Editing Behavioral ecology (section)

====Parent–offspring conflict====
[[File:Blackbird chicks in nest.JPG|thumb|left|Blackbird chicks in a nest]]
According to [[Robert Trivers|Robert Trivers's]] theory on relatedness,{{Citation needed|date=December 2012}} each offspring is related to itself by 1, but is only 0.5 related to their parents and siblings. Genetically, offspring are predisposed to behave in their own self-interest while parents are predisposed to behave equally to all their offspring, including both current and future ones. Offspring selfishly try to take more than their fair shares of [[parental investment]], while parents try to spread out their parental investment equally amongst their present young and future young.
There are many examples of parent–offspring conflict in nature. One manifestation of this is asynchronous hatching in birds. A behavioral ecology hypothesis is known as Lack's brood reduction hypothesis (named after [[David Lack]]).{{Citation needed|date=December 2012}} Lack's hypothesis posits an evolutionary and ecological explanation as to why birds lay a series of eggs with an asynchronous delay leading to nestlings of mixed age and weights. According to Lack, this brood behavior is an ecological insurance that allows the larger birds to survive in poor years and all birds to survive when food is plentiful.<ref name="Amundsen96">{{Cite journal |last1 = Amundsen|first1 = T. |last2 = Slagsvold |first2 = T. |title = Lack's Brood Reduction Hypothesis and Avian Hatching Asynchrony: What's Next? |journal = Oikos |volume = 76 |issue = 3 |pages=613–620 |year = 1996 |doi = 10.2307/3546359 |jstor = 3546359}}</ref><ref name="Piganowski92">{{Cite journal |last = Pijanowski |first = B. C. |title = A Revision of Lack's Brood Reduction Hypothesis |journal = The American Naturalist |volume = 139 |issue = 6 |pages=1270–1292 |year = 1992 |doi = 10.1086/285386|s2cid = 84884060 }}</ref> We also see sex-ratio conflict between the queen and her workers in social [[hymenoptera]]. Because of [[haplodiploidy]], the workers (offspring) prefer a 3:1 female to male sex allocation while the queen prefers a 1:1 sex ratio. Both the queen and the workers try to bias the sex ratio in their favor.<ref>{{cite journal |last1=Trivers |first1=Robert L. |last2=Willard |first2=Dan E. |title=Natural selection of parental ability to vary the sex ratio of offspring |journal=Science |year=1976 |issue=191 |pages=90–92 |bibcode=1973Sci...179...90T |volume=179 |doi=10.1126/science.179.4068.90 |pmid=4682135|s2cid=29326420 }}</ref> In some species, the workers gain control of the sex ratio, while in other species, like ''[[Bombus terrestris|B. terrestris]]'', the queen has a considerable amount of control over the colony sex ratio.<ref>{{cite journal |author1=Bourke, A.F.G.  |author2=F.L.W. Ratnieks  |name-list-style=amp| year = 2001 | title = Kin-selected conflict in the bumble-bee ''Bombus terrestris'' (Hymenoptera: Apidae) | journal = Proceedings of the Royal Society of London B | volume = 268 |issue=1465  | pages = 347–355 | doi=10.1098/rspb.2000.1381 | pmid=11270430 | pmc=1088613}}</ref> Lastly, there has been recent evidence regarding [[genomic imprinting]] that is a result of parent–offspring conflict. Paternal genes in offspring demand more maternal resources than maternal genes in the same offspring and vice versa. This has been shown in imprinted genes like [[IGF-2|insulin-like growth factor-II]].<ref>{{cite journal |last=Haig|first=D.|author2=Graham, C.|title=Genomic imprinting and the strange case of the insulin-like growth factor-II receptor|journal=Cell|year=1991|volume=64|issue=6|pages=1045–1046|doi=10.1016/0092-8674(91)90256-x |pmid=1848481|s2cid=33682126}}</ref>