Furthermore, the neutral theory is not merely a neutral model, to be used as a null hypothesis against which more interesting hypotheses can be tested. The neutral theory of evolution articles inference. He first proposed the theory in 1968 to explain the unexpectedly high rate of evolutionary change and very. All that is needed for genetic drift to occur is a finite population. The neutral theory of molecular evolution by motoo kimura. The neutral theory of molecular evolution holds that most evolutionary changes at the molecular level, and most of the variation within and between species, are. The nearlyneutral theory represents a development of kimuras neutral theory of molecular evolution that makes testable predictions that go beyond a mere null model. He first proposed the theory in 1968 to explain the unexpectedly high rate of evolutionary change and very large amount of intraspecific variability at the molecular level that had been uncovered by new techniques in molecular biology. The neutral theory of evolution postulates the accumulation of neutral mutations, such as accidental duplication of a section of dna that causes no harm. I want to end by pointing out that there are lots of people me and my group included who have already been wrestling with this issue, with lots of interesting ideas and results already out there. The neutral theory of molecular evolution is that most evolutionary change at the molecular level is driven by random drift rather than natural selection. The unified neutral theory of biogeography and biodiversity should stimulate research in new theoretical and empirical directions by ecologists, evolutionary biologists, and biogeographers.
Zukerkandl and pauling 1965 noticed an approximately uniform rate of amino acid substitution, with time measures in. Motoo kimura revolutionized evolutionary biology with his random drift theory of molecular evolution the neutral theoryand his groundbreaking theoretical work in population genetics. Neutral theory and phenotypic evolution molecular biology. The neutral theory is an excellent example of a theory which made an important contribution to the consolidation of a discipline, not because molecular evolution is logically structured around the neutral theory, but because it brought together different kinds of reasoning, because it helped to exert a socioprofessional break between. Molecular clock k neutral theory 1968 predicts that the rate of molecular evolution substitution should be approxim ately constant over time, where time is measures in generations. A neutral theory of molecular evolution the good men project. A neutral theory of molecular function michael eisen. The neutral theory of molecular evolution contends that at the molecular level most evolutionary changes and polymorphisms within species are not caused by natural selection, but by random genetic drift. Book description motoo kimura, as founder of the neutral theory, is uniquely placed to write this book. The unified neutral theory of biodiversity and biogeography here unified theory or untb is a hypothesis and the title of a monograph by ecologist stephen hubbell. Sep 07, 2012 a neutral theory of molecular function this blog post by michael eisen wrestles with the idea of junk dna. Pdf the neutral theory of molecular evolution in the genomic era. He first proposed the theory in 1968 to explain the unexpectedly high rate of evolutionary change and very large amount of intraspecific variability at the molecular level that had been uncovered by new techniques in.
The neutral theory of molecular evolution describes the pattern of nucleotide sequence evolution under the forces of mutation and random genetic drift in the absence of selection. We argue that the neutral theory was supported by unreliable theoretical and empirical evidence from the beginning, and that in light of modern, genomescale data, we can firmly reject its universality. The neutral theory, formally known as the neutral theory of molecular evolution, was independently proposed by m. Kimura in 1968 see kimura 1983, cited under general overviews, the neutral hypothesis of phenotypic evolution, and outstanding questions. The neutral theory of molecular evolution is an influential monograph written in 1983 by japanese evolutionary biologist motoo kimura. The neutral theory of molecular evolution ebook by motoo. In this perspective, we evaluate the explanatory power of the neutral theory of molecular evolution, 50 years after its introduction by kimura.
Free learning resources for students covering all major areas of biology. Under these conditions, the rate at which one nucleotide replaces another in a population the substitution rate should equal the rate of mutation at that site mutation rate, regardless of the size of the population. The neutral theory states that evolution at the level of the dna and proteins, is dominated by random processes and most evolution at the molecular level would then be nonadaptive. Genetic drift is the null hypothesis because it is the result of evolutions occurring in finite populations. While the neutral theory was proposed specifically to explain dna and protein sequence evolution, the impact of the neutral theory is beyond the field of molecular evolution. The neutral theory provided a muchdesired null hypothesis to test empirical genetic data against. This volume collects fiftyseven of kimuras most important papers and covers forty years of his diverse and original contributions to our understanding of how. Kimura is justly regarded as the father and chief architect of the neutral theory, but the title of nonneutral evolution refers, in fact, to an article published by king and jukes 1969. Neutral theory in light of natural selection molecular. That is most observed nucleotide polymorphisms within populations and. Explanation of neutral theory of molecular evolution in the largest biology dictionary online. Kimura 1968 initially viewed as a challenge to darwinian evolution e.
I want to end by pointing out that there are lots of people me and my group included who have already been wrestling with this issue, with lots of. A neutral mutation is one that does not adversely affect either an organisms phenotype nor its fitness. Population genetics, molecular evolution, and the neutral. The neutral theory of molecular evolution genetics. Hughes said so in the first draft of a paper on the neutral theory austin hughes, nearneutrality. No clear null hypotheses exist in these tests, so they are likely to generate many false. The neutral mutationrandom drift hypothesis as an evolutionary.
Rates and patterns of molecular evolution neutral theory predictions a particularly valuable use of neutral theory is as a rigid null hypothesis. And because it is unknown, the neutral theory can hypothetically explain almost any observed rates of evolution. Recent evidence has strongly supported several of these predictions, including the prediction that slightly deleterious variants will accumulate in a species that has undergone. Neutral theory of molecular evolution an overview sciencedirect. The unified neutral theory of biodiversity and biogeography. Population genetics, molecular evolution, and the neutral theory. Due to the degeneracy of the genetic code, some point mutations are silent with no amino acid replacements. While the neutral theory of molecular evolution existed since his article in 1968, kimura felt the need to write a monograph with uptodate information and evidences showing the importance of his theory in evolution. And because it is unknown, the neutral theory can hypothetically explain almost any. The neutral theory, formally known as the neutral theory of molecular evolution, was.
View neutral evolution from anthro 105 at hunter college, cuny. Kimura originally called his theory the neutral theory of molecular evolution. Evolution by random drift is as rapid as the rate at which neutral mutations arise. Kimura is justly regarded as the father and chief architect of the neutral theory, but the title of non neutral evolution refers, in fact, to an article published by king and jukes 1969. According to the neutral theory of molecular evolution, the rate at which molecular changes accumulate between species should be equal to the rate of neutral mutations and hence relatively constant across species. There are a few books on the neutral theory, and kimura 1983. Neutral theory of molecular evolution overview news medical. Neutral theory of molecular evolution uab barcelona.
Pdf the neutral theory of molecular evolution has been widely accepted and is the guiding principle. The most widely used methods for measuring selection are based on comparisons with the neutral theory, in which variation is shaped by the interaction between mutation and random genetic drift chapter 15. Thus molecular genetic considerations enter in, and this forms something of a link between molecular evolution analysis and human disease investigation. The neutral theory of molecular evolution contends that at the molecular level. The neutral theory of molecular evolution reprint, motoo kimura. He compared the amino acid sequences of hemoglobin. Hubbell is professor of plant biology at the university of georgia and staff scientist at the smithsonian tropical research institute in panama. Apr, 2003 the unified neutral theory of biodiversity or untb, hereafter used to refer to either the theory or hubbells 2001 book 1 predicts that species abundance distributions sads should follow the. The theory applies only for evolution at the molecular level, and is compatible with phenotypic evolution. Later it became clear that the exact form of molecular evolution does not neatly fit the original neutral theory, purely neutral, in several respects. The unified neutral theory of biodiversity or untb, hereafter used to refer to either the theory or hubbells 2001 book 1 predicts that species abundance distributions sads should follow the. Sep 07, 2019 as i argued above, the field of molecular evolution developed a powerful intellectual core in no small part because researchers had to reckon with the powerful neutral null hypothesis meaning. It appeared in science, and was perhaps as influential in establishing neutralism as part of the evolutionary mainstream as the more theoretical work of.
The neutral theory does not suggest that random drift explains all evolutionary change. The neutral theory makes a wide variety of predictions, and one or more of these predictions may be tested in any given molecular dataset. The neutral theory of molecular evolution by kimura in 1968 states that most evolutionary changes at the molecular level are caused by random genetic drift of selectively neutral nucleotide substitutions. Molecular evolution and the neutral theory questions and. Pdf the neutral theory of molecular evolution in the. A lucid and comprehensive textbook on molecular evolution. The theory is now best described as null hypothesis that one should now test your much more easily obtained genomic data against. Using the theory of genetic drift, motoo kimura developed a neutral theory of molecular evolution that is the basis for analyzing dna sequence variation within and among species, and is often considered the null hypothesis that should be rejected if alternative hypotheses, such as natural. Feb 24, 2011 the most widely used methods for measuring selection are based on comparisons with the neutral theory, in which variation is shaped by the interaction between mutation and random genetic drift chapter 15. Motoo kimura, as founder of the neutral theory, is uniquely placed to write this book. Neutral theory of molecular evolution definition and examples. In this single most important book of evolutionary biology since the 1960s, the neutral theory is lucidly, comprehensively, and forcefully.
The neutral theory serves as a wellunderstood null hypothesis, and deviations from it may be caused by various kinds of selection. A neutral theory of molecular function this blog post by michael eisen wrestles with the idea of junk dna. In sharp contrast to the darwinian theory of evolution by natural selection, the neutral theory claims that the overwhelming majority of evolutionary changes at the molecular level are caused by random fixation due to random sampling drift in finite populations of selectively neutral i. The neutral theory instead posits a positive thesis about nature. Neutral theory evolutionary biology oxford bibliographies. Neutral evolution evolutionary geneticslead editor bob. As i argued above, the field of molecular evolution developed a powerful intellectual core in no small part because researchers had to reckon with the powerful neutral null hypothesis.
More broadly, evolutionary genetics and human genetics, which in 1980 barely spoke the same language, are now increasingly interrelated. The neutral theory of molecular evolution wikipedia. For evolutionary biologists, neutrality is commonly considered the null hypothesis against which adaptation is tested even in studies of phenotypic evolution. The phrase neutral theory of evolution is a generalization, but one that is ultimately derived from and exemplified most clearly by kimuras theory. The neutral theory of molecular evolution motoo kimura. The hypothesis aims to explain the diversity and relative abundance of species in ecological communities, although like other neutral theories of ecology, hubbells hypothesis. The neutral theory of evolution postulates the accumulation of neutral mutations, such as accidental duplication. The neutral theory of molecular evolution holds that most evolutionary changes at the molecular level, and most of the variation within and between species, are due to random genetic drift of mutant alleles that are selectively neutral. Nearly neutral theory of molecular evolution wikipedia. A test of the unified neutral theory of biodiversity nature. Zukerkandl and pauling 1965 noticed an approximately uniform rate of amino acid substitution, with time measures in years.
1229 833 434 74 107 674 214 1312 776 1603 1438 651 966 1473 616 1443 121 223 131 437 702 672 1139 554 635 1163 1054 1412 582 1072 1347