Definition of "Regime of selection"
I'll kick this off with an attempt at a definition: a selection regime is

the set of selective pressures on a population


As in, "alteration of selection regime resulting from harvest" (Mooney &amp; McGraw 2007)

or "Human-induced nutrient input can change the selection regime and lead to the loss of biodiversity. For example, eutrophication caused speciation reversal in polymorphic whitefish populations through a flattening of littoral–pelagic selection gradients." (Hirsch et al 2013)


 Hirsch PE, Eckmann R, Oppelt C, Behrmann-Godel J. 2013. Phenotypic and genetic divergence within a single whitefish form - detecting the potential for future divergence. Evolutionary Applications 6: 1119–1132.
 Mooney E, McGraw J. 2007. Alteration of selection regime resulting from harvest of American ginseng, Panax quinquefolius. Conserv Genet 8: 57–67.