Theory 03/Existing data/Biogeography
Ranges Lag Velocity
The claim
Observed range shifts lag climate velocity by a fraction set by dispersal rate rather than by the magnitude of warming.
01Mechanism
A species can only track the isotherm at the speed it disperses; the shortfall accumulates as an extinction debt.
02Prediction
Lag should scale with dispersal, not with warming.
03Refutation
Lag tracking warming would remove the dispersal term.