Editing Behavioral ecology (section)

====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>