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Letters to Nature

Nature 400, 354-357 (22 July 1999) | doi:10.1038/22521; Received 28 January 1999; Accepted 1 June 1999

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On the origin of species by sympatric speciation

Ulf Dieckmann1 & Michael Doebeli2

  1. Adaptive Dynamics Network, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria
  2. Zoology Institute, University of Basel, Rheinsprung 9, CH-4051 Basel, Switzerland

Correspondence to: Ulf Dieckmann1 Correspondence and requests for materials should be addressed to U.D. (e-mail: Email: dieckman@iiasa.ac.at).

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Understanding speciation is a fundamental biological problem. It is believed that many species originated through allopatric divergence, where new species arise from geographically isolated populations of the same ancestral species1, 2, 3. In contrast, the possibility of sympatric speciation (in which new species arise without geographical isolation) has often been dismissed, partly because of theoretical difficulties2,3. Most previous models analysing sympatric speciation concentrated on particular aspects of the problem while neglecting others4, 5, 6, 7, 8, 9, 10. Here we present a model that integrates a novel combination of different features and show that sympatric speciation is a likely outcome of competition for resources. We use multilocus genetics to describe sexual reproduction in an individual-based model, and we consider the evolution of assortative mating (where individuals mate preferentially with like individuals) depending either on an ecological character affecting resource use or on a selectively neutral marker trait. In both cases, evolution of assortative mating often leads to reproductive isolation between ecologically diverging subpopulations. When assortative mating depends on a marker trait, and is therefore not directly linked to resource competition, speciation occurs when genetic drift breaks the linkage equilibrium between the marker and the ecological trait. Our theory conforms well with mounting empirical evidence for the sympatric origin of many species10, 11, 12, 13, 14, 15, 16, 17, 18.

  1. Adaptive Dynamics Network, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria
  2. Zoology Institute, University of Basel, Rheinsprung 9, CH-4051 Basel, Switzerland

Correspondence to: Ulf Dieckmann1 Correspondence and requests for materials should be addressed to U.D. (e-mail: Email: dieckman@iiasa.ac.at).