INVASION ECOLOGY…CURIOUSER & CURIOUSER ALIEN INVASION.

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ALIEN INVASION

Invasion ecologyCURIOUSER & CURIOUSERALIEN INVASIONvocabularyindigenous = native to a particular placebiogeographical = 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 enemiesPathogensParasitesPredatorsStudies are splitBiogeographical analyses show a reduction in the diversity of enemies in the introduced range compared with the native rangeCommunity studies imply no significant enemy differences between natives and invasivesToo simple to describe processes at work?Evolution of Increased Competitive Ability hypothesis(EICA)Blossey & Ntzold (1995)ObservationsUsually a lag period between time of introduction & point at which it is considered invasiveInvasive 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 resourcesInvasion modelLocal adaptationPhenotypic plasticitySpecies frequencyIntroduced NaturalizedLagInvasiveSexton et al. 2002. Ecological Applications 12:1652-1660.Plasticity and adaptive evolution can lead to greater invasiveness