In This Article Expand or collapse the "in this article" section Ecological Relevance of Speciation

  • Introduction
  • General Overviews
  • What Are Species? The Biological Species Concept and the Genotypic Cluster Species Concept
  • What Is Ecological Speciation?
  • How to Test for Ecological Speciation
  • Forms of Ecologically Based Reproductive Isolation
  • Genetics of Ecological Speciation
  • Genomics of Ecological Speciation
  • Eco-Evolutionary Dynamics
  • Additional Important Topics and Unresolved Issues in Ecological Speciation

Ecology Ecological Relevance of Speciation
Glen Ray Hood, Scott P. Egan
  • LAST REVIEWED: 19 November 2021
  • LAST MODIFIED: 11 January 2018
  • DOI: 10.1093/obo/9780199830060-0197


In 1859, Charles Darwin described the formation of new species as “that mystery of mysteries.” Some 150 years later, biologists have made incredible progress in understanding the forces that promote, maintain, and constrain organismal biodiversity. The formation of new species, termed “speciation,” is the evolutionary process whereby a group of inbreeding populations diverges into two or more reproductively isolated groups. Ecology has always played a pivotal role in the verbal models of speciation, however, since the late 20th century, the role that ecology plays during speciation has been the subject of intensified research efforts. Specifically, we now know that ecological considerations can be essential to the formation of new species if and when barriers to gene flow evolve between populations as a result of ecologically based divergent natural selection. In this regard, research in the field of “ecological speciation” has focused on theoretical and quantitative considerations in the following three areas: (1) the ecological (i.e., environmental) sources of divergent natural selection, (2) the evolution of ecologically based barriers of reproductive isolation between diverging populations, and (3) the link between changes in the specific gene(s) or gene regions involved in the evolution of reproductive isolation and the distribution of those genes throughout the genome within and between diverging populations. In this article, we first provide a broad overview of the ecological speciation literature and a guide to important historical and contemporary texts that form the basis for the modern approach to ecological speciation. Next, we summarize important contemporary literature associated with the empirical and theoretical study of divergent natural selection, ecologically based reproductive isolation, and the genetics and genomics of ecological speciation. In addition, we highlight literature in the field of eco-evolutionary dynamics aimed at specifically understanding how evolutionary dynamics affect ecology and how ecology affects evolutionary biology. We then review literature regarding the role that next-generation sequencing and the “genomic revolution” are playing in elucidating the role of ecology in the speciation process. Lastly, we conclude by providing literature sources that assesses current unanswered questions in the field that show that, while parts of Darwin’s “mystery” have been solved, there is much left to be discovered.

General Overviews

There are several literature sources that highlight the patterns and processes promoting ecological speciation. The general role that ecology plays in the speciation process is typically outlined in most college-level ecology and organismal biology textbooks, and has been discussed in great detail in a number of book-length reviews, including Schluter 2000, Coyne and Orr 2004, and Nosil 2012. In addition, there have been a number of scientific articles addressing this topic, including a general overview of the topic in Rundle and Nosil 2005 and comprehensive taxa-specific reviews for insects in Berlocher and Feder 2002; fish in Schluter and Rambaut 1996; birds in Price 2008; bacteria in Horner-Devine, et al. 2004; and plants in Givnish 2010. The edited book Howard and Berlocher 1998 contains thirty-three chapters from different authors addressing methodological, theoretical, and quantitative treatments of speciation, with many specifically focusing on various aspects of the role of ecology in the speciation process.

  • Berlocher, S. H., and J. L. Feder. 2002. Sympatric speciation in insects: Moving beyond controversy? Annual Review of Entomology 47.1: 773–815.

    DOI: 10.1146/annurev.ento.47.091201.145312

    An in-depth review of sympatric speciation (i.e., speciation in the absence of geographic barriers to gene flow) in insects with special attention paid to the role of ecology during the speciation process.

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

    One of the most comprehensive book-length reviews of the process of speciation. Specifically, chapters 5, 7, and 8 focus on ecological speciation and the evolution of reproductive isolation.

  • Givnish, T. 2010. Ecology of plant speciation. Taxon 59.5: 1326–1366.

    An in-depth review of ecological speciation and adaptive radiations of plants, including a detailed discussion of the role of pollinators in plant speciation.

  • Horner-Devine, M. C., K. M. Carney, and B. J. M. Bohannan. 2004. An ecological perspective on bacterial biodiversity. Proceedings of the Royal Society B: Biological Sciences 271.1535: 113–122.

    DOI: 10.1098/rspb.2003.2549

    A unique review that compares and contrasts ecological patterns of plant and animal biodiversity with bacteria.

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

    An edited volume with thirty-three chapters by various authors, which provides a comprehensive review of reproductive isolation, divergent natural selection, and (ecological) speciation.

  • Nosil, P. 2012. Ecological speciation. New York: Oxford Univ. Press.

    DOI: 10.1093/acprof:osobl/9780199587100.001.0001

    The most recent, comprehensive, book-length review of ecological speciation.

  • Price, T. 2008. Speciation in birds. Boulder, CO: Roberts.

    A comprehensive book-length review of general patterns and processes of speciation in birds, including the role of ecology in the speciation process.

  • Rundle, H. D., and P. Nosil. 2005. Ecological speciation. Ecology Letters 8.3: 336–352.

    DOI: 10.1111/j.1461-0248.2004.00715.x

    A general review article on the evolution of divergent natural selection, sexual selection, reproductive isolation, and the geographic context of and genetic basis for ecological speciation across diverse taxa.

  • Schluter, D. 2000. The ecology of adaptive radiation. New York: Oxford Univ. Press.

    This book reviews the process of adaptive radiations (i.e., when a single ancestral species diversifies into multiple new species that use a diversity of different environments) and the role that ecology plays in adaptive divergence.

  • Schluter, D., and A. Rambaut. 1996. Ecological speciation in postglacial fishes. Philosophical Transactions of the Royal Society B: Biological Sciences 351.1341: 807–814.

    DOI: 10.1098/rstb.1996.0075

    A review of ecological speciation in fish with a focus on evidence for divergent natural selection between diverging populations of various taxa living in postglacial lakes.

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