From lagging to leading: Increased phenological asynchrony in a Batesian mimicry complex

Climate change disrupts ecological systems by shifting species
distributions and altering phenological patterns, significantly affecting
interspecific interactions like Batesian mimicry. Effective mimicry relies
on the spatial and temporal overlap between mimics and their models to
deter predators. This idea has persisted despite emerging data that
challenges it. To assess phenological position and flight season changes,
we extracted flight season data for model bumblebee species and mimicking
hoverflies for the Scandinavian peninsula, spanning a little over
century-and-a-half. We estimated shifts in the annual mean flight season
and the phenological order of emergence in our Batesian system while
accounting for yearly survey variations. We found compelling evidence of a
temporal shift in flight season dynamics in the Batesian system. Mimics
historically flew significantly earlier than models, but in more recent
years, there has been a pronounced trend towards mimics flying later than
models. This temporal decoupling highlights potential impacts on mimicry
effectiveness, as mismatches with peak model activity periods could
increase the predation risk for mimics. The shift from mimics emerging
earlier to models flying earlier is particularly concerning, underscoring
the fitness consequences of climate-driven changes on ecological
interactions.