, Volume 169, Issue 3, pp 703–712

Determinants of extinction in fragmented plant populations: Crepis sancta (asteraceae) in urban environments

Population ecology - Original research

DOI: 10.1007/s00442-011-2229-0

Cite this article as:
Dornier, A. & Cheptou, PO. Oecologia (2012) 169: 703. doi:10.1007/s00442-011-2229-0


Local populations are subject to recurrent extinctions, and small populations are particularly prone to extinction. Both demographic (stochasticity and the Allee effect) and genetic factors (drift load and inbreeding depression) potentially affect extinction. In fragmented populations, regular dispersal may boost population sizes (demographic rescue effect) or/and reduce the local inbreeding level and genetic drift (genetic rescue effect), which can affect extinction risks. We studied extinction processes in highly fragmented populations of the common species Crepis sancta (Asteraceae) in urban habitats exhibiting a rapid turnover of patches. A four-year demographic monitoring survey and microsatellite genotyping of individuals allowed us to study the determinants of extinction. We documented a low genetic structure and an absence of inbreeding (estimated by multilocus heterozygosity), which suggest that genetic factors were not a major cause of patch extinction. On the contrary, local population size was the main factor in extinction, whereas connectivity was shown to decrease patch extinction, which we interpreted as a demographic rescue effect that was likely due to better pollination services for reproduction. This coupling of demographic and genetic tools highlighted the importance of dispersal in local patch extinctions of small fragmented populations connected by gene flow.


DemographyExtinctionFragmentationRescue effectGenetic structure

Supplementary material

442_2011_2229_MOESM1_ESM.pdf (80 kb)
Supplementary material 1 (PDF 80 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.UMR 5175 CEFE-CNRS, Centre d’Ecologie Fonctionnelle et Evolutive (CNRS)Montpellier Cedex 05France