Intraspecific variation in the consumption of exotic prey – a mechanism that increases biotic resistance against invasive species?


Nils O. L. Carlsson, The County Administrative Board, Environmental Department, SE-205 15 Malmö, Sweden. E-mail:


1. Hyper-successful exotic species can both displace the native prey that formerly made up a native predator’s diet and represent an abundant potential prey resource for native predators. Little is known about how this drastic change affects native predators, or their short- and long term potential to regulate the exotic species.

2. We compared zebra mussel consumption by pumpkinseed sunfish (Lepomis gibbosus), redbreast sunfish (Lepomis auritus) and rock bass (Ambloplites rupestris) from populations that were either previously exposed to zebra mussels or naive to them.

3. Fish from populations with longer exposure to zebra mussels consumed many more zebra mussels than fish from populations with shorter or no previous exposure to zebra mussels.

4. Our experiment does not allow us to identify the mechanisms that underlie the patterns we found, but we discuss several plausible scenarios and their ecological implications.

5. Predator adaptation to exotic prey may be an important but overlooked factor in invasion biology. The initial response to exotic prey by a native predator may be a poor estimate of its ability to present biotic resistance to the invasion over the long term.