Sympatric Speciation

by

Axel Meyer, Andreas F. Kautt

• LAST REVIEWED: 13 December 2021
• LAST MODIFIED: 26 August 2014
• DOI: 10.1093/obo/9780199941728-0053

Introduction

Speciation can be described as the process of the splitting of cohesive groups of organisms into distinct entities; that is, the evolution of biological species (cladogenesis). In sexually reproducing organisms, this distinctness can come about and be maintained only if the exchange of genetic material between groups is strongly reduced. That reproductive isolation should be the defining characteristic of species is the central tenet of the biological species concept, the most commonly used species concept in the field of evolutionary biology. Hence, speciation research is concerned mainly with understanding the nature and evolution of barriers to interbreeding between organismal groups. The role of geography and, specifically, geographic isolation in this regard has been subject to one of the most persistent debates in the field of speciation research. While the initiation of speciation in geographic isolation (i.e., allopatric speciation) is supported both by several lines of evidence and a compelling body of underlying theory, speciation without the mediating effect of geographic isolation (i.e., sympatric speciation) has long been controversial. Mainly, sympatric speciation has been considered either as unlikely to occur at all or to play a substantial role in terms of the frequency of its occurrence. Yet, the study of sympatric speciation has received renewed interest since the early 1980s, and empirical and theoretical support for its plausibility has accumulated. Thus, the reality of sympatric speciation is no longer in doubt. Nevertheless, its importance as a mode of speciation and the circumstances under which it happens continue to be debated. Estimates of the frequency of different modes of speciation typically assign only a minor role to sympatric speciation, apart from examples from certain animal and plant taxa. But, the importance of sympatric speciation for evolutionary biology goes beyond its relative frequency in generating biodiversity. Its conceptual and empirical challenges have stimulated advances of broader importance for our understanding of the general mechanisms involved in the process of speciation. Thus, the study of speciation in a setting without geographic isolation, whether viewed from a geographical perspective as sympatric speciation or considered in a population-genetic point of view as an extreme case of speciation with gene flow, will likely continue to attract the attention of future generations of evolutionary biologists.

General Overviews

A basic overview on geographic modes of speciation that is accessible to the broad readership can be found in Futuyma 2013, a textbook on evolution. Entire books devoted to the topic of speciation usually discuss sympatric speciation and often provide a detailed discussion. Mayr 1963 was one of the first books concerned with the topic of speciation, and, although now obviously outdated, it still makes for excellent reading in order to understand the early history of speciation research and the beginnings of the debate about sympatric speciation. Several papers compiled in Otte and Endler 1989 deal with sympatric speciation and provide an overview of the subject. Howard and Berlocher 1998 includes contributions by various authors in the field of speciation research. One section is devoted to mechanisms of speciation and emphasizes possible modes of sympatric speciation. A timely and lucid review on speciation is found in Coyne and Orr 2004. In this book, Jerry Coyne and H. Allen Orr also define four criteria for inferring that a certain past speciation event in the wild is best explained by sympatric speciation: (1) modern species’ ranges are sympatric, (2) there is substantial reproductive isolation between species, (3) species are sister groups, and (4) a past allopatric phase is unlikely. These criteria have become the conservative “gold standard” in evolutionary biology. Via 2001 and Bolnick and Fitzpatrick 2007 focus specifically on the mode of sympatric speciation and offer excellent overviews. A concise overview on speciation in plants is given in Rieseberg and Willis 2007.

• Bolnick, D. I., and B. M. Fitzpatrick. 2007. Sympatric speciation: Models and empirical evidence. Annual Review of Ecology, Evolution, and Systematics 38:459–487.

  DOI: 10.1146/annurev.ecolsys.38.091206.095804

  NNNThis review paper begins with a brief general introduction, followed by a discussion of the empirical evidence for sympatric speciation and its frequency in nature. Subsequent sections provide an overview on the multitude of existing theoretical models and evaluate the justification of assumptions with respect to empirical data.

• Coyne, J. A., and H. A. Orr. 2004. Speciation. Sunderland, MA: Sinauer.

  NNNWritten by two authorities in the field of speciation research, this book represents the most comprehensive early-21st-century treatise on speciation and has become a must-read for those interested in speciation. Sympatric speciation and the evidence for it from theoretical models, experimental work, and natural populations are discussed in chapter 4.

• Futuyma, D. J. 2013. Evolution. 3d ed. Sunderland, MA: Sinauer.

  NNNEvolution is an introductory textbook in evolutionary biology. An overview of the different geographic modes of speciation can be found in chapter 18. First published in 2005.

• Howard, D. J., and S. H. Berlocher, eds. 1998. Endless forms: Species and speciation. New York: Oxford Univ. Press.

  NNNThe contributions in this book resulted from a symposium in honor of Guy Bush, who was a strong advocate of the plausibility of sympatric speciation, especially in insects. Bush’s interests in sympatric speciation are reflected in a number of chapters in the book.

• Mayr, E. 1963. Animal species and evolution. Cambridge, MA: Belknap.

  DOI: 10.4159/harvard.9780674865327

  NNNOne of Mayr’s most influential books. In a section of chapter 15 the evidence for sympatric speciation is critically assessed. Reprinted as recently as 1979.

• Otte, D., and J. A. Endler, eds. 1989. Speciation and its consequences. Sunderland, MA: Sinauer.

  NNNThis volume arose from a symposium on speciation and consists of twenty-five papers and a concluding review. Several contributions are primarily concerned with sympatric speciation.

• Rieseberg, L. H., and J. H. Willis. 2007. Plant speciation. Science 317.5840: 910–914.

  DOI: 10.1126/science.1137729

  NNNIn this brief review the authors describe several aspects of speciation in plants. One section is devoted to hybrid and polyploid speciation, which is an important mode of sympatric speciation in plants. A list of case studies on sympatric speciation in plants is provided in the supplementary materials.

• Via, S. 2001. Sympatric speciation in animals: The ugly duckling grows up. In Special issue: Speciation. Trends in Ecology & Evolution 16.7: 381–390.

  DOI: 10.1016/S0169-5347(01)02188-7

  NNNThis review is part of a special issue on speciation and begins with a brief recapitulation of the history of sympatric speciation and then moves on to describe the underlying mechanisms of, and favorable conditions for, sympatric speciation. This discussion is based both on empirical and theoretical work.