Three energy variables predict ant abundance at a geographical scale.
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 two order of magnitude span in the abundance (nests m(-2)) 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.
Kaspari
M
M
Department of Zoology, University of Oklahoma, Norman 73019-0235, USA. mkaspari@ou.edu
Alonso
L
L
O'Donnell
S
S
D000818:Animals; D001000:Ants / Q000502:physiology*; D017753:Ecosystem; D004734:Energy Metabolism; D011156:Population Density; D013696:Temperature