A hybrid zone provides evidence for incipient ecological speciation in Heliconius butterflies Academic Article


  • Molecular Ecology


  • In Heliconius butterflies, it has been proposed that speciation occurs through a combination of divergence in ecological habitat preferences and mimetic colour patterns. Here we test this hypothesis by investigating a parapatric form of the widespread species Heliconius erato. Mendelian (colour patterns) and molecular genetic data permit us to address hypotheses about introgression and genetic differentiation between different populations. Combined analysis of colour pattern, microsatellite loci and mitochondrial DNA showed that Heliconius erato venus and Heliconius erato chestertonii form a bimodal hybrid zone implying partial reproductive isolation. In a sample of 121 individuals collected in sympatry, 25% were hybrids representing a significant deficit of heterozygotes compared to the Hardy-Weinberg expectation. Seven microsatellite loci, analysed for a subset of these individuals, showed marked differentiation between the parental taxa, and unambiguously identified two genotypic clusters concordant with our phenotypic classification of individuals. Mitochondrial DNA analysis showed H. erato venus as a monophyletic group well differentiated from H. erato chestertonii, implying a lack of historical introgression between the populations. Heliconius erato chestertonii is therefore an incipient species that maintains its integrity despite high levels of hybridization. Moreover, H. erato chestertonii is found at higher altitudes than other races of H. erato and has a distinct colour pattern and mimetic relationship. Hence, there are now two examples of parapatric incipient species related to H. erato, H. himera and H. erato chestertonii, both of which are associated with higher altitudes, more arid habitats and distinct mimetic relationships. This implies that parapatric habitat adaptation is a likely cause of speciation in this group.

publication date

  • 2008-11-1


  • 17


  • Butterflies
  • Color
  • Ecosystem
  • Heliconius
  • Heliconius erato
  • Heterozygote
  • Microsatellite Repeats
  • Mitochondrial DNA
  • Molecular Biology
  • Population
  • Reproductive Isolation
  • Sympatry
  • Venus
  • analysis
  • butterflies
  • butterfly
  • color
  • divergence
  • genetic differentiation
  • genetic variation
  • habitat
  • habitat preferences
  • habitat selection
  • habitats
  • heterozygosity
  • hybrid zone
  • hybridization
  • introgression
  • loci
  • microsatellite repeats
  • mitochondrial DNA
  • molecular genetics
  • reproductive isolation
  • sampling
  • sympatry
  • taxonomy
  • test
  • testing

International Standard Serial Number (ISSN)

  • 0962-1083

number of pages

  • 14

start page

  • 4699

end page

  • 4712