Theory 01/The rival is a confound/Biogeography
Lag or Detection Bias?
The claim
Observed range shifts lag climate velocity by an amount set by dispersal rate.
01The rival explanation
The lag is an artefact of detection: newly colonised sites are recorded late, and extinctions from rear edges are noticed even later, so any census shows a lag regardless of ecology.
02What would tell them apart
Detection bias should scale with survey effort and observer density; dispersal lag should scale with the species' dispersal ability, independently of how well it is watched.
03Prediction
Lag should correlate with dispersal traits after controlling for survey intensity.
04Refutation
If lag tracks survey intensity and not dispersal, the rival wins.