MBE Advance Access published online on January 27, 2009
Molecular Biology and Evolution, doi:10.1093/molbev/msp017
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Research Article |
Gene expression divergence and hybrid misexpression between lake whitefish species pairs (Coregonus spp. Salmonidae).
1 Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
3 Max-Planck-Institute for Evolutionary Biology, August.Thienemann Straße 2, D-24306 Plön, Germany
2 Corresponding author: sebastien.renaut.1{at}ulaval.ca IBIS (Institut de Biologie Intégrative et des Systèmes), Pavillon Charles-Eugène-Marchand, Université Laval, Québec (Québec) G1V 0A6, Canada Phone: 1 418 656 2131 - 8455 Fax: 1 418 656 717
Received for publication December 18, 2008. Revision received January 12, 2009. Accepted for publication January 23, 2009.
Genome-wide analyses of the transcriptome have confirmed that gene misexpression may underlie reproductive isolation mechanisms in inter-specific hybrids. Here, using a 16,006 features cDNA microarray, we compared and contrasted gene expression divergence at two ontogenetic stages in incipient species of normal and dwarf whitefish (Coregonus clupeaformis), to that of first generation (normal X dwarf) and second generation hybrid crosses [backcross: (normal X dwarf) X normal ]. Our goal was to identify the main mode of action responsible for gene transcription and to discover key genes misexpressed in hybrids. Very few transcripts (5 out of 4950 expressed) differed in mean expression level between parentals and hybrids at the embryonic stage, in contrast to 16-week old juvenile fish for which 617 out of 5359 transcripts differed significantly. We also found evidence for more misexpression in backcross hybrids whereby non-additivity explained a larger fraction of hybrid inheritance patterns in backcross (54%) compared to F1-hybrids (9%). Gene expression in hybrids was more variable than in pure crosses and transgressive patterns of expression were ubiquitous in hybrids. In backcross embryos in particular, the expression of three key developmental genes involved in protein folding and mRNA translation was severely disrupted. Accordingly, gene misexpression in hybrids adds to other factors previously identified as contributing to the reproductive isolation of incipient species of lake whitefish.
Key Words: Coregonus hybridization microarray reproductive isolation speciation transgressive segregation