Adaptive Significance of Variations in Reproductive Habit in the Agavaceae II: Pollinator Foraging Behavior and Selection for Increased Reproductive Expenditure

A coevolutionary hypothesis accounting for the evolution of Big Bang reproduction in yuccas and agaves is proposed. Particular attention is paid to the selective consequences of pollinator foraging behavior and reciprocally to the effects of plant reproductive expenditures on pollinator foraging strategies. Several lines of evidence, both observational and experimental, supporting the theory are presented. This evidence incidentally supports the notion that insect pollinators visit flowers in qualitative accord with the dictates of optimal diet theory.