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Speciation: Introduction

  1. John A Hvala1,
  2. Troy E Wood2,3

Published Online: 16 JUL 2012

DOI: 10.1002/9780470015902.a0001709.pub3



How to Cite

Hvala, J. A. and Wood, T. E. 2012. Speciation: Introduction. eLS. .

Author Information

  1. 1

    University of Wisconsin, Madison, Wisconsin, USA

  2. 2

    University of Münster, Institute for Evolution and Biodiversity, Germany

  3. 3

    US Geological Survery, Flagstaff, Arizona, USA

Publication History

  1. Published Online: 16 JUL 2012


Speciation is the formation of two or more new species from one ancestral species. How new species form is a complex process and a fundamental biological question. Answering this question provides insights into patterns of biodiversity and informs conservation strategies. Research on the causes and patterns of speciation is heavily influenced by species concepts – how we define species. The biological species concept is perhaps the most influential, and it groups individuals into species on the basis of the ability to interbreed. Consequently, most research on the process of speciation is driven by the search for mechanisms that affect reproductive compatibility among closely related lineages. Once formed, a new species can maintain its identity by sharing advantageous genes among dispersed and reproductively compatible populations. Conversely, distinguishing traits can be maintained between species via isolating mechanisms. These contrasting mechanisms produce discrete clusters of phenotypic variation rather than a continuum of forms.

Key Concepts:

  • Speciation tends to form clusters of biodiversity rather than continuous gradients.

  • Species concepts heavily influence conclusions about how speciation occurs.

  • Choice of species concept depends on the goal of the research and the organisms being studied.

  • Species remain distinct from each other because of various isolating mechanisms, which prevent gene flow between species.

  • Isolating mechanisms have a genetic basis.

  • Hybridisation between species pairs often occurs in nature and can yield insights into the causes of speciation.

  • Hybridisation can lead to the fusion of two species into one, to reinforcement of reproductive barriers, or even to the formation of new ‘hybrid species’ that are ecologically distinct and genetically isolated from their parent species.


  • allopatry;
  • cline;
  • hybridisation;
  • isolating mechanism;
  • polyploidy;
  • postmating barrier;
  • premating barrier;
  • reinforcement;
  • sympatry