Nuclear mitochondrial DNA (numt) in the atlantic rock crab cancer irroratus say, 1817 (decapoda, cancridae)

A study on the origin of a newly colonized population of the Atlantic rock crab, Cancer irroratus Say, 1817, in Icelandic coastal waters based on mtDNA variation revealed a challenging problem. Variation of the mitochondrial cytochrome oxidase subunit I gene (COI), which has played a pivotal role in phylogeographic studies, was assessed. Most individuals were found to carry two or more different genetic fragments and several ambiguous sites, with two segregating nucleotides, both within the Icelandic population and in samples from North America (Newfoundland, New Brunswick and Nova Scotia). Analyses of the DNA fragments, from clones and separate DNA extractions from the mitochondria and nucleus from undeveloped eggs and their mothers, support that ambiguous sites are caused by mitochondrial fragments incorporated in the nuclear genome (numts). A comparison of the variation in the newly colonized population in Iceland and the North American populations did not reveal any detectable bottleneck in the Icelandic population.