INVASION ECOLOGY…CURIOUSER & CURIOUSER ALIEN INVASION

vocabulary indigenous = native to a particular place biogeographical = the branch of biology that studies the geographical distribution of organisms

The Enemy Release Hypothesis (ERH) Relates the success of non-indigenous species (NIS) to reduced control by enemies  Pathogens  Parasites  Predators Studies are split  Biogeographical analyses show a reduction in the diversity of enemies in the introduced range compared with the native range  Community studies imply no significant enemy differences between natives and invasives Too simple to describe processes at work?

Evolution of Increased Competitive Ability hypothesis (EICA) Blossey & Nötzold (1995) Observations  Usually a lag period between time of introduction & point at which it is considered invasive  Invasive plants seem to be more virulent in habitats into which they have been introduced (as compared with their native habitats) Presumed a sort of naturalization through modification Predicts that much of the invasive potential of an invasive species is derived from its ability to evolve to reallocate its resources

Invasion model Local adaptation Phenotypic plasticity Species frequency Introduced NaturalizedLagInvasive Sexton et al Ecological Applications 12: Plasticity and adaptive evolution can lead to greater invasiveness