Energy Theory posits three processes that link local abundance of ectotherms to geographical gradients in temperature.   A survey of 49 New World habitats found a 2 order of magnitude span in the abundance (nests / m²) of ground nesting ants (Formicidae).   Abundance increased with net primary productivity (r²=0.55), a measure of the baseline supply of harvestable energy.   

Abundance further increased with mean temperature (r²=0.056), a constraint on foraging activity for this thermophilic taxon.  Finally, for a given mean temperature, ants were more abundant in seasonal sites with longer, colder winters (r²=0.082) that help ectotherm taxa sequester harvested energy in non-productive months.   

All three variables are currently changing on a global scale.  All should be useful in predicting biotic responses to climate change.