Regional divergence and mosaic spatial distribution of two closely related damselfly species (Enallagma hageni and Enallagma ebrium)

J Evol Biol. 2012 Jan;25(1):196-209. doi: 10.1111/j.1420-9101.2011.02418.x. Epub 2011 Nov 28.


North American Enallagma damselflies radiated during the Pleistocene, and species differ mainly by reproductive structures. Although morphologically very different, Enallagma hageni and Enallagma ebrium are genetically very similar. Partitioning of genetic variation (AFLP), isolation by distance and clustering analyses indicate that these morphospecies are locally differentiated genetically. Spatial analyses show that they are rarely sympatric at local sites, and their distributions form a mosaic of patches where one is clearly dominant over hundreds of square kilometers. However, these morphospecies are also not genetically more similar when they are sympatric, indicating that hybridization is probably not occurring. Given that these morphospecies are ecologically equivalent, strong assortative mating, reproductive interference and fast post-glacial recolonization may explain the origin and maintenance of these distributional patches across eastern North America. By limiting opportunities for gene flow, reproductive interference may play an unsuspected role in accelerating genetic differentiation in the early phases of nonecological speciation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amplified Fragment Length Polymorphism Analysis
  • Animals
  • Cluster Analysis
  • Female
  • Gene Flow
  • Genetic Speciation*
  • Hybridization, Genetic
  • Insecta / classification
  • Insecta / genetics*
  • Male
  • Phylogeny
  • Polymorphism, Restriction Fragment Length
  • Population Dynamics
  • Regression Analysis
  • Reproductive Isolation
  • Sympatry