Storage and the delayed costs of reproduction in the understorey perennialLathyrus vernus

Ehrlen, J Van Groenendael, J

J. Ehrlen et J. Van Groenendael, Storage and the delayed costs of reproduction in the understorey perennialLathyrus vernus, J ECOLOGY, 89(2), 2001, pp. 237-246

40

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

89

2

2001

237 - 246

ISI

0022-0477(200104)89:2<237:SATDCO>2.0.ZU;2-4

1 A trade-off between current and future reproduction, often referred to as the cost of reproduction, is a fundamental assumption in life history theo ry. In long-lived plants, large absolute differences in size between indivi duals, storage of resources between reproductive events and organ preformat ion may make such costs difficult to demonstrate, especially when only natu ral variation is considered. 2 The long-lived legume Lathyrus vernus shows large size differences compar ed with variation in carbon resource allocation, and is known to store reso urces in below-ground rhizomes. We therefore followed individual plants ove r a period of 4 consecutive years. We examined the cost of reproductive inv estment by comparing the performance of untreated plants that differed in s ize and herbivore damage. We also compared controls with plants where we ex perimentally reduced flowering in terms of fitness measured as: survival, g rowth, flower number, fruit:flower ratio and storage. 3 Natural patterns of flowering and fruiting provided no evidence of a nega tive relationship between current and future reproduction. Individuals that produced fruits did not experience a fewer probability of surviving and pr oducing fruits the following season compared with flowering individuals tha t failed to produce any fruits, even when differences in above-ground size and herbivore damage were taken into account. 4 Flower removal in a single season increased the allocation to the rhizome but the size of shoot buds for the next season was not increased. Experime ntal manipulation of reproductive effort by repeated removal of flowers dur ing 3 consecutive years, however, resulted in a significant increase in veg etative size and the probability of flowering and setting fruit compared wi th control plants. 5 While long-term data on natural variation in fruit production and short-t erm experimental data provided no evidence of a cost of reproduction, such a cost is still present, although detectable only after repeated flower rem oval.