Comparison of a mitochondrial gene and a corresponding nuclear pseudogene

Abstract

Nuclear copies of mitochondrial genes have been reported several times. Presented here is a direct comparison of a fragment of the mitochondrial gene coding for Cytochrome b and its assumed nuclear pseudogene in a phylogenetic context. By studying eight such sets of genes a direct measurement of relative rates of several types of substitutions were made. As expected mitochondrial third position transitions are the fastest accumulating substitutions, here indicated to be at least up to 39 times faster than corresponding positions in the supposed nuclear pseudogene. Translocated mitochondrial genes, evolving much slower than their functional 'counterpart', reflect the ancestral-pre-translocated form of the gene. A warning is given against unwanted inclusion of paralogous sequences in phylogenetic analysis and against the use of versatile primers that can promote such incidents.