Evolution of the mitochondrial genetic system: an overview (original) (raw)
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The adaptive evolution of the mammalian mitochondrial genome
BMC Genomics, 2008
The mitochondria produce up to 95% of a eukaryotic cell's energy through oxidative phosphorylation. The proteins involved in this vital process are under high functional constraints. However, metabolic requirements vary across species, potentially modifying selective pressures. We evaluate the adaptive evolution of 12 protein-coding mitochondrial genes in 41 placental mammalian species by assessing amino acid sequence variation and exploring the functional implications of observed variation in secondary and tertiary protein structures.
Mitochondrial DNA: more than an evolutionary bystander
Functional Ecology, 2014
1. The vast majority of studies employing mtDNA in evolutionary biology and ecology have used it as a means to infer demographic and historical patterns without pondering the underlying functional implications. In contrast, the biochemical and medical communities often aim to understand the influence of specific mtDNA mutations on mitochondrial functions, but rarely consider the evolutionary and ecological implications.
Mitochondrial Genome Evolution
2013
Mitochondria are membrane-enclosed organelles present in most eukaryotic cells that generate the majority of the cells ATP supply. Derived from a proteobacterial ancestor, mitochondria harbor their own, drastically reduced genome. Starting from a prokaryote-like ancestral state encoding a complete rRNA operon, a complete set of tRNAs required for translation, and key enzymes of the respiratory chain as well as some ribosomal proteins, the mitogenome has been dramatically restructured and further reduced in many of the eukaryote lineages.
Mitochondrial DNA and two perspectives on evolutionary genetics
… Journal of the …, 1985
This essay reviews comparative studies of animal mitochondria1 DNA (mtDNA), with emphasis on findings made and ideas developed at Berkeley. It argues that such studies are bringing together two previous paths of progress in evolutionary biology. One path is that of those who worked far above the species level and were concerned with genealogical trees, time scales and the accumulation of new mutations on surviving molecular lineages. The other path is that of those who worked at and below the species level and were concerned mainly with population structure, migration and the frequencies of alleles that existed in an ancestral population. This fusion of paths is made possible by the high rate at which mutations accumulate on mtDNA lineages and by this molecule's uniparental and apparently haploid mode of inheritance. These properties make mtDNA a superb tool for building trees and time scales relating molecular lineages at and below the species level. In addition, owing to its mode of inheritance, mtDNA is more sensitive to bottlenecks in population size and to population subdivision than are nuclear genes. Joint comparative studies of both mtDNA and nuclear DNA variability give us valuable insights into how effective population size has varied through time. Such studies also give insight into the conditions under which mtDNA from one species can colonize another species.
Genetic aspects of mitochondrial genome evolution
Molecular Phylogenetics and Evolution, 2013
Many years of extensive studies of metazoan mitochondrial genomes have established differences in gene arrangements and genetic codes as valuable phylogenetic markers. Understanding the underlying mechanisms of replication, transcription and the role of the control regions which cause e.g. different gene orders is important to assess the phylogenetic signal of such events. This review summarises and discusses, for the Metazoa, the general aspects of mitochondrial transcription and replication with respect to control regions as well as several proposed models of gene rearrangements. As whole genome sequencing projects accumulate, more and more observations about mitochondrial gene transfer to the nucleus are reported. Thus occurrence and phylogenetic aspects concerning nuclear mitochondrial-like sequences (NUMTS) is another aspect of this review.
Rapid evolution of animal mitochondrial DNA
Proceedings of the …, 1979
Mitochondrial DNA was purified from four species of higher primates (Guinea baboon, rhesus macaque, guenon, and human) and digested with 11 restriction endonucleases. A cleavage map was constructed for the mitochondrial DNA of each species. Comparison of the maps, aligned with respect to the origin and direction of DNA replication, revealed that the species differ from one another at most of the cleavage sites. The degree of divergence in nucleotide sequence at these sites was calculated from the fraction of cleavage sites shared by each pair of species. By plotting the degree of divergence in mitochondrial DNA against time of divergence, the rate of base substitution could be calculated from the initial slope of the curve. The value obtained, 0.02 substitutions per base pair per million years, was compared with the value for single-copy nuclear DNA. The rate of evolution of the mitochondrial MAnome appears to exceed that of the single-copy fraction of the nuclear genome by a factor of about 10. This high rate may be due, in part, to an elevated rate of mutation in mitochondrial DNA. Because of the high rate of evolution, mitochondrial DNA is likely to be an extremely useful molecule to employ for high-resolution analysis of the evolutionary process.
Frontiers in Ecology and Evolution, 2019
Natural selection acts on the phenotype. Therefore, many mistakenly expect to observe its signatures only in the organism, while overlooking its impact on tissues, cells and subcellular compartments. This is particularly crucial in the case of the mitochondrial genome (mtDNA), which, unlike the nucleus, resides in multiple cellular copies that may vary in sequence (heteroplasmy) and quantity among tissues. Since the mitochondrion is a hub for cellular metabolism, ATP production, and additional activities such as nucleotide biosynthesis and apoptosis, mitochondrial dysfunction leads to both tissue-specific and systemic disorders. Therefore, strong selective pressures act to maintain mitochondrial function via removal of deleterious mutations via purifying (negative) selection. In parallel, selection also acts on the mitochondrion to allow adaptation of cells and organisms to new environments and physiological conditions (positive selection). Nevertheless, unlike the nuclear genetic information, the mitochondrial genetic system incorporates closely interacting bi-genomic factors (i.e., encoded by the nuclear and mitochondrial genomes). This is further complicated by the order of magnitude higher mutation rate of the vertebrate mtDNA as compared to the nuclear genome. Such mutation rate difference generates a generous mtDNA mutational landscape for selection to act, but also requires tight mito-nuclear co-evolution to maintain mitochondrial activities. In this essay we will consider the unique mitochondrial signatures of natural selection at the organism, tissue, cell, and single mitochondrion levels.