EXPERIMENTAL ECOLOGICAL GENETICS IN PLANTAGO. VII. REPRODUCTIVE EFFORT IN POPULATIONS OF P. LANCEOLATA L.

Abstract

The allocation of resources to the processes of growth, reproduction, and survival has been considered crucial to an understanding of life history evolution. Allocation patterns have been seen as the physiological basis of between different life history stages and the presumption of such trade-offs has been an integral part of much of life history evolution theory (Pianka and Parker, 1975; Wilbur, 1977; Law, 1979). Moreover, allocation patterns themselves are often thought of as traits and subject to selection forces similar to those acting on mortality and fecundity schedules (Gadgil and Bossert, 1970; Schaffer and Gadgil, 1975). The focus of many studies on resource allocation has been on the amount of resources devoted to parts relative to the amount devoted to vegetative parts, the proportion of the total resource budget devoted to reproduction being termed reproductive effort. The connection with life-history is clear in that the allocation to tissues will be related to fecundity, and the allocation to vegetative tissues will be related to survivorship and/or future fecundity. In spite of the development of an extensive body of theory on life-history evolution (for review see Stearns, 1976), many of the basic questions regarding actual resource allocation patterns have remained largely unanswered (Hirschfield and Tinkle, 1975) even though they were first posited in relation to plant populations in the seminal paper of Harper (1967). In particular, only a few studies have addressed the problem of measuring the rel-