Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Speciation in a ring


The evolutionary divergence of a single species into two has never beendirectly observed in nature, primarily because speciation can take a longtime to occur. A ring species, in which a chain of intergrading populationsencircles a barrier and the terminal forms coexist without interbreeding,provides a situation in which variation in space can be used to infer variationin time1,2,3. Here we reconstruct the pathway to speciationbetween two reproductively isolated forms of greenish warbler (Phylloscopustrochiloides). These two taxa do not interbreed in central Siberia butare connected by a long chain of intergrading populations encircling the TibetanPlateau to the south4. Molecular data and climatic history implythat the reproductively isolated taxa came into contact following expansionsnorthward around the western and eastern sides of the plateau. Parallel selectionpressures for increased song complexity during the northward expansions havebeen accompanied by divergence in song structure. Playback experiments showthat the two Siberian forms do not recognize each other's songs. Our resultsshow how gradual divergence in a trait involved in mate choice leads to theformation of new species.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Geographic range of the greenish warbler species complex, along withresearch sites and representative song spectrograms.
Figure 2: Geographic variation in the song of the greenish warbler as quantifiedby principal components analysis.
Figure 3: Relationship between geographic distance and song recognition.
Figure 4: Mitochondrial DNA gene tree based on variation in 1,200 bpin the neighbourhood of the control region and ND6 gene.
Figure 5: Variation in four traits (mean ± s.e.) around the ring of greenishwarbler populations.


  1. Mayr, E. Systematicsand the Origin of Species (Dover, New York, 1942).

    Google Scholar 

  2. Wake, D. B., Yanev, K. P. & Frelow, M. M. in Speciation and its Consequences (eds Otte,D. & Endler, J.) 134–157 (Sinauer, Sunderland,MA, 1989).

    Google Scholar 

  3. Wake, D. B. & Schneider, C. J. Taxonomy of the plethodontidsalamander genus Ensatina. Herpetologica 54, 279–298 (1998).

    Google Scholar 

  4. Ticehurst, C. B. A Systematic Review of the Genus Phylloscopus (Johnson Reprint, NewYork, 1938).

    Google Scholar 

  5. Martens, J. M. in Ecology and Evolution of Acoustic Communication in Birds (eds Kroodsma,D. E. & Miller, E. H.) 221–240 (Cornell Univ.Press, Ithaca, 1996).

    Google Scholar 

  6. Irwin, D. E., Alström, P., Olsson, U. & Benowitz-Fredericks, Z. M. Cryptic species in the genus Phylloscopus (Old World leaf warblers). Ibis (in the press).

  7. Irwin, D. E. Song variation in an avian ring species. Evolution 54, 998–1010 (2000).

    CAS  Article  PubMed  Google Scholar 

  8. Frenzel, B. The Pleistocene vegetation of northern Eurasia. Science 161, 637–649 (1968).

    ADS  CAS  Article  PubMed  Google Scholar 

  9. Mayr, E. Populations,Species, and Evolution (Harvard Univ. Press, Cambridge, 1970).

    Google Scholar 

  10. Highton, R. Is Ensatina eschscholtzii a ring-species? Herpetologica 54, 254–278 (1998).

    Google Scholar 

  11. Wang, C.-W. The Forests of China (Maria Moors Cabot Foundation Publication No. 5,Botanical Museum, Harvard Univ., Cambridge, MA, 1961).

    Google Scholar 

  12. Menzies, N. K. Forest and Land Management in Imperial China (St. Martin’s, NewYork, 1994).

    Book  Google Scholar 

  13. Marchetti, K. Dark habitats and bright birds illustrate the role of the environment in speciesdivergence. Nature 362, 149–152 (1993).

    ADS  Article  Google Scholar 

  14. Marchetti, K. & Price, T. The adaptive significance of colourpatterns in the Old World leaf warblers, genus Phylloscopus. Oikos 79, 410–412 (1997).

    Article  Google Scholar 

  15. Price, T. Morphology and ecology of breeding warblers along an altitudinal gradientin Kashmir, India. J. Anim. Ecol. 60, 643–664 (1991).

    Article  Google Scholar 

  16. Orr, M. R. & Smith, T. B. Ecology and speciation. Trends Ecol. Evol. 13, 502–506(1998).

    CAS  Article  PubMed  Google Scholar 

  17. Rundle, H. D., Nagel, L., Boughman, J. W. & Schluter, D. Natural selection and parallel speciation in sympatric sticklebacks. Science 287, 306–308 (2000).

    ADS  CAS  Article  Google Scholar 

  18. West-Eberhard, M. J. Sexual selection, social competition and speciation. Quart. Rev.Biol. 58, 155–183 (1983).

    Article  Google Scholar 

  19. Bensch, S. & Härlid, A. Mitochondrial gene rearrangementsin songbirds. Mol. Biol. Evol. 17, 107–113 (2000).

    CAS  Article  PubMed  Google Scholar 

  20. Thompson, J. D., Higgins, D. G. & Gibson, T. J. CLUSTAL W: improving the sensitivity of progressivemultiple sequence alignment through sequence weighting, position specificgap penalites and weight matrix choice. Nucleic Acids Res. 22, 4673–4680 (1994).

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  21. Strimmer, K. & von Haeseler, A. Quartet-puzzling: a quartetmaximum-likelihood method for reconstructing tree topologies. Mol. Biol. Evol. 13, 964–969(1996).

    CAS  Article  Google Scholar 

  22. Bensch, S., Price, T. & Kohn, J. Isolation and characterization of microsatellite loci in a Phylloscopus warbler. Mol. Ecol. 6, 91–92 (1997).

    CAS  Article  PubMed  Google Scholar 

Download references


We thank J. Kohn for the use of his laboratory; P. Alström, K. Marchetti,U. Olsson, A. Richman, J. Tiainen, the British Museum and the Burke Museumfor samples; Z. Benowitz-Fredericks, J. Gibson, S. Gross, J. Irwin, G.Kelberg, A. Knorre, K. Marchetti and B. Sheldon for help in the field; A.Asbeck, M. Bouvier, H. Neville, K. Petren, R. Radtkey and A. Richmanfor technical assistance; T. Case, J. Coyne, M. Dantzker, D. Holway,J. Irwin, J. Kohn, T. Pärt, A. Qvarnström, A. Suarez, N. Tsutsui,M. Turelli, A. Uy and S. Vehrencamp for comments on the manuscript. Forfinancial support we thank the American Ornithologists’ Union, The ExplorersClub, the Jeanne Messier Memorial Fund, the National Geographic Society, theNational Science Foundation and Sigma Xi.

Author information

Authors and Affiliations


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Irwin, D., Bensch, S. & Price, T. Speciation in a ring. Nature 409, 333–337 (2001).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing