Pleiotropy natural selection and the evolution of senescence pdf
Natural selection must have favored a shift toward earlier sexual maturity until an evolutionarily stable strategy was reached between the benefits of early reproduction and the costs associated with acceler-
Understanding equilibria is an essential step toward a nonequilibrium theory and should provide greater insights than we now possess. I first discuss different theoretical approaches to the definition of evolutionary equilibria.
Pleiotropy, natural selection, and the evolution of senescence. Evolution 1957;11:398–411]. Because middle-aged women faced greater risks of maternal death during pregnancy and their offspring’s infancy than did younger women, offspring of middle-aged women may not have received the needed level of prolonged maternal investment to survive to reproductive age. I put forward the “absent
]) that provides the basis for evolutionary explanations of senescence via either antagonistic pleiotropy or mutation–selection balance. Any factor that changed the age pattern of the selection gradient would change the tendency to senescence.
onistic pleiotropy and mutation accumulation, two mechanisms for the evolution of senescence. Reverse selection for early-life fitness was applied to laboratory populations of Drosophila mela- nogaster that had been previously selected for late-life fitness.
Williams GC (1957) Pleiotropy, natural selection, and the evolution of senescence. tioning in unicellular systems and its effects on aging. Proc Natl Acad Sci USA 105: Evolution 11:398–411.
pleiotropy). The late-life negative effects in the ‘selection shadow’ cannot The late-life negative effects in the ‘selection shadow’ cannot be effectively eliminated by selection, leading to senescence.
Natural selection favours the fixation of such mutations if their life-average effect is beneficial (antagonistic pleiotropy model, Williams 1957). The relative contribution of these two kinds of mutation to senescence evolution has been debated, but few empirical data are available.
The strength (‘force’) of selection measures how strongly natural selection acts on changes in survival and/or fecundity. Often, but not always, the force of selection declines with age. If this is the case, then alleles with neutral effects on fitness early in life but with deleterious effects late in life can accumulate in a population, unchecked by selection (mutation accumulation
21/06/2015 · Aging makes us grow weaker, frailer, slower, sicker, and eventually kills us. Why doesn’t natural selection prevent it? (Made for the KhanAcademy talent search.)
In contrast, the black colour of the back based on eumelanin is unrelated to sexual selection, but is under natural selection due to intense abrasion of this feather tract. 5 These findings suggest that the relative importance of natural and sexual selection are important determinants of the pattern and rate of senescence of colour.
Pleiotropy, Natural Selection, and the Evolution of Senescence Created Date: 20160807184145Z
This paper reviews theories of the evolution of senescence. The population genetic basis for the decline with age in sensitivity of fitness to changes in survival and fecundity is discussed. It is shown that this creates a presure of selection that disproportionately favors performance early in life
Most theoretical models for the evolution of senescence have assumed a very large, well mixed population. Here, we investigate how limited dispersal and kin competition might influence the evolution of ageing by deriving indicators of the force of selection, similar to Hamilton (Hamilton 1966 J. Theor.
In the late 19th century, the evolutionary approach to the problem of ageing was initiated by August Weismann, who argued that natural selection was more important for ageing than any physiological mechanism. In the mid-twentieth century, J. B. S. Haldane, P. B. Medawar and G. C. Williams informally
natural selection among individuals. A mutation that would increase an individual’s fitness would become fixed. The level of mortality is a consequence of the level of …

Selection and senescence a variational approach

The Evolutionary Theory of Aging YouTube
16 T. B. L. Kirkwood and M. R. Rose Evolution of senescence common element in both these theories is the conclusion that, in effect, natural selection trades late survival for
Williams, G. C. Pleiotropy, Natural Selection, and the Evolution of Senescence. Society for the Study of Evolution. 1957 Society for the Study of Evolution. 1957 – Denham Harman proposes the free radical theory of aging
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics. The word senescence can refer either to cellular senescence or to senescence …
Although theories of the evolution of senescence differ in the mode of action by which genes are thought to control the aging process, they all view the rate of senescence as an adaptable feature
In particular, G. C. Williams’s hypothesis for senescence through antagonistic pleiotropy has proved to be one of the most well-known applications of pleiotropy in evolution and medicine. Following a suggestion by M edawar (1952) , W illiams (1957) suggested that genes with antagonistic effects at different life stages could contribute to aging in a way that natural selection could not alter.
17/11/2012 · Introduction: the evolution of senescence and the meaning of age-specificity. The higher the age of an organism, the greater the organism’s contribution to fitness that cannot be affected by any event happening at that age, because that contribution lies in the past.

Here I explore the possibility that sexual conflict may explain sex-specific differences in longevity and may act as a driving force in the evolution of senescence. I present comparative evidence for this hypothesis and discuss the potential relevance of sexual conflict theory to the search for specific genes that influence longevity. One implication of a sexual conflict theory of aging is
Antagonistic pleiotropy, as it applies to aging, hypothesizes that animals possess genes that enhance fitness early in life but diminish it in later life and that such genes can be favored by natural selection because selection is stronger early in life even as they cause the aging phenotype to emerge. No genes of the sort hypothesized by Williams were known 60 years ago, but modern molecular
December 21st, 2018 – Natural selection is the differential survival and reproduction of individuals due to differences in phenotype It is a key mechanism of evolution the …
Enquiry into the evolution of ageing aims to explain why survival, reproductive success, and functioning of almost all living organisms decline at old age. Leading hypotheses [1] [2] suggest that a combination of limited resources, and an increasing risk of death by environmental causes determine an “optimal” level of self-maintenance , i.e. the repair of molecular and cellular level damage
20/07/2012 · Pleiotropy, natural selection, and the evolution of senescence. Evolution 11 , 398–41110.2307/2406060 [ Cross Ref ] Articles from Frontiers in Genetics are provided here courtesy of Frontiers Media SA
At first sight, the nearly universal existence of senescence in species of multicellular organisms is paradoxical, given that natural selection supposedly causes the evolution …
Abstract Most theoretical work on the evolution of senescence has assumed that all individuals within a population are equally susceptible to extrinsic sources of mortality. An influential qualitative prediction based on this assumption is Williams’s hypothesis, which states that more rapid senescence is expected to evolve when the magnitude of
1 Why organisms age: Evolution of senescence under positive pleiotropy? Alexei A. Maklakov1, Locke Rowe2 and Urban Friberg3,4 1Ageing Research Group, Department of Animal Ecology, Evolutionary Biology
This fundamental observation forms the basis of the antagonistic pleiotropy theory of senescence, explaining how selection for effective reproduction early in life can lead to increased mortality at later ages [15 x Pleiotropy, natural selection and the evolution of senescence.
George Williams, then a professor at Michigan State University, published a paper in 1957 titled Pleiotropy, Natural Selection, and the Evolution of Senescence (Evolution 11 398-411). Pleiotropy is defined as a situation in which a single gene controls more than one trait.

The null mutations in the yeast morphological pleiotropy data yield a = 2.9, but we expect natural random mutations to have a much smaller a, because most natural mutations affect the function of a gene only slightly and thus have on average much smaller phenotypic effects than gene deletions do .
文章 . Williams, G.C. Pleiotropy, natural selection and the evolution of senescence. Evolution？1957, 11, 398–411, doi:10.2307/2406060. 被如下文章引用：
antagonistic pleiotropy, mortality source interactions, and the evolutionary theory of senescence Most theoretical work on the evolution of senescence has assumed that all individuals within a population are equally susceptible to extrinsic sources of mortality.
Understanding the evolution of senescence was once seen as the greatest challenge in evolutionary biology and our current understanding of it hinges on the idea that once organisms begin reproducing, natural selection progressively weakens . To understand why, consider an organism that reproduces steadily and has a fixed probability of dying. As this organism grows older, more and more of its
Williams, G. C. Pleiotropy, natural selection and the evolution of senescence. Evolution 11, 398–411 (1957). evolution of a threshold dimorphism 3. Reznick, D. A., Bryga, H. & Endler, J. A. Experimentally induced life-history evolution in a natural population. Nature 346, 357–359 (1990). Joseph L. Tomkins & Gordon S. Brown 4. Charlesworth, B. Evolution in Age Structured Populations
Antagonistic pleiotropy centres on genetic effects that enhance fitness early in life but depress it late in life. 1 Such mutations are able to spread because the force of selection is stronger earlier in life, since more individuals are alive at this stage than at later ages.
Altern im Lichte der Evolution (Aging in the light of evolution). Pleiotropy, natural selection, and the evolution of senescence. (1998). Queen lifespan and colony characteristics in ants and termites. (2005). Reproductive effort is inversely proportional to average adult life span.
Publisher’s PDF, also known as Version of record Published In: evolution of senescence. Based on this idea, Medawar pro-posed a particular genetic mechanism – that senescence evolves by the accumulation in the genome of harmful alleles, such as those predisposing to cancer, dementia, or heart disease, whose effects appear sufficiently late in life that “the force of natural selection
Natural Selection Williams George C PDF
Senescence (/ s ɪ ˈ n ɛ s ə n s /) (from Latin: senescere, meaning “to grow old,” from senex) or biological aging (also spelled biological ageing) is the gradual deterioration of function characteristic of most complex lifeforms, arguably found in all biological kingdoms, that on the level of the organism increases mortality after maturation.
Quantitative genetics of age at reproduction in wild swans: Support for antagonistic pleiotropy models of senescence Anne Charmantier*, Christopher …
A second model, antagonistic pleiotropy (AP; Williams 1957), imagines that genes can contribute to the evolution of senescence if mutations arise that increase …
plants, and whether age-dependent selection indeed would allow the evolution of plant senescence. By focusing on selection, the question of
But, his theory was dismissed by G.C. Williams in his seminal paper titled ‘Pleiotropy, Natural Selection, and the Evolution of Senescence.’ In this paper he put forward his own theory (W.D. Hamilton formalized it in a 1966 paper) of senescence which is the accepted theory even now. – edward o wilson intelligent evolution pdf The selection shadow is a concept involved with the evolutionary theories of ageing that states that selection pressures on an individual decrease as an individual ages and passes sexual maturity, resulting in a “shadow” of time where selective fitness is not considered.
sive decline of Hamilton’s forces of natural selection. To my mind, this definition is consistent with most previous definitions of aging used by the majority of evolution-ary biologists. Most evolutionary biologists define aging as an age-dependent or age-pro-gressive decline in intrinsic physiological function, leading to an increase in age-specific mortality rate (i.e., a decrease in
The genetic basis of Alzheimer’s disease is becoming clear; it appears to fit the postulates of the two main theories of the evolution of senescence, with both …
Darwin’s Theory of Natural Selection and senescence, and began to think in terms of Lamarck’s notion of the direct effects of the environment, especially the possible impact of the imponderable fluids of heat and electricity (Notebooks, 175). If the device of environmental impact were to meet what seemed to be the empirical requirement—as evidenced by the pattern of fossil deposits
Mutation accumulation. Selection is ineffective at removing mutations with effects in old age. Antagonistic pleiotropy. Early reproduction is favoured by natural selection.
• Aging results because of pleiotropy • Natural selection continues after reproduction “Evolution: Medicine’s Missing Basic Science” Prof. Randolph M. Nesse The screen versions of these slides have full details of copyright and acknowledgements 3 7 Percent of schools that include topic in medical curriculum (n = 55) Nesse & Schiffman, 2000 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% …
Williams’ 1957 paper Pleiotropy, natural selection, and the evolution of senescence was influential in 20th century evolutionary biology. It contains three important ideas. [4] In this paper Williams proposed that senescence should be generally synchronized by natural selection .
This is the theory of antagonistic pleiotropy. 2. EVOLUTION OF SENESCENCE Antagonistic pleiotropy introduces the idea of a trade-off between early benefit and late cost, and the (a) Population genetics important thing about the declining action of selection The first hints of a population genetic approach to with adult age is that it takes only a small fitness benefit the problem of senescence
Williams GC (1957) Pleiotropy, natural selection and the evolution of senescence. Evolution 11:398–411 CrossRef Google Scholar Williams PD, Day T (2003) Antagonistic pleiotropy, mortality source interactions, and the evolutionary theory of senescence.
200 p E-Book (PDF) provides extensive descriptions of programmed and non-programmed aging theories, underlying evolution controversies, historical perspective, and applicable genetics and observational evidence.
Pleiotropy. Pleiotropy being supposedly more often deleterious, it has been proposed that coding changes may be selected against more than cis-regulatory change, thus predicting a prevalence of cis-regulatory changes in evolution (Carroll, 2005; Stern, 2000).
that, other things being equal, natural selection places a greater relative weight onchanges in early survival or repro- duction than on changes at later ages. Provided that the appropriategeneticvariability is available, thiswill leadtothe evolution of a life history in which mortality increases and reproductive performance declines with age (4-8). There are two major models of the paths by
Williams’ 1957 paper Pleiotropy, Natural Selection, and the Evolution of Senescence is one of the most influential in 20th century evolutionary biology, and contains at least 3 foundational ideas. The central hypothesis of antagonistic pleiotropy remains the prevailing evolutionary explanation of senescence.
When time is expressed in years, rate of senescence is related to initial mortality rate by . This result implies that natural selection in response to variation among taxa in has resulted in the evolutionary modification of factors that influence the rate of aging in natural populations.
The rate of senescence shown by any species will reflect the balance between this direct adverse selection of senescence as an unfavorable character and the indirect favorable selection through the age-related bias in the selection of pleiotropic genes.
Senescence vs. sustenance evolutionary-demographic CORE
Williams GC 1957 Pleiotropy, natural selection, & the evolution of senescence. Evolution 11:398-411. 2/21 Cooperative Rearing & Shared Intentionality Hawkes K 2014 Primate sociality to human cooperation, why us & not them? Hum Nat 25 (1):28-48. Department and University Policies
Contribution number 92 from the Department of Natural Science, Michigan State University. The author wishes to thank Dr. Hugh N. Mozingo, Dr. Dennis W. Strawbridge, and his wife, Doris C. Williams, for their help in the preparation of this paper.
In so far as it is associated with declining fertility and increasing mortality, senescence is directly detrimental to reproductive success. Natural selection should therefore act in the direction of postponing or eliminating senescence from the life history. The widespread occurrence of senescence
senescence hypotheses that have played a role in our evolution. Other theories Other theories could also be important, but available data precludes testing them.
Under these circumstances, it is commonly assumed that natural and sexual selection act in opposite directions, effectively limiting the evolution of conspicuous signals and preferences. We
4 The Evolution of Senescence Between Zeus and the

Different roles of natural and sexual selection on
Williams, G.C. 1957. Pleiotropy, natural selection, and
Evolution Medicine’s Missing Basic Science Prof. Randolph

Age-specificity and the evolution of senescence a discussion

Sexual selection effects on the evolution of senescence

Evolution of senescence Alzheimer’s disease and evolution

George C. Williams Simple English Wikipedia the free
evolution of bible translations example biology – Kin competition natal dispersal and the moulding of
George C. Williams Expands On The Theory Of Antagonistic

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Selection shadow Wikipedia
Genomic patterns of pleiotropy and the evolution of

The rate of senescence shown by any species will reflect the balance between this direct adverse selection of senescence as an unfavorable character and the indirect favorable selection through the age-related bias in the selection of pleiotropic genes.
Contribution number 92 from the Department of Natural Science, Michigan State University. The author wishes to thank Dr. Hugh N. Mozingo, Dr. Dennis W. Strawbridge, and his wife, Doris C. Williams, for their help in the preparation of this paper.
This fundamental observation forms the basis of the antagonistic pleiotropy theory of senescence, explaining how selection for effective reproduction early in life can lead to increased mortality at later ages [15 x Pleiotropy, natural selection and the evolution of senescence.
Here I explore the possibility that sexual conflict may explain sex-specific differences in longevity and may act as a driving force in the evolution of senescence. I present comparative evidence for this hypothesis and discuss the potential relevance of sexual conflict theory to the search for specific genes that influence longevity. One implication of a sexual conflict theory of aging is
Williams’ 1957 paper Pleiotropy, natural selection, and the evolution of senescence was influential in 20th century evolutionary biology. It contains three important ideas. [4] In this paper Williams proposed that senescence should be generally synchronized by natural selection .
natural selection among individuals. A mutation that would increase an individual’s fitness would become fixed. The level of mortality is a consequence of the level of …
200 p E-Book (PDF) provides extensive descriptions of programmed and non-programmed aging theories, underlying evolution controversies, historical perspective, and applicable genetics and observational evidence.
Under these circumstances, it is commonly assumed that natural and sexual selection act in opposite directions, effectively limiting the evolution of conspicuous signals and preferences. We
The selection shadow is a concept involved with the evolutionary theories of ageing that states that selection pressures on an individual decrease as an individual ages and passes sexual maturity, resulting in a “shadow” of time where selective fitness is not considered.
文章 . Williams, G.C. Pleiotropy, natural selection and the evolution of senescence. Evolution？1957, 11, 398–411, doi:10.2307/2406060. 被如下文章引用：
1 Why organisms age: Evolution of senescence under positive pleiotropy? Alexei A. Maklakov1, Locke Rowe2 and Urban Friberg3,4 1Ageing Research Group, Department of Animal Ecology, Evolutionary Biology
pleiotropy). The late-life negative effects in the ‘selection shadow’ cannot The late-life negative effects in the ‘selection shadow’ cannot be effectively eliminated by selection, leading to senescence.
A second model, antagonistic pleiotropy (AP; Williams 1957), imagines that genes can contribute to the evolution of senescence if mutations arise that increase …

Virulence evolution and the timing of disease life-history
Selection shadow Wikipedia

antagonistic pleiotropy, mortality source interactions, and the evolutionary theory of senescence Most theoretical work on the evolution of senescence has assumed that all individuals within a population are equally susceptible to extrinsic sources of mortality.
Williams, G. C. Pleiotropy, natural selection and the evolution of senescence. Evolution 11, 398–411 (1957). evolution of a threshold dimorphism 3. Reznick, D. A., Bryga, H. & Endler, J. A. Experimentally induced life-history evolution in a natural population. Nature 346, 357–359 (1990). Joseph L. Tomkins & Gordon S. Brown 4. Charlesworth, B. Evolution in Age Structured Populations
The selection shadow is a concept involved with the evolutionary theories of ageing that states that selection pressures on an individual decrease as an individual ages and passes sexual maturity, resulting in a “shadow” of time where selective fitness is not considered.
Under these circumstances, it is commonly assumed that natural and sexual selection act in opposite directions, effectively limiting the evolution of conspicuous signals and preferences. We
Understanding equilibria is an essential step toward a nonequilibrium theory and should provide greater insights than we now possess. I first discuss different theoretical approaches to the definition of evolutionary equilibria.
• Aging results because of pleiotropy • Natural selection continues after reproduction “Evolution: Medicine’s Missing Basic Science” Prof. Randolph M. Nesse The screen versions of these slides have full details of copyright and acknowledgements 3 7 Percent of schools that include topic in medical curriculum (n = 55) Nesse & Schiffman, 2000 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% …

Evolutionary mechanisms of senescence SpringerLink
What is Aging? PubMed Central (PMC)

Enquiry into the evolution of ageing aims to explain why survival, reproductive success, and functioning of almost all living organisms decline at old age. Leading hypotheses [1] [2] suggest that a combination of limited resources, and an increasing risk of death by environmental causes determine an “optimal” level of self-maintenance , i.e. the repair of molecular and cellular level damage
16 T. B. L. Kirkwood and M. R. Rose Evolution of senescence common element in both these theories is the conclusion that, in effect, natural selection trades late survival for
Antagonistic pleiotropy, as it applies to aging, hypothesizes that animals possess genes that enhance fitness early in life but diminish it in later life and that such genes can be favored by natural selection because selection is stronger early in life even as they cause the aging phenotype to emerge. No genes of the sort hypothesized by Williams were known 60 years ago, but modern molecular
Pleiotropy, Natural Selection, and the Evolution of Senescence Created Date: 20160807184145Z
This is the theory of antagonistic pleiotropy. 2. EVOLUTION OF SENESCENCE Antagonistic pleiotropy introduces the idea of a trade-off between early benefit and late cost, and the (a) Population genetics important thing about the declining action of selection The first hints of a population genetic approach to with adult age is that it takes only a small fitness benefit the problem of senescence
Williams’ 1957 paper Pleiotropy, natural selection, and the evolution of senescence was influential in 20th century evolutionary biology. It contains three important ideas. [4] In this paper Williams proposed that senescence should be generally synchronized by natural selection .
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics. The word senescence can refer either to cellular senescence or to senescence …
The selection shadow is a concept involved with the evolutionary theories of ageing that states that selection pressures on an individual decrease as an individual ages and passes sexual maturity, resulting in a “shadow” of time where selective fitness is not considered.
Williams, G. C. Pleiotropy, Natural Selection, and the Evolution of Senescence. Society for the Study of Evolution. 1957 Society for the Study of Evolution. 1957 – Denham Harman proposes the free radical theory of aging
Although theories of the evolution of senescence differ in the mode of action by which genes are thought to control the aging process, they all view the rate of senescence as an adaptable feature
senescence hypotheses that have played a role in our evolution. Other theories Other theories could also be important, but available data precludes testing them.