ABSTRACT
Microevolutionary processes are being investigated by the study of genetic diversity in the mitochondrial genome. In higher plants the structural organization of the mitochondrial genome is less clear and it has been demonstrated that the mitochondrion contains a population of heterogeneous circular molecules of deoxyribonucleic acid which can be distinguished on the basis of size. In the mitochondrial code more groups of four codons can be read by a single Transfer RNA. The mitochondrial genome of most animals is very compact and shows little structural diversity between closely related species or strains when compared to that found in fungi or in higher plants. The mitochondrial genomes of closely related species of fungi show considerable structural and size variation. Restriction map variation in the mitochondrial genomes of both species provided the basis for parsimonious phylogenetic tree construction. Phylogenetic comparisons and the estimation of evolutionary rates are largely based on restriction map data.
