Title: Phenotypic shifts caused by predation: selection or life-history shifts?
Authors: Stoks, Robby ×
De Block, Marjan
Van Gossum, H
De Bruyn, L #
Issue Date: 1999
Publisher: Kluwer academic publ
Series Title: Evolutionary ecology vol:13 issue:2 pages:115-129
Abstract: Predators can impose both selection and life-history shifts in prey populations. Because both processes may affect phenotypic distributions, the estimates of selection differentials may be biased. We carried out two field experiments to disentangle these separate effects. We studied whether dragonfly predation by Aeshna cyanea changes the distributions in body size and lamellae morphology in the damselfly Lestes sponsa. Damselflies have caudal lamellae which are used in escapes by swimming. In a first experiment, we manipulated predator presence (No Aeshna, Encaged Aeshna or Free-ranging Aeshna) and stopped the experiment when all larvae had moulted once. In a second experiment, larvae were confronted with a Free-ranging Aeshna but collected before moulting, and survivors were compared with a control sample taken at the start of the experiment. The presence of Aeshna largely reduced the survival probabilities of the Lestes larvae at a very similar rate in both experiments. Daily survival probabilities did not differ between the No Aeshna and Encaged Aeshna treatments. In the Free-ranging Aeshna treatment of the first experiment, size was reduced compared to the other two treatments, creating a significant apparent selection differential. This was probably mainly due to predator-induced reduced growth because in the second experiment, where growth effects were excluded, size of the survivors did not differ from the control sample. In both experiments there was a significant selection pressure for larger lamellae. Standardized directional selection differentials were similar in both experiments (0.57 and 0.28 phenotypic standard deviation units). No survival selection on lamellae shape was detected. These results are in agreement with previous findings that lamellae size, but not lamellae shape, enhances swimming performance and thereby predator escape in this species.
ISSN: 0269-7653
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Ecology, Evolution and Biodiversity Conservation Section
Laboratory for Aquatic Ecology and Evolutionary Biology (-)
× corresponding author
# (joint) last author

Files in This Item:
File Description Status SizeFormat
Stoks EvolEcol 1999.pdf Published 126KbAdobe PDFView/Open Request a copy

These files are only available to some KU Leuven Association staff members


All items in Lirias are protected by copyright, with all rights reserved.

© Web of science