Data from: Phenological shifts in hoverflies (Diptera: Syrphidae): linking measurement and mechanism

An understanding of ecological and evolutionary responses to global
environmental change requires both a robust measurement of the change that
is occurring and a mechanistic framework for understanding the drivers of
that change. Such a requirement provides a challenge because biological
monitoring is often ad hoc, and mechanistic experiments are often
performed under highly simplified conditions. This study integrates
multiple datasets to evaluate our current knowledge of the measurement and
mechanism of phenological shifts in a key pollinator taxon: the hoverflies
(Diptera: Syrphidae). First, two large, complementary and independent
monitoring datasets are used to test for trends in phenology: an ad hoc
national recording scheme containing >620,000 records, and
standardised monitoring with consistent methods over 30 years. Results
show that ad hoc and standardised recording data give quantitatively the
same value for phenological advance in hoverflies (ca. 12 days°C-1 on
average at the beginning of the flight period), supporting the value of
biological recording for the measurement of global ecological change.
While the end of the flight period appears static in ad hoc recording, the
standardised dataset suggests a similar advance as in the beginning of the
flight period. Second, an extensive traits dataset and a novel database of
laboratory-derived developmental data on Syrphidae (153 published studies)
are used to test for mechanistic patterns in phenological shifts. The only
species trait that influenced phenology was voltinism, where species with
more generations per year exhibit stronger phenological advances. We
demonstrate considerable variation in the laboratory-derived sensitivity
to temperature but this does not match field-derived measures of
phenology. The results demonstrate that, as for many taxa, we have a
strong understanding of the patterns of global ecological change but that
we currently lack a detailed mechanistic understanding of those processes
despite extensive research into the fundamental biology of some taxonomic
groups.