Editing Behavioral ecology (section)

==Parental care and family conflicts==
[[Parental investment|Parental care]] is the investment a parent puts into their offspring—which includes protecting and feeding the young, preparing burrows or nests, and providing eggs with yolk.<ref name="Clutton-Brock 1991">{{cite book|last=Clutton-Brock|first=T.H.|title=The Evolution of Parental Care|year=1991|publisher=Princeton University Press|location=Princeton NJ}}</ref>  There is great variation in parental care in the animal kingdom. In some species, the parents may not care for their offspring at all, while in others the parents exhibit single-parental or even bi-parental care. As with other topics in behavioral ecology, interactions within a family involve conflicts. These conflicts can be broken down into three general types: sexual (male–female) conflict, parent–offspring conflict, and sibling conflict.

===Types of parental care===
There are many different patterns of [[Parental investment|parental care]] in the animal kingdom. The patterns can be explained by physiological constraints or ecological conditions, such as mating opportunities. In invertebrates, there is no parental care in most species because it is more favorable for parents to produce a large number of eggs whose fate is left to chance than to protect a few individual young. In other cases, parental care is indirect, manifested via actions taken before the offspring is produced, but nonetheless essential for their survival; for example, female ''[[Lasioglossum figueresi]]'' sweat bees excavate a nest, construct brood cells, and stock the cells with pollen and nectar before they lay their eggs, so when the larvae hatch they are sheltered and fed, but the females die without ever interacting with their brood.<ref name= "Wcislo2">{{cite journal | last1 = Wcislo | first1 = W. T. | last2 = Wille | first2 = A. | last3 = Orozco | first3 = E. | year = 1993 | title = Nesting biology of tropical solitary and social sweat bees, ''Lasioglossum (Dialictus) figueresi'' Wcislo and ''L. (D.) aeneiventre'' (Friese) (Hymenoptera: Halictidae) | journal = Insectes Sociaux| volume = 40 | pages = 21–40 | doi=10.1007/BF01338830| s2cid = 6867760 }}</ref> In birds, biparental care is the most common, because reproductive success directly depends on the parents' ability to feed their chicks. Two parents can feed twice as many young, so it is more favorable for birds to have both parents delivering food. In mammals, female-only care is the most common. This is most likely because females are internally fertilized and so are holding the young inside for a prolonged period of [[gestation]], which provides males with the opportunity to desert. Females also feed the young through [[lactation]] after birth, so males are not required for feeding. Male parental care is only observed in species where they contribute to feeding or carrying of the young, such as in [[marmoset]]s.<ref>{{cite journal|last=Daly|first=M.|title=Why Don't Male Mammals Lactate?|journal=Journal of Theoretical Biology|year=1979|volume=78|pages=325–345|doi=10.1016/0022-5193(79)90334-5|pmid=513786|issue=3|bibcode=1979JThBi..78..325D}}</ref>  In fish there is no parental care in 79% of [[Osteichthyes|bony fish]].<ref>{{cite journal|last=Gross|first=M.R.|author2=R.C Sargent|title=The evolution of male and female parentental care in fishes|journal=American Zoologist|year=1985|volume=25|issue=3|pages=807–822|doi=10.1093/icb/25.3.807|doi-access=free}}</ref>  In fish with parental care, it usually limited to selecting, preparing, and defending a nest, as seen in [[sockeye salmon]], for example.<ref name="Female colour">{{cite journal|last=Foote|first=Chris J|author2=Brown, Gayle S |author3=Hawryshyn, Craig W |title=Female colour and male choice in sockeye salmon: implications for the phenotypic convergence of anadromous and nonanadromous morphs|journal=Animal Behaviour|date=1 January 2004 |volume=67|issue=1|pages=69–83|doi=10.1016/j.anbehav.2003.02.004|s2cid=53169458}}</ref> Also, parental care in fish, if any, is primarily done by males, as seen in [[Goby|gobies]] and [[Ophioblennius atlanticus|redlip blennies]].<ref>{{cite journal|last=Svensson|author2=Magnhagen, C.|s2cid=24806138|title=Parental behavior in relation to the occurrence of sneaking in the common goby|journal=Animal Behaviour|volume=56|pages=175–179 |doi=10.1006/anbe.1998.0769 |pmid=9710475 |issue=1|date=Jul 1998}}</ref><ref name="Clutton-Brock 1991"/>  The cichlid fish ''[[Variabilichromis moorii|V. moorii]]'' exhibits biparental care.<ref name="Sturmbauer yellow">{{cite journal|last=Sturmbauer|first=Christian|author2=Corinna Fuchs|author3=Georg Harb|author4=Elisabeth Damm |author5=Nina Duftner |author6=Michaela Maderbacher|author7=Martin Koch|author8=Stephan Koblmüller |title=Abundance, Distribution, and Territory Areas of Rock-dwelling Lake Tanganyika Cichlid Fish Species |journal=Hydrobiologia|year=2008|volume=615|issue=1 |pages=57–68 |url=https://link.springer.com/chapter/10.1007/978-1-4020-9582-5_5|access-date=30 September 2013|doi=10.1007/s10750-008-9557-z|s2cid=23056207|url-access=subscription}}</ref> In species with internal fertilization, the female is usually the one to take care of the young. In cases where fertilization is external the male becomes the main caretaker.

===Familial conflict===
Familial conflict is a result of trade-offs as a function of lifetime [[parental investment]]. Parental investment was defined by [[Robert Trivers]] in 1972 as "any investment by the parent in an individual offspring that increases the offspring's chance of surviving at the cost of the parent's ability to invest in other offspring".{{Citation needed|date=December 2012}} Parental investment includes behaviors like guarding and feeding. Each parent has a limited amount of parental investment over the course of their lifetime. Investment trade-offs in offspring quality and quantity within a brood and trade offs between current and future broods leads to conflict over how much parental investment to provide and to whom parents should invest in. There are three major types of familial conflict: sexual, parent–offspring, and sibling–sibling conflict.<ref name="Davies" />

====Sexual conflict====
{{Main|Sexual conflict}}
[[File:Great Tit (Parus major) (2).jpg|thumb|Great tit]]
There is conflict among parents as to who should provide the care as well as how much care to provide. Each parent must decide whether or not to stay and care for their offspring, or to desert their offspring. This decision is best modeled by [[Game theory|game theoretic]] approaches to [[evolutionarily stable strategies]] (ESS) where the best strategy for one parent depends on the strategy adopted by the other parent. Recent research has found response matching in parents who determine how much care to invest in their offspring. Studies found that parent [[great tit]]s match their partner's increased care-giving efforts with increased provisioning rates of their own.<ref>{{cite journal|last=Johnstone|first=R.A.|author2=Hinde, C.A.|title=Negotiation over offspring care--how should parents respond to each other's efforts?|journal=Behavioral Ecology|year=2006|issue=5|pages=818–827|doi=10.1093/beheco/arl009|volume=17|doi-access=free}}</ref>  This cued parental response is a type of behavioral negotiation between parents that leads to stabilized compensation. Sexual conflicts can give rise to antagonistic co-evolution between the sexes to try to get the other sex to care more for offspring. For example, in the waltzing fly ''[[Prochyliza xanthostoma]]'', ejaculate feeding maximizes female reproductive success and minimizes the female's chance of mating multiply.<ref name=":1">{{Cite journal|last1=Bonduriansky|first1=Russell|last2=Wheeler|first2=Jill|last3=Rowe|first3=Locke|date=2005-02-01|title=Ejaculate feeding and female fitness in the sexually dimorphic fly Prochyliza xanthostoma (Diptera: Piophilidae)|journal=Animal Behaviour|volume=69|issue=2|pages=489–497|doi=10.1016/j.anbehav.2004.03.018|s2cid=16357692|issn=0003-3472}}</ref> Evidence suggests that the sperm evolved to prevent female waltzing flies from mating multiply in order to ensure the male's paternity.<ref name=":1" />

====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>

====Parent–offspring conflict resolution====
Parents need an honest signal from their offspring that indicates their level of hunger or need, so that the parents can distribute resources accordingly. Offspring want more than their fair share of resources, so they exaggerate their signals to wheedle more parental investment. However, this conflict is countered by the cost of excessive begging. Not only does excessive begging attract predators, but it also retards chick growth if begging goes unrewarded.<ref>{{cite journal|last=Kilner|first=R. M.|title=A Growth Cost of Begging in Captive Canary Chicks|journal=Proceedings of the National Academy of Sciences of the United States of America |year=2001|volume=98|pages=11394–11398 |bibcode=2001PNAS...9811394K|doi=10.1073/pnas.191221798|issue=20|pmid=11572988|pmc=58740|doi-access=free}}</ref>  Thus, the cost of increased begging enforces offspring honesty.

Another resolution for parent–offspring conflict is that parental provisioning and offspring demand have actually coevolved, so that there is no obvious underlying conflict. [[Cross-fostering]] experiments in [[great tit]]s (''Parus major'') have shown that offspring beg more when their biological mothers are more generous.<ref>{{cite journal|last=Kolliker|first=M. |author2=Brinkhof, M. |author3=Heeb, P. |author4=Fitze, P. |author5=Richner, H.|title=The Quantitative Genetic Basis of Offspring Solicitation and Parental Response in a Passerine Bird with Parental Care|journal=Proceedings of the Royal Society B: Biological Sciences|year=2000|volume=267|pages=2127–2132|doi=10.1098/rspb.2000.1259|issue=1457 |pmid=11416919 |pmc=1690782}}</ref> Therefore, it seems that the willingness to invest in offspring is co-adapted to offspring demand.

====Sibling–sibling conflict====
[[File:Galápagos fur seals (4229111296).jpg|thumb|Galápagos fur seals]]
The lifetime [[parental investment]] is the fixed amount of parental resources available for all of a parent's young, and an offspring wants as much of it as possible. Siblings in a brood often compete for parental resources by trying to gain more than their fair share of what their parents can offer. Nature provides numerous examples in which sibling rivalry escalates to such an extreme that one sibling tries to kill off broodmates to maximize parental investment (''See [[Siblicide]]''). In the [[Galápagos fur seal]], the second pup of a female is usually born when the first pup is still suckling. This competition for the mother's milk is especially fierce during periods of food shortage such as an [[El Niño–Southern Oscillation|El Niño]] year, and this usually results in the older pup directly attacking and killing the younger one.<ref>{{cite journal |last=Trillmitch|first=F.|author2=Wolf, J.B.W.|title=Parent–offspring and sibling conflict in Galapagos fur seals and sea lions|journal=Behavioral Ecology and Sociobiology|year=2008|volume=62|pages=363–375 |doi=10.1007/s00265-007-0423-1 |issue=3|s2cid=41834534}}</ref>

In some bird species, sibling rivalry is also abetted by the [[wikt:asynchronous|asynchronous]] hatching of eggs. In the [[blue-footed booby]], for example, the first egg in a nest is hatched four days before the second one, resulting in the elder chick having a four-day head start in growth. When the elder chick falls 20-25% below its expected weight threshold, it attacks its younger sibling and drives it from the nest.<ref name="Drummond">{{cite journal|last=Drummond|first=H.|author2=Chavelas, C.G.|title=Food shortage influences sibling sggression in the Blue-footed Booby|journal=Animal Behaviour|year=1989|volume=37|pages=806–819|doi=10.1016/0003-3472(89)90065-1|s2cid=53165189}}</ref>

Sibling relatedness in a brood also influences the level of sibling–sibling conflict. In a study on [[passerine]] birds, it was found that chicks begged more loudly in species with higher levels of [[Promiscuity|extra-pair paternity]].<ref>{{cite journal |last1=Briskie |first1=James V. |last2=Naugler |first2=Christopher T. |last3=Leech |first3=Susan M. |title=Begging intensity of nestling birds varies with sibling relatedness |journal=Proceedings of the Royal Society B: Biological Sciences |year=1994 |volume=258 |pages=73–78 |bibcode=1994RSPSB.258...73B |doi=10.1098/rspb.1994.0144 |issue=1351|s2cid=85105883 }}</ref>

===Brood parasitism===
{{Main|Brood parasite}}
[[File:Reed warbler cuckoo.jpg|thumb|right|upright|Adult [[reed warbler]] feeding a common cuckoo chick]]
Some animals [[Deception in animals|deceive other species]] into providing all parental care. These brood parasites selfishly exploit their hosts' parents and host offspring. The [[common cuckoo]] is a well known example of a brood parasite. Female cuckoos lay a single egg in the nest of the host species and when the cuckoo chick hatches, it ejects all the host eggs and young. Other examples of brood parasites include [[honeyguides]], [[cowbirds]], and the [[large blue butterfly]].<ref>{{cite journal |last1=Spottiswoode |first1=C. N. |last2=Stevens |first2=M. |title=Visual modelling shows that avian host parents use multiple visual cues in rejecting parasitic eggs |journal=Proceedings of the National Academy of Sciences of the United States of America |year=2010 |issue=19 |pages=8672–8676 |bibcode=2010PNAS..107.8672S |volume=107 |doi=10.1073/pnas.0910486107 |pmid=20421497 |pmc=2889299|doi-access=free }}</ref><ref>{{cite journal|last1=Kliner|first1=R.M.|title=Brood parasitic cowbird nestlings use host young to procure resources|journal=Science|year=2004|issue=5685|pages=877–879|bibcode=2004Sci...305..877K|last2=Madden|first2=Joah R.|last3=Hauber|first3=Mark E.|volume=305|doi=10.1126/science.1098487|pmid=15297677|s2cid=30084518}}</ref><ref>{{cite journal|last1=Thomas|first1=J.A.|title=Butterfly mimics of ants|journal=Nature|year=2004|issue=7015|pages=283–284|doi=10.1038/432283a|last2=Settele|first2=Josef|volume=432|bibcode = 2004Natur.432..283T|pmid=15549080|s2cid=4379000|doi-access=free}}</ref>
Brood parasite offspring have many strategies to induce their host parents to invest parental care. Studies show that the common cuckoo uses vocal mimicry to reproduce the sound of multiple hungry host young to solicit more food.<ref>{{cite journal|last=Davies|first=N.B.|title=Cuckoo adaptations: trickery and tuning|journal=Journal of Zoology |year=2011|volume=281|pages=1–14|doi=10.1111/j.1469-7998.2011.00810.x |doi-access=free}}</ref>  Other cuckoos use visual deception with their wings to exaggerate the begging display. False gapes from brood parasite offspring cause host parents to collect more food.<ref>{{cite journal|last=Tanaka|first=K. D.|author2=Ueda, K. |title=Horsfield's hawk-cuckoo nestlings simulate multiple gapes for begging |journal=Science |year=2005 |issue=5722 |page=653|doi=10.1126/science.1109957|volume=308 |pmid=15860618|s2cid=42439025}}</ref> Another example of a brood parasite is ''Phengaris'' butterflies such as  ''[[Phengaris rebeli]]'' and ''[[Phengaris arion]]'', which differ from the cuckoo in that the butterflies do not oviposit directly in the nest of the host, an ant species ''[[Myrmica schencki]]''.<ref name="Akino">{{cite journal|last=Akino|first=T|author2=J. J. Knapp |author3=J. A. Thomas|author4=G. W. Elmes|title=Chemical mimicry and host specificity in the butterfly ''Maculinea rebeli'', a social parasite of Myrmica ant colonies|journal=Proceedings of the Royal Society B: Biological Sciences |year=1999 |volume=266 |issue=1427 |pages=1419–1426 |doi=10.1098/rspb.1999.0796|pmc=1690087}}</ref><ref name=":0">{{cite journal |last=Thomas|first=Jeremy |author2=Karsten Schönrogge |author3=Simona Bonelli |author4=Francesca Barbero |author5=Emilio Balletto |title=Corruption of ant acoustical signals by mimetic social parasites |journal=Communicative and Integrative Biology |year=2010|volume=3|issue=2|pages=169–171 |doi=10.4161/cib.3.2.10603 |pmid=20585513|pmc=2889977}}</ref> Rather, the butterfly larvae release chemicals that deceive the ants into believing that they are ant larvae, causing the ants to bring the butterfly larvae back to their own nests to feed them.<ref name="Akino"/><ref name=":0"/> Other examples of brood parasites are ''[[Polistes sulcifer]]'', a paper wasp that has lost the ability to build its own nests so females lay their eggs in the nest of a host species, ''[[Polistes dominula]]'', and rely on the host workers to take care of their brood,<ref name="Dapporto">{{cite journal|last1=Dapporto|first1=L.|last2=Cervo|first2=R.|last3=Sledge|first3=M. F.|last4=Turillazzi|first4=S.|title=Rank integration in dominance hierarchies of host colonies by the paper wasp social parasite ''Polistes sulcifer'' (Hymenoptera, Vespidae) |journal=Journal of Insect Physiology |date=2004 |volume=50 |issue=2–3 |pages=217–223 |doi=10.1016/j.jinsphys.2003.11.012 |pmid=15019524 }}</ref> as well as ''[[Bombus bohemicus]],'' a bumblebee that relies on host workers of various other ''[[Bumblebee|Bombus]]'' species.<ref>{{cite journal | last1 = Kreuter | first1 = Kirsten | last2 = Bunk | first2 = Elfi | year = 2011 | title = How the social parasitic bumblebee ''Bombus bohemicus'' sneaks into power of reproduction | journal = Behavioral Ecology and Sociobiology | volume = 66 | issue = 3| pages = 475–486 | doi = 10.1007/s00265-011-1294-z | s2cid = 7124725 }}</ref> Similarly, in ''[[Eulaema meriana]]'', some Leucospidae wasps exploit the brood cells and nest for shelter and food from the bees.<ref>{{Cite journal|title = Nest Architecture and Nesting Ecology of the Orchid Bee ''Eulaema meriana'' (Hymenoptera: Apinae: Euglossini) |journal = Journal of the Kansas Entomological Society|date = 2001-07-01|pages = 142–165|volume = 74|issue = 3|first1 = Sydney A.|last1 = Cameron |first2 = Santiago |last2 = Ramírez |jstor=25086012}}</ref><ref>{{Cite journal|title = Burrow sharing and nest transfer in the digger wasp ''Philanthus gibbosus'' (Fabricius)|journal = Animal Behaviour|pages = 302–308|volume = 21 |issue = 2 |doi = 10.1016/s0003-3472(73)80071-5|first = Howard E.|last = Evans |year=1973}}</ref> ''[[Vespula austriaca]]'' is another wasp in which the females force the host workers to feed and take care of the brood.<ref>{{Cite journal|title = A North American Host of the Yellowjacket Social Parasite Vespula austriaca (Panzer) (Hymenoptera: Vespidae)|last1 = Reed|first1 = H. C.|date = 1979|journal = Entomological News|last2 = Akre|first2 = R. D.|issue = 2|volume = 90|pages = 110–113|last3 = Garnett|first3 = W. B.}}</ref> In particular, ''[[Bombus hyperboreus]]'', an Arctic bee species, is also classified as a brood parasite in that it attacks and enslaves other species within their subgenus, ''Alpinobombus'' to propagate their population.<ref>{{cite journal | last1 = Gjershaug | first1 = Jan Ove | year = 2009 | title = The social parasite bumblebee ''Bombus hyperboreus'' Schönherr, 1809 usurp nest of ''Bombus balteatus'' Dahlbom, 1832 (Hymenoptera, Apidae) in Norway | journal = Norwegian Journal of Entomology | volume = 56 | issue = 1| pages = 28–31 }}</ref>