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Non-ecological speciation, niche conservatism and thermal adaptation: how are they connected?

Abstract

During the last decade, the ecological theory of adaptive radiation, and its corollary “ecological speciation”, has been a major research theme in evolutionary biology. Briefly, this theory states that speciation is mainly or largely the result of divergent selection, arising from niche differences between populations or incipient species. Reproductive isolation evolves either as a result of direct selection on mate preferences (e.g. reinforcement), or as a correlated response to divergent selection (“by-product speciation”). Although there are now many tentative examples of ecological speciation, I argue that ecology’s role in speciation might have been overemphasised and that non-ecological and non-adaptive alternatives should be considered more seriously. Specifically, populations and species of many organisms often show strong evidence of niche conservatism, yet are often highly reproductively isolated from each other. This challenges niche-based ecological speciation and reveals partial decoupling between ecology and reproductive isolation. Furthermore, reproductive isolation might often evolve in allopatry before ecological differentiation between taxa or possibly through learning and antagonistic sexual interactions, either in allopatry or sympatry. Here I discuss recent theoretical and empirical work in this area, with some emphasis on odonates (dragonflies and damselflies) and suggest some future avenues of research. A main message from this paper is that the ecology of species differences is not the same as ecological speciation, just like the genetics of species differences does not equate to the genetics of speciation.

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Acknowledgments

I am grateful to Jessica Ware for becoming inviting me to contribute to this special issue of Organisms, Diversity & Evolution. I dedicate this article to Mike May. I also wish to thank Göran Arnqvist, Mats Björklund, Andrew Hendry, Anna Qvarnström and Jon Ågren for discussions about ecological vs nonecological speciation during a visit to the Evolutionary Biology Centre (EBC) at Uppsala University in September 2011, and to John Wiens (SUNY, Stony Brook) for providing critical and constructive comments on the first draft of this manuscript. Although we do not agree on all points, your different viewpoints have helped to clarify my own ideas. Finally, I wish to thank Andrew Hendry for kindly providing the raw figure and material for Fig. 1, which is built partly on his previous publications and a book in progress. Funding for my research has been provided by The Swedish Research Council (VR), Gyllenstiernska Krapperupsstiftelsen and the Entomological Society in Lund (ESIL).

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Svensson, E.I. Non-ecological speciation, niche conservatism and thermal adaptation: how are they connected?. Org Divers Evol 12, 229–240 (2012). https://doi.org/10.1007/s13127-012-0082-6

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Keywords

  • Mike May Festschrift
  • Calopteryx
  • Learning
  • Learned mate preferences
  • Niche
  • Sexual conflict
  • By-product speciation
  • IR-camera
  • Thermal imaging
  • Ectotherms
  • Sexual isolation