GARD 1.5 range shapefiles used in: Global diversity patterns are explained by diversification rates at ancient, not shallow, timescales

Explaining global species richness patterns is a “Holy Grail” of ecology
and evolution. These richness patterns are often attributed to spatial
variation in diversification rates (speciation minus extinction).
Surprisingly, prominent studies of birds, fish, and angiosperms reported
higher diversification rates at higher latitudes (mismatched with
richness). Yet these studies only examined diversification rates at
relatively recent timescales. Here, we quantify global richness patterns
among lizard and snake species (10,213; 94%) and explore their underlying
causes. We found that diversification rates at more recent timescales in
squamates also show mismatched patterns of rates and richness. However,
diversification rates at deeper timescales were positively related to
richness. These observations may help resolve the paradoxical results of
previous studies. Remarkably, these diversification patterns are largely
unrelated to climate. Instead, higher tropical richness is related to
ancient occupation of tropical regions. Thus, these large-scale diversity
patterns are only understood by considering climate, deep-time
diversification rates, and the time spent in different regions.