The balance of terror: An alternative mechanism for competitive trade-offsand its implications for invading species

This article uses models to propose an explanation for three observations i n community ecology: the apparent overreaction of prey to attack by special ist predators, the existence of a common trade-off among components of comp etitive ability in communities of unrelated competitors, and the ability of invading species to break the native trade-off. Strategies that increase r esource collection ability are assumed to increase vulnerability to attack by specialist consumers according to a Vulnerability function. If competito rs compete for a common resource and share the same form of the vulnerabili ty function, then they are favored to converge on the same evolutionarily s table level of competitiveness or trade-off curve even if the parameters de scribing their specialized consumers differ. The position of the common str ategy or trade-off curve depends on the whole guild, with more speciose gui lds tending to favor higher levels of competitiveness. Invaders can break t he native trade-off if they come from a guild with a higher trade-off curve , an effect possibly enhanced evolutionarily by escape from specialist cons umers.