The adaptive significance of variations in reproductive habit in the Agavaceae

Abstract

Of considerable interest to students of life history phenomena is the identification of circumstances that favour the evolution of life cycles in which a single episode of reproduction is followed by rapid degeneration and death of the reproductive individual. Among non-annual plants and animals, this kind of life history is relatively uncommon, but curiously has arisen independently in several groups (for example, palms, periodic cicadas, bamboos, salmon). In this chapter, we summarise evidence implicating pollinator foraging behaviour as the factor which has led to the evolution of “Big Bang” reproduction in yuccas and agaves. In addition we also consider the effects of variation in plant reproductive expenditure on the pollinators, and finally the way in which plants and pollinators may have coevolved.