Laws of natural selection

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Sigler's Laws of Natural Selection (English Edition) eBook: Hall, Timothy: tina-turner.se: Kindle-Shop. Keywords: adaptation, Darwin reception, Heinrich Georg Bronn, law, paleontology, the idea of species transformation by natural selection left the key pages. "The old argument of design in nature," he writes, "which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered. Many translated example sentences containing "theory of natural selection" of an axiomatic order, by which groups of natural laws, which for their part are - in. Many translated example sentences containing "natural selection" – German-​English dictionary and search engine for German translations.

Laws of natural selection

Many translated example sentences containing "natural selection" – German-​English dictionary and search engine for German translations. "The old argument of design in nature," he writes, "which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered. To me the conception of this law of Nature [i.e. natural selection] came intuitively as a self-evident fact, almost without an effort of concentrated thought.

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Chad hunt An Historical Sketch. The nonrandom survival and reproductive success of a small percentage of the individuals of a population owing to their possession of, at that moment, characters which enhance their ability to survive and reproduce. The historical context Goddess rapture natural selection: the case of Patrick Matthew. Morphology Embryology Rudimentary Organs. Evolution Revolution Explore the revolution and the controversies around it. Natural Wet&puffy.
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Laws of natural selection Chapter VI Difficulties Michelle thorne blow job the Theory. Matthew, P. January Voyage of the Beagle Birth of a Theory. The Evolution of Life, Mofos emma evins track full video On the tendency of varieties to depart indefinitely from the original type in: Contributions to the Theory of Natural Selection.
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In particular, if the trait is quantitative and univariate then both higher and lower trait Riley grey pornstar are favoured. Evolutionary Biology. In the 's, the biologist Kettlewell did release-recapture experiments using both morphs. An example is the ABO blood type antigens in humans, where three alleles Nat chatnappa of the black alley the phenotype. The above point generalizes: what is quantifiable as selection and drift in type recursions is made definite by how fitness variables and effective population Xxx videos 18 function in those Tangas casera. This gave dark-coloured moths Carmel moore vids better chance of surviving to produce dark-coloured offspring, and in Submissive sex videos fifty years from the first dark moth being caught, nearly all of the moths in industrial Manchester were dark. Sexual Selection. Scientists at the time realized that evolution took Sophie turner porn but did not know how species evolved. Colorado University Press. Do Doggy style porn gif name each other?

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In order for natural selection to operate on a trait, the trait must possess heritable variation and must confer an advantage in the competition for resources.

If one of these requirements does not occur, then the trait does not experience natural selection. Natural selection operates by comparative advantage, not an absolute standard of design.

Natural selection can only work on existing variation within a population. Such variations arise by mutation, a change in some part of the genetic code for a trait.

Mutations arise by chance and without foresight for the potential advantage or disadvantage of the mutation.

In other words, variations do not arise because they are needed. Let's look at an example to help make natural selection clear. Industrial melanism is a phenomenon that affected over 70 species of moths in England.

It has been best studied in the peppered moth, Biston betularia. Prior to , the typical moth of the species had a light pattern see Figure 2.

Dark colored or melanic moths were rare and were therefore collectors' items. Figure 2. Image of Peppered Moth. During the Industrial Revolution, soot and other industrial wastes darkened tree trunks and killed off lichens.

The light-colored morph of the moth became rare and the dark morph became abundant. In , the first melanic morph was seen; by , it was far more common -- illustrating rapid evolutionary change.

Eventually light morphs were common in only a few locales, far from industrial areas. The cause of this change was thought to be selective predation by birds, which favored camouflage coloration in the moth.

In the 's, the biologist Kettlewell did release-recapture experiments using both morphs. A brief summary of his results are shown below.

By observing bird predation from blinds, he could confirm that conspicuousness of moth greatly influenced the chance it would be eaten.

Recapture Success. So far in today's lecture we have emphasized that natural selection is the cornerstone of evolutionary theory.

It provides the mechanism for adaptive change. Any change in the environment such as a change in the background color of the tree trunk that you roost on is likely to lead to local adaptation.

Any widespread population is likely to experience different environmental conditions in different parts of its range. As a consequence it will soon consist of a number of sub-populations that differ slightly, or even considerably.

The following are examples that illustrate the adaptation of populations to local conditions. Figure 3: Subspecies of the rat snake Elaphe obsoleta , which interbreed where their ranges meet.

Figure 4. Hull has a similar definition: a replicator is an entity that passes on its structure largely intact in successive replications Hull Germ-line replicators have the potential to have indefinitely many descendants; they contrast with somatic replicators, the genes found in body cells, which produce copies only as part of mitosis and whose lineages of descendants end when the body dies.

Natural selection will occur wherever we find active germ-line replicators Dawkins Dawkins distinguished replicators from vehicles, his notion meant to replace and generalize that of organism.

Hull proposed the notion of interactor as a similar complement to the notion of replicator. Neither notion, however, is meant to further delineate the circumstances in which selection occurs, or to narrow the scope of application of evolutionary theory for further discussion of these notions, see entry on units and levels of selection.

This is evident, for Hull at least, insofar as genes may be both replicators and interactors The view that evolutionary theory is a theory that applies to active germ-line replicators has come under fire from a multitude of directions.

Genes need not be germ-line to undergo selection, as it is at least arguable that the immune system exhibits selection processes Okasha Copying is beside the point, since only similarity across generations, rather than identity, is necessary for evolutionary change Godfrey-Smith , and entries on units and levels of selection and replication and reproduction.

For his part, Hull seems to agree with this last point, as he allows that organisms might well count as replicators, at least in cases in which they reproduce asexually Hull 28— Despite the bevy of attacks on replicator selectionism, replicator selectionists have not, to my knowledge at least, been criticized for being too permissive and allowing that systems that do not evolve count as undergoing selection.

But germ-line replicators may exert a causal influence on their probability of being copied without spreading in a natural population as a result, as in some cases of frequency-dependent selection of systems already at equilibrium.

In cases of frequency-dependent selection, variant genes cause their own reproduction, but the extent of influence on reproduction is a function of their frequency.

Suppose each type spreads when it is rarer. Because causing replication may not lead to differential replication in these and other cases, replicator selectionists do not effectively take evolution to be necessary for selection while Lewontin and those who follow his basic approach typically do do so.

One natural way to arbitrate the issue of whether systems that undergo selection must evolve is to attend to the point of statements of principles of natural selection, or statements of the requirements for selection.

Many theorists take it that the point of these principles is to set out the scope of a theory in the special sciences that deals with selection and evolution, evolutionary theory.

Lewontin claims that the theory of evolution by natural selection rests on his three principles Equally, Godfrey-Smith claims that statements of conditions for evolution by natural selection exhibit the coherence of evolutionary theory and capture some of its core principles For these writers, the or at least a point of the principles seems to be to capture the domain of application of the theory we have inherited from Darwin.

Darwin would have been surprised to hear that his theory of natural selection was circumscribed so as to apply only to evolving populations. He himself constructed an explanation of a persistent polymorphism, heterostyly, using his own theory.

Plants exhibiting heterostyly develop two, or sometimes three, different forms of flower whose reproductive organisms vary in a number of ways, principally length.

Some plants exhibit different forms of flower on the same plant, while some are dimorphic and trimorphic, with only one sort of flower per plant.

Darwin interpreted the flower variations as conducive to intercrossing, which he thought was beneficial, at least for many organisms.

Populations should not evolve directionally such that a single form of flower spreads throughout the population; instead, multiple variants should be retained, a polymorphism.

Darwin thinks it clear that heterostyly is an adaptation:. The benefit which heterostyled dimorphic plants derive from the existence of the two forms is sufficiently obvious [….

Darwin 30; thanks to Jim Lennox for this reference. Even though the population is not evolving, but instead remaining the same over time, it exhibits an adaptation that consists in this persistent lack of change, an adaptation that Darwin thought explicable using his theory.

These sorts of behaviors result from specific assignments of values for theoretical parameters in many of the very same models that are used to explain simple directional selection where a single variant spreads throughout a population, as in the wolf case discussed in the introduction.

The point is that systems seemingly governed by evolutionary theory exhibit a variety of different sorts of dynamics, and this variety includes both different sorts of evolution, including at least cyclical and directional, as well as a lack of evolution at all, as in cases of stabilizing selection.

Consider in particular how the difference between stabilizing and directional selection in the simplest deterministic models of diploid evolution lies in the value of a single parameter in the genotypic selection model, heterozygote fitness:.

If we hold evolution as a condition for selection, we will issue the curious ruling that a system governed by the first sort of model falls within the scope of evolutionary theory while a system governed by the second sort of model only does so up until it reaches a stable intermediate state but then no longer.

Moreover, populations exhibiting stable polymorphisms resulting from heterozygote superiority, or overdominance, are just one case among many different sorts of systems that equally exhibit stable polymorphisms.

The above models are deterministic, while the dynamics of natural systems are to some extent random. A system governed by both the deterministic equations and the binomial sampling equation is said to undergo drift; all natural systems do so.

For more on drift, effective population size, and randomness in evolutionary theory, see entry on genetic drift.

A system exhibiting heterozygote superiority whose dynamics are a function of the binomial sampling equation will not simply rest at its stable intermediate frequency but will hover around it, in some generations evolving toward it, more rarely evolving away, and in some generations exhibiting no evolution at all.

Which of these cases are cases in which the system undergoes natural selection in the capacious sense? That is, which cases are cases in which the system falls within the purview of evolutionary theory?

A natural answer is all of them. To answer in this way, however, we must not make evolution necessary for natural selection. This last pattern of argument can be extended.

Indeed, given that every natural system undergoing selection also undergoes drift, evolutionary theory is arguably applicable also to systems that undergo drift even in the absence of selection in the focused sense.

Is the point at which the values equalize so momentous that it marks the point at which systems governed by the equations cease to fall within the purview of one theory and instead fall within the purview of another?

If Brandon is right, then conditions for the application of evolutionary theory must not even include conditions for selection in the focused sense, much less conditions for evolutionary change.

The point of stating conditions for evolution by natural selection need not be to state the conditions of deployment of a particular theory in the special sciences.

Godfrey-Smith mentions that the principles may be important to discussions of extensions of evolutionary principles to new domains.

Statements of the conditions for evolution by natural selection might have value for other reasons. But evolutionary theory is, despite the name, at least arguably a theory that is applicable to more systems than just those that evolve, as the replicator selectionists would have it.

One of the two chief uses of the notion of natural selection is as an interpretation of one or another quantity in formal models of evolutionary processes; this is the focused sense distinguished above.

Two different quantities are called selection in different formal models widely discussed by philosophers. This is standard textbook usage Rice ; Hedrick The recursive structure of these models is important.

They can be used to infer how a system will behave into the future though of course only if causes of the variables in the system do not change their values in dynamically-relevant ways that are not explicitly modeled in the recursive equations.

Writers working with type recursion models have developed explicit interpretations of their theoretical terms, including the fitness variables quantifying selection.

So, for instance, Beatty and Millstein defend the view that the fitness coefficients representing selection in type recursions should be understood as modeling a discriminate sampling process, while drift, controlled by effective population size, should be understood as indiscriminate sampling Beatty ; Millstein Philosophers have also contended that particular terms in models of systems featuring the formation of groups or collectives should be understood as quantifying the influence of selection at different levels.

Kerr and Godfrey-Smith discuss one such system of recursions; Jantzen defends an alternative parameterization of group selection as part of different system of equations.

See also Krupp for causal-graphical conceptualization of the notion of group selection. For much more on multi-level selection, see entry on units and levels of selection.

The other formal model of particular interest to philosophers is the Price Equation. The Price Equation represents the extent of evolution in a system with respect to a given trait across a single generation using statistical functions:.

In the Price Equation, selection is associated with the first right-hand side quantity, while the second represents transmission bias.

Identities among algebraic functions of statistical functions make possible the mathematical manipulation of the Price Equation such that it may feature a variety of different quantities.

As with type recursions, quantities in various transformations of the Price Equation are equated with selection at different levels for different systems; Okasha, following Price, treats the covariance of the fitness of collectives with the phenotype of collectives as collective-level selection, while the average of the within-collective covariances between particle character and particular fitness is identified with particle-level selection.

The Price Equation can equally be manipulated to yield distinct notions of inheritance; Bourrat distinguishes temporal, persistence, and generational heritabilities and argues for the temporal notion as appropriate for the purposes of stating conditions for evolution by natural selection Bourrat The distinction between type recursions and the Price Equation is important, because selection is interpreted differently in each.

The two formalisms will issue in different verdicts about whether, and the extent to which, focused selection operates within a single system.

To see this, consider how type recursions are structured such that inferences about dynamics over multiple generations may be made by means of them.

If fitness coefficients in these models quantify selection, and these take fixed values as they do in the genotypic selection model considered above and a great many others , then the extent of selection will remain the same over the time period governed by the model: the fitness variables remain at fixed values so selection remains an unchanging influence.

Consider, for instance, the extent to which the population evolves, according to the genotypic selection model above, when the following values are plugged into the model:.

If we understand selection as quantified by the fitness coefficients in this sort of set-up, then the whole time, selection operates in a constant fashion, since the fitness coefficients remain fixed.

In particular, the operation of selection is the same when the system is evolving toward its stable equilibrium as when it remains at that stable equilibrium.

By contrast, the covariance term in Price Equation model of the system will diminish in value until it reaches zero as the system evolves to its equilibrium state.

When selection is identified with the covariance between type and reproduction, the frequency of the different types matters to the extent of selection.

When selection is identified with fitness variables in type recursions, the frequency of different types has no influence on the extent of selection in the system.

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In kin selection and intragenomic conflict , gene-level selection provides a more apt explanation of the underlying process. Group selection , if it occurs, acts on groups of organisms, on the assumption that groups replicate and mutate in an analogous way to genes and individuals.

There is an ongoing debate over the degree to which group selection occurs in nature. Finally, selection can be classified according to the resource being competed for.

Sexual selection results from competition for mates. Sexual selection typically proceeds via fecundity selection, sometimes at the expense of viability.

Ecological selection is natural selection via any means other than sexual selection, such as kin selection, competition, and infanticide. Following Darwin, natural selection is sometimes defined as ecological selection, in which case sexual selection is considered a separate mechanism.

Sexual selection as first articulated by Darwin using the example of the peacock 's tail [81] refers specifically to competition for mates, [84] which can be intrasexual , between individuals of the same sex, that is male—male competition, or intersexual , where one gender chooses mates , most often with males displaying and females choosing.

Phenotypic traits can be displayed in one sex and desired in the other sex, causing a positive feedback loop called a Fisherian runaway , for example, the extravagant plumage of some male birds such as the peacock.

Aggression between members of the same sex is sometimes associated with very distinctive features, such as the antlers of stags , which are used in combat with other stags.

More generally, intrasexual selection is often associated with sexual dimorphism , including differences in body size between males and females of a species.

Natural selection is seen in action in the development of antibiotic resistance in microorganisms. Since the discovery of penicillin in , antibiotics have been used to fight bacterial diseases.

The widespread misuse of antibiotics has selected for microbial resistance to antibiotics in clinical use, to the point that the methicillin-resistant Staphylococcus aureus MRSA has been described as a "superbug" because of the threat it poses to health and its relative invulnerability to existing drugs.

A similar situation occurs with pesticide resistance in plants and insects. Arms races are not necessarily induced by man; a well-documented example involves the spread of a gene in the butterfly Hypolimnas bolina suppressing male-killing activity by Wolbachia bacteria parasites on the island of Samoa , where the spread of the gene is known to have occurred over a period of just five years [90] [91].

A prerequisite for natural selection to result in adaptive evolution, novel traits and speciation is the presence of heritable genetic variation that results in fitness differences.

Genetic variation is the result of mutations, genetic recombinations and alterations in the karyotype the number, shape, size and internal arrangement of the chromosomes.

Any of these changes might have an effect that is highly advantageous or highly disadvantageous, but large effects are rare.

In the past, most changes in the genetic material were considered neutral or close to neutral because they occurred in noncoding DNA or resulted in a synonymous substitution.

However, many mutations in non-coding DNA have deleterious effects. Some mutations occur in "toolkit" or regulatory genes. Changes in these often have large effects on the phenotype of the individual because they regulate the function of many other genes.

Most, but not all, mutations in regulatory genes result in non-viable embryos. Some nonlethal regulatory mutations occur in HOX genes in humans, which can result in a cervical rib [95] or polydactyly , an increase in the number of fingers or toes.

Established traits are not immutable; traits that have high fitness in one environmental context may be much less fit if environmental conditions change.

In the absence of natural selection to preserve such a trait, it becomes more variable and deteriorate over time, possibly resulting in a vestigial manifestation of the trait, also called evolutionary baggage.

In many circumstances, the apparently vestigial structure may retain a limited functionality, or may be co-opted for other advantageous traits in a phenomenon known as preadaptation.

A famous example of a vestigial structure, the eye of the blind mole-rat , is believed to retain function in photoperiod perception.

Speciation requires a degree of reproductive isolation —that is, a reduction in gene flow. However, it is intrinsic to the concept of a species that hybrids are selected against, opposing the evolution of reproductive isolation, a problem that was recognised by Darwin.

The problem does not occur in allopatric speciation with geographically separated populations, which can diverge with different sets of mutations.

Poulton realized in that reproductive isolation could evolve through divergence, if each lineage acquired a different, incompatible allele of the same gene.

Selection against the heterozygote would then directly create reproductive isolation, leading to the Bateson—Dobzhansky—Muller model , further elaborated by H.

Allen Orr [98] and Sergey Gavrilets. Natural selection acts on an organism's phenotype, or physical characteristics. Phenotype is determined by an organism's genetic make-up genotype and the environment in which the organism lives.

When different organisms in a population possess different versions of a gene for a certain trait, each of these versions is known as an allele.

It is this genetic variation that underlies differences in phenotype. An example is the ABO blood type antigens in humans, where three alleles govern the phenotype.

Some traits are governed by only a single gene, but most traits are influenced by the interactions of many genes. A variation in one of the many genes that contributes to a trait may have only a small effect on the phenotype; together, these genes can produce a continuum of possible phenotypic values.

When some component of a trait is heritable, selection alters the frequencies of the different alleles, or variants of the gene that produces the variants of the trait.

Selection can be divided into three classes, on the basis of its effect on allele frequencies: directional, stabilizing, and purifying selection.

This process can continue until the allele is fixed and the entire population shares the fitter phenotype.

This process can continue until the allele is eliminated from the population. Purifying selection conserves functional genetic features, such as protein-coding genes or regulatory sequences , over time by selective pressure against deleterious variants.

Some forms of balancing selection do not result in fixation, but maintain an allele at intermediate frequencies in a population.

This can occur in diploid species with pairs of chromosomes when heterozygous individuals with just one copy of the allele have a higher fitness than homozygous individuals with two copies.

This is called heterozygote advantage or over-dominance, of which the best-known example is the resistance to malaria in humans heterozygous for sickle-cell anaemia.

Maintenance of allelic variation can also occur through disruptive or diversifying selection , which favours genotypes that depart from the average in either direction that is, the opposite of over-dominance , and can result in a bimodal distribution of trait values.

Finally, balancing selection can occur through frequency-dependent selection, where the fitness of one particular phenotype depends on the distribution of other phenotypes in the population.

The principles of game theory have been applied to understand the fitness distributions in these situations, particularly in the study of kin selection and the evolution of reciprocal altruism.

A portion of all genetic variation is functionally neutral, producing no phenotypic effect or significant difference in fitness. Motoo Kimura 's neutral theory of molecular evolution by genetic drift proposes that this variation accounts for a large fraction of observed genetic diversity.

As a result, the genetic variation at those sites is higher than at sites where variation does influence fitness. Natural selection reduces genetic variation by eliminating maladapted individuals, and consequently the mutations that caused the maladaptation.

At the same time, new mutations occur, resulting in a mutation—selection balance. The exact outcome of the two processes depends both on the rate at which new mutations occur and on the strength of the natural selection, which is a function of how unfavourable the mutation proves to be.

Genetic linkage occurs when the loci of two alleles are in close proximity on a chromosome. During the formation of gametes, recombination reshuffles the alleles.

The chance that such a reshuffle occurs between two alleles is inversely related to the distance between them. Selective sweeps occur when an allele becomes more common in a population as a result of positive selection.

As the prevalence of one allele increases, closely linked alleles can also become more common by " genetic hitchhiking ", whether they are neutral or even slightly deleterious.

A strong selective sweep results in a region of the genome where the positively selected haplotype the allele and its neighbours are in essence the only ones that exist in the population.

Selective sweeps can be detected by measuring linkage disequilibrium , or whether a given haplotype is overrepresented in the population. Since a selective sweep also results in selection of neighbouring alleles, the presence of a block of strong linkage disequilibrium might indicate a 'recent' selective sweep near the centre of the block.

Background selection is the opposite of a selective sweep. If a specific site experiences strong and persistent purifying selection, linked variation tends to be weeded out along with it, producing a region in the genome of low overall variability.

Because background selection is a result of deleterious new mutations, which can occur randomly in any haplotype, it does not produce clear blocks of linkage disequilibrium, although with low recombination it can still lead to slightly negative linkage disequilibrium overall.

Darwin's ideas, along with those of Adam Smith and Karl Marx , had a profound influence on 19th century thought, including his radical claim that "elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner" evolved from the simplest forms of life by a few simple principles.

Natural selection had the power, according to Stephen Jay Gould , to "dethrone some of the deepest and most traditional comforts of Western thought", such as the belief that humans have a special place in the world.

In the words of the philosopher Daniel Dennett , "Darwin's dangerous idea" of evolution by natural selection is a "universal acid," which cannot be kept restricted to any vessel or container, as it soon leaks out, working its way into ever-wider surroundings.

This unlimited applicability has been called universal Darwinism. How life originated from inorganic matter remains an unresolved problem in biology.

One prominent hypothesis is that life first appeared in the form of short self-replicating RNA polymers.

These conditions are: heritability, variation of type , and competition for limited resources. The fitness of an early RNA replicator would likely have been a function of adaptive capacities that were intrinsic i.

In , the embryologist Wilhelm Roux published Der Kampf der Theile im Organismus The Struggle of Parts in the Organism in which he suggested that the development of an organism results from a Darwinian competition between the parts of the embryo, occurring at all levels, from molecules to organs.

According to this cellular Darwinism, random variation at the molecular level generates diversity in cell types whereas cell interactions impose a characteristic order on the developing embryo.

The social implications of the theory of evolution by natural selection also became the source of continuing controversy.

Friedrich Engels , a German political philosopher and co-originator of the ideology of communism , wrote in that "Darwin did not know what a bitter satire he wrote on mankind, and especially on his countrymen, when he showed that free competition, the struggle for existence, which the economists celebrate as the highest historical achievement, is the normal state of the animal kingdom.

For example, in , Konrad Lorenz , in writings that he subsequently disowned, used the theory as a justification for policies of the Nazi state.

He wrote " The racial idea as the basis of our state has already accomplished much in this respect. More recently, work among anthropologists and psychologists has led to the development of sociobiology and later of evolutionary psychology, a field that attempts to explain features of human psychology in terms of adaptation to the ancestral environment.

The most prominent example of evolutionary psychology, notably advanced in the early work of Noam Chomsky and later by Steven Pinker , is the hypothesis that the human brain has adapted to acquire the grammatical rules of natural language.

By analogy to the action of natural selection on genes, the concept of memes —"units of cultural transmission," or culture's equivalents of genes undergoing selection and recombination—has arisen, first described in this form by Richard Dawkins in [] and subsequently expanded upon by philosophers such as Daniel Dennett as explanations for complex cultural activities, including human consciousness.

In , Alfred J. Lotka proposed that natural selection might be understood as a physical principle that could be described in terms of the use of energy by a system, [] [] a concept later developed by Howard T.

Odum as the maximum power principle in thermodynamics , whereby evolutionary systems with selective advantage maximise the rate of useful energy transformation.

The principles of natural selection have inspired a variety of computational techniques, such as "soft" artificial life , that simulate selective processes and can be highly efficient in 'adapting' entities to an environment defined by a specified fitness function.

Goldberg , [] identify optimal solutions by simulated reproduction and mutation of a population of solutions defined by an initial probability distribution.

Darwinian evolution by natural selection is pervasive in literature, whether taken optimistically in terms of how humanity may evolve towards perfection, or pessimistically in terms of the dire consequences of the interaction of human nature and the struggle for survival.

Among major responses is Samuel Butler 's pessimistic Erewhon "nowhere", written mostly backwards. In H. Wells imagined " The Man of the Year Million ", transformed by natural selection into a being with a huge head and eyes, and shrunken body.

From Wikipedia, the free encyclopedia. This is the latest accepted revision , reviewed on 10 October For other uses, see Natural Selection disambiguation.

Mechanism of evolution by differential survival and reproduction of individuals. Darwin's finches by John Gould. Key topics. Introduction to evolution Common descent Evidence.

Processes and outcomes. Natural history. History of evolutionary theory. Fields and applications. Applications of evolution Biosocial criminology Ecological genetics Evolutionary aesthetics Evolutionary anthropology Evolutionary computation Evolutionary ecology Evolutionary economics Evolutionary epistemology Evolutionary ethics Evolutionary game theory Evolutionary linguistics Evolutionary medicine Evolutionary neuroscience Evolutionary physiology Evolutionary psychology Experimental evolution Phylogenetics Paleontology Selective breeding Speciation experiments Sociobiology Systematics Universal Darwinism.

Social implications. Evolution as fact and theory Social effects Creation—evolution controversy Objections to evolution Level of support. Main article: History of evolutionary thought.

Main articles: Inception of Darwin's theory and Development of Darwin's theory. Further information: Coloration evidence for natural selection.

Main article: Modern synthesis 20th century. Main article: Genetic variation. Main article: Fitness biology. Main article: Competition biology.

Further information: Sexual selection. Further information: Antimicrobial resistance. Main articles: Evolution and Darwinism. Main article: Speciation.

Main article: Genotype—phenotype distinction. Main article: Directional selection. Main articles: Genetic variation and Genetic drift.

Main article: Universal Darwinism. Main article: Abiogenesis. Main article: Evolution in fiction. Journal of the History of Biology.

Proceedings of the American Philosophical Society. Encyclopedia of Sciences and Religions : 74—77 — via Springer. Berlin: — Evolution: The History of an Idea 3rd ed.

Journal of the History of Ideas. Strickberger's Evolution 4th ed. Jones and Bartlett. Darwin Correspondence Project. Letter Retrieved 1 August Retrieved 12 January Summer John's Law Review.

Jamaica, NY. This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr.

Darwin has called 'natural selection, or the preservation of favoured races in the struggle for life. Philosophy of Science. Archived from the original PDF on 25 December Retrieved 4 August Archived from the original on 14 June Retrieved 22 May The Science of Life.

London: Amalgamated Press. December Journal of Genetics. Blackwell Publishing. Journal of Theoretical Biology.

International Journal of Developmental Biology. Developmental Biology. Nature Reviews Genetics. November University of Michigan.

Retrieved 9 November Stanford Encyclopedia of Philosophy. Retrieved 28 July June Bibcode : Natur. Communications Biology.

Allen August Nat Rev Genet. Current Science. Statistics in Medicine. Bibcode : Sci Proceedings of the National Academy of Sciences.

Bibcode : PNAS.. Biology Letters. Palaeogeography, Palaeoclimatology, Palaeoecology. Bibcode : PPP November—December The American Naturalist.

Brussels, Belgium. Sexual Conflict. Princeton University Press. Nature Education. May Bibcode : PLoSO.. On the Origin of Species 1st edition.

Chapter 4, page This depends January Current Biology. Behavioural Processes. March The Quarterly Review of Biology. The Guardian.

Clinical Microbiology and Infection. Aureus Infections among Patients in the Emergency Department". New England Journal of Medicine. Human Molecular Genetics.

Developmental constraints, Hox genes, and cancer". Journal of Experimental Zoology. Bibcode : PNAS July Rudiment with Hidden Function?

Reviews in Cell Biology and Molecular Medicine. Online Mendelian Inheritance in Man. National Library of Medicine. Retrieved 7 November The neutral theory of molecular evolution.

Cambridge University Press. Macmillan Reference US. Biology 4th ed. Benjamin Cummings. Trends in Genetics. Genetics Research. The New York Review of Books.

Universitätsverlag Göttingen. April Scientific American. Bibcode : SciAm. Archived from the original on 4 August Retrieved 11 August American Journal of Psychiatry Letter to the editor.

Eisenberg quoting translation of Durch Domestikation verursachte Störungen arteigenen Verhaltens , p. Hall, C. Self-Organization and Maximum Empower.

The cause of this change was thought to be selective predation by birds, which favored camouflage coloration in the moth.

In the 's, the biologist Kettlewell did release-recapture experiments using both morphs. A brief summary of his results are shown below.

By observing bird predation from blinds, he could confirm that conspicuousness of moth greatly influenced the chance it would be eaten.

Recapture Success. So far in today's lecture we have emphasized that natural selection is the cornerstone of evolutionary theory.

It provides the mechanism for adaptive change. Any change in the environment such as a change in the background color of the tree trunk that you roost on is likely to lead to local adaptation.

Any widespread population is likely to experience different environmental conditions in different parts of its range. As a consequence it will soon consist of a number of sub-populations that differ slightly, or even considerably.

The following are examples that illustrate the adaptation of populations to local conditions. Figure 3: Subspecies of the rat snake Elaphe obsoleta , which interbreed where their ranges meet.

Figure 4. Finally, we will look at a statistical way of thinking about selection. Suppose that each population can be portrayed as a frequency distribution for some trait -- beak size, for instance.

Note again that variation in a trait is the critical raw material for evolution to occur. What will the frequency distribution look like in the next generation?

Figures 5a-c. First, the proportion of individuals with each value of the trait size of beak, or body weight might be exactly the same.

Second, there may be directional change in just one direction. Third and with such rarity that its existence is debatable , there might be simultaneous change in both directions e.

Figures 5a-c capture these three major categories of natural selection. Figure 6. Under stabilizing selection , extreme varieties from both ends of the frequency distribution are eliminated.

The frequency distribution looks exactly as it did in the generation before see Figure 5a. Probably this is the most common form of natural selection, and we often mistake it for no selection.

A real-life example is that of birth weight of human babies see Figure 6. Under directional selection , individuals at one end of the distribution of beak sizes do especially well, and so the frequency distribution of the trait in the subsequent generation is shifted from where it was in the parental generation see Figure 5b.

This is what we usually think of as natural selection. Industrial melanism was such an example. Figure 7. The fossil lineage of the horse provides a remarkable demonstration of directional succession.

The full lineage is quite complicated and is not just a simple line from the tiny dawn horse Hyracotherium of the early Eocene, to today's familiar Equus.

Overall, though, the horse has evolved from a small-bodied ancestor built for moving through woodlands and thickets to its long- legged descendent built for speed on the open grassland.

This evolution has involved well- documented changes in teeth, leg length, and toe structure see Figure 7. Under diversifying disruptive selection , both extremes are favored at the expense of intermediate varieties see Figure 5c.

This is uncommon, but of theoretical interest because it suggests a mechanism for species formation without geographic isolation see the lecture on speciation.

Darwin's theory of evolution fundamentally changed the direction of future scientific thought, though it was built on a growing body of thought that began to question prior ideas about the natural world.

The core of Darwin's theory is natural selection, a process that occurs over successive generations and is defined as the differential reproduction of genotypes.

Natural selection requires heritable variation in a given trait, and differential survival and reproduction associated with possession of that trait.

Examples of natural selection are well-documented, both by observation and through the fossil record. Selection acts on the frequency of traits, and can take the form of stabilizing, directional, or diversifying selection.

London: J. Evolutionary Biology. Sunderland, Mass: Sinauer Associates, Inc. The Selfish Gene. Oxford: Oxford University Press.

Laws Of Natural Selection

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