and pollinators, are
known to be shaped by both evolutionary history and ecological factors.
However, the relative importance of neutral- and
niche-based ecological processes is still under debate,
and little is known about which ecological factors are most
important for explaining phylogenetic patterns in interaction networks.
Using a plant-bumble bee network comprising 2428 interactions
between 29 plant species and 12 bumble bee species in
the Himalaya-Hengduan mountains, we tested for phylogenetic
signal and whether phylogenetic pattern was explained by 14 plant and four
bumble bee ecological traits. We also tested whether trait matching
between bumble bee tongue length and flower tube depth explained
interaction patterns. All of the measured traits contributed to
explaining the phylogenetic attraction pattern, among them, species
abundances, nectar volume, and nectar sugar
concentration were the most important predictors. Meanwhile, trait
mismatch between bumble bee tongue length and flower tube depth
failed to predict the interactions, with short-tongued
bees generalized across tube depths. Our findings
suggest neutral-based process seems to matter more than
niche-based processes in this system and help to predict
how interactions will respond when key traits are
altered by pollinator declines and global change effects.