title: Effects of fragmentation on plant adaptation to urban environments.
abstract: Urban ecosystems are relatively recent and heavily human-altered terrestrial ecosystems with a surprisingly high diversity of animals, plants and other organisms. Urban habitats are also strongly fragmented and subject to higher temperatures, providing a compelling model for studying adaptation to global change. Crepis sancta (Asteraceae), an annual Mediterranean wasteland weed, occupies fragmented urban environments as well as certain unfragmented landscapes in southern France. We tested for shifts in dispersal, reproductive traits and size across a rural-urban gradient to learn whether and how selection may be driving changes in life history in urban and fragmented habitats. We specifically compared the structure of quantitative genetic variation and of neutral markers (microsatellites) between urban and rural and between fragmented and unfragmented habitats. We showed that fragmentation provides a better descriptor of trait variation than urbanization per se for dispersal traits. Fragmentation also affected reproductive traits and plant size though one rural population did conform to this scheme. Our study shows the role of fragmentation for dispersal traits shift in urban environments and a more complex pattern for other traits. We discuss the role of pollinator scarcity and an inhospitable matrix as drivers of adaptation.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'.
authors.affiliation: CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valery, Montpellier, EPHE - 1919, route de Mende, 34293 Montpellier Cedex 05, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dubois
authors.affiliation: CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valery, Montpellier, EPHE - 1919, route de Mende, 34293 Montpellier Cedex 05, France pierre-olivier.cheptou@cefe.cnrs.fr.
authors.forename: Pierre-Olivier
authors.identifier: 0000-0002-5739-5176
authors.initials: PO
authors.lastname: Cheptou
mesh_terms: D000220:Adaptation, Biological; D027468:Crepis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017753:Ecosystem; D005602:France; D014644:Genetic Variation; D000071421:Life History Traits; D018895:Microsatellite Repeats; D063148:Plant Dispersal; D012098:Reproduction; D014507:Urbanization
keywords: Asteraceae; Crepis sancta; adaptation; dispersal; fragmentation; urban ecosystems