Different factors dominate in each guild in Aculeata communities along
an elevational gradient in a boreal forest
Abstract
The response of communities to climate change is expected to vary among
feeding guilds. To evaluate the response of guilds to environmental
factors without considering the taxonomic specificities, it is useful to
examine Aculeata bees and wasps, which consist of closely related taxa
including different guilds, pollinators, predators, and parasitoids. In
this study, we evaluated changes in species diversity (SD) and
functional traits of each feeding guild along an elevational gradient in
a boreal forest in northern Japan. We used yellow pan traps to collect
Aculeata bees and wasps at 200–1600 m above sea level. We investigated
six functional traits (trophic level, flight duration, body size,
elevational range, nesting position, and soil dependency) and the
horizontal distribution of the species. The SD of all Aculeata predators
and parasitoids decreased with an increase in elevation; however, the SD
of pollinators did not show any specific trend. Although the functional
trait composition of all Aculeata species did not show any trend, that
of each feeding guild responded to elevation in different ways.
Pollinators increased in body size and showed a decrease in flight
duration with increasing elevation, suggesting that tolerance and
seasonal escape from physical stress at high elevations are important
for shaping pollinator communities. Predators showed increased
elevational range and above-ground nesting species with increasing
elevation, suggesting that the ability to live in a wider range of
environments and avoid unsuitable soil environments at high elevations
might be important. Parasitoids changed their hosts and variable traits
with increasing elevation, suggesting that brood parasitoids have
difficulty in surviving at high elevation. The traits for each guild
responded in different ways, even if they were dominated by the same
environmental factors. Differences in the response of functional traits
would produce different patterns of community formation in different
guilds during further climate change.