Editing Behavioral ecology (section)

==Social behaviors==
Animals [[cooperate]] with each other to increase their own [[Fitness (biology)|fitness]].<ref name="Davies_SocialBehavior" /> These altruistic, and sometimes spiteful behaviors can be explained by [[Hamilton's rule]], which states that ''rB-C > 0'' where ''r''= relatedness, ''B''= benefits, and ''C''= costs.<ref name=hamilton>{{cite journal|last=Bergstrom |first=Theodore|title=Evolution of Social Behavior: Individual and Group Selection |journal=The Journal of Economic Perspectives|date=Spring 2002 |volume=16 |issue=2 |doi=10.1257/0895330027265 |jstor=2696497 |pages=67–88|citeseerx=10.1.1.377.5059|s2cid=125841 }}</ref>

===Kin selection===
{{Main|Kin selection}}

Kin selection refers to evolutionary strategies where an individual acts to favor the [[reproductive success]] of relatives, or [[Kinship|kin]], even if the action incurs some cost to the organism's own survival and ability to [[procreate]].<ref name="Davies_SocialBehavior">{{cite book|last1=Davies |last2=Krebs |last3=West |first1=Nicholas B.|first2= John R. |first3=Stuart A.|title=An Introduction to Behavioral Ecology|year=2012|publisher=Wiley-Blackwell|location=West Sussex, UK|isbn=978-1-4051-1416-5|pages=307–333}}</ref> [[John Maynard Smith]] coined the term in 1964,<ref>{{cite journal |last=Smith |first=J. M. |year=1964 |title=Group Selection and Kin Selection |journal=Nature |volume=201 |issue=4924 |pages=1145–1147 |doi=10.1038/2011145a0 |bibcode = 1964Natur.201.1145S |s2cid=4177102 }}</ref> although the concept was referred to by [[Charles Darwin]] who cited that helping relatives would be favored by [[group selection]]. Mathematical descriptions of kin selection were initially offered by [[R. A. Fisher]] in 1930<ref>{{cite book |title=The Genetical Theory of Natural Selection |last=Fisher |first=R. A. |year=1930 |publisher=Clarendon Press |location=Oxford |url=https://archive.org/details/in.ernet.dli.2015.221869}}</ref> and [[J. B. S. Haldane]] in 1932.<ref>{{cite book |title= The Causes of Evolution |last=Haldane |first=J.B.S. |year=1932 |publisher= Longmans, Green & Co |location= London |url=https://archive.org/details/causesofevolutio00hald_0}}</ref> and 1955.<ref>{{cite journal |last=Haldane |first=J. B. S. |year=1955 |title=Population Genetics |journal=New Biology |volume=18 |pages=34–51 }}</ref> [[W. D. Hamilton]] popularized the concept later, including the mathematical treatment by [[George R. Price|George Price]] in 1963 and 1964.<ref name=Ham63>{{cite journal |last=Hamilton |first=W. D. |year=1963 |title=The evolution of altruistic behavior |journal=[[American Naturalist]] |volume=97 |issue= 896|pages=354–356 |doi=10.1086/497114 |s2cid=84216415 }}</ref><ref name=Ham64>{{cite journal |last=Hamilton |first=W. D. |year=1964 |title=The Genetical Evolution of Social Behavior |journal=Journal of Theoretical Biology |volume=7 |issue=1 |pages=1–16 |doi=10.1016/0022-5193(64)90038-4 |pmid=5875341|title-link=The Genetical Evolution of Social Behavior |bibcode=1964JThBi...7....1H |s2cid=5310280 }}</ref>

Kin selection predicts that individuals will harbor personal costs in favor of one or multiple individuals because this can maximize their genetic contribution to future generations. For example, an organism may be inclined to expend great time and energy in [[parental investment]] to [[Parenting|rear]] [[offspring]] since this future generation may be better suited for propagating genes that are highly shared between the parent and offspring.<ref name="Davies_SocialBehavior"/> Ultimately, the initial actor performs apparent [[altruistic]] actions for kin to enhance its own reproductive [[Fitness (biology)|fitness]]. In particular, organisms are hypothesized to act in favor of kin depending on their genetic [[Coefficient of relationship|relatedness]].<ref name=Ham63 /><ref name=Ham64 /> So, individuals are inclined to act altruistically for siblings, grandparents, cousins, and other relatives, but to differing degrees.<ref name="Davies_SocialBehavior"/>

====Inclusive fitness====
[[Inclusive fitness]] describes the component of reproductive success in both a focal individual and their relatives.<ref name="Davies_SocialBehavior"/> Importantly, the measure embodies the sum of direct and indirect fitness and the change in their reproductive success based on the actor's behavior.<ref name=West_etal2007b>{{cite journal |last1=West |last2=Griffin |last3=Gardner|first1=S.A. |first2=A.S. |first3=A.|title=Social semantics: altruism, cooperation, mutualism, strong reciprocity and group selection|journal=Journal of Evolutionary Biology |year=2007b|volume=20|issue=2|pages=415–432|doi=10.1111/j.1420-9101.2006.01258.x |pmid=17305808|s2cid=1792464 |doi-access=free}}</ref> That is, the effect an individual's behaviors have on: being personally better-suited to reproduce offspring, and aiding descendant and non-descendant relatives in their reproductive efforts.<ref name="Davies_SocialBehavior"/> [[Natural selection]] is predicted to push individuals to behave in ways that maximize their inclusive fitness. Studying inclusive fitness is often done using predictions from Hamilton's rule.

===Kin recognition===
{{Main|Kin recognition}}

====Genetic cues====
One possible method of kin selection is based on genetic cues that can be recognized phenotypically.<ref>{{cite journal |last1=Holmes |first1=Warren G. |last2=Sherman |first2=Paul W. |title=Kin recognition in animals |journal=American Scientist |date=January 1983 |volume=71 |issue=1 |page=46-55 |url=https://www.jstor.org/stable/27851817}}</ref> Genetic recognition has been exemplified in a species that is usually not thought of as a social creature: [[amoebae]]. Social amoebae form fruiting bodies when starved for food. These amoebae preferentially formed slugs and fruiting bodies with members of their own lineage, which is clonally related.<ref name=Mehdiabadi>{{cite journal |author=Mehdiabadi, N. J. |author2=C. N. Jack |author3=T. T. Farnham |title=Kin preference in a social microbe|journal=Nature |year=2006 |volume=442 |pages=881–882 |doi=10.1038/442881a |pmid=16929288 |issue=7105 |bibcode = 2006Natur.442..881M |s2cid=4335666|display-authors=etal}}</ref> The genetic cue comes from variable lag genes, which are involved in signaling and adhesion between cells.<ref name=Benabentos>{{cite journal |author=Benabentos, R. |author2=S. Hirose |author3=R. Sucgang |title=Polymorphic members of the ''lag''-gene family mediate kin discrimination in ''Dictyostelium'' |journal=Current Biology |year=2009| volume=19 |pages=567–572 |doi=10.1016/j.cub.2009.02.037 |pmid=19285397 |issue=7 |pmc=2694408 |display-authors=etal}}</ref>

Kin can also be recognized a genetically determined odor, as studied in the primitively social sweat bee, ''[[Lasioglossum zephyrus]]''. These bees can even recognize relatives they have never met and roughly determine relatedness.<ref>{{Cite journal|title = Kin recognition in the sweat bee, ''Lasioglossum zephyrum'' |journal = Behavior Genetics|date = 1988-07-01|issn = 0001-8244|pages = 425–438|volume = 18|issue = 4|doi = 10.1007/BF01065512|pmid = 3190637|first = Les|last = Greenberg|s2cid = 44298800}}</ref> The Brazilian stingless bee ''[[Schwarziana quadripunctata]]'' uses a distinct combination of chemical [[hydrocarbon]]s to recognize and locate kin.  Each chemical odor, emitted from the organism's [[epicuticle]]s, is unique and varies according to age, sex, location, and hierarchical position.<ref name=nunes09>{{cite journal |last1=Nunes |first1=T. M. |last2=Turatti |first2=I. C. C.|last3=Mateus |first3=S. |last4=Nascimento |first4=F. S. |last5=Lopes |first5=N. P. |last6=Zucchi |first6=R. |year=2009|title=Cuticular hydrocarbons in the stingless bee ''Schwarziana quadripunctata'' (Hymenoptera, Apidae, Meliponini): Differences between colonies, castes and age |journal=Genetics and Molecular Research |volume=8 |issue=2 |pages=589–595 |doi=10.4238/vol8-2kerr012 |pmid=19551647|doi-access=free }}</ref> Similarly, individuals of the stingless bee species ''[[Trigona fulviventris]]'' can distinguish kin from non-kin through recognition of a number of compounds, including hydrocarbons and fatty acids that are present in their wax and floral oils from plants used to construct their nests.<ref>{{Cite journal|title = Nestmate recognition cues in a stingless bee, ''Trigona fulviventris'' |last1 = Buchwald|first1 = Robert|date = 2005 |journal = Animal Behaviour|doi = 10.1016/j.anbehav.2005.03.017|last2 = Breed|first2 = Michael D. |issue = 6 |volume = 70|pages = 1331–1337|s2cid = 53147658}}</ref> In the species, ''[[Osmia rufa]],'' kin selection has also been associated with mating selection. Females, specifically, select males for mating with whom they are genetically more related to.<ref>{{Cite journal|title = Open-cell parasitism shapes maternal investment patterns in the red mason bee ''Osmia rufa'' |journal = Behavioral Ecology|date = 2006-09-01|issn = 1045-2249 |pages = 839–848|volume = 17|issue = 5|doi = 10.1093/beheco/arl017|first = Karsten|last = Seidelmann|doi-access = free}}</ref>

Some animals recognize kin by "self-referencing:" comparing the phenotypes of others to themselves.  For example, Belding's ground squirrels recognize relatives by comparing their own odor and those of littermates with odors of squirrels they encounter.<ref name="Holmes">{{cite journal |last1=Holmes |first1=Warren G. |last2=Sherman |first2=Paul W. |title=The ontogeny of kin recognition in two species of ground squirrels |journal=American Zoologist |date=August 1982 |volume=22 |issue=3 |pages=491-517 |doi=10.1093/icb/22.3.491}}</ref> These phenotypes come in the form of scent from dorsal and anal glands, and each animal has its own repertoire of odors. If another individual's odor phenotype matches itself closely enough, it is likely a relative. Laboratory tests<ref name="Holmes" /> indicate that females can discriminate between kin and nonkin, close and distant relatives and, within-litters, between full-siblings and maternal half-siblings. Field observations<ref>{{cite book |last=Sherman |first=Paul W. |editor-last1=Barlow |editor-first1=George W. |editor-last2=Silverberg |editor-first2=James |editor-last3=Livingstone |editor-first3=Frank B. |title=Sociobiology:Beyond Nature/Nurture? |publisher=Westview Press |date=June 1980 |pages=505-544 |chapter=Chapter 20: The limits of ground squirrel nepotism |isbn=978-0891583721}}</ref><ref>{{cite journal |last1= Sherman |first1= P.W. |date= July 1981 |title= Kinship, demography, and Belding's ground squirrel nepotism |journal= Behavioral Ecology and Sociobiology |volume= 8 |issue= 4 |pages= 251–259 |doi= 10.1007/BF00299523|s2cid= 7935876 }}</ref> confirm that females cooperate with their closest kin more than with distant kin, and behave aggressively toward nonrelatives.<ref name="Holmes" /> Golden hamsters<ref>{{cite journal |last1=Mateo |first1=Jill M. |last2=Johnston |first2=Robert E. |title=Kin recognition and the "armpit effect": evidence of self-referent phenotype matching |journal=Proceedings of the Royal Society of London B |date=April 2000 |volume=267 |issue=1444 |page=695-700 |doi=10.1098/rspb.2000.1058|pmc=1690595 }}</ref> and bluegill sunfish<ref>{{cite journal |last1=Neff |first1=Bryan D. |last2=Sherman |first2=Paul W. |title=In vitro fertilization reveals offspring recognition via self-referencing in a fish with paternal care and cuckoldry |journal=Ethology |date=March 2005 |volume=111 |issue=4 |pages=425-438 |doi=10.1111/j.1439-0310.2005.01075.x}}</ref> also can use themselves as
referents to discriminate close relatives from distant kin and nonkin.

====Environmental cues====
There are two simple rules that many animals follow to determine who is kin.  These rules can be exploited, but exist because they are generally successful.

The first rule is 'treat anyone in my home as kin.'  This rule is readily seen in the [[reed warbler]], a bird species that only focuses on chicks in their own nest.  If its own kin is placed outside of the nest, a parent bird ignores that chick.  This rule can sometimes lead to odd results, especially if there is a parasitic bird that lays eggs in the reed warbler nest.  For example, an adult [[cuckoo]] may sneak its egg into the nest.  Once the cuckoo hatches, the reed warbler parent feeds the invading bird like its own child.  Even with the risk for exploitation, the rule generally proves successful.<ref name=Davies/><ref name="reedwarbler">{{cite journal |author1=Davies, N. B.  |author2=M. de L. Brooke  |name-list-style=amp|title=Cuckoos versus reed warblers: Adaptations and counteradaptations |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=36 |year=1988 |issue= 1|pages=262–284 |doi=10.1016/S0003-3472(88)80269-0|s2cid=53191651 }}</ref>

The second rule, named by [[Konrad Lorenz]] as 'imprinting,' states that those who you grow up with are kin.  Several species exhibit this behavior, including, but not limited to the [[Belding's ground squirrel]].<ref name=Davies/> Experimentation with these squirrels showed that regardless of true genetic relatedness, those that were reared together rarely fought. Further research suggests that there is partially some genetic recognition going on as well, as siblings that were raised apart were less aggressive toward one another compared to non-relatives reared apart.<ref name="squirrel">{{cite journal |author1=Holmes, W.G  |author2=P.W. Sherman  |name-list-style=amp|year=1982 |title=The ontogeny of kin recognition in two species of ground squirrels |journal=[[American Zoologist]] |volume=22 |issue=3  |pages=491–517 |doi=10.1093/icb/22.3.491|doi-access=free }}</ref>

Another way animals may recognize their kin include the interchange of unique signals.  While song singing is often considered a sexual trait between males and females, male–male song singing also occurs. For example, male vinegar flies ''[[Zaprionus tuberculatus]]'' can recognize each other by song.<ref>{{Cite journal|last1=Bennet-Clark|first1=H. C.|last2=Leroy|first2=Y.|last3=Tsacas|first3=L.|date=1980-02-01|title=Species and sex-specific songs and courtship behaviour in the genus Zaprionus (Diptera-Drosophilidae)|journal=Animal Behaviour|volume=28|issue=1|pages=230–255|doi=10.1016/S0003-3472(80)80027-3|s2cid=53194769|issn=0003-3472}}</ref>

===Cooperation===
Cooperation is broadly defined as behavior that provides a benefit to another individual that specifically evolved for that benefit.  This excludes behavior that has not been expressly selected for to provide a benefit for another individual, because there are many commensal and parasitic relationships where the behavior one individual (which has evolved to benefit that individual and no others) is taken advantage of by other organisms. Stable cooperative behavior requires that it provide a benefit to both the actor and recipient, though the benefit to the actor can take many different forms.<ref name=Davies/>

====Within species====
Within species cooperation occurs among members of the same species.  Examples of intraspecific cooperation include cooperative breeding (such as in weeper capuchins) and cooperative foraging (such as in wolves). There are also forms of cooperative defense mechanisms, such as the "fighting swarm" behavior used by the stingless bee ''[[Tetragonula carbonaria]]''.<ref name=gloag2008>{{cite journal |author=Gloag, R. |year=2008 |title=Nest defence in a stingless bee: What causes fighting swarms in ''Trigona carbonaria'' (Hymenoptera, Meliponini)? |journal=Insectes Sociaux |volume=55 |issue=4 |pages=387–391 |display-authors=etal |doi=10.1007/s00040-008-1018-1|s2cid=44720135 }}</ref> Much of this behavior occurs due to kin selection.  Kin selection allows cooperative behavior to evolve where the actor receives no direct benefits from the cooperation.<ref name=Davies/>

Cooperation (without kin selection) must evolve to provide benefits to both the actor and recipient of the behavior.  This includes reciprocity, where the recipient of the cooperative behavior repays the actor at a later time. This may occur in vampire bats but it is uncommon in non-human animals.<ref name = wilkinson>{{cite journal | author = Wilkinson, G.S. | year = 1984 | title = Reciprocal food sharing in the vampire bat | journal = Nature | volume = 308 | pages = 181–184 | bibcode = 1984Natur.308..181W | doi = 10.1038/308181a0 | issue = 5955| s2cid = 4354558 }}</ref>  Cooperation can occur willingly between individuals when both benefit directly as well.  Cooperative breeding, where one individual cares for the offspring of another, occurs in several species, including [[wedge-capped capuchin#Alloparenting|wedge-capped capuchin]] monkeys.<ref name = obrien4>{{cite journal |author1=O'Brien, Timothy G.  |author2=John G. Robinson  |name-list-style=amp| year = 1991 | title = Allomaternal Care by Female Wedge-Capped Capuchin Monkeys: Effects of Age, Rank and Relatedness | journal  = Behaviour | volume = 119 |issue=1–2  | pages = 30–50 | doi = 10.1163/156853991X00355}}</ref>

Cooperative behavior may also be enforced, where their failure to cooperate results in negative consequences.  One of the best examples of this is [[worker policing]], which occurs in social insect colonies.<ref>{{cite journal|last=Ratnieks|first=Francis L. W.|author2=Heikki Helanterä|title=The evolution of extreme altruism and inequality in insect societies|journal=Philosophical Transactions of the Royal Society B|date=October 2009 |volume=364 |issue=1553|pages=3169–3179 |doi=10.1098/rstb.2009.0129 |pmid=19805425 |pmc=2781879}}</ref>

The [[cooperative pulling paradigm]] is a popular experimental design used to assess if and under which conditions animals cooperate. It involves two or more animals pulling rewards towards themselves via an apparatus they can not successfully operate alone.<ref name="de Waal">de Waal, Frans (2016). "Are We Smart Enough To Know How Smart Animals Are?" {{isbn|978-1-78378-305-2}}, p. 276</ref>

====Between species====
Cooperation can occur between members of different species.  For interspecific cooperation to be evolutionarily stable, it must benefit individuals in both species.  Examples include pistol shrimp and goby fish, nitrogen fixing microbes and legumes,<ref name=postgate>{{cite book |author=Postgate, J |year=1998 |title=Nitrogen Fixation, 3rd Edition |publisher=Cambridge University Press, Cambridge UK}}</ref> ants and aphids.<ref name = dawkins>{{cite book | author = Dawkins, Richard | year = 1976 | title = The Selfish Gene | publisher = Oxford University Press}}</ref>  In ants and aphids, aphids secrete a sugary liquid called honeydew, which ants eat.  The ants provide protection to the aphids against predators, and, in some instances, raise the aphid eggs and larvae inside the ant colony. This behavior is analogous to human domestication.<ref name = dawkins/> The genus of goby fish, ''[[Elacatinus]]'' also demonstrate cooperation by removing and feeding on [[ectoparasites]] of their clients.<ref>{{Cite journal|author1=M.C. Soares |author2=I.M. Côté |author3=S.C. Cardoso |author4=R.Bshary |name-list-style=amp|date=August 2008| title = The cleaning goby mutualism: a system without punishment, partner switching or tactile stimulation | journal =Journal of Zoology| volume =276 |issue =3 | pages =306–312 | doi=10.1111/j.1469-7998.2008.00489.x|url=http://doc.rero.ch/record/28974/files/Soares_Marta_C._-_The_cleaning_goby_mutualism_a_system_without_20120417.pdf }}</ref>  The species of wasp ''[[Polybia rejecta]]'' and ants ''Azteca chartifex'' show a cooperative behavior protecting one another's nests from predators.

[[Market (economics)|Market]] economics often govern the details of the cooperation:  e.g. the amount exchanged between individual animals follow the rules of [[supply and demand]].<ref>{{cite news|last1=Crair|first1=Ben|title=The Secret Economic Lives of Animals|url=https://www.bloomberg.com/features/2017-biological-markets/|access-date=1 August 2017|work=[[Bloomberg News]]|date=1 August 2017}}</ref>

===Spite===
[[Hamilton's rule#Kin selection|Hamilton's rule]] can also predict spiteful behaviors between non-relatives.<ref name=Davies/> A spiteful behavior is one that is harmful to both the actor and to the recipient. Spiteful behavior is favored if the actor is less related to the recipient than to the average member of the population making r negative and if rB-C is still greater than zero. [[Spite (game theory)|Spite]] can also be thought of as a type of altruism because harming a non-relative, by taking his resources for example, could also benefit a relative, by allowing him access to those resources. Furthermore, certain spiteful behaviors may provide harmful short term consequences to the actor but also give long term reproductive benefits.<ref name=spite>{{cite journal|last=Foster |first=Kevin |author2=Tom Wenseleers|author3=Francis L. W. Ratnieks|title=Spite: Hamilton's unproven theory|journal=Annales Zoologici Fennici |date=10 September 2001|pages=229–238 |url=http://www.sekj.org/PDF/anz38-free/anz38-229p.pdf}}</ref> Many behaviors that are commonly thought of as spiteful are actually better explained as being selfish, that is benefiting the actor and harming the recipient, and true spiteful behaviors are rare in the animal kingdom.

An example of spite is the sterile soldiers of the [[polyembryonic]] parasitoid wasp. A female wasp lays a male and a female egg in a caterpillar. The eggs divide asexually, creating many genetically identical male and female larvae. Sterile soldier wasps also develop and attack the relatively unrelated brother larvae so that the genetically identical sisters have more access to food.<ref name="Davies" />

Another example is bacteria that release [[bacteriocins]].<ref name="Davies" /> The bacteria that releases the bacteriocin may have to die to do so, but most of the harm is to unrelated individuals who are killed by the bacteriocin. This is because the ability to produce and release the bacteriocin is linked to an immunity to it. Therefore, close relatives to the releasing cell are less likely to die than non-relatives.