The Red Queen hypothesis is a

hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

evolutionary biology Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life fo ...

proposed in 1973, that species must constantly

adapt ADAPT (formerly American Disabled for Attendant Programs Today) is a United States grassroots disability rights organization with chapters in 30 states and Washington, D.C. They use nonviolent direct action in order to bring about disability just ...

, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species. The hypothesis was intended to explain the constant (age-independent) extinction probability as observed in the

paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

record caused by co-evolution between competing

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

; however, it has also been suggested that the Red Queen hypothesis explains the advantage of

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

(as opposed to

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...

) at the level of individuals,Bell, G. (1982). The Masterpiece Of Nature: The Evolution and Genetics of Sexuality. University of California Press, Berkeley, 378 pp. and the positive correlation between

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

and

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

rates in most higher taxa.

Origin

In 1973,

Leigh Van Valen Leigh Van Valen (August 12, 1935 – October 16, 2010) was a U.S. evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago. Research and interests Amongs ...

proposed the hypothesis as an "explanatory tangent" to explain the "law of extinction" known as "Van Valen's law", which states that the probability of

does not depend on the lifetime of the species or higher-rank taxon, instead being constant over millions of years for any given taxon. However, the probability of extinction is strongly related to adaptive zones, because different taxa have different probabilities of extinction. In other words, extinction of a species occurs randomly with respect to age, but nonrandomly with respect to ecology. Collectively, these two observations suggest that the effective environment of any homogeneous group of organisms deteriorates at a stochastically constant rate. Van Valen proposed that this is the result of an evolutionary zero-sum game driven by

interspecific competition Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...

: the evolutionary progress (= increase in fitness) of one species deteriorates the fitness of coexisting species, but because coexisting species evolve as well, no one species gains a long-term increase in fitness, and the overall fitness of the system remains constant. Van Valen coined the hypothesis "Red Queen" because under his hypothesis, species have to "run" or evolve in order to stay in the same place, or else go extinct as the Red Queen said to Alice in

Lewis Carroll Charles Lutwidge Dodgson (; 27 January 1832 – 14 January 1898), better known by his pen name Lewis Carroll, was an English author, poet and mathematician. His most notable works are ''Alice's Adventures in Wonderland'' (1865) and its sequel ...

's ''

Through the Looking-Glass ''Through the Looking-Glass, and What Alice Found There'' (also known as ''Alice Through the Looking-Glass'' or simply ''Through the Looking-Glass'') is a novel published on 27 December 1871 (though indicated as 1872) by Lewis Carroll and the ...

'' in her explanation of the nature of Looking-Glass Land:

Examples

Positive correlation between speciation and extinction rates (Stanley's rule)

Palaeontological data suggest that high speciation rates correlate with high extinction rates in almost all major taxa. This correlation has been attributed to a number of ecological factors, but it may result also from a Red Queen situation, in which each speciation event in a clade deteriorates the fitness of coexisting species in the same clade (provided that there is

phylogenetic niche conservatism The term phylogenetic niche conservatism has seen increasing use in recent years in the scientific literature, though the exact definition has been a matter of some contention. Fundamentally, phylogenetic niche conservatism refers to the tendency ...

Evolution of sex

Discussions of the evolution of sex was not part of Van Valen's Red Queen hypothesis, which addressed evolution at scales above the species level. The microevolutionary version of the Red Queen hypothesis was proposed by Bell (1982), also citing Lewis Carroll, but not citing Van Valen. The Red Queen hypothesis is used independently by Hartung. Genome Parliaments and Sex with the Red Queen. In: Alexander, R.D., Tinkle, D. W., Eds. Natural Selection and Social Behavior: Recent Research and New Theory. New York: Chiron Press, 1981, 382-402 and Bell to explain the evolution of sex, by

John Jaenike John Jaenike is an ecologist and evolutionary biologist, and currently a professor at the University of Rochester New York. Jaenike was an early proponent of the Red Queen Hypothesis, using the idea to explain the maintenance of sex. Jaenike is ...

to explain the maintenance of sex and

W. D. Hamilton William Donald Hamilton (1 August 1936 – 7 March 2000) was a British evolutionary biologist, recognised as one of the most significant evolutionary theorists of the 20th century. Hamilton became known for his theoretical work expounding a ...

to explain the role of sex in response to parasites. In all cases, sexual reproduction confers species variability and a faster generational response to

selection Selection may refer to: Science * Selection (biology), also called natural selection, selection in evolution ** Sex selection, in genetics ** Mate selection, in mating ** Sexual selection in humans, in human sexuality ** Human mating strateg ...

by making offspring genetically unique. Sexual species are able to improve their genotype in changing conditions. Consequently, co-evolutionary interactions, between host and parasite, for example, may select for sexual reproduction in hosts in order to reduce the risk of infection. Oscillations in

genotype frequencies Genetic variation in populations can be analyzed and quantified by the frequency of alleles. Two fundamental calculations are central to population genetics: allele frequencies and genotype frequencies. Genotype frequency in a population is the n ...

are observed between parasites and hosts in an antagonistic coevolutionary way without necessitating changes to the phenotype. In multi-host and multi-parasite coevolution, the Red Queen dynamics could affect what host and parasite types will become dominant or rare. Science writer

Matt Ridley Matthew White Ridley, 5th Viscount Ridley, (born 7 February 1958), is a British science writer, journalist and businessman. He is known for his writings on science, the environment, and economics and has been a regular contributor to ''Th ...

popularized the term in connection with

sexual selection Sexual selection is a mode of natural selection in which members of one biological sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of t ...

in his 1993 book '' The Red Queen'', in which he discussed the debate in theoretical biology over the adaptive benefit of

to those species in which it appears. The connection of the Red Queen to this debate arises from the fact that the traditionally accepted Vicar of Bray hypothesis only showed adaptive benefit at the level of the species or group, not at the level of the

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

(although the protean "Vicar of Bray" adaptation is very useful to some species that belong to the lower levels of the

food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...

). By contrast, a Red-Queen-type thesis suggesting that organisms are running arms races with their

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s can explain the utility of sexual reproduction at the level of the gene by positing that the role of sex is to preserve genes that are currently disadvantageous, but that will become advantageous against the background of a likely future population of parasites. Further evidence of the Red Queen hypothesis was observed in allelic effects under sexual selection. The Red Queen hypothesis leads to the understanding that allelic recombination is advantageous for populations that engage in aggressive biotic interactions, such as predator-prey or parasite-host interactions. In cases of parasite-host relations, sexual reproduction can quicken the production of new multi-locus genotypes allowing the host to escape parasites that have adapted to the prior generations of typical hosts. Mutational effects can be represented by models to describe how recombination through sexual reproduction can be advantageous. According to the mutational deterministic hypothesis, if the deleterious mutation rate is high, and if those mutations interact to cause a general decline in organismal fitness, then sexual reproduction provides an advantage over asexually reproducing organisms by allowing populations to eliminate the deleterious mutations not only more rapidly, but also most effectively. Recombination is one of the fundamental means that explain why many organisms have evolved to reproduce sexually. Sexual organisms must spend resources to find mates. In the case of

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, usually one of the sexes contributes more to the survival of their offspring (usually the mother). In such cases, the only adaptive benefit of having a second sex is the possibility of

, by which organisms can improve their genotype. Evidence for this explanation for the evolution of sex is provided by the comparison of the rate of

molecular evolution Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics ...

of genes for kinases and

immunoglobulin An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

s in the

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

with genes coding other

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s. The genes coding for immune system proteins evolve considerably faster. Further evidence for the Red Queen hypothesis was provided by observing long-term dynamics and parasite coevolution in a mixed sexual and asexual population of snails (''

Potamopyrgus antipodarum The New Zealand mud snail (''Potamopyrgus antipodarum'') is a species of very small freshwater snail with a gill and an operculum. This aquatic gastropod mollusk is in the family Tateidae. It is native to New Zealand, where it is found throug ...

''). The number of sexuals, the number of asexuals, and the rates of parasitic infection for both were monitored. It was found that clones that were plentiful at the beginning of the study became more susceptible to parasites over time. As parasite infections increased, the once-plentiful clones dwindled dramatically in number. Some clonal types disappeared entirely. Meanwhile, sexual snail populations remained much more stable over time. In 2011, researchers used the microscopic roundworm '' Caenorhabditis elegans'' as a host and the pathogenic bacterium ''

Serratia marcescens ''Serratia marcescens'' () is a species of rod-shaped, Gram-negative bacteria in the family Yersiniaceae. It is a facultative anaerobe and an opportunistic pathogen in humans. It was discovered in 1819 by Bartolomeo Bizio in Padua, Italy.Serra ...

'' to generate a host–parasite coevolutionary system in a controlled environment, allowing them to conduct more than 70 evolution experiments testing the Red Queen hypothesis. They genetically manipulated the mating system of ''C. elegans'', causing populations to mate either sexually, by self-fertilization, or a mixture of both within the same population. Then they exposed those populations to the ''S. marcescens'' parasite. It was found that the self-fertilizing populations of ''C. elegans'' were rapidly driven extinct by the coevolving parasites, while sex allowed populations to keep pace with their parasites, a result consistent with the Red Queen hypothesis. Currently, there is no consensus among biologists on the main selective forces maintaining sex. The competing models to explain the adaptive function of sex have been reviewed by Birdsell and Wills.

Evolution of aging

Red Queen hypothesis in predator-prey model

The Red Queen hypothesis has been invoked by some authors to explain evolution of aging. The main idea is that aging is favored by natural selection since it allows faster adaptation to changing conditions, especially in order to keep pace with the evolution of pathogens, predators and prey.

Interspecies race

A number of predator/prey species couple compete via running speed. "The rabbit runs faster than the fox, because the rabbit is running for his life while the fox is only running for his dinner."

Aesop Aesop ( or ; , ; c. 620–564 BCE) was a Greek fabulist and storyteller credited with a number of fables now collectively known as ''Aesop's Fables''. Although his existence remains unclear and no writings by him survive, numerous tales cre ...

The predator-prey relationship can also be established in the microbial world, producing the same evolutionary phenomenon that occurs in the case of foxes and rabbits. A recently observed example has as protagonists '' M.xanthus'' (predator) and ''

E.coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Esche ...

'' (prey) in which a parallel evolution of both species can be observed through genomic and phenotypic modifications, producing in future generations a better adaptation of one of the species that is counteracted by the evolution of the other, thus generating an arms race that can only be stopped by the extinction of one of the species. The interactions between parasitoid wasps and insect larvae, necessary for the parasitic wasp's life cycle, are also a good illustration of a race. Evolutionary strategy was found by both partners to respond to the pressure generated by the mutual association of lineages. For example, the

parasitoid wasp Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causin ...

group, ''Campoletis sonorensis'', is able to fight against the immune system of its hosts, ''

Heliothis virescens ''Chloridea virescens'', commonly known as the tobacco budworm, is a moth of the family Noctuidae found throughout the eastern and southwestern United States along with parts of Central America and South America. It is a major pest of field cro ...

'' (

Lepidopteran Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described specie ...

) with the association of a

polydnavirus A polydnavirus (PDV) is a member of the family ''Polydnaviridae'' of insect viruses. There are two genera in the family: '' Bracovirus'' and '' Ichnovirus''. Polydnaviruses form a symbiotic relationship with parasitoid wasps; ( ichnoviruses ( ...

(PDV) (''Campoletis sonorensis'' PDV). During the oviposition process, the parasitoid transmits the virus (''Cs''PDV) to the insect larva. The ''Cs''PDV will alter the physiology, growth and development of the infected insect larvae to the benefit of the parasitoid.

Competing evolutionary ideas

A competing evolutionary idea is the

court jester hypothesis The court jester hypothesis is used in reference to the idea that abiotic forces (including climate), rather than biotic competition between species, function as a major driving force behind the processes in evolution which produce speciation. ...

, which indicates that an arms race is not the driving force of evolution on a large scale, but rather it is abiotic factors. The

Black Queen hypothesis The Black Queen hypothesis (BQH) is reductive evolution theory which seeks to explain how natural selection (as opposed to genetic drift) can drive gene loss. In a microbial community, different members may have genes which produce certain chemic ...

is a theory of reductive evolution that suggests natural selection can drive organisms to reduce their genome size. In other words, a gene that confers a vital biological function can become dispensable for an individual organism if its community members express that gene in a "leaky" fashion. Like the Red Queen hypothesis, the Black Queen hypothesis is a theory of co-evolution.

Trivia

Van Valen originally submitted his article to the ''

Journal of Theoretical Biology The ''Journal of Theoretical Biology'' is a biweekly peer-reviewed scientific journal covering theoretical biology, as well as mathematical, computational, and statistical aspects of biology. Some research areas covered by the journal include cell ...

'', where it was accepted for publication. However, because "the manner of processing depended on payment of page charges", Van Valen withdrew his manuscript and founded a new Journal called ''

Evolutionary Theory Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

'', in which he published his manuscript as the first paper. Van Valen's acknowledgement to the

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...

ran: "I thank the National Science Foundation for regularly rejecting my (honest) grant applications for work on real organisms, thus forcing me into theoretical work".