The Shape of the Trade-Off Function Between Reproduction and Future Performance in Plantago

ways results in the same cost regardless of the level of RO; Fig. 1, upper panel). Two basic approaches have been used to examine the relationship between reproduction and fu-ture performance (Reznick 1985; Stearns 1989; Bailey 1992). The first experimentally controls reproduction by various means (e.g., removal of flower buds, photoperiod manipulations, control of pollination) and then compares the subsequent performance of the treatments. Most studies of this nature choose to induce only two (rarely three) lev-els of RO. Obviously, with only two different levels it is impossible to determine whether the relationship between RO and vegetative performance is linear or curvilinear. The second approach to examining the cost of reproduction uses correlation analysis to compare the subsequent perfor-mance of plants that differ naturally in the level of RO