Editing Behavioral ecology (section)

==Altruism and conflict in social insects==
[[File:HoneyAnt.jpg|thumb|left|Honeypot ant]]
Many insect species of the order [[Hymenoptera]] (bees, ants, wasps) are [[Eusociality|eusocial]]. Within the nests or hives of social insects, individuals engage in specialized tasks to ensure the survival of the colony. Dramatic examples of these specializations include changes in body morphology or unique behaviors, such as the engorged bodies of the [[honeypot ant]] ''Myrmecocystus mexicanus'' or the [[waggle dance]] of honey bees and a wasp species, ''[[Vespula vulgaris]]''.

In many, but not all social insects, reproduction is monopolized by the queen of the colony. Due to the effects of a [[haplodiploid]] mating system, in which unfertilized eggs become male [[Drone (bee)|drones]] and fertilized eggs become worker females, average [[Coefficient of relationship|relatedness]] values between sister workers can be higher than those seen in humans or other [[eutheria]]n mammals. This has led to the suggestion that [[kin selection]] may be a driving force in the evolution of eusociality, as individuals could provide cooperative care that establishes a favorable benefit to cost ratio ([[Hamilton's rule|rB-c > 0]]).<ref name=StrassmannEusociality>{{cite journal|last=Strassmann|first=Joan E.|author2=David C. Queller|title=Insect societies as divided organisms: The complexities of purpose and cross-purpose|journal=PNAS|date=May 2007|volume=104|pages=8619–8626 |doi=10.1073/pnas.0701285104|pmid=17494750 |pmc=1876438|issue=suppl. 1|bibcode = 2007PNAS..104.8619S |doi-access=free}}</ref>  However, not all social insects follow this rule. In the social wasp ''Polistes dominula'', 35% of the nest mates are unrelated.<ref name="Baker">{{cite journal|title=Territorial behaviour of the Nymphalid butterflies, ''Aglais urticae'' (L.) and ''Inachis io'' (L.) |author=Baker, R. R. |journal=Journal of Animal Ecology|volume=41|issue=2|year=1972|pages=453–469 |doi=10.2307/3480|jstor=3480 }}</ref><ref name="Drummond" /> In many other species, unrelated individuals only help the queen when no other options are present. In this case, subordinates work for unrelated queens even when other options may be present. No other social insect submits to unrelated queens in this way. This seemingly unfavorable behavior parallels some vertebrate systems. It is thought that this unrelated assistance is evidence of altruism in ''P. dominula''.<ref name="Baker" />

[[File:Naked Molerats 004.jpg|thumb|Naked mole-rats]]
Cooperation in social organisms has numerous ecological factors that can determine the benefits and costs associated with this form of organization. One suggested benefit is a type of "life insurance" for individuals who participate in the care of the young. In this instance, individuals may have a greater likelihood of transmitting genes to the next generation when helping in a group compared to individual reproduction. Another suggested benefit is the possibility of "fortress defense", where soldier castes threaten or attack intruders, thus protecting related individuals inside the territory. Such behaviors are seen in the snapping shrimp ''[[Synalpheus regalis]]'', a gall-forming aphid ''[[Pemphigus spyrothecae]]''.<ref name=FortressDefense>{{cite journal |last=Duffy |first=Emmett J. |author2=Cheryl L. Morrison|author3=Kenneth S. Macdonald|title=Colony defense and behavioral differentiation in the eusocial shrimp ''Synalpheus regalis'' |journal=Behavioral Ecology and Sociobiology|date=April 2002 |volume=51 |issue=5 |pages=488–495 |doi=10.1007/s00265-002-0455-5 |s2cid=25384748 }}</ref><ref name=AphidFortress>{{cite journal|last=Foster|first=W.A.|title=Experimental evidence for effective and altruistic colony defence against natural predators by soldiers of the gall-forming aphid ''Pemphigus spyrothecae'' (Hemiptera: Pemphigidae)|journal=Behavioral Ecology and Sociobiology|date=December 1990|volume=27|issue=6|pages=421–430|doi=10.1007/BF00164069|s2cid=37559224}}</ref>, and [[naked mole-rats]].<ref name="Sherman 1991">{{Cite book |last1=Sherman |first1=Paul W. |title=The Biology of the Naked Mole-rat |last2=Jarvis |first2=Jennifer U.M. |last3=Alexander |first3=Richard D. |publisher=Princeton University Press |year=1991 |isbn=978-0691024486 |location=Princeton, N.J. |name-list-style=vanc}}</ref>  A third ecological factor that is posited to promote eusociality is the distribution of resources: when food is sparse and concentrated in patches, eusociality is favored. Evidence supporting this third factor comes from studies of [[naked mole-rats]] and [[Damaraland mole-rat]]s, which have communities containing a single pair of reproductive individuals.<ref name=DamaralandEusocial>{{cite journal|last=Jarvis|first=Jennifer U. M. |author2=Nigel C. Bennett|author3=Andrew C. Spinks|title=Food availability and foraging by wild colonies of Damaraland mole-rats (''Cryptomys damarensis''): implications for sociality|journal=Oecologia|date=January 1998 |volume=113 |issue=2 |pages=290–298|doi=10.1007/s004420050380|pmid=28308209 |bibcode=1998Oecol.113..290J|s2cid=20472674 }}</ref>

===Conflicts in social insects===
Although eusociality has been shown to offer many benefits to the colony, there is also potential for conflict. Examples include the sex-ratio conflict and [[worker policing]] seen in certain species of social Hymenoptera such as ''[[Dolichovespula media]]'', ''[[Dolichovespula sylvestris]],'' ''[[Dolichovespula norwegica]]''<ref>{{Cite journal|title = Co-occurrence of three types of egg policing in the Norwegian wasp Dolichovespsula wasp|last1 = Bonckaert|first1 = W.|date = 2001|journal = Behavioral Ecology and Sociobiology|doi = 10.1007/s00265-010-1064-3|first6 = T.|last2 = Tofilski|first2 = A.|first3 = F.S.|last3 = Nascimento|first4 = J.|last4 = Billen|first5 = F.L.W.|last5 = Ratnieks|last6 = Wenseleers |volume=65 |issue = 4|pages=633–640|s2cid = 2186614|url = https://lirias.kuleuven.be/handle/123456789/285105|url-access = subscription}}</ref> and ''[[Vespula vulgaris]].''<ref name=ESS>{{cite journal|last=Wenseleers|first=Tom|author2=Heikki Helanterä |author3=Adam G. Hart|author4=Francis L. W. Ratnieks|title=Worker reproduction and policing in insect societies: an ESS analysis|journal=Journal of Evolutionary Biology|date=May 2004|volume=17|issue=5|pages=1035–1047 |doi=10.1111/j.1420-9101.2004.00751.x|pmid=15312076|doi-access=free}}</ref><ref name="Foster">{{cite journal|last1=Foster|first1=Kevin R. |title=Colony kin structure and male production in ''Dolichovespula'' wasps|journal=Molecular Ecology |date=2001 |volume=10 |issue=4 |pages=1003–1010|doi=10.1046/j.1365-294X.2001.01228.x|pmid=11348506 |s2cid=12009153 }}</ref> The queen and the worker wasps either indirectly kill the laying-workers' offspring by neglecting them or directly condemn them by cannibalizing and scavenging.<ref>[[Vespula vulgaris#Defensive behaviors]]</ref>

The sex-ratio conflict arises from a [[relatedness]] asymmetry, which is caused by the [[haplodiploidy]] nature of [[Hymenoptera]].  For instance, workers are most related to each other because they share half of the genes from the queen and inherit all of the father's genes.  Their total relatedness to each other would be 0.5+ (0.5 x 0.5) = 0.75. Thus, sisters are three-fourths related to each other.  On the other hand, males arise from unfertilized larva, meaning they only inherit half of the queen's genes and none from the father.  As a result, a female is related to her brother by 0.25, because 50% of her genes that come from her father have no chance of being shared with a brother.  Her relatedness to her brother would therefore be 0.5 x 0.5=0.25.<ref name=Davies/>{{rp|382}}

According to Trivers and Hare's population-level sex-investment ratio theory, the ratio of relatedness between sexes determines the sex investment ratios.<ref name=sex>{{cite journal |author=Andrew F. G. Bourke |title=Sex allocation in a facultatively polygynous ant: between-population and between-colony variation |journal=Behavioral Ecology |year=1999|volume=10|issue=4|pages=409–421 |doi=10.1093/beheco/10.4.409 |doi-access=free }}</ref> As a result, it has been observed that there is a tug-of-war between the queen and the workers, where the queen would prefer a 1:1 female to male ratio because she is equally related to her sons and daughters (r=0.5 in each case).  However, the workers would prefer a 3:1 female to male ratio because they are 0.75 related to each other and only 0.25 related to their brothers.<ref name=Davies/>{{rp|382}} [[Allozyme]] data of a colony may indicate who wins this conflict.<ref name=Colony>{{cite journal |author=Jurgen Heinze|title=Colony structure and reproduction in the ant, ''Leptothorax acervorum''|journal=Behavioral Ecology |year=1994|volume=6|issue=4|pages=359–367 |doi=10.1093/beheco/6.4.359 |last2=Lipski |first2=Norbert |last3=Schlehmeyer |first3=Kathrin |last4=Hōlldobler |first4=Bert}}</ref>

Conflict can also arise between workers in colonies of social insects. In some species, worker females retain their ability to mate and lay eggs. The colony's queen is related to her sons by half of her genes and a quarter to the sons of her worker daughters. Workers, however, are related to their sons by half of their genes and to their brothers by a quarter. Thus, the queen and her worker daughters would compete for reproduction to maximize their own reproductive fitness. Worker reproduction is limited by other workers who are more related to the queen than their sisters, a situation occurring in many polyandrous hymenopteran species. Workers police the egg-laying females by engaging in [[oophagy]] or directed acts of aggression.<ref name=Policing.Bee>{{cite journal |last=Ratnieks|first=Francis L.W.|author2=P. Kirk Visscher|title=Worker policing in the honeybee |journal=Nature |date=December 1989 |volume=342 |issue=6251|pages=796–797 |doi=10.1038/342796a0 |bibcode = 1989Natur.342..796R |s2cid=4366903}}</ref><ref>{{cite journal|last=Gobin|first=Bruno |author2=J. Billen |author3=C. Peeters |title=Policing behaviour towards virgin egg layers in a polygynous ponerine ant|journal=Animal Behaviour |date=November 1999 |volume=58|issue=5|pages=1117–1122|pmid=10564615|doi=10.1006/anbe.1999.1245|s2cid=16428974 }}</ref>

===The monogamy hypothesis===
The monogamy hypothesis states that the presence of monogamy in insects is crucial for [[eusociality]] to occur. This is thought to be true because of Hamilton's rule that states that rB-C>0. By having a [[monogamous]] mating system, all of the offspring have high relatedness to each other. This means that it is equally beneficial to help out a sibling, as it is to help out an offspring. If there were many fathers the relatedness of the colony would be lowered.<ref name=Davies/>{{rp|371–375}}

This monogamous mating system has been observed in insects such as termites, ants, bees and wasps.<ref name=Davies/>{{rp|371–375}} In termites the queen commits to a single male when founding a nest. In ants, bees and wasps the queens have a functional equivalent to lifetime monogamy. The male can even die before the founding of the colony. The queen can store and use the sperm from a single male throughout their lifetime, sometimes up to 30 years.<ref name=Davies/>{{rp|371–375}}

In an experiment looking at the mating of 267 hymenopteran species, the results were mapped onto a [[phylogeny]]. It was found that monogamy was the ancestral state in all the independent transitions to eusociality. This indicates that monogamy is the ancestral, likely to be crucial state for the development of eusociality. In species where queens mated with multiple mates, it was found that these were developed from lineages where sterile castes already evolved, so the multiple mating was secondary.<ref>{{cite journal|last=Boomsma|first=J.J|title=Kin selection versus sexual selection: why the ends to not meet|journal=Current Biology|date=21 August 2007 |volume=17 |issue=16 |pages=R673–R683 |doi=10.1016/j.cub.2007.06.033|pmid=17714661|s2cid=886746|doi-access=free}}</ref>  In these cases, multiple mating is likely to be advantageous for reasons other than those important at the origin of eusociality. Most likely reasons are that a diverse worker pool attained by multiple mating by the queen increases disease resistance and may facilitate a division of labor among workers<ref name=Davies/>{{rp|371–375}}