Ecologies of ideologies: Explaining party entry and exit in West-European parliaments, 1945–2013

Marc van de Wardt*, Joost Berkhout, Floris Vermeulen

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


This study introduces a population-ecological approach to the entry and exit of political parties. A primary proposition of population ecology is that organizational entry and exit depends on the number of organizations already present: that is, density. We propose that political parties mainly experience competition from parties in the same ideological niche (left, centre, right). Pooled time-series analyses of 410 parties, 263 elections and 18 West-European countries largely support our expectations. We find that political parties are more likely to exit when density within their niche increases. Also there is competition between adjacent ideological niches, i.e. between centrist and right-wing niches. In contrast to our expectations, neither density nor institutional rules impact party entry. This raises important questions about the rationale of prospective entrants.

Original languageEnglish
Pages (from-to)239-259
Number of pages21
JournalEuropean Union Politics
Issue number2
Publication statusPublished - 1 Jun 2017
Externally publishedYes


  • Party competition
  • party entry
  • party exit
  • party system change
  • population ecology


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