Open in a separate window. Fig 1. George Williams' Adaptation and Natural Selection and Richard Dawkins' The Selfish Gene were instrumental in introducing the gene's-eye view to evolutionary biology. Current views If the Selfish DNA papers marked the beginning of the serious study of selfish genetic elements, the subsequent decades have seen an explosion in theoretical advances and empirical discoveries. The logic of selfish genetic elements Though selfish genetic elements show a remarkable diversity in the way they promote their own transmission, some generalizations about their biology can be made.
Rule 2: The presence of selfish genetic elements is often revealed in hybrids The presence of selfish genetic elements can be difficult to detect in natural populations. Examples of selfish genetic elements Segregation distorters Some selfish genetic elements manipulate the genetic transmission process to their own advantage, and so end up being overrepresented in the gametes Fig 2.
Fig 2. Homing endonucleases A phenomenon closely related to segregation distortion is homing endonucleases. Fig 3. Homing endonucleases can recognize a target sequence, cut it, and then use it own sequence as a template during double strand break repair. This converts a heterozygote into a homozygote. Transposable elements Transposable elements TEs include a wide variety of DNA sequences that all have the ability to move to new locations in the genome of their host.
Fig 4. Transposable elements self-replicate through two main mechanisms: via an RNA intermediate "copy-and-paste"; class 1 or straight excision-insertion "cut-and-paste"; class 2. B chromosomes B chromosomes refer to chromosomes that are not required for the viability or fertility of the organism, but exist in addition to the normal A set.
Fig 5. Genetic conflicts often arise because not all genes are inherited in the same way. Selfish mitochondria Genomic conflicts often arise because not all genes are inherited in the same way.
Genomic imprinting Another sort of conflict that genomes face is that between the mother and father competing for control of gene expression in the offspring, including the complete silencing of one parental allele. Fig 6. Igf2 is an example of genomic imprinting. Greenbeards A greenbeard gene is a gene that have the ability to recognize copies of itself in another individuals and then make its carrier act preferentially toward such individuals.
Following Dawkins, a greenbeard is usually defined as a gene, or set of closely linked genes, that has three effects[ 89 , 90 ]: It gives carriers of the gene a phenotypic label, such as a green beard. The carrier is able to recognize other individuals with the same label. Fig 7. The simplest form of greenbeard mechanism. Consequences to the host of selfish genetic elements Species extinction Perhaps one of the clearest ways to see that the process of natural selection does not always have organismal fitness as the sole driver is when selfish genetic elements have their way without restriction.
Speciation Selfish genetic elements have been shown to play a role in speciation. Genome size variation Attempts to understand the extraordinary variation in genome size C-value —animals vary 7, fold and land plants some 2,fold—has a long history in biology. Applications of selfish genetic elements in agriculture and biotechnology Cytoplasmic male sterility in plant breeding A common problem for plant breeders is unwanted self-fertilization.
Mathematical theory of selfish genetic elements Much of the confusion regarding ideas about selfish genetic elements center on the use of language and the way the elements and their evolutionary dynamics are described. Segregation distorters The mouse t-allele is a classic example of a segregation distorter system that has been modeled in great detail. Gene drive systems The idea of spreading a gene into a population as a means of population control is actually quite old, and models for the dynamics of introduced compound chromosomes date back to the s.
Transposable elements To model the dynamics of transposable elements TEs within a genome, one has to realize that the elements behave like a population within each genome, and they can jump from one haploid genome to another by horizontal transfer. Future directions Selfish genetic elements have gone from being seen as genetic oddities with little significance to be considered major players in evolution.
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References 1. Selfish genetic elements. Trends Ecol Evol. Intranuclear conflict and its role in evolution. Genetic conflicts. Q Rev Biol. The role of selfish genetic elements in eukaryotic evolution. Nat Rev Genet. Genetic conflicts: the usual suspects and beyond. J Exp Biol. The meaning of intragenomic conflict. Nat Ecol Evol. Williams GC. Dawkins R. Selfish DNA: the ultimate parasite. Doolittle WF, Sapienza C. Selfish genes, the phenotype paradigm and genome evolution.
Burt A, Trivers R. Werren JH. Selfish genetic elements, genetic conflict, and evolutionary innovation. Gershenson S. A new sex-ratio abnormality in Drosophila obscura. Parasitic nature of extra fragment chromosomes. Botaniska Notiser. Rhoades MM. Preferential segregation in maize. Lewis D. Male sterility in natural populations of hermaphrodite plants the equilibrium between females and hermaphrodites to be expected with different types of inheritance. New Phytol. McClintock B. The origin and behavior of mutable loci in maize.
Controlling elements and the gene. Curr Zool. Selfish Genes. Current Problems in Sociobiology. Cambridge University Press; Hull DL. The Philosophy of Evolution. Cavalier-Smith T. How selfish is DNA? Dover G. Ignorant DNA? Dover G, Doolittle WF. Modes of genome evolution. Selfish DNA. Cosmides LM, Tooby J. Cytoplasmic inheritance and intragenomic conflict. J Theor Biol. Rice WR. Nothing in genetics makes sense except in light of genomic conflict.
Annu Rev Ecol Evol Syst. Leigh EG. Freeman, Cooper; Hickey DA. Selfish DNA: a sexually-transmitted nuclear parasite. Wright S, Finnegan D. Genome evolution: sex and the transposable element. Curr Biol.
Transposon dynamics and the breeding system. Charlesworth B, Langley CH. The evolution of self-regulated transposition of transposable elements. Nordborg M. Linkage disequilibrium, gene trees and selfing: an ancestral recombination graph with partial self-fertilization. Arkhipova I, Meselson M.
Transposable elements in sexual and ancient asexual taxa. Mating system shifts and transposable element evolution in the plant genus Capsella. BMC Genomics. Sex drives intracellular conflict in yeast. J Evol Biol. Selfish DNA and breeding system in flowering plants. The Piwi-piRNA pathway provides an adaptive defense in the transposon arms race. Crespi B, Nosil P. Conflictual speciation: species formation via genomic conflict.
Selfish senes and plant speciation. Evol Biol. Ganetzky B. On the components of segregation distortion in Drosophila melanogaster. Brittnacher JG, Ganetzky B. On the Components of Segregation Distortion in Drosophila melanogaster. Nature of enhancer of SD. Construction and analysis of free duplications for the Responder locus. Powers PA, Ganetzky B.
Molecular analysis of the Sd locus. The selfish Segregation Distorter gene complex of Drosophila melanogaster. Curtsinger JW. Artificial selection on the sex ratio in Drosophila pseudoobscura. J Hered. Lyon MF. Transmission ratio distortion in mice. Annu Rev Genet. Burt A. Site-specific selfish genes as tools for the control and genetic engineering of natural populations. Burt A, Koufopanou V.
Homing endonuclease genes: the rise and fall and rise again of a selfish element. Curr Opin Genet Dev. A synthetic homing endonuclease-based gene drive system in the human malaria mosquito. Gantz VM, Bier E. Genome editing. The mutagenic chain reaction: a method for converting heterozygous to homozygous mutations. Concerning RNA-guided gene drives for the alteration of wild populations.
Ravindran S. Barbara McClintock and the discovery of jumping genes. Lisch D. How important are transposons for plant evolution? Roles for retrotransposon insertions in human disease.
J Theor Biol 89 : 83 — An Introduction to Behavioural Ecology. Walden : Wiley Blackwellls. Dawkins R , The Selfish Gene. Replicator selection and the extended phenotype. Z Tierpsychol 47 : 61 — Dawkins R , a. The Extended Phenotype. Dawkins R , b. Replicators and vehicles. Current Problems in Sociobiology.
Cambridge : Cambridge University Press , 45 — Parasites, desiderata lists, and the paradox of the organism. Parasitology : S63 — S Burying the vehicle. Behav Brain Sci 17 : — Dennett DC , Homunculi rule. Biol Phil 26 : — Doolittle WF , Hierarchical approaches to genome evolution. Can J Phil : — Is junk DNA bunk? Proc Natl Acad Sci : — Doolittle WF Sapienza C , Selfish genes, the phenotype paradigm and genome evolution.
Dover G , Ignorant DNA? Nature : Dover G Doolittle WF , Modes of genome evolution. Genomics in the light of evolutionary transitions. Evolution 64 : — Eberhard WG , Evolutionary consequences of intracellular organelle competition.
Quart Rev Biol 55 : — Edwards AWF , Biol Rev 89 : — The C-value enigma and the evolution of eukaryotic genome content. Ewens WJ , Mathematical Population Genetics I. Theoretical Introduction. Berlin : Springer. Fisher RA , The correlation between relatives on the supposition of Mendelian inheritance. Trans R Soc Edinburgh 52 : — The Genetical Theory of Natural Selection. Foster KR , Balancing synthesis with pluralism in sociobiology. J Evol Biol 19 : — The sociobiology of molecular systems.
Nat Rev Genet 12 : — Francis RC , Gardner A Grafen A , Capturing the superorganism: a formal theory of group adaptation. J Evol Biol 22 : — Gardner A Welch JJ , A formal theory of the selfish gene. J Evol Biol 24 : — Godfrey-Smith P , The replicator in retrospect. Biol Phil 15 : — Darwinian Populations and Natural Selection. Gould SJ , Caring groups and selfish genes.
Nat Hist 86 : 20 — What happens to bodies if genes act for themselves? In: Gould SJ , editor. New York : Norton , — Caring groups, selfish genes.
In: Sober E , editor. Conceptual Issues in Evolutionary Biology. Cambridge : MIT Press , 85 — The Structure of Evolutionary Theory. Cambridge : Harvard University Press. Grafen A , Formal Darwinism, the individual-as-maximising-agent analogy, and bet-hedging. Proc R Soc Ser B : — Optimization of inclusive fitness. J Theor Biol : — The formal Darwinism project: a mid-term report.
J Evol Biol 20 : — The simplest formal argument for fitness optimization. J Genet 87 : — The formal Darwinism project in outline. Biol Phil 29 : — Gregory TR , Coincidence, coevolution, or causation? DNA content, cell size, and the C-value enigma. Biol Rev 76 : 65 — Macroevolution, hierarchy theory, and the C-value enigma. Paleobiology 30 : — The Evolution of the Genome.
New York : Elsevier. Molecules and macroevolution: a Gouldian view of the genome. Stephen J. Gould: the scientific legacy. New York : Springer. Why genomics needs multilevel evolutionary theory. Evolutionary theory: a hierarchical perspective. Chicago : University of Chicago Press , — Griesemer J , The units of evolutionary transitions. Selection 1 : 67 — Haig D , Genomic imprinting and the theory of parent—offspring conflict. Semin Dev Biol 3 : — Gestational drive and the green-bearded placenta.
The social gene. Behavioural Ecology: An Evolutionary Approach. Oxford : Blackwell Publisher , — Genomic Imprinting and Kinship. New Brunswick : Rutgers University Press. Intragenomic politics. Cytogenet Genome Res : 68 — The strategic gene. Biol Phil 27 : — Genetic dissent and individual compromise. Haig D Grafen A , Genetic scrambling as a defence against meiotic drive. Haldane JBS , The Causes of Evolution. Hamilton WD , The evolution of altruistic behavior.
Am Nat 97 : — The genetical evolution of social behaviour I and II. Extraordinary sex ratios. A sex-ratio theory for sex linkage and inbreeding has new implications in cytogenetics and entomology. The play by nature. Narrow Roads of Gene Land , vol.
Evolution of Social Behaviour. New York : WH Freeman. Higgs PG Lehman N , The RNA world: molecular cooperation at the origins of life. Nat Rev Genet 16 : 7 — Hull DL , Individuality and selection. Annu Rev Ecol Syst 11 : — Hurst LD , Adaptation and selection of genomic parasites. San Diego : Academic Press , — Genetic conflicts. Quart Rev Biol 71 : — The role of selfish genetic elements in eukaryotic evolution. Nat Rev Genet 2 : — Jain HK , Incidental DNA.
Keller L , Levels of Selection in Evolution. Transposable elements, parasitic DNA, and genome evolution. Evolution 55 : 1 — Lewis D , Male sterility in natural populations of hermaphrodite plants: the equilibrium between females and hermaphrodites to be expected with different types of inheritance. New Phytol 40 : 56 — Lewontin RC , Evolution and the theory of games. J Theor Biol 1 : — Selfish DNA is non-transcribed, non-coding, and contributes nothing to the well-being of the organism; in most cases it is selectively neutral.
Once it arises, selfish DNA is passively replicated and passed on from parent to offspring. Changes in its frequency in the population are due to drift. Only if a non-coding sequence interfered with the construction of the organism or if it accumulated to such an extent that the cell cycle was slowed down by the need to replicate it all, would selection act to reduce it.
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