Data from: Geographic signatures in species turnover: decoupling colonization and extinction across a latitudinal gradient

High latitude communities have low species richness and are rapidly
warming with climate change. Thus, temporal changes in community
composition are expected to be greatest at high latitudes. However, at the
same time traits such as body size can also change with latitude,
potentially offsetting or increasing changes to community composition over
time. We tested how zooplankton communities (copepods and cladocerans)
have changed over a 25-75 year time span by assessing colonization and
extinction rates from lakes across an 1800 km latitudinal gradient, and
further tested whether species traits predict rates of community change
over time. Lake-level dissimilarity, measured with Sorenson distance,
decreased at higher latitudes. This decrease was due to higher
colonization rates of cladocerans in lower latitude lakes and consistent
extinction rates across the latitudinal gradient. At the species level,
colonization increased with regional occupancy, and tended to be higher
for smaller bodied, locally abundant, species. Local extinction rates were
negatively correlated with local abundance and regional occupancy, but
were not influenced by body size. None of these species-specific
characteristics changed predictably with latitude. Contrary to our
expectations, low-latitude zooplankton communities changed more rapidly
than high-latitude communities by becoming more species rich, not by
losing species that were historically present. Moreover, colonization and
extinction trends suggest that lakes have become increasingly dominated by
species with smaller body sizes and that are already common locally and
regionally. Together, these findings indicate that rates of species
turnover in freshwater lakes across a latitudinal gradient are not
predicted by rates of temperature change, but that turnover is nonetheless
resulting in trait-shifts that favour small, generalist species.