title: Rarity value and species extinction: the anthropogenic Allee effect.
abstract: Standard economic theory predicts that exploitation alone is unlikely to result in species extinction because of the escalating costs of finding the last individuals of a declining species. We argue that the human predisposition to place exaggerated value on rarity fuels disproportionate exploitation of rare species, rendering them even rarer and thus more desirable, ultimately leading them into an extinction vortex. Here we present a simple mathematical model and various empirical examples to show how the value attributed to rarity in some human activities could precipitate the extinction of rare species-a concept that we term the anthropogenic Allee effect. The alarming finding that human perception of rarity can precipitate species extinction has serious implications for the conservation of species that are rare or that may become so, be they charismatic and emblematic or simply likely to become fashionable for certain activities.
authors.affiliation: Ecologie, Systématique, et Evolution, UMR CNRS 8079, Universite Paris-Sud, Orsay, France. franck.courchamp@u-psud.fr
authors.forename: Franck
authors.initials: F
authors.lastname: Courchamp
authors.forename: Elena
authors.initials: E
authors.lastname: Angulo
authors.forename: Philippe
authors.initials: P
authors.lastname: Rivalan
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hall
authors.forename: Laetitia
authors.initials: L
authors.lastname: Signoret
authors.forename: Leigh
authors.initials: L
authors.lastname: Bull
authors.forename: Yves
authors.initials: Y
authors.lastname: Meinard
mesh_terms: D000818:Animals; D000829:Animals, Domestic; D044822:Biodiversity; D036262:Empirical Research; D053476:Extinction, Biological; D006801:Humans; D008519:Medicine, Traditional; D008962:Models, Theoretical