MBE Advance Access originally published online on October 16, 2008
Molecular Biology and Evolution 2009 26(1):155-166; doi:10.1093/molbev/msn235
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Research Articles |
Candidate Genes and Adaptive Radiation: Insights from Transcriptional Adaptation to the Limnetic Niche among Coregonine Fishes (Coregonus spp., Salmonidae)
* Québec Océan, Département de Biologie, Université Laval, Québec G1V 0A6, Canada
Zoological Institute, University of Bern, CH-3012 Bern, Switzerland
Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway
E-mail: julie.jeukens.1{at}ulaval.ca.
Accepted for publication October 10, 2008.
In the past 40 years, there has been increasing acceptance that variation in levels of gene expression represents a major source of evolutionary novelty. Gene expression divergence is therefore likely to be involved in the emergence of incipient species, namely, in a context of adaptive radiation. In the lake whitefish species complex (Coregonus clupeaformis), previous microarray experiments have led to the identification of candidate genes potentially implicated in the parallel evolution of the limnetic dwarf lake whitefish, which is highly distinct from the benthic normal lake whitefish in life history, morphology, metabolism, and behavior, and yet diverged from it only 
15,000 years before present. The aim of the present study was to address transcriptional divergence for six candidate genes among lake whitefish and European whitefish (Coregonus lavaretus) species pairs, as well as lake cisco (Coregonus artedi) and vendace (Coregonus albula). The main goal was to test the hypothesis that parallel phenotypic adaptation toward the use of the limnetic niche in coregonine fishes is accompanied by parallelism in candidate gene transcription as measured by quantitative real-time polymerase chain reaction. Results obtained for three candidate genes, whereby parallelism in expression was observed across all whitefish species pairs, provide strong support for the hypothesis that divergent natural selection plays an important role in the adaptive radiation of whitefish species. However, this parallelism in expression did not extend to cisco and vendace, thereby infirming transcriptional convergence between limnetic whitefish species and their limnetic congeners for these genes. As recently proposed (Lynch 2007a. The evolution of genetic networks by non-adaptive processes. Nat Rev Genet. 8:803–813), these results may suggest that convergent phenotypic evolution can result from nonadaptive shaping of genome architecture in independently evolved coregonine lineages.
Key Words: Coregonus • parallel evolution • adaptive radiation • convergence • fish • gene expression
Diethard Tautz, Associate Editor
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  S. Renaut, A.W. Nolte, and L. Bernatchez Gene Expression Divergence and Hybrid Misexpression between Lake Whitefish Species Pairs (Coregonus spp. Salmonidae) Mol. Biol. Evol., April 1, 2009; 26(4): 925 - 936. [Abstract] [Full Text] [PDF]
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