Editing Ecology (section)

== Relation to evolution ==
{{main|Evolutionary ecology}}

Ecology and evolutionary biology are considered sister disciplines of the life sciences. [[Natural selection]], [[Biological life cycle|life history]], [[Developmental biology|development]], [[adaptation]], [[populations]], and [[heredity|inheritance]] are examples of concepts that thread equally into ecological and evolutionary theory. Morphological, behavioural, and genetic traits, for example, can be mapped onto evolutionary trees to study the historical development of a species in relation to their functions and roles in different ecological circumstances. In this framework, the analytical tools of ecologists and evolutionists overlap as they organize, classify, and investigate life through common systematic principles, such as [[phylogenetics]] or the [[Linnaean taxonomy|Linnaean system of taxonomy]].<ref name="Miles93"/> The two disciplines often appear together, such as in the title of the journal ''[[Trends in Ecology and Evolution]]''.<ref name="TREE">{{cite web | editor-last=Craze | editor-first=P. | title=Trends in Ecology and Evolution | publisher=Cell Press, Elsevier, Inc | url=http://www.cell.com/trends/ecology-evolution/home | date=2 August 2012 | archive-url=http://arquivo.pt/wayback/20090724103422/http://www.cell.com/trends/ecology-evolution/home | archive-date=24 July 2009 | access-date=9 December 2009 }}</ref> There is no sharp boundary separating ecology from evolution, and they differ more in their areas of applied focus. Both disciplines discover and explain emergent and unique properties and processes operating across different spatial or temporal scales of organization.<ref name="Levins80" /><ref name="Lovelock03" /> While the boundary between ecology and evolution is not always clear, ecologists study the abiotic and biotic factors that influence evolutionary processes,<ref name="Allee49"/><ref name="Ricklefs96"/> and evolution can be rapid, occurring on ecological timescales as short as one generation.<ref>{{cite journal | last=Yoshida | first=T | title=Rapid evolution drives ecological dynamics in a predator–prey system | journal=Nature | volume=424 | issue=6946 | pages=303–306 | publisher=Nature Publishing Group| doi=10.1038/nature01767 | pmid=12867979 | year=2003 | bibcode=2003Natur.424..303Y| s2cid=4425455 }}</ref>

=== Behavioural ecology ===
{{Main|Behavioural ecology}}
[[File:Chameleon spectra.jpg|left|upright=1.6|thumb|Social display and colour variation in differently adapted species of [[chameleons]] (''Bradypodion'' spp.). Chameleons change their skin colour to match their background as a behavioural defence mechanism and also use colour to communicate with other members of their species, such as dominant (left) versus submissive (right) patterns shown in the three species (A-C) above.<ref name="Stuart-Fox08"/>]]

All organisms can exhibit behaviours. Even plants express complex behaviour, including memory and communication.<ref name="Karban08"/> Behavioural ecology is the study of an organism's behaviour in its environment and its ecological and evolutionary implications. Ethology is the study of observable movement or behaviour in animals. This could include investigations of motile [[sperm]] of plants, mobile [[phytoplankton]], [[zooplankton]] swimming toward the female egg, the cultivation of fungi by [[weevils]], the mating dance of a [[salamander]], or social gatherings of [[amoeba]].<ref name="Tinbergen63"/><ref name="Hamner85"/><ref name="Strassmann00"/><ref name="Sakurai85"/><ref name="Anderson61"/>

Adaptation is the central unifying concept in behavioural ecology.<ref>{{cite web|url=http://www.behavecol.com/pages/society/welcome.html |title=Behavioral Ecology |publisher=International Society for Behavioral Ecology |access-date=15 April 2011 |archive-url=https://web.archive.org/web/20110410105207/http://www.behavecol.com/pages/society/welcome.html |archive-date=10 April 2011}}</ref> Behaviours can be recorded as traits and inherited in much the same way that eye and hair colour can. Behaviours can evolve by means of natural selection as adaptive traits conferring functional utilities that increases reproductive fitness.<ref name="Gould82"/><ref name="Wilson00"/>

[[File:Common jassid nymphs and ants02.jpg|thumb|upright|'''Mutualism:''' [[Leafhopper]]s (''Eurymela fenestrata'') are protected by [[meat ant|ants]] (''Iridomyrmex purpureus'') in a [[Mutualism (biology)|mutualistic]] relationship. The ants protect the leafhoppers from predators and stimulate feeding in the leafhoppers, and in return, the leafhoppers feeding on plants exude honeydew from their anus that provides energy and nutrients to tending ants.<ref name="Eastwood04"/>]]

Predator-prey interactions are an introductory concept into food-web studies as well as behavioural ecology.<ref name="Ives04"/> Prey species can exhibit different kinds of behavioural adaptations to predators, such as avoid, flee, or defend. Many prey species are faced with multiple predators that differ in the degree of danger posed. To be adapted to their environment and face predatory threats, organisms must balance their energy budgets as they invest in different aspects of their life history, such as growth, feeding, mating, socializing, or modifying their habitat. 

Hypotheses posited in behavioural ecology are generally based on adaptive principles of conservation, optimization, or efficiency.<ref name="Begon05"/><ref name="Allee49"/><ref name="Krebs93"/> For example, "[t]he threat-sensitive predator avoidance hypothesis predicts that prey should assess the degree of threat posed by different predators and match their behaviour according to current levels of risk"<ref name="Webb10"/> or "[t]he optimal [[Escape distance|flight initiation distance]] occurs where expected postencounter fitness is maximized, which depends on the prey's initial fitness, benefits obtainable by not fleeing, energetic escape costs, and expected fitness loss due to predation risk."<ref name="Cooper10"/>

Elaborate sexual [[display (zoology)|displays]] and posturing are encountered in the behavioural ecology of animals. The [[birds-of-paradise]], for example, sing and display elaborate ornaments during [[courtship]]. These displays serve a dual purpose of signalling healthy or well-adapted individuals and desirable genes. The displays are driven by [[sexual selection]] as an advertisement of quality of traits among [[suitors]].<ref name="Kodric-Brown84"/>

=== Cognitive ecology ===

Cognitive ecology integrates theory and observations from [[evolutionary ecology]] and [[neurobiology]], primarily [[cognitive science]], in order to understand the effect that animal interaction with their habitat has on their cognitive systems and how those systems restrict behavior within an ecological and evolutionary framework.<ref name=Palacios>{{cite journal |journal=Biology Research |volume=36 |issue=1 |pages=95–99 |year=2003 |title=An "enactive" approach to integrative and comparative biology: Thoughts on the table |author=Adrian G Palacios, [[Francisco Bozinovic]] |doi=10.4067/S0716-97602003000100008 |pmid=12795209 |last2=Bozinovic |doi-access=free }}</ref> "Until recently, however, cognitive scientists have not paid sufficient attention to the fundamental fact that cognitive traits evolved under particular natural settings. With consideration of the selection pressure on cognition, cognitive ecology can contribute intellectual coherence to the multidisciplinary study of cognition."<ref name=Dukas>{{cite book |title=Cognitive Ecology: The Evolutionary Ecology of Information Processing and Decision Making |author=Reuven Dukas |editor=Reuven Dukas |isbn=978-0-226-16932-3 |year=1998 |chapter=§1.3 Why study cognitive ecology? |publisher=University of Chicago Press |chapter-url=https://books.google.com/books?id=nNRXQM7_R0UC&pg=PA4 |page=4 |access-date=27 June 2015 |archive-date=18 March 2015 |archive-url=https://web.archive.org/web/20150318140450/http://books.google.com/books?id=nNRXQM7_R0UC&pg=PA4 |url-status=live }}</ref><ref name=Dukas2>{{cite book |title=Cognitive Ecology II |chapter=Introduction |pages=1 ''ff'' |author1=Reuven Dukas |author2=John M. Ratcliffe |editor1=Reuven Dukas |editor2=John M. Ratcliffe |isbn=978-0-226-16937-8 |publisher=University of Chicago Press |year=2009 |quote=Cognitive ecology focuses on the ecology and evolution of "cognition" defined as the neuronal processes concerned with the acquisition, retention, and use of information....we ought to rely on ecological and evolutionary knowledge for studying cognition. |chapter-url=https://books.google.com/books?id=TAiAcZ0Q9LQC&pg=PA1 |access-date=27 June 2015 |archive-date=18 March 2015 |archive-url=https://web.archive.org/web/20150318133553/http://books.google.com/books?id=TAiAcZ0Q9LQC&pg=PA1 |url-status=live }}</ref> As a study involving the 'coupling' or interactions between organism and environment, cognitive ecology is closely related to [[enactivism]],<ref name=Palacios/> a field based upon the view that "...we must see the organism and environment as bound together in reciprocal specification and selection...".<ref name=Varela>{{cite book |author1=Francisco J Varela |author2=Evan Thompson |author3=Eleanor Rosch |year=1993 |title=The Embodied Mind: Cognitive Science and Human Experience |publisher=MIT Press |url=https://books.google.com/books?id=QY4RoH2z5DoC |isbn=978-0-262-26123-4 |page=174 |access-date=27 June 2015 |archive-date=1 August 2020 |archive-url=https://web.archive.org/web/20200801065309/https://books.google.com/books?id=QY4RoH2z5DoC |url-status=live }}</ref>

=== Social ecology ===
{{main|Social ecology (academic field)}}

Social-ecological behaviours are notable in the [[social insects]], [[slime moulds]], [[social spider]]s, [[human society]], and [[naked mole-rat]]s where [[eusocialism]] has evolved. Social behaviours include reciprocally beneficial behaviours among kin and nest mates<ref name="Strassmann00" /><ref name="Wilson00" /><ref name="Sherman95"/> and evolve from kin and group selection. [[Kin selection]] explains altruism through genetic relationships, whereby an altruistic behaviour leading to death is rewarded by the survival of genetic copies distributed among surviving relatives. The social insects, including [[ant]]s, [[bee]]s, and [[wasp]]s are most famously studied for this type of relationship because the male drones are [[Cloning|clones]] that share the same genetic make-up as every other male in the colony.<ref name="Wilson00" /> In contrast, [[group selection]]ists find examples of altruism among non-genetic relatives and explain this through selection acting on the group; whereby, it becomes selectively advantageous for groups if their members express altruistic behaviours to one another. Groups with predominantly altruistic members survive better than groups with predominantly selfish members.<ref name="Wilson00" /><ref name="Wilson07"/>

=== Coevolution ===
{{main|Coevolution}}
[[File:Bombus 6867.JPG|thumb|right|[[Bumblebee]]s and the [[flower]]s they [[pollination|pollinate]] have coevolved so that both have become dependent on each other for survival.]]
[[File:Parasitismus.jpg|thumb|upright|'''Parasitism:''' A harvestman [[arachnid]] being parasitized by [[mite]]s. The harvestman is being consumed, while the mites benefit from traveling on and feeding off of their host.]]

Ecological interactions can be classified broadly into a [[host (biology)|host]] and an associate relationship. A host is any entity that harbours another that is called the associate.<ref name="Page91"/> Relationships [[Interspecific interaction|between species]] that are mutually or reciprocally beneficial are called [[mutualisms]]. Examples of mutualism include [[fungus-growing ants]] employing agricultural symbiosis, bacteria living in the guts of insects and other organisms, the [[fig wasp]] and [[Prodoxidae|yucca moth]] pollination complex, [[lichen]]s with fungi and photosynthetic [[algae]], and [[coral]]s with photosynthetic algae.<ref name="Herre99"/><ref name="Gilbert90"/> If there is a physical connection between host and associate, the relationship is called [[symbiosis]]. Approximately 60% of all plants, for example, have a symbiotic relationship with [[arbuscular mycorrhizal fungi]] living in their roots forming an exchange network of carbohydrates for [[nutrients|mineral nutrients]].<ref name="Kiers06"/>

Indirect mutualisms occur where the organisms live apart. For example, trees living in the equatorial regions of the planet supply oxygen into the atmosphere that sustains species living in distant polar regions of the planet. This relationship is called [[commensalism]] because many others receive the benefits of clean air at no cost or harm to trees supplying the oxygen.<ref name="Odum05" /><ref>{{cite journal|last1=Strain | first1=B. R.|year=1985|title=Physiological and ecological controls on carbon sequestering in terrestrial ecosystems|journal=Biogeochemistry|volume=1|issue=3|pages=219–232|doi=10.1007/BF02187200| bibcode=1985Biogc...1..219S| s2cid=98479424}}</ref> If the associate benefits while the host suffers, the relationship is called [[parasitism]]. Although parasites impose a cost to their host (e.g., via damage to their reproductive organs or [[propagule]]s, denying the services of a beneficial partner), their net effect on host fitness is not necessarily negative and, thus, becomes difficult to forecast.<ref name="Bronstein01"/><ref name="Irwin10"/> Co-evolution is also driven by competition among species or among members of the same species under the banner of reciprocal antagonism, such as grasses competing for growth space. The [[Red Queen Hypothesis]], for example, posits that parasites track down and specialize on the locally common genetic defense systems of its host that drives the evolution of sexual reproduction to diversify the genetic constituency of populations responding to the antagonistic pressure.<ref name="Boucher82"/><ref name="King09">{{cite journal | last1=King | first1=K. C. | last2=Delph | first2=L. F. | last3=Jokela | first3=J. | last4=Lively | first4=C. M. | title=The geographic mosaic of sex and the Red Queen | journal=Current Biology | volume=19 | issue=17 | pages=1438–1441 | doi=10.1016/j.cub.2009.06.062| year=2009 | pmid=19631541| s2cid=12027050 | doi-access=free | bibcode=2009CBio...19.1438K }}</ref>

=== Biogeography ===
{{Main|Biogeography}}

Biogeography (an amalgamation of ''biology'' and ''geography'') is the comparative study of the geographic distribution of organisms and the corresponding evolution of their traits in space and time.<ref name="Parenti90"/> The ''[[Journal of Biogeography]]'' was established in 1974.<ref name="JBiog">{{cite web | title = Journal of Biogeography – Overview | publisher = Wiley | url = http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2699/homepage/ProductInformation.html | access-date = 16 March 2018 | url-status=live | archive-url = https://archive.today/20130209095040/http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2699/homepage/ProductInformation.html | archive-date = 9 February 2013| doi = 10.1111/(ISSN)1365-2699}}</ref> Biogeography and ecology share many of their disciplinary roots. For example, [[Island biogeography|the theory of island biogeography]], published by the Robert MacArthur and [[Edward O. Wilson]] in 1967<ref name="MacArthur67" /> is considered one of the fundamentals of ecological theory.<ref name="Wiens04"/>

Biogeography has a long history in the natural sciences concerning the spatial distribution of plants and animals. Ecology and evolution provide the explanatory context for biogeographical studies.<ref name="Parenti90" /> Biogeographical patterns result from ecological processes that influence range distributions, such as [[Animal migration|migration]] and [[Biological dispersal|dispersal]].<ref name="Wiens04" /> and from historical processes that split populations or species into different areas. The biogeographic processes that result in the natural splitting of species explain much of the modern distribution of the Earth's biota. The splitting of lineages in a species is called [[Allopatric speciation|vicariance biogeography]] and it is a sub-discipline of biogeography.<ref name="Morrone95"/> There are also practical applications in the field of biogeography concerning ecological systems and processes. For example, the range and distribution of biodiversity and invasive species responding to climate change is a serious concern and active area of research in the context of [[global warming]].<ref name="Svennin08" /><ref name="Landhäusser09"/>

==== r/K selection theory ====
{{Main|r/K selection theory}}

A population ecology concept is r/K selection theory,{{Cref2|D}} one of the first predictive models in ecology used to explain [[Life history theory|life-history evolution]]. The premise behind the r/K selection model is that natural selection pressures change according to [[population densities|population density]]. For example, when an island is first colonized, density of individuals is low. The initial increase in population size is not limited by competition, leaving an abundance of available [[Resource (biology)|resources]] for rapid population growth. These early phases of [[population growth]] experience ''density-independent'' forces of natural selection, which is called ''r''-selection. As the population becomes more crowded, it approaches the island's carrying capacity, thus forcing individuals to compete more heavily for fewer available resources. Under crowded conditions, the population experiences density-dependent forces of natural selection, called ''K''-selection.<ref name="Reznick02"/>

In the ''r/K''-selection model, the first variable ''r'' is the intrinsic rate of natural increase in population size and the second variable ''K'' is the carrying capacity of a population.<ref name="Begon05" /> Different species evolve different life-history strategies spanning a continuum between these two selective forces. An ''r''-selected species is one that has high birth rates, low levels of parental investment, and high rates of mortality before individuals reach maturity. Evolution favours high rates of [[fecundity]] in ''r''-selected species. Many kinds of insects and [[invasive species]] exhibit ''r''-selected [[Phenotypic trait|characteristics]]. In contrast, a ''K''-selected species has low rates of fecundity, high levels of parental investment in the young, and low rates of mortality as individuals mature. Humans and elephants are examples of species exhibiting ''K''-selected characteristics, including longevity and efficiency in the conversion of more resources into fewer offspring.<ref name="MacArthur67"/><ref name="Pianka72"/>

=== Molecular ecology ===
{{Main|Molecular ecology}}

The important relationship between ecology and genetic inheritance predates modern techniques for molecular analysis. Molecular ecological research became more feasible with the development of rapid and accessible genetic technologies, such as the [[Polymerase chain reaction|polymerase chain reaction (PCR)]]. The rise of molecular technologies and the influx of research questions into this new ecological field resulted in the publication ''[[Molecular Ecology]]'' in 1992.<ref name="MolEcol">{{Cite journal| title = Molecular Ecology| editor-last=Rieseberg| editor-first= L.| publisher = Wiley| doi = 10.1111/(ISSN)1365-294X| journal = Molecular Ecology}}</ref> [[Molecular ecology]] uses various analytical techniques to study genes in an evolutionary and ecological context. In 1994, [[John Avise]] also played a leading role in this area of science with the publication of his book, ''Molecular Markers, Natural History and Evolution''.<ref name="Avise94"/> 

Newer technologies opened a wave of genetic analysis into organisms once difficult to study from an ecological or evolutionary standpoint, such as bacteria, fungi, and [[nematode]]s. Molecular ecology engendered a new research paradigm for investigating ecological questions considered otherwise intractable. Molecular investigations revealed previously obscured details in the tiny intricacies of nature and improved resolution into probing questions about behavioural and biogeographical ecology.<ref name="Avise94"/> For example, molecular ecology revealed [[Promiscuity#Other animals|promiscuous]] sexual behaviour and multiple male partners in [[tree swallow]]s previously thought to be socially [[Monogamy in animals|monogamous]].<ref name="Obryan07"/> In a biogeographical context, the marriage between genetics, ecology, and evolution resulted in a new sub-discipline called [[phylogeography]].<ref name="Avise00"/>