Data from: Forecasting range shifts using abundance distributions along environmental gradients

Globally, many species’ distributions are shifting in response to
contemporary climate change. However, the direction and rate of shifts
remain difficult to predict, impeding managers' abilities to allocate
resources most effectively. Here, we explore a new approach for
forecasting species' range-limit shifts that requires only abundance
data along environmental (eg elevational) gradients. We hypothesized that
species’ abundance distributions could provide information on the
likelihood of future range-limit shifts. We tested this prediction using
data from several transect studies that compared historical and
contemporary distributions. Consistent with our prediction, we found that
strong asymmetry in abundance distributions (ie “leaning” distributions)
indeed preceded species’ lower-limit range shifts (Fisher's exact
test P < 0.001, R2 = 0.28). Accordingly, surveying
abundances along environmental gradients may be one promising,
cost-effective method for forecasting local shifts. Ideally, practitioners
will be able to incorporate this approach into species-specific management
planning and to inform on-the-ground conservation efforts.