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Polyphyly and gene flow between non-sibling Heliconius species
Vanessa Bull1, Margarita Beltrán, Chris D Jiggins
1Galton Laboratory, Department of Biology, University College London, 4 Stephenson Way, London NW1 2HE, UK. Vanessa.Bull@fss.pnn.police.uk
BMC Biology
|April 25, 2006
Summary
Gene flow between Heliconius butterfly species is more common than previously thought. Recent transfer of specific gene variants (Mpi haplotypes) between H. cydno and H. melpomene demonstrates ongoing interspecific gene flow.
Area of Science:
- Evolutionary Biology
- Genetics
- Zoology
Background:
- Traditional views considered gene flow between animal species rare and evolutionarily insignificant.
- Modern molecular techniques allow for more sensitive investigations into species interactions.
- This study focuses on two divergent butterfly species, Heliconius cydno and H. melpomene, with overlapping distributions.
Purpose of the Study:
- To investigate the extent and impact of gene flow between two morphologically and ecologically distinct butterfly species.
- To determine if interspecific gene transfer occurs between Heliconius cydno and Heliconius melpomene.
- To assess the role of introgression in the evolutionary history of these species.
Main Methods:
- DNA sequencing of mitochondrial (cytochrome oxidase subunits I and II) and nuclear loci (triose-phosphate isomerase, mannose-6-phosphate isomerase, cubitus interruptus).
- Analysis of haplotype genealogies to infer patterns of gene flow and speciation.
- Exclusion of the dopa decarboxylase gene due to potential duplicate loci.
Main Results:
- Mitochondrial and triose-phosphate isomerase genealogies suggest reciprocal monophyly between the species.
- Identical or similar mannose-6-phosphate isomerase and cubitus interruptus haplotypes were found in sympatric populations, indicating genealogical polyphyly.
- Evidence strongly supports recent transfer of mannose-6-phosphate isomerase haplotypes between the species.
Conclusions:
- Species boundaries can remain permeable to gene flow long after speciation events.
- Interspecific gene flow, even between non-sibling species, can be a significant evolutionary force.
- This study provides the first evidence of interspecific gene flow in Heliconius butterflies, potentially facilitating adaptation transfer for Müllerian mimicry.