PARENT SESSION
Oral Session # 95: Predator - Prey Ecology III: Aquatic Systems.
Presiding: J Vonesh
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 201.
Rapid evolution drives ecological dynamics in a predator-prey system.
Yoshida, Takehito 1, Jones, Laura1, Ellner, Stephen 1, Fussmann, Gregor2, Hairston, Nelson*,1, 1 Department of Ecology and Evolutionary Biology, Ithaca, New York, USA2 Institute fuer Biochemie und Biologie, Potsdam, Germany, Germany
ABSTRACT- The accumulating evidence for rapid evolution indicates that ecological and evolutionary dynamics can occur on similar time-scales. Theoretical studies have predicted that rapid evolution can affect ecological dynamics but predictions remain inconclusive: for example, depending on assumptions, prey evolution can stabilize or destabilize predator-prey dynamics. Using laboratory microcosms, we studied the effect on predator-prey (rotifer-alga) cycles of rapid prey evolution in response to oscillating predator density, in order to test explicit predictions of a model for this system allowing prey evolution. Here we report an evolutionary tradeoff between algal competitive ability and defense against consumption. We then demonstrate its effect on cycle dynamics by manipulating the evolutionary potential of the prey population. Single-clone algal cultures (lacking genetic variability) produced short cycle periods and typical quarter-phase lags between prey and predator densities, while multi-clonal (genetically variable) algal cultures produced long cycles with prey and predator densities nearly out of phase, exactly as predicted. These results confirm that prey evolution can dramatically alter predator-prey dynamics, hence attempts to understand population oscillations in nature cannot ignore potential effects from ongoing rapid evolution.
Key words: population dynamics, population cycles, natural selection, microcosms