Selection on flowering time in a life-cycle context

The main way in which plants can exert control over their local environment is by the timing of different events within their life cycles. Regarding timing of flowering as an integrated part of both the annual cycle and of the whole life cycle, rather than as an isolated event, has important implications for how we assess selection on timing of reproduction and interpret existing phenological patterns in perennial plants. I argue that: 1) we have little unequivocal evidence of pollinator-mediated selection on flowering time, but perhaps more evidence of antagonist-mediated selection; 2) much of selection on flowering time might occur before flowers have developed and after reproduction; 3) vital rates of non-flowering individuals can influence the strength and direction of selection on flowering time, and 4) differences in the direction of selection on flowering date between years might well correspond to consistent selection on the mechanisms determining flowering time. Overall, a life cycle perspective on timing of flowering is likely to facilitate the identification of selective agents and the understanding of the complex mechanisms underlying spatial and temporal variation in selection as well as to enable more accurate predictions of responses to environmental change.