Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change.

ABSTRACT: Ecological responses to climate change may occur gradually with changing conditions, or they may occur rapidly once some threshold or "tipping point" has been reached. Here, we use a high-resolution, 30-year data set on the upper vertical limit of a high intertidal alga to demonstrate that distributional shifts in this species do not keep pace with gradual trends in air temperature or sea level, but rather occur in sudden, discrete steps. These steps occur when unusually warm air temperatures are associated with unusually calm seas and are contingent in the sense that neither atmospheric nor sea conditions by themselves were sufficient to generate the underlying physiological challenge. Shifts in the upper limit did not correlate with large environmental perturbations such as El Niños; rat

SUBMITTER: Harley CD 

PROVIDER: S-EPMC2708713 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature