Scientists have not yet sorted out the underlying evolutionary forces that lead to the presence of dominance hierarchies in so many eusocial species; division of labor, competition for production of males, and suppression of production of both males and females are the leading hypotheses. which can be easily rearranged to produce Hamilton’s rule: Put into words, the relatedness of the individual that profits from the altruistic act of the focal individual must be higher than the C/B ratio this act imposes. In social insects, such as wasps and bees, workers remove eggs laid by other workers, because they are more related to the queen’s eggs than to the worker-laid eggs. The Elusive Calculus of Insects’ Altruism and Kin Selection How the ultra-cooperative behavior of ants, bees and other social insects could have evolved continues to challenge formal analysis. Scientists have not yet sorted out the underlying evolutionary forces that lead to the presence of dominance hierarchies in so many eusocial species; division of labor, competition for production of males, and suppression of production of both males and females are the leading hypotheses. A very simple example will explain the concept. Kin selection is believed to be the mechanism behind the evolution of eusociality. It is often analyzed with Hamilton’s inclusive-fitness rule. Canto: The term ‘kin selection’ was first used by John Maynard Smith in the early sixties but it was first mooted by Darwin (who got it right about honey bees), and its mathematics were worked out back in the 1930s. In 2010, however, biologist E.O. Altruism is a genetic trait, which may or may not be expressed by the individuals that carry it. Kin selection may be used to explain the evolution of human societies as well as the social structures in insects such ants, wasps, bees and termites. Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. But how can it be, if only the queen bee is having babies? Kin selection works not on individuals but on genotypes. The answer comes from mathematical population genetic models, but the idea is easy to understand. Maybe that's because it's nature's perfect system for quelling worker revolt. Queen bees are the sole egg laying females in In other words, kin selection theory predicts when individuals should behave altruistically and also when they should curtail their selfishness. Whilst these results could all fit with contemporary kin selection theory, some doubt has been cast on this (Dunny et al., 2008). Therefore, the delayed, contingent response required for both reciprocity and punishment necessitates that individuals can distinguish different partners. As with group selection, it is a consequence of the properties of groups that cause allele frequency change. When this happens, mothers produce a female-biased offspring sex ratio, to reduce this competition between brothers. The two kinds of estimates can diverge if pedigrees are taken back too far. "One researcher even risked great danger to get a honeybee in Syria," Zayed said. In the simplest example, an offspring gets half its genes directly from its mother and is therefore related by 1/2 to her. aeruginosa and its production of iron-scavenging siderophores. For selection to increase the frequency of an allele, that allele has to do better than the average allele in the population. [1] Kin altruism can look like altruistic behaviour whose evolution is driven by kin selection. Of course, there is usually some additional total identity between offspring and mother; for example, an offspring allele derived from the father might also, by chance, be identical to one in the mother. Therefore, any particular trait – depending on its mode of inheritance – is often transmitted from a parent to its offspring with a probability smaller than 1. But the queen doesn't need to adapt as much, because her environment is always stable. Julian Wimpenny, in Advances in Microbial Physiology, 2009. Every so often, a honeybee queen leaves the hive where she was born to found a new colony. According to Queller (2006) kin selection is defined by how a "gene can produce copies of itself by increasing the fitness of its bearer (direct fitness) or by increasing the fitness of its relatives who share copies of the gene (indirect fitness)" (p.165). It's hard not to ponder the implications of those queens with their static, unchanging behavior inside the hive. This model challenges stereotypic assumptions that complex societies require a central directing figure for efficient functioning. William Donald Hamilton (1936–2000) discovered the principle of ‘kin selection’, which seemed for a long while to answer this question. Inclusive fitness and direct fitness lead to correct predictions about the direction of evolution under kin selection but obscure the true causal story, which in both cases is, at least in part, group selection. Though humans are very different from social insects, there is still something poignant in the lifecycles of honeybees for us city-dwelling Homo sapiens. The existence of dominance hierarchies in a broad range of primitively eusocial species (or, in the case of the naked mole-rat, a highly eusocial species) suggests that reproductive suppression may not be an entirely voluntary act on the part of the workers. She's fed and groomed by workers. Thus, group selection appears not to be yet strong enough to counteract dissolutive kin selection. That is, if the benefits (b) conferred on kin, weighted by the relatedness (r) of the donor to the recipient, is greater than the cost (c) conferred on the donor, then such an action is favored by natural selection (this also puts Haldane’s quip on firm theoretical ground). After all, the queen is either mother or sister to every bee in her colony. In order for C/B to become smaller than r = 0.5, the altruist’s act must at least double the receiver’s fitness in order for the altruist to gain representation in the next generation. I'm trying to understand what problem led to a development of kin selection. However, it can also explain selfish behaviors and is important for understanding conflicts between individuals. David C. Queller, in Encyclopedia of Animal Behavior (Second Edition), 2019. Both of these methods measure relatedness across the genome, whereas what really matters in the models of kin selection is relatedness at a locus that affects the behavior. At that time, it was so innovative that it almost failed to be published and was largely ignored for a decade. It was suggested that survival might depend on the proximity of kin and that, at high concentrations of closely located kin, the latter would out-compete cheaters. Likewise, these cousins are related to their common grandparents by r = 0.25 or r = 1/4. Microsatellites are short tandem repeats of DNA, such as the doublet CA repeated nine times in succession. These two methods, statistical and pedigree, generally give the same answers, although statistical estimates based on molecular markers include some sampling variance. We use cookies to help provide and enhance our service and tailor content and ads. Darwin’s ‘struggle for existence’ is a struggle for reproduction. And they deal with changes in the environment with changes in worker behavior. Kin Selection is what I always invoke if someone hits me with one of those stupid "gay people are useless because evolution" speeches. A range of more subtle possibilities arise whenever there is the potential for cooperation or conflict between relatives. As noted in eqn [1], w should be composed of the fitness a of the focal individual and the contribution x of its relatives: The contribution x to individual i’s inclusive fitness w is then the sum of all alleles in the gene pool that are shared by i and its relatives j: where r is the coefficient of relatedness between individual i and its relative j, and b is the fitness of j. Unlike kin selection, however, where altruistic acts are disseminated simply as a function of coefficients of genetic relatedness, reciprocity and punishment require targeting specific individuals. Thus, fitness denotes the capability of an allele to spread in a population: if the fitness value for a given allele is greater than 1, it will increase in frequency; and if it is smaller than 1, it will decrease in frequency. An ordinary diploid, sexually produced organism shares 50% of its genes with either of its parents. As the term "kin selection" suggests, a sterile bee is still helping natural selection along, even if it's only by making it easier for her queen to lay eggs. Although mathematically it is possible – and even sometimes heuristically invaluable – to make all fitness variation under kin selection a property of genes or of individuals, this obscures the true causal forces that bring about gene-frequency change under kin selection. Relatedness to a maternal half sibling is 1/4, the average of 1/2 for genes identical by descent through the mother, and 0 for genes identical by descent through the father. Using kin selection theory, David Haig, professor, Harvard University, developed models predicting intragenomic conflict, which Queller then extended to social insect societies. The co-operative behaviour of social insects like the honey bee can be explained by kin selection.. Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Zayed pointed out that the famously aggressive behavior of African honeybees is a direct result of adapting to an environment full of predators like the honey badger who attack hives. As with group selection, it is a consequence of the properties of groups that cause allele frequency change. If a worker has a mutation that makes it better at finding food in a new region, evolutionary reason would predict that mutation ought to be passed along to the next generation of workers. “In 2003, David Queller published a key model using kin selection theory that predicted that under queenless conditions in a honey bee colony, the patrigenes would promote selfish behavior in the workers, while the matrigenes would promote altruistic behavior,” Galbraith said. But how do you pass on those good mutations in honeybee colonies, where most bees are sterile workers who never have babies? Whats kin selection: sterile castes and eusociality • Eusocial species have a division of reproductive labour based on castes, some of which are sterile • Hymenopteran insects (bees, wasps, ants) In many insects, related males (brothers) compete with each other for mates (often their sisters), before these females disperse to lay eggs elsewhere. In other parts of the world, such as Yemen, bees have adapted to be excellent at air conditioning their hives in the hot desert air. In some highly eusocial insects, there is a distinct possibility that queens engage in chemical suppression of the workers in the colony. If the relatedness between the parasites infecting a host is high, they are expected to prudently exploit that host, causing less damage and mortality (virulence). She's in this benign environment, afforded by the actions of workers who collect food and nurse the brood and thermo-regulate the hive. Kin selection is based on 'inclusive fitness', the idea that, for example, sterile workers can accrue reproductive benefits by helping their relatives. Kin selection works because relatives share genes. B. Brembs, in Brenner's Encyclopedia of Genetics (Second Edition), 2013. Kin selection is a way of understanding allele frequency change as a consequence of the actions and interactions among individuals who share alleles by recent common descent – ie, kin. Usually, the occurrence of sterile in social insects such as honey bees is an example of kin selection. Processes encouraging kin selection, if it turns out to be a real phenomenon, include population viscosity which enables organisms to stay physically close and not to disperse. This might constitute a difficult task, however, since all its competitors try to do the same. Its key insight is that individuals will evolve to act as if they value effects on their interactants’ fitnesses proportional to the degree of genetic relatedness between them, relatedness being the degree of allele sharing above random expectation. A mystery in ant behavioral biology is the question of how the queen’s reproductive dominance is maintained in the colony. According to theory, high relatedness favored kin selection and ought to reduce the incidence of cheating genotypes developing whilst the converse is true where relatedness is low. Inbreeding will alter these coefficients by providing additional paths for nonrandom identity by descent. The example of siderophore production and the development of cheaters raises problems concerning the survival of the non-cheating organism. Hamilton’s theory was published in the Journal of Theoretical Biology in 1964. Behavioral dominance should be obvious and, if it were present, it probably already would have been discovered. Kin selection, a type of natural selection that considers the role relatives play when evaluating the genetic fitness of a given individual. We can thus reformulate eqn [2] as, Obviously, if the allele in question infers a fitness cost (i.e., ai < 1), wi will be greater than 1 only if r is sufficiently high (given that the higher fitness b of the relative also means higher cost). Honeybees using their wings to fan the hive and keep it cool. Figure 38-20 Haplodiploidy in honey bees, showing degrees of relatedness of a female worker bee (labeled SELF) to individuals she might raise. J.R. Stevens, M.D. D.C. Queller, in Encyclopedia of Animal Behavior, 2010. More complicated cases can be calculated by pedigree diagrams and tracing all the connections between classes of relatives. Or, intriguingly, perhaps worker function has evolved so that workers perform their tasks quite independently of any knowledge of the presence of the queen. Thus, kin selection and inclusive fitness may be able to explain many altruistic behaviors that have perplexed biologists for many years. And he said it makes perfect sense, considering that workers are the front line when it comes to the colony's survival in the environment. Thus, through Hamilton's theory of kin selection… Photo of a perfect worker bee, with nectar in her belly and pollen on her legs, by Alex Wild. Through their behavior they bear brunt of changes in environment. After an intensive analysis, the team discovered that there are certain regions of the honeybee genome that are undergoing rapid positive selection. Thus, in order to transmit as many of one’s genes into the next generation as possible (and hence be evolutionarily successful), an organism has to produce as many surviving offspring as possible in order to maximize the probability of transmitting all its genetic information. Kin altruism can look like altruistic behaviour whose evolution is driven by kin selection. Reformulating eqn [4] into a cost/benefit (C/B) relation, describing the necessity of wi being greater than 1 if the allele of interest is to spread, yields. When finally noticed, its influence spread exponentially until it became one of the most cited papers in all of biology. Hamilton introduced a method of accounting for kin selection called inclusive fitness that assigned all of the fitness effects of an allele to the individual bearer of that allele. Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Save big on laptops, tablets, outdoor furnishings, everyday household items, and more! For example, unrelated individuals will sometimes have negative estimates.
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