Editing Ecological niche (section)

=== Types ===
Below is a list of ways that species can partition their niche.  This list is not exhaustive, but illustrates several classic examples.
[[File:Wolffia-Spirodela.jpg|thumb|[[Duckweed]] on a pond. Niche differentiation by size: [[Spirodela polyrhiza|greater duckweed]], [[Lemna minor|lesser duckweed]] and [[Wolffia arrhiza|rootless dwarf duckweed]]]]

====Resource partitioning====

Resource partitioning is the phenomenon where two or more species divides out resources like food, space, resting sites etc. to coexist. For example, some lizard species appear to coexist because they consume insects of differing sizes.<ref name="Caldwell1999">{{cite journal|last1=Caldwell|first1=Janalee P|last2=Vitt|first2=Laurie J|title=Dietary asymmetry in leaf litter frogs and lizards in a transitional northern Amazonian rain forest|journal=Oikos|date=1999|volume=84|issue=3|pages=383–397|doi=10.2307/3546419|jstor=3546419|bibcode=1999Oikos..84..383C }}</ref>  Alternatively, species can coexist on the same resources if each species is limited by different resources, or differently able to capture resources.  Different types of [[phytoplankton]] can coexist when different species are differently limited by nitrogen, phosphorus, silicon, and light.<ref name="Grover1997book">{{cite book|last1=Grover|first1=James P.|title=Resource competition|date=1997|publisher=Chapman & Hall|location=London|isbn=978-0412749308|edition=1st}}{{page needed|date=March 2018}}</ref>  In the [[Galapagos Islands]], [[Darwin's finches|finches]] with small beaks are more able to consume small seeds, and finches with large beaks are more able to consume large seeds.  If a species' density declines, then the food it most depends on will become more abundant (since there are so few individuals to consume it).  As a result, the remaining individuals will experience less competition for food.

Although "resource" generally refers to food, species can partition other non-consumable objects, such as parts of the habitat.  For example, [[warbler]]s are thought to coexist because they nest in different parts of trees.<ref name=MacArthur1958>{{cite journal|last1=MacArthur|first1=Robert H.|title=Population Ecology of Some Warblers of Northeastern Coniferous Forests|journal=Ecology|date=October 1958|volume=39|issue=4|pages=599–619|doi=10.2307/1931600|jstor=1931600|bibcode=1958Ecol...39..599M }}</ref>  Species can also partition habitat in a way that gives them access to different types of resources.  As stated in the introduction, [[anole]] lizards appear to coexist because each uses different parts of the forests as perch locations.<ref name=Pacala&Roughgarden1985 />  This likely gives them access to different species of insects.

Research has determined that plants can recognize each other's root systems and differentiate between a clone, a plant grown from the same mother plants seeds, and other species. Based on the root secretions, also called exudates, plants can make this determination.<ref name="Biedrzycki 4123–4128">{{Cite journal |last1=Biedrzycki |first1=M. L. |last2=Bais |first2=H. P. |date=2010-08-08 |title=Kin recognition in plants: a mysterious behaviour unsolved |url=http://dx.doi.org/10.1093/jxb/erq250 |journal=Journal of Experimental Botany |volume=61 |issue=15 |pages=4123–4128 |doi=10.1093/jxb/erq250 |pmid=20696656 |issn=0022-0957}}</ref> The communication between plants starts with the secretions from plant roots into the rhizosphere. If another plant that is kin is entering this area the plant will take up exudates. The exudate, being several different compounds, will enter the plants root cell and attach to a receptor for that chemical halting growth of the root meristem in that direction, if the interaction is kin.<ref>{{Cite journal |last=Witzany |first=Günther |date=July 2006 |title=Plant Communication from Biosemiotic Perspective |journal=Plant Signaling & Behavior |volume=1 |issue=4 |pages=169–178 |doi=10.4161/psb.1.4.3163 |pmid=19521482 |pmc=2634023 |s2cid=5036781 |issn=1559-2324|doi-access=free |bibcode=2006PlSiB...1..169W }}</ref>

Simonsen discusses how plants accomplish root communication with the addition of beneficial rhizobia and fungal networks and the potential for different genotypes of the kin plants, such as the legume M. Lupulina, and specific strains of nitrogen fixing bacteria and rhizomes can alter relationships between kin and non-kin competition.<ref>{{Cite journal |last1=Simonsen |first1=Anna K. |last2=Chow |first2=Theresa |last3=Stinchcombe |first3=John R. |date=December 2014 |title=Reduced plant competition among kin can be explained by Jensen's inequality |journal=Ecology and Evolution |language=en |volume=4 |issue=23 |pages=4454–4466 |doi=10.1002/ece3.1312 |issn=2045-7758 |pmc=4264895 |pmid=25512842|bibcode=2014EcoEv...4.4454S }}</ref> This means there could be specific subsets of genotypes in kin plants that selects well with specific strains that could outcompete other kin.<ref name="Biedrzycki 4123–4128"/> What might seem like an instance in kin competition could just be different genotypes of organisms at play in the soil that increase the symbiotic efficiency.

====Predator partitioning====
Predator partitioning occurs when species are attacked differently by different predators (or [[natural enemy|natural enemies]] more generally).  For example, trees could differentiate their niche if they are consumed by different species of [[specialist predator|specialist herbivores]], such as herbivorous insects.  If a species density declines, so too will the density of its natural enemies, giving it an advantage.  Thus, if each species is constrained by different natural enemies, they will be able to coexist.<ref name=grover1994>{{cite journal |doi=10.1086/285603 |jstor=2462643 |title=Assembly Rules for Communities of Nutrient-Limited Plants and Specialist Herbivores |journal=The American Naturalist |volume=143 |issue=2 |pages=258–82 |year=1994 |last1=Grover |first1=James P |s2cid=84342279 }}</ref>  Early work focused on specialist predators;<ref name=grover1994 /> however, more recent studies have shown that predators do not need to be pure specialists, they simply need to affect each prey species differently.<ref name=Chesson&Kuang2008>{{cite journal|last1=Chesson|first1=Peter|last2=Kuang|first2=Jessica J.|title=The interaction between predation and competition|journal=Nature|date=13 November 2008|volume=456|issue=7219|pages=235–238|doi=10.1038/nature07248|pmid=19005554|bibcode=2008Natur.456..235C|s2cid=4342701}}</ref><ref>{{cite journal|last1=Sedio|first1=Brian E.|last2=Ostling|first2=Annette M.|last3=Ris Lambers|first3=Janneke Hille|title=How specialised must natural enemies be to facilitate coexistence among plants?|journal=Ecology Letters|date=August 2013|volume=16|issue=8|pages=995–1003|doi=10.1111/ele.12130|pmid=23773378|bibcode=2013EcolL..16..995S |hdl=2027.42/99082|url=https://deepblue.lib.umich.edu/bitstream/2027.42/99082/1/ele12130.pdf|hdl-access=free}}</ref>  The [[Janzen–Connell hypothesis]] represents a form of predator partitioning.<ref name=gilbert2005>{{cite book|last1=Gilbert|first1=Gregory|editor1-last=Burlesem|editor1-first=David|editor2-last=Pinard|editor2-first=Michelle|editor3-last=Hartley|editor3-first=Sue|title=Biotic interactions in the tropics: their role in the maintenance of species diversity|date=2005|publisher=Cambridge University Press|location=Cambridge, UK|isbn=9780521609852|pages=[https://archive.org/details/bioticinteractio0000unse/page/141 141–164]|url=https://archive.org/details/bioticinteractio0000unse/page/141}}</ref>

====Conditional differentiation====
'''Conditional differentiation''' (sometimes called '''temporal niche partitioning''') occurs when species differ in their competitive abilities based on varying environmental conditions. For example, in the [[Sonoran Desert]], some [[annual plant]]s are more successful during wet years, while others are more successful during dry years.<ref name=Angert_etal_2009>{{cite journal|last1=Angert|first1=Amy L.|last2=Huxman|first2=Travis E.|last3=Chesson|first3=Peter|last4=Venable|first4=D. Lawrence|title=Functional tradeoffs determine species coexistence via the storage effect|journal=Proceedings of the National Academy of Sciences|date=14 July 2009|volume=106|issue=28|pages=11641–11645|doi=10.1073/pnas.0904512106|pmid=19571002|pmc=2710622|bibcode=2009PNAS..10611641A|doi-access=free}}</ref>  As a result, each species will have an advantage in some years, but not others.  When environmental conditions are most favorable, individuals will tend to compete most strongly with member of the same species.  For example, in a dry year, dry-adapted plants will tend to be most limited by other dry-adapted plants.<ref name=Angert_etal_2009 />  This can help them to coexist through a [[storage effect]].

====Competition-predation trade-off====
Species can differentiate their niche via a competition-predation trade-off if one species is a better competitor when predators are absent, and the other is better when predators are present.  Defenses against predators, such as toxic compounds or hard shells, are often metabolically costly.  As a result, species that produce such defenses are often poor competitors when predators are absent.  Species can coexist through a competition-predation trade-off if predators are more abundant when the less defended species is common, and less abundant if the well-defended species is common.<ref name=holt_etal1994>{{cite journal|last1=Holt|first1=Robert D.|last2=Grover|first2=James|last3=Tilman|first3=David|title=Simple Rules for Interspecific Dominance in Systems with Exploitative and Apparent Competition|journal=The American Naturalist|date=November 1994|volume=144|issue=5|pages=741–771|doi=10.1086/285705|s2cid=84641233}}</ref>  This effect has been criticized as being weak, because theoretical models suggest that only two species within a community can coexist because of this mechanism.<ref name=chase_etal2002>{{cite journal|last1=Chase|first1=Jonathan M.|last2=Abrams|first2=Peter A.|last3=Grover|first3=James P.|last4=Diehl|first4=Sebastian|last5=Chesson|first5=Peter|last6=Holt|first6=Robert D.|last7=Richards|first7=Shane A.|last8=Nisbet|first8=Roger M.|last9=Case|first9=Ted J.|title=The interaction between predation and competition: a review and synthesis|journal=Ecology Letters|date=March 2002|volume=5|issue=2|pages=302–315|doi=10.1046/j.1461-0248.2002.00315.x|bibcode=2002EcolL...5..302C |citeseerx=10.1.1.361.3087}}</ref>