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Secondary contact seeds phenotypic novelty in cichlid fishes

Nichols, Paul; Genner, Martin J.; van Oosterhout, Cock; Smith, Alan; Parsons, Paul; Sungani, Harold; Swanstrom, Jennifer; Joyce, Domino A.


Paul Nichols

Martin J. Genner

Cock van Oosterhout

Alan Smith

Paul Parsons

Harold Sungani

Jennifer Swanstrom


Theory proposes that genomic admixture between formerly reproductively isolated populations can generate phenotypic novelty for selection to act upon. Secondary contact may therefore be a significant promoter of phenotypic novelty that allows species to overcome environmental challenges and adapt to novel environments, including during adaptive radiation. To date, this has largely been considered from the perspective of interspecific hybridization at contact zones. However, it is also possible that this process occurs more commonly between natural populations of a single species, and thus its importance in adaptive evolution may have been underestimated. In this study, we tested the consequences of genomic introgression during apparent secondary contact between phenotypically similar lineages of the riverine cichlid fish Astatotilapia calliptera. We provide population genetic evidence of a secondary contact zone in the wild, and then demonstrate using mate-choice experiments that both lineages can reproduce together successfully in laboratory conditions. Finally, we show that genomically admixed individuals display extreme phenotypes not observed in the parental lineages. Collectively, the evidence shows that secondary contact can drive the evolution of phenotypic novelty, suggesting that pulses of secondary contact may repeatedly seed genetic novelty, which when coupled with ecological opportunity could promote rapid adaptive evolution in natural circumstances.


Nichols, P., Genner, M. J., van Oosterhout, C., Smith, A., Parsons, P., Sungani, H., …Joyce, D. A. (2015). Secondary contact seeds phenotypic novelty in cichlid fishes. Proceedings of the Royal Society B: Biological Sciences, 282(1798), Article ARTN 20142272.

Journal Article Type Article
Acceptance Date Oct 14, 2014
Online Publication Date Jan 7, 2015
Publication Date Jan 7, 2015
Deposit Date Dec 17, 2015
Publicly Available Date Nov 23, 2017
Journal Proceedings of the Royal Society. B, Biological sciences
Print ISSN 0962-8452
Electronic ISSN 1471-2954
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 282
Issue 1798
Article Number ARTN 20142272
Keywords Introgression, Admixture, Secondary contact, Phenotypic novelty, Haplochromine fishes, River capture
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