"False signature" of past population expansions in North Atlantic minke whales mitochondrial control region sequences

• Main Authors: Palsboll, Per, Tison, J. -L., Bérubé, Martine, Hammarstrom, Ingrid, Sears, Richard, Ramp, Christian
• Format: Conference Object
• Language: English
• Published: 2009
• Subjects: Beluga; Beluga*; Fin whale; minke whale; narwhal*; North Atlantic
• Online Access: https://hdl.handle.net/11370/7612c224-65ab-4413-99f6-cf085b4f29b4; https://research.rug.nl/en/publications/7612c224-65ab-4413-99f6-cf085b4f29b4

The most common approach used to assess the demographic history during evolutionary time is by analysis of DNA sequences, typically mitochondrial (mt) DNA. The shape of the genealogy estimated all sampled mt control region sequences in a population differs between expanding, stable and declining populations. The mt control region genealogies estimated from population samples in several North Atlantic cetaceans (e.g., minke whale, fin whale, beluga and narwhal) are highly consistent with exponential population expansions during recent evolutionary time. These results agree well with the distribution of the ice coverage during the last glaciations. We sequenced additional mt genes (cytochrome b and cytochrome oxidase I) in addition to the entire control region in samples from North Atlantic minke whales. While the mt control region showed the previously reported expansion signature, the distribution of genetic variation at the other two genes was as expected for a population of constant population size. As all three genes are fully linked the effects of selection and/or demographic changes is expected to be observed at all three genes, contrary to our observation. The cause for the discrepancy appears to be due to the extreme site-heterogeneity in substitution rates at the mt control region. Our results have implications for the many studies in cetaceans, and other species which have inferred demographic history from sequence variation in the mt control region.