Sexual selection

sexually selectedmale-male competitionintrasexual selectionsexual competitionintrasexual competitionintrasexualselectedMale–male competitionMate choicepotential mates
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection).wikipedia
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Natural selection

selectionselectiveselected
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection).
Other factors affecting reproductive success include sexual selection (now often included in natural selection) and fecundity selection.

Sexual selection in amphibians

male advertisement callcalladvertisement call
For instance, in the breeding season, sexual selection in frogs occurs with the males first gathering at the water's edge and making their mating calls: croaking.
Sexual selection in amphibians involves sexual selection processes in amphibians, including frogs, salamanders and newts.

Sex

biological sexsexesanatomical sex
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection).
For instance, mate choice and sexual selection can accelerate the evolution of physical differences between the sexes.

Sexual dimorphism

sexually dimorphicdimorphicdimorphism
Sexual selection can lead males to extreme efforts to demonstrate their fitness to be chosen by females, producing sexual dimorphism in secondary sexual characteristics, such as the ornate plumage of birds such as birds of paradise and peafowl, or the antlers of deer, or the manes of lions, caused by a positive feedback mechanism known as a Fisherian runaway, where the passing-on of the desire for a trait in one sex is as important as having the trait in the other sex in producing the runaway effect.
These differences may be subtle or exaggerated, and may be subjected to sexual selection.

Charles Darwin

DarwinDarwinianCharles Robert Darwin
The concept was first articulated by Charles Darwin and Alfred Russel Wallace who described it as driving species adaptations and that many organisms had evolved features whose function was deleterious to their individual survival, and then developed by Ronald Fisher in the early 20th century.
In 1871 he examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals (1872).

Ronald Fisher

R.A. FisherR. A. FisherFisher
The concept was first articulated by Charles Darwin and Alfred Russel Wallace who described it as driving species adaptations and that many organisms had evolved features whose function was deleterious to their individual survival, and then developed by Ronald Fisher in the early 20th century. Ronald Fisher, the English statistician and evolutionary biologist developed a number of ideas about sexual selection in his 1930 book The Genetical Theory of Natural Selection including the sexy son hypothesis and Fisher's principle.
He outlined Fisher's principle, the Fisherian runaway and sexy son hypothesis theories of sexual selection.

Fisherian runaway

runaway evolutionrunaway selectionFisher's runaway model
Sexual selection can lead males to extreme efforts to demonstrate their fitness to be chosen by females, producing sexual dimorphism in secondary sexual characteristics, such as the ornate plumage of birds such as birds of paradise and peafowl, or the antlers of deer, or the manes of lions, caused by a positive feedback mechanism known as a Fisherian runaway, where the passing-on of the desire for a trait in one sex is as important as having the trait in the other sex in producing the runaway effect.
Fisherian runaway or runaway selection is a sexual selection mechanism proposed by the mathematical biologist Ronald Fisher in the early 20th century, to account for the evolution of exaggerated male ornamentation by persistent, directional female choice.

Sexy son hypothesis

good genesgood genes hypothesisgood genes theory
Although the sexy son hypothesis indicates that females would prefer male offspring, Fisher's principle explains why the sex ratio is 1:1 almost without exception. Ronald Fisher, the English statistician and evolutionary biologist developed a number of ideas about sexual selection in his 1930 book The Genetical Theory of Natural Selection including the sexy son hypothesis and Fisher's principle.
The sexy son hypothesis in evolutionary biology and sexual selection—proposed by Ronald Fisher in 1930—states that a female's ideal mate choice among potential mates is one whose genes will produce male offspring with the best chance of reproductive success.

The Descent of Man, and Selection in Relation to Sex

The Descent of ManDescent of ManThe Descent of Man and Selection in Relation to Sex
Sexual selection was first proposed by Charles Darwin in The Origin of Species (1859) and developed in The Descent of Man and Selection in Relation to Sex (1871), as he felt that natural selection alone was unable to account for certain types of non-survival adaptations.
The Descent of Man, and Selection in Relation to Sex is a book by English naturalist Charles Darwin, first published in 1871, which applies evolutionary theory to human evolution, and details his theory of sexual selection, a form of biological adaptation distinct from, yet interconnected with, natural selection.

Alfred Russel Wallace

WallaceAlfred WallaceA. R. Wallace
The concept was first articulated by Charles Darwin and Alfred Russel Wallace who described it as driving species adaptations and that many organisms had evolved features whose function was deleterious to their individual survival, and then developed by Ronald Fisher in the early 20th century.
He also corresponded with Darwin about a variety of topics, including sexual selection, warning colouration, and the possible effect of natural selection on hybridisation and the divergence of species.

Reproductive success

passing ofreproductive assurancereproductive outcomes
These two forms of selection mean that some individuals have better reproductive success than others within a population, either because they are more attractive or prefer more attractive partners to produce offspring.
This includes mate choice and sexual selection as an important factor in reproductive success, which is another reason why reproductive success is different from fitness as individual choices and outcomes are more important than genetic differences.

Deer

Cervidaestagfawn
Sexual selection can lead males to extreme efforts to demonstrate their fitness to be chosen by females, producing sexual dimorphism in secondary sexual characteristics, such as the ornate plumage of birds such as birds of paradise and peafowl, or the antlers of deer, or the manes of lions, caused by a positive feedback mechanism known as a Fisherian runaway, where the passing-on of the desire for a trait in one sex is as important as having the trait in the other sex in producing the runaway effect.
Antlers might be one of the most exaggerated male secondary sexual characteristics, and are intended primarily for reproductive success through sexual selection and for combat.

Camouflage

cryptic colorationcamouflagedcamouflaging
He argued that male-male competitions were forms of natural selection, but that the "drab" peahen's coloration is itself adaptive as camouflage.
However, he overstated the case in the 1909 book Concealing-Coloration in the Animal Kingdom, arguing that "All patterns and colors whatsoever of all animals that ever preyed or are preyed on are under certain normal circumstances obliterative" (that is, cryptic camouflage), and that "Not one 'mimicry' mark, not one 'warning color'... nor any 'sexually selected' color, exists anywhere in the world where there is not every reason to believe it the very best conceivable device for the concealment of its wearer", and using paintings such as Peacock in the Woods (1907) to reinforce his argument.

Assortative mating

disassortative matingassortive matingmate assortatively
Sexual preference creates a tendency towards assortative mating or homogamy.
Assortative mating (also referred to as positive assortative mating or homogamy) is a mating pattern and a form of sexual selection.

Evolutionary biology

evolutionary biologistevolutionary biologistsevolutionary
Ronald Fisher, the English statistician and evolutionary biologist developed a number of ideas about sexual selection in his 1930 book The Genetical Theory of Natural Selection including the sexy son hypothesis and Fisher's principle.
The investigational range of current research widened to encompass the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution, such as sexual selection, genetic drift, and biogeography.

Bateman's principle

The conditions determining which sex becomes the more limited resource in intersexual selection have been hypothesized with Bateman's principle, which states that the sex which invests the most in producing offspring becomes a limiting resource for which the other sex competes, illustrated by the greater nutritional investment of an egg in a zygote, and the limited capacity of females to reproduce; for example, in humans, a woman can only give birth every ten months, whereas a male can become a father numerous times in the same period.
Although Bateman's principle served as a cornerstone for the study of sexual selection for many decades, it has recently been subject to criticism.

Handicap principle

costly signalhandicap Costly-signaling theory
The handicap principle of Amotz Zahavi, Russell Lande and W. D. Hamilton, holds that the fact that the male is able to survive until and through the age of reproduction with such a seemingly maladaptive trait is taken by the female to be a testament to his overall fitness.
For example, in the case of sexual selection, the theory suggests that animals of greater biological fitness signal this status through handicapping behaviour or morphology that effectively lowers this quality.

Fisher's principle

Fisher's theoryFisher's prediction of a 1:1 male to female sex ratioFisher's theory of sex ratio selection
Although the sexy son hypothesis indicates that females would prefer male offspring, Fisher's principle explains why the sex ratio is 1:1 almost without exception. Ronald Fisher, the English statistician and evolutionary biologist developed a number of ideas about sexual selection in his 1930 book The Genetical Theory of Natural Selection including the sexy son hypothesis and Fisher's principle.
In Chapter 6 "Sexual Reproduction and Sexual Selection", Fisher wrote under the heading "Natural Selection and the sex-ratio" (page 141) the explanation described by Eric Charnov and James J. Bull as being "characteristically terse" and "cryptic":

On the Origin of Species

The Origin of SpeciesOrigin of SpeciesOn the Origin of Species by Means of Natural Selection
Sexual selection was first proposed by Charles Darwin in The Origin of Species (1859) and developed in The Descent of Man and Selection in Relation to Sex (1871), as he felt that natural selection alone was unable to account for certain types of non-survival adaptations.
Darwin proposes sexual selection, driven by competition between males for mates, to explain sexually dimorphic features such as lion manes, deer antlers, peacock tails, bird songs, and the bright plumage of some male birds.

Bird

birdsAvesavian
Sexual selection can lead males to extreme efforts to demonstrate their fitness to be chosen by females, producing sexual dimorphism in secondary sexual characteristics, such as the ornate plumage of birds such as birds of paradise and peafowl, or the antlers of deer, or the manes of lions, caused by a positive feedback mechanism known as a Fisherian runaway, where the passing-on of the desire for a trait in one sex is as important as having the trait in the other sex in producing the runaway effect.
Birds have evolved a variety of mating behaviours, with the peacock tail being perhaps the most famous example of sexual selection and the Fisherian runaway.

Secondary sex characteristic

secondary sexual characteristicsecondary sex characteristicssecondary sexual characteristics
Sexual selection can lead males to extreme efforts to demonstrate their fitness to be chosen by females, producing sexual dimorphism in secondary sexual characteristics, such as the ornate plumage of birds such as birds of paradise and peafowl, or the antlers of deer, or the manes of lions, caused by a positive feedback mechanism known as a Fisherian runaway, where the passing-on of the desire for a trait in one sex is as important as having the trait in the other sex in producing the runaway effect.
Secondary sex characteristics are believed to be the product of sexual selection for traits which display fitness, giving an organism an advantage over its rivals in courtship and in aggressive interactions.

The Genetical Theory of Natural Selection

Ronald Fisher, the English statistician and evolutionary biologist developed a number of ideas about sexual selection in his 1930 book The Genetical Theory of Natural Selection including the sexy son hypothesis and Fisher's principle.
Using his knowledge of statistics, the Fisherian runaway, which explores how sexual selection can lead to a positive feedback runaway loop, producing features such as the peacock's plumage.

Sexual conflict

conflict between the sexessexually antagonisticconflict
Focusing on the effect of sexual conflict, as hypothesized by William Rice, Locke Rowe and Göran Arnvist, Thierry Lodé argues that divergence of interest constitutes a key for evolutionary process.
Some regard sexual conflict as a subset of sexual selection (which was traditionally regarded as mutualistic), while others suggest it is a separate evolutionary phenomenon.

Russell Lande

LandeRussell S. LandeRussell Scott Lande
The handicap principle of Amotz Zahavi, Russell Lande and W. D. Hamilton, holds that the fact that the male is able to survive until and through the age of reproduction with such a seemingly maladaptive trait is taken by the female to be a testament to his overall fitness.
He later applied and extended these results to study a wide variety of topics in evolutionary biology, including: sexual selection, speciation, the evolution of phenotypic plasticity, of self-fertilization, of life history, of a species range in space and time.

Marlene Zuk

In 1984, Hamilton and Marlene Zuk introduced the "Bright Male" hypothesis, suggesting that male elaborations might serve as a marker of health, by exaggerating the effects of disease and deficiency.
In 1982, she and W. D. Hamilton proposed the "good genes" hypothesis of sexual selection.