Editing Habitat fragmentation (section)

==Implications ==

=== Habitat and biodiversity loss ===
{{Main|biodiversity loss}}
One of the major ways that habitat fragmentation affects [[biodiversity]] is by reducing the amount of suitable habitat available for organisms. Habitat fragmentation often involves both [[habitat destruction]] and the subdivision of previously continuous habitat.<ref>{{cite journal|last1=Fahrig|first1=Lenore|title=Effects of Habitat Fragmentation on Biodiversity|journal=Annual Review of Ecology, Evolution, and Systematics|date=November 2003|volume=34|issue=1|pages=487–515|doi=10.1146/annurev.ecolsys.34.011802.132419}}</ref> Plants and other [[Sessility (zoology)|sessile]] organisms are disproportionately affected by some types of habitat fragmentation because they cannot respond quickly to the altered spatial configuration of the habitat.<ref name="Lienert2004">{{cite journal|last1=Lienert|first1=Judit|title=Habitat fragmentation effects on fitness of plant populations – a review|journal=Journal for Nature Conservation|date=July 2004|volume=12|issue=1|pages=53–72|doi=10.1016/j.jnc.2003.07.002|bibcode=2004JNatC..12...53L }}</ref> Habitat fragmentation consistently reduces biodiversity by 13 to 75% and impairs key ecosystem functions by decreasing biomass and altering [[nutrient cycle]]s. This underscores the severe and lasting ecological impacts of fragmentation, which could be highlighted in the sections discussing the consequences of fragmentation.<ref name="ReferenceA">{{Cite journal |last1=Haddad |first1=Nick M. |last2=Brudvig |first2=Lars A. |last3=Clobert |first3=Jean |last4=Davies |first4=Kendi F. |last5=Gonzalez |first5=Andrew |last6=Holt |first6=Robert D. |last7=Lovejoy |first7=Thomas E. |last8=Sexton |first8=Joseph O. |last9=Austin |first9=Mike P. |last10=Collins |first10=Cathy D. |last11=Cook |first11=William M. |last12=Damschen |first12=Ellen I. |last13=Ewers |first13=Robert M. |last14=Foster |first14=Bryan L. |last15=Jenkins |first15=Clinton N. |date=2015-03-06 |title=Habitat fragmentation and its lasting impact on Earth's ecosystems |journal=Science Advances |language=en |volume=1 |issue=2 |pages=e1500052 |doi=10.1126/sciadv.1500052 |issn=2375-2548 |pmc=4643828 |pmid=26601154|bibcode=2015SciA....1E0052H }}</ref>

Habitat loss, which can occur through the process of habitat fragmentation, is considered to be the greatest threat to species.<ref>{{cite journal | last1 = Wilcove | first1 = David S. |display-authors=etal | year = 1998 | title = Quantifying Threats to Imperiled Species in the United States | jstor = 1313420 | journal = BioScience | volume = 48 | issue = 8| pages = 607–615 | doi=10.2307/1313420| doi-access = free}}</ref> But, the effect of the configuration of habitat patches within the landscape, independent of the effect of the amount of habitat within the landscape (referred to as fragmentation per se<ref name="Fahrig2003">{{cite journal | last1 = Fahrig | first1 = L | year = 2003 | title = Effects of habitat fragmentation on biodiversity | journal = Annual Review of Ecology, Evolution, and Systematics | volume = 34 | pages = 487–515 | doi=10.1146/annurev.ecolsys.34.011802.132419}}</ref>), has been suggested to be small.<ref name="Fahrig2013">{{cite journal | last1 = Fahrig | first1 = L | year = 2013 | title = Rethinking patch size and isolation effects: the habitat amount hypothesis | journal = J. Biogeogr. | volume = 40 | issue = 9| pages = 1649–1663 | doi = 10.1111/jbi.12130 | bibcode = 2013JBiog..40.1649F | doi-access = free}}</ref> A review of empirical studies found that, of the 381 reported significant effect of habitat fragmentation per se on species occurrences, abundances or diversity in the scientific literature, 76% were positive whereas 24% were negative.<ref name="Fahrig2017">{{cite journal | last1 = Fahrig | first1 = L | year = 2017 | title = Ecological Responses to Habitat Fragmentation Per Se | journal = Annual Review of Ecology, Evolution, and Systematics | volume = 48 | pages = 1–23 | doi = 10.1146/annurev-ecolsys-110316-022612}}</ref> Despite these results, the scientific literature tends to emphasize negative effects more than positive effects.<ref>{{Cite book |last=Fahrig |first=Lenore |url=https://academic.oup.com/book/26688/chapter/195480099 |title=Forty years of bias in habitat fragmentation research |date=2017-12-21 |publisher=Oxford University Press |volume=1 |language=en |doi=10.1093/oso/9780198808978.003.0005|isbn=978-0-19-880897-8 }}</ref> Positive effects of habitat fragmentation per se imply that several small patches of habitat can have higher conservation value than a single large patch of equivalent size.<ref name="Fahrig2017" /> Land sharing strategies could therefore have more positive impacts on species than land sparing strategies.<ref name="Fahrig2017" /> Although the negative effects of habitat loss are generally viewed to be much larger than that of habitat fragmentation, the two events are heavily connected and observations are not usually independent of one another.<ref>{{Cite journal |doi=10.1016/j.biocon.2018.07.022| s2cid=52839843 | title=Is habitat fragmentation good for biodiversity? | year=2018 | last1=Fletcher | first1=Robert J. | last2=Didham | first2=Raphael K. | last3=Banks-Leite | first3=Cristina | last4=Barlow | first4=Jos | last5=Ewers | first5=Robert M. | last6=Rosindell | first6=James | last7=Holt | first7=Robert D. | last8=Gonzalez | first8=Andrew | last9=Pardini | first9=Renata | last10=Damschen | first10=Ellen I. | last11=Melo | first11=Felipe P.L. | last12=Ries | first12=Leslie | last13=Prevedello | first13=Jayme A. | last14=Tscharntke | first14=Teja | last15=Laurance | first15=William F. | last16=Lovejoy | first16=Thomas | last17=Haddad | first17=Nick M. | journal=Biological Conservation | volume=226 | pages=9–15 | bibcode=2018BCons.226....9F | url=https://eprints.lancs.ac.uk/id/eprint/126675/1/Fletcher_etal_2018_Biological_Conservation.pdf }}</ref>[[File:Indiana Dunes Habitat Fragmentation.jpg|thumb|right|300px|Habitat fragmented by numerous roads near the [[Indiana Dunes National Park]].]]
Area is the primary determinant of the number of species in a fragment<ref name="Rosenzweig">{{cite book | last = Rosenzweig | first = Michael L. | author-link = Michael Rosenzweig | title = Species diversity in space and time | year = 1995 | publisher = [[Cambridge University Press]] | location = Cambridge}}</ref> and the relative contributions of demographic and genetic processes to the risk of global population extinction depend on habitat configuration, stochastic environmental variation and species features.<ref>{{cite journal | last1 = Robert | first1 = A | year = 2011 | title = Find the weakest link. A comparison between demographic, genetic and demo-genetic metapopulation extinction times | journal = BMC Evolutionary Biology | volume = 11 | issue = 1 | page = 260 | doi = 10.1186/1471-2148-11-260 | pmid = 21929788 | pmc = 3185286 | bibcode = 2011BMCEE..11..260R | doi-access = free }}</ref> Minor fluctuations in climate, resources, or other factors that would be unremarkable and quickly corrected in large populations can be catastrophic in small, isolated populations. Thus fragmentation of habitat is an important cause of species extinction.<ref name="Rosenzweig" /> Population dynamics of subdivided populations tend to vary [[wikt:asynchronous|asynchronous]]ly. In an unfragmented landscape a declining population can be "rescued" by immigration from a nearby expanding population. In fragmented landscapes, the distance between fragments may prevent this from happening. Additionally, unoccupied fragments of habitat that are separated from a source of [[Colonisation (biology)|immigrants]] by some barrier are less likely to be repopulated than adjoining fragments. Even small species such as the [[Columbia spotted frog]] are reliant on the [[rescue effect]]. Studies showed 25% of juveniles travel a distance over 200m compared to 4% of adults. Of these, 95% remain in their new locale, demonstrating that this journey is necessary for survival.<ref>{{cite journal |author1=Funk W.C. |author2=Greene A.E. |author3=Corn P.S. |author4=Allendorf F.W. | year = 2005 | title = High dispersal in a frog species suggests that it is vulnerable to habitat fragmentation | journal = [[Biology Letters|Biol. Lett.]] | volume = 1 | issue = 1| pages = 13–6 | doi=10.1098/rsbl.2004.0270|pmid=17148116 |pmc=1629065|bibcode=2005BiLet...1...13F }}</ref>

Additionally, habitat fragmentation leads to [[edge effect]]s. Microclimatic changes in light, temperature, and wind can alter the ecology around the fragment, and in the interior and exterior portions of the fragment.<ref>{{Cite journal|last1=Magnago|first1=Luiz Fernando Silva|last2=Rocha|first2=Mariana Ferreira|last3=Meyer|first3=Leila|last4=Martins|first4=Sebastião Venâncio|last5=Meira-Neto|first5=João Augusto Alves|date=September 2015|title=Microclimatic conditions at forest edges have significant impacts on vegetation structure in large Atlantic forest fragments|journal=Biodiversity and Conservation|language=en|volume=24|issue=9|pages=2305–2318|doi=10.1007/s10531-015-0961-1|bibcode=2015BiCon..24.2305M |s2cid=16927557|issn=0960-3115|url=http://www.locus.ufv.br/handle/123456789/21347|url-access=subscription}}</ref> [[wildfire|Fires]] become more likely in the area as humidity drops and temperature and wind levels rise. Exotic and pest species may establish themselves easily in such disturbed environments, and the proximity of domestic animals often upsets the natural ecology. Also, habitat along the edge of a fragment has a different climate and favours different species from the interior habitat. Small fragments are therefore unfavourable for species that require interior habitat. The percentage preservation of contiguous habitats is closely related to both genetic and species biodiversity preservation. Generally a 10% remnant contiguous habitat will result in a 50% [[biodiversity loss]].<ref>{{Cite book |last=Quammen |first=David |title=The song of the dodo: Island biogeography in an age of extinctions |date=2004 |publisher=Scribner |isbn=978-0-684-82712-4 |location=New York, NY}}</ref>

Much of the remaining terrestrial [[wildlife]] habitat in many third world countries has experienced fragmentation through the development of [[Urban sprawl|urban expansion]] such as roads interfering with [[habitat loss]]. Aquatic species’ habitats have been fragmented by [[dam]]s and [[Interbasin transfer|water diversions]].<ref name="Habitat Loss">{{Cite web|url=https://www.nwf.org/Home/Educational-Resources/Wildlife-Guide/Threats-to-Wildlife/Habitat-Loss|title=Habitat Loss|website=National Wildlife Federation|language=en|access-date=2020-03-06}}</ref> These fragments of habitat may not be large or connected enough to support species that need a large territory where they can find mates and food. The loss and fragmentation of habitats makes it difficult for migratory species to find places to rest and feed along their migration routes.<ref name="Habitat Loss" />

The effects of current fragmentation will continue to emerge for decades. Extinction debts are likely to come due, although the counteracting immigration debts may never fully be paid. Indeed, the experiments here reveal ongoing losses of biodiversity and ecosystem functioning two decades or longer after fragmentation occurred. Understanding the relationship between transient and long-term dynamics is a substantial challenge that ecologists must tackle, and fragmentation experiments will be central for relating observation to theory.<ref name="Haddad2015"/>

===Informed conservation===
Habitat fragmentation is often a cause of species becoming [[threatened]] or [[endangered]].<ref>{{Cite journal|last1=Crooks|first1=Kevin R.|last2=Burdett|first2=Christopher L.|last3=Theobald|first3=David M.|last4=King|first4=Sarah R. B.|last5=Di Marco|first5=Moreno|last6=Rondinini|first6=Carlo|last7=Boitani|first7=Luigi|date=2017-07-18|title=Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals|journal=Proceedings of the National Academy of Sciences|language=en|volume=114|issue=29|pages=7635–7640|doi=10.1073/pnas.1705769114|issn=0027-8424|pmc=5530695|pmid=28673992|bibcode=2017PNAS..114.7635C |doi-access=free}}</ref> The existence of viable habitat is critical to the survival of any species, and in many cases, the fragmentation of any remaining habitat can lead to difficult decisions for conservation biologists. Given a limited amount of resources available for conservation is it preferable to protect the existing isolated patches of habitat or to buy back land to get the largest possible contiguous piece of land. In rare cases, a [[conservation reliant species]] may gain some measure of disease protection by being distributed in isolated habitats, and when controlled for overall habitat loss some studies have shown a positive relationship between species richness and fragmentation; this phenomenon has been called the habitat amount hypothesis, though the validity of this claim has been disputed.<ref name="Fahrig2013" /><ref>{{Cite journal|last=Hanski|first=Ilkka|date=May 2015|editor-last=Triantis|editor-first=Kostas|title=Habitat fragmentation and species richness|journal=Journal of Biogeography|language=en|volume=42|issue=5|pages=989–993|doi=10.1111/jbi.12478|bibcode=2015JBiog..42..989H |s2cid=84220990 |doi-access=}}</ref> The ongoing debate of what size fragments are most relevant for conservation is often referred to as [[SLOSS debate|SLOSS]] (Single Large or Several Small). Habitat loss in a biodiversity hotspot can result in a localized extinction crisis, generally speaking habitat loss in a hotspot location can be a good indicator or predictor of the number of threatened and extinct endemic species.<ref>{{Cite journal |last1=Brooks |first1=Thomas M. |last2=Mittermeier |first2=Russell A. |last3=Mittermeier |first3=Cristina G. |last4=da Fonseca |first4=Gustavo A. B. |last5=Rylands |first5=Anthony B. |last6=Konstant |first6=William R. |last7=Flick |first7=Penny |last8=Pilgrim |first8=John |last9=Oldfield |first9=Sara |last10=Magin |first10=Georgina |last11=Hilton-Taylor |first11=Craig |date=August 2002 |title=Habitat Loss and Extinction in the Hotspots of Biodiversity |url=https://doi.org/10.1046/j.1523-1739.2002.00530.x |journal=Conservation Biology |volume=16 |issue=4 |pages=909–923 |doi=10.1046/j.1523-1739.2002.00530.x |bibcode=2002ConBi..16..909B |s2cid=44009934 |issn=0888-8892|url-access=subscription }}</ref>

One solution to the problem of habitat fragmentation is to link the fragments by preserving or planting [[Habitat corridor|corridors]] of native vegetation. In some cases, a bridge or underpass may be enough to join two fragments.<ref>{{cite web|title=Wildlife Crossings: Animals survive with bridges and tunnels|url=http://www.wilderutopia.com/environment/wildlife/wildlife-crossings-animals-survive-bridges-tunnels/|publisher=Wilder Eutopia|access-date=19 December 2017|date=2013-05-19}}</ref> This has the potential to mitigate the problem of isolation but not the loss of interior habitat. Wildlife corridors can help animals to move and occupy new areas when food sources or other natural resources are lacking in their core habitat, and animals can find new mates in neighbouring regions so that [[genetic diversity]] can increase. Species that relocate seasonally can do so more safely and effectively when it does not interfere with human development barriers.

Due to the continuous expansion of urban landscapes, current research is looking at [[green roof]]s being possible vectors of habitat corridors.  A recent study has found that green roofs are beneficial in connecting the habitats of arthropods, specifically bees and weevils.<ref>{{Cite journal |last1=Braaker |first1=S. |last2=Ghazoul |first2=J. |last3=Obrist |first3=M. K. |last4=Moretti |first4=M. |date=April 2014 |title=Habitat connectivity shapes urban arthropod communities: the key role of green roofs |url=http://dx.doi.org/10.1890/13-0705.1 |journal=Ecology |volume=95 |issue=4 |pages=1010–1021 |doi=10.1890/13-0705.1 |pmid=24933819 |bibcode=2014Ecol...95.1010B |s2cid=41070926 |issn=0012-9658}}</ref>

Another mitigation measure is the enlargement of small remnants to increase the amount of interior habitat. This may be impractical since developed land is often more expensive and could require significant time and effort to restore.

The best solution is generally dependent on the particular species or ecosystem that is being considered. More mobile species, like most birds, do not need connected habitat while some smaller animals, like rodents, may be more exposed to predation in open land. These questions generally fall under the headings of [[metapopulation]]s [[island biogeography]].

=== Genetic risks ===
As the remaining habitat patches are smaller, they tend to support smaller populations of fewer species.<ref>{{cite book|last1=Simberloff|first1=Daniel|date=1 January 1998|chapter=Small and Declining Populations|title=Conservation Science and Action|language=en|pages=116–134|doi=10.1002/9781444313499.ch6|isbn=978-1-4443-1349-9}}</ref> Small populations are at an increased risk of a variety of genetic consequences that influence their long-term survival.<ref>{{cite book|title=Introduction to conservation genetics|last1=Frankham|first1=Richard|last2=Ballou|first2=Jonathan D.|last3=Briscoe|first3=David A.|date=2009|publisher=Cambridge University Press|isbn=978-0-521-70271-3|edition=2nd|location=Cambridge}}</ref> Remnant populations often contain only a subset of the genetic diversity found in the previously continuous habitat. In these cases, processes that act upon underlying genetic diversity, such as [[adaptation]], have a smaller pool of fitness-maintaining alleles to survive in the face of environmental change. However, in some scenarios, where subsets of genetic diversity are partitioned among multiple habitat fragments, almost all original genetic diversity can be maintained despite each individual fragment displaying a reduced subset of diversity.<ref name="Borrell2018">{{cite journal |last1=Borrell |first1=James S. |last2=Wang |first2=Nian |last3=Nichols |first3=Richard A. |last4=Buggs |first4=Richard J. A. |title=Genetic diversity maintained among fragmented populations of a tree undergoing range contraction |journal=Heredity |date=15 August 2018 |volume=121 |issue=4 |pages=304–318 |doi=10.1038/s41437-018-0132-8 |pmid=30111882 |pmc=6134035|bibcode=2018Hered.121..304B }}</ref><ref>{{Cite journal |last1=Mustajärvi |first1=Kaisa |last2=Siikamäki |first2=Pirkko |last3=Rytkönen |first3=Saara |last4=Lammi |first4=Antti |date=2001 |title=Consequences of plant population size and density for plant-pollinator interactions and plant performance: Plant-pollinator interactions |journal=Journal of Ecology |language=en |volume=89 |issue=1 |pages=80–87 |doi=10.1046/j.1365-2745.2001.00521.x|s2cid=84923092 |doi-access=free }}</ref>

==== Gene Flow and Inbreeding ====
[[Gene flow]] occurs when individuals of the same species exchange genetic information through reproduction. Populations can maintain genetic diversity through [[Animal migration|migration]]. When a habitat becomes fragmented and reduced in area, gene flow and migration are typically reduced. Fewer individuals will migrate into the remaining fragments, and small disconnected populations that may have once been part of a single large population will become reproductively isolated. Scientific evidence that gene flow is reduced due to fragmentation depends on the study species. While trees that have long-range pollination and dispersal mechanisms may not experience reduced gene flow following fragmentation,<ref>{{cite journal |last1=Kramer |first1=Andrea T. |last2=Ison |first2=Jennifer L. |last3=Ashley |first3=Mary V. |last4=Howe |first4=Henry F. |title=The Paradox of Forest Fragmentation Genetics |journal=Conservation Biology |date=August 2008 |volume=22 |issue=4 |pages=878–885 |doi=10.1111/j.1523-1739.2008.00944.x |pmid=18544089|bibcode=2008ConBi..22..878K |s2cid=1665248 }}</ref> most species are at risk of reduced gene flow following habitat fragmentation.<ref name="Lienert2004" />

Reduced gene flow, and reproductive isolation can result in [[inbreeding]] between related individuals. Inbreeding does not always result in negative fitness consequences, but when inbreeding is associated with fitness reduction it is called [[inbreeding depression]]. Inbreeding becomes of increasing concern as the level of [[homozygosity]] increases, facilitating the expression of deleterious alleles that reduce the fitness. Habitat fragmentation can lead to inbreeding depression for many species due to reduced gene flow.<ref name="Pavolva2017">{{cite journal |last1=Pavlova |first1=Alexandra |last2=Beheregaray |first2=Luciano B. |last3=Coleman |first3=Rhys |last4=Gilligan |first4=Dean |last5=Harrisson |first5=Katherine A. |last6=Ingram |first6=Brett A. |last7=Kearns |first7=Joanne |last8=Lamb |first8=Annika M. |last9=Lintermans |first9=Mark |last10=Lyon |first10=Jarod |last11=Nguyen |first11=Thuy T. T. |last12=Sasaki |first12=Minami |last13=Tonkin |first13=Zeb |last14=Yen |first14=Jian D. L. |last15=Sunnucks |first15=Paul |title=Severe consequences of habitat fragmentation on genetic diversity of an endangered Australian freshwater fish: A call for assisted gene flow |journal=Evolutionary Applications |date=July 2017 |volume=10 |issue=6 |pages=531–550 |doi=10.1111/eva.12484 |pmid=28616062 |pmc=5469170|bibcode=2017EvApp..10..531P }}</ref><ref>{{cite journal |last1=Wang |first1=W |last2=Qiao |first2=Y |last3=Li |first3=S |last4=Pan |first4=W |last5=Yao |first5=M |title=Low genetic diversity and strong population structure shaped by anthropogenic habitat fragmentation in a critically endangered primate, Trachypithecus leucocephalus |journal=Heredity |date=15 February 2017 |volume=118 |issue=6 |pages=542–553 |doi=10.1038/hdy.2017.2 |pmid=28198816 |pmc=5436025|bibcode=2017Hered.118..542W }}</ref> Inbreeding depression is associated with conservation risks, like local extinction.<ref>{{Cite journal|last1=Hedrick|first1=Philip W.|last2=Kalinowski|first2=Steven T.|date=November 2000|title=Inbreeding Depression in Conservation Biology|journal=Annual Review of Ecology and Systematics|language=en|volume=31|issue=1|pages=139–162|doi=10.1146/annurev.ecolsys.31.1.139|bibcode=2000AnRES..31..139H |issn=0066-4162}}</ref>

==== Genetic drift ====
Small populations are more susceptible to [[genetic drift]]. Genetic drift is random changes to the genetic makeup of populations and leads to reductions in genetic diversity. The smaller the population is, the more likely genetic drift will be a driving force of evolution rather than natural selection. Because genetic drift is a random process, it does not allow species to become more adapted to their environment. Habitat fragmentation is associated with increases to genetic drift in small populations which can have negative consequences for the genetic diversity of the populations.<ref name="Pavolva2017" /> However, research suggests that some tree species may be resilient to the negative consequences of genetic drift until population size is as small as ten individuals or less.<ref name="Borrell2018" />

===== Genetic consequences of habitat fragmentation for plant populations =====

Habitat fragmentation decreases the size and increases plant populations' spatial isolation. With [[genetic variation]] and increased methods of inter-population [[genetic divergence]] due to increased effects of [[Genetic drift|random genetic drift]], elevating [[inbreeding]] and reducing gene flow within plant species. While genetic variation may decrease with remnant population size, not all fragmentation events lead to genetic losses and different types of genetic variation. Rarely, fragmentation can also increase gene flow among remnant populations, breaking down local genetic structure.<ref>{{Cite journal|last1=Young|first1=Andrew|last2=Boyle|first2=Tim|last3=Brown|first3=Tony|date=1996|title=The population genetic consequences of habitat fragmentation for plants|journal=Trends in Ecology & Evolution|language=en|volume=11|issue=10|pages=413–418|doi=10.1016/0169-5347(96)10045-8|pmid=21237900|bibcode=1996TEcoE..11..413Y }}</ref>

==== Adaptation ====
In order for populations to evolve in response to natural selection, they must be large enough that natural selection is a stronger evolutionary force than genetic drift. Recent studies on the impacts of habitat fragmentation on adaptation in some plant species have suggested that organisms in fragmented landscapes may be able to adapt to fragmentation.<ref>{{cite journal |last1=Matesanz |first1=Silvia |last2=Rubio Teso |first2=María Luisa |last3=García-Fernández |first3=Alfredo |last4=Escudero |first4=Adrián |title=Habitat Fragmentation Differentially Affects Genetic Variation, Phenotypic Plasticity and Survival in Populations of a Gypsum Endemic |journal=Frontiers in Plant Science |date=26 May 2017 |volume=8 |pages=843 |doi=10.3389/fpls.2017.00843 |pmid=28603529 |pmc=5445106|doi-access=free |bibcode=2017FrPS....8..843M }}</ref><ref>{{cite journal |last1=Dubois |first1=Jonathan |last2=Cheptou |first2=Pierre-Olivier |title=Effects of fragmentation on plant adaptation to urban environments |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |date=5 December 2016 |volume=372 |issue=1712 |pages=20160038 |doi=10.1098/rstb.2016.0038 |pmid=27920383 |pmc=5182434}}</ref> However, there are also many cases where fragmentation reduces adaptation capacity because of small population size.<ref>{{cite journal |last1=Legrand |first1=Delphine |last2=Cote |first2=Julien |last3=Fronhofer |first3=Emanuel A. |last4=Holt |first4=Robert D. |last5=Ronce |first5=Ophélie |last6=Schtickzelle |first6=Nicolas |last7=Travis |first7=Justin M. J. |last8=Clobert |first8=Jean |title=Eco-evolutionary dynamics in fragmented landscapes |journal=Ecography |date=January 2017 |volume=40 |issue=1 |pages=9–25 |doi=10.1111/ecog.02537 |url=http://aura.abdn.ac.uk/bitstream/2164/9606/1/Legrand_et_al_2016_Ecography.pdf |hdl=2164/9606|doi-access=free |bibcode=2017Ecogr..40....9L }}</ref>

==== Examples of impacted species ====
Some species that have experienced genetic consequences due to habitat fragmentation are listed below: 
[[File:Macquarie perch.jpg|thumb|Macquarie perch]]

* ''[[Macquaria australasica]]''<ref name="Pavolva2017" /><ref>{{Cite web|url=http://fishesofaustralia.net.au/home/species/1594|title=Macquaria australasica|website=fishesofaustralia.net.au|language=en|access-date=2018-06-06}}</ref>
*''[[Fagus sylvatica]]''<ref>{{cite journal |last1=Jump |first1=A. S. |last2=Penuelas |first2=J. |title=Genetic effects of chronic habitat fragmentation in a wind-pollinated tree |journal=Proceedings of the National Academy of Sciences |date=12 May 2006 |volume=103 |issue=21 |pages=8096–8100 |doi=10.1073/pnas.0510127103 |pmid=16698935 |pmc=1472435 |bibcode=2006PNAS..103.8096J|doi-access=free }}</ref>
*''[[Betula nana]]''<ref name="Borrell2018" />
*''[[Rhinella ornata]]''<ref>{{cite journal |last1=Dixo |first1=Marianna |last2=Metzger |first2=Jean Paul |last3=Morgante |first3=João S. |last4=Zamudio |first4=Kelly R. |title=Habitat fragmentation reduces genetic diversity and connectivity among toad populations in the Brazilian Atlantic Coastal Forest |journal=Biological Conservation |date=August 2009 |volume=142 |issue=8 |pages=1560–1569 |doi=10.1016/j.biocon.2008.11.016|bibcode=2009BCons.142.1560D }}</ref>
*''[[Ochotona princeps]]''<ref>{{cite journal |last1=Peacock |first1=Mary M. |last2=Smith |first2=Andrew T. |title=The effect of habitat fragmentation on dispersal patterns, mating behavior, and genetic variation in a pika ( Ochotona princeps ) metapopulation |journal=Oecologia |date=24 November 1997 |volume=112 |issue=4 |pages=524–533 |doi=10.1007/s004420050341 |pmid=28307630 |bibcode=1997Oecol.112..524P |s2cid=2446276}}</ref>
*''[[Uta stansburiana]]''<ref name="Delany2010">{{cite journal |last1=Delaney |first1=Kathleen Semple |last2=Riley |first2=Seth P. D. |last3=Fisher |first3=Robert N. |last4=Fleischer |first4=Robert C. |title=A Rapid, Strong, and Convergent Genetic Response to Urban Habitat Fragmentation in Four Divergent and Widespread Vertebrates |journal=PLOS ONE |date=16 September 2010 |volume=5 |issue=9 |pages=e12767 |doi=10.1371/journal.pone.0012767 |pmid=20862274 |pmc=2940822 |bibcode=2010PLoSO...512767D|doi-access=free }}</ref>
*''[[Plestiodon skiltonianus]]''<ref name="Delany2010" />
*''[[Sceloporus occidentalis]]''<ref name="Delany2010" />
*''[[Chamaea fasciata]]''<ref name="Delany2010" />

=== Effect on animal behaviours===
Although the way habitat fragmentation affects the genetics and extinction rates of species has been heavily studied, fragmentation has also been shown to affect species' behaviours and cultures as well. This is important because social interactions can determine and have an effect on a species' fitness and survival. Habitat fragmentation alters the resources available and the structure of habitats, as a result, alters the behaviours of species and the dynamics between differing species. Behaviours affected can be within a species such as reproduction, mating, foraging, species dispersal, communication and movement patterns or can be behaviours between species such as predator-prey relationships.<ref name="Banks2007">{{cite journal |last1=Banks |first1=Sam C |last2=Piggott |first2=Maxine P |last3=Stow |first3=Adam J |last4=Taylor |first4=Andrea C |title=Sex and sociality in a disconnected world: a review of the impacts of habitat fragmentation on animal social interactions |journal=Canadian Journal of Zoology |date=2007 |volume=85 |issue=10 |pages=1065–1079 |doi=10.1139/Z07-094}}</ref> In addition, when animals happen to venture into unknown areas in between fragmented forests or landscapes, they can supposedly come into contact with humans which puts them at a great risk and further decreases their chances of survival.<ref name="Haddad2015">{{Cite journal|last1=Haddad|first1=Nick M.|last2=Brudvig|first2=Lars A.|last3=Clobert|first3=Jean|last4=Davies|first4=Kendi F.|last5=Gonzalez|first5=Andrew|last6=Holt|first6=Robert D.|last7=Lovejoy|first7=Thomas E.|last8=Sexton|first8=Joseph O.|last9=Austin|first9=Mike P.|last10=Collins|first10=Cathy D.|last11=Cook|first11=William M.|date=2015-03-01|title=Habitat fragmentation and its lasting impact on Earth's ecosystems|journal=Science Advances|language=en|volume=1|issue=2|pages=e1500052|doi=10.1126/sciadv.1500052|pmid=26601154|pmc=4643828|bibcode=2015SciA....1E0052H|issn=2375-2548}}{{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref>

==== Predation behaviours ====
Habitat fragmentation due to anthropogenic activities has been shown to greatly affect the predator-prey dynamics of many species by altering the number of species and the members of those species.<ref name="Banks2007" /> This affects the natural predator-prey relationships between animals in a given community <ref name="Banks2007" /> and forces them to alter their behaviours and interactions, therefore resetting the so-called "behavioral space race".<ref name="Shneider2001">{{cite journal |last1=Shneider |first1=Michael F |title=Habitat loss, fragmentation and predator impact: spatial implications for prey conservation |journal=Journal of Applied Ecology |date=2001 |volume=38 |issue=4 |pages=720–735|doi=10.1046/j.1365-2664.2001.00642.x|bibcode=2001JApEc..38..720S |doi-access=free }}</ref> The way in which fragmentation changes and re-shapes these interactions can occur in many different forms. Most prey species have patches of land that are a refuge from their predators, allowing them the safety to reproduce and raise their young. Human introduced structures such as roads and pipelines alter these areas by facilitating predator activity in these refuges, increasing predator-prey overlap.<ref name="Shneider2001" /> The opposite could also occur in the favour of prey, increasing prey refuge and subsequently decreasing predation rates. Fragmentation may also increase predator abundance or predator efficiency and therefore increase predation rates in this manner.<ref name="Shneider2001" /> Several other factors can also increase or decrease the extent to which the shifting predator-prey dynamics affect certain species, including how diverse a predators diet is and how flexible habitat requirements are for predators and prey.<ref name="Banks2007" /> Depending on which species are affected and these other factors, fragmentation and its effects on predator-prey dynamics may contribute to species extinction.<ref name="Banks2007" /> In response to these new environmental pressures, new adaptive behaviours may be developed. Prey species may adapt to increased risk of predation with strategies such as altering mating tactics or changing behaviours and activities related to food and foraging.<ref name="Banks2007" />

===== Boreal woodland caribous =====
In the boreal woodland caribous of British Columbia, the effects of fragmentation are demonstrated. The species refuge area is peatland bog which has been interrupted by linear features such as roads and pipelines.<ref name="DeMars2017">{{cite journal |last1=DeMars |first1=Craig A |last2=Boutin |first2=Stan |title=Nowhere to hide: Effects of linear features on predator-prey dynamics in a large mammal system |journal=Journal of Animal Ecology |date=September 4, 2017 |volume=87 |issue=1 |pages=274–284 |doi=10.1111/1365-2656.12760|pmid=28940254 |doi-access=free}}</ref> These features have allowed their natural predators, the wolf, and the black bear to more efficiently travel over landscapes and between patches of land.<ref name="DeMars2017" /> Since their predators can more easily access the caribous' refuge, the females of the species attempt to avoid the area, affecting their reproductive behaviours and offspring produced.<ref name="DeMars2017" />

==== Communication behaviours ====
Fragmentation affecting the communication behaviours of birds has been well studied in Dupont's Lark. The Larks primarily reside in regions of Spain and are a small passerine bird which uses songs as a means of cultural transmission between members of the species.<ref name="DeMars2017" /> The Larks have two distinct vocalizations, the song, and the territorial call. The territorial call is used by males to defend and signal territory from other male Larks and is shared between neighbouring territories when males respond to a rivals song.<ref name="Laiolo2005">{{cite journal |last1=Laiolo |first1=Paola |last2=Tella |first2=José L |title=Habitat fragmentation affects culture transmission: patterns of song matching in Dupont's lark |journal=Journal of Applied Ecology |date=2005 |volume=42 |issue=6 |pages=1183–1193 |doi=10.1111/j.1365-2664.2005.01093.x|bibcode=2005JApEc..42.1183L |hdl=10261/57878 |hdl-access=free}}</ref> Occasionally it is used as a threat signal to signify an impending attack on territory.<ref name="Laiolo2007">{{cite journal |last1=Laiolo |first1=Paola |last2=Tella |first2=José L |title=Erosion of animal cultures in fragmented landscapes |journal= Frontiers in Ecology and the Environment|date=2007 |volume=5 |issue=2 |pages=68–72 |doi=10.1890/1540-9295(2007)5[68:eoacif]2.0.co;2}}</ref> A large song repertoire can enhance a male's ability to survive and reproduce as he has a greater ability to defend his territory from other males, and a larger number of males in the species means a larger variety of songs being transmitted.<ref name="Laiolo2005" /> Fragmentation of the Dupont's Lark territory from agriculture, forestry and urbanization appears to have a large effect on their communication structures.<ref name="Laiolo2007" /> Males only perceive territories of a certain distance to be rivals and so isolation of territory from others due to fragmentation leads to a decrease in territorial calls as the males no longer have any reason to use it or have any songs to match.<ref name="Laiolo2007" />

[[Human]]s have also brought on varying implications into ecosystems which in turn affect animal behaviour and responses generated.<ref>{{Cite journal|last1=Wong|first1=B. B. M.|last2=Candolin|first2=U.|date=2015-05-01|title=Behavioral responses to changing environments|journal=Behavioral Ecology|language=en|volume=26|issue=3|pages=665–673|doi=10.1093/beheco/aru183|issn=1045-2249|doi-access=free|hdl=10.1093/beheco/aru183|hdl-access=free}}</ref> Although there are some species which are able to survive these kinds of harsh conditions, such as, cutting down wood in the forests for [[Pulp and paper industry|pulp and paper]] industries, there are animals which can survive this change but some that cannot. An example includes, varying [[aquatic insect]]s are able to identify appropriate ponds to lay their eggs with the aid of [[Polarized light pollution|polarized light]] to guide them, however, due to [[ecosystem]] modifications caused by humans they are led onto artificial structures which emit artificial light which are induced by dry asphalt dry roads for an example.<ref>{{Cite web|url=https://www.researchgate.net/publication/221958968|title=polarized Light Pollution: a new kind of ecological photopollution|website=Research Gate}}</ref>

=== Effect on microorganisms ===
While habitat fragmentation is often associated with its effects on large plant and animal populations and biodiversity, due to the interconnectedness of ecosystems there are also significant effects that it has on the [[microbiota]] of an environment. Increased fragmentation has been linked to reduced populations and diversity of fungi responsible for decomposition, as well as the insects they are host to.<ref name="Nordén2013">{{Cite journal|last1=Nordén|first1=Jenni|last2=Penttilä|first2=Reijo|last3=Siitonen|first3=Juha|last4=Tomppo|first4=Erkki|last5=Ovaskainen|first5=Otso|date=May 2013|editor-last=Thrall|editor-first=Peter|title=Specialist species of wood-inhabiting fungi struggle while generalists thrive in fragmented boreal forests|journal=Journal of Ecology|language=en|volume=101|issue=3|pages=701–712|doi=10.1111/1365-2745.12085|s2cid=85037421 |issn=0022-0477|doi-access=free|bibcode=2013JEcol.101..701N }}</ref><ref>{{Cite journal |last1=Kiesewetter |first1=Kasey N. |last2=Otano |first2=Leydiana |last3=Afkhami |first3=Michelle E. |date=June 2023 |title=Fragmentation disrupts microbial effects on native plant community productivity |url=https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2745.14097 |journal=Journal of Ecology |language=en |volume=111 |issue=6 |pages=1292–1307 |doi=10.1111/1365-2745.14097 |bibcode=2023JEcol.111.1292K |issn=0022-0477}}</ref> This has been linked to simplified food webs in highly fragmented areas compared to old growth forests.<ref>{{Cite journal|last1=Komonen|first1=Atte|last2=Penttila|first2=Reijo|last3=Lindgren|first3=Mariko|last4=Hanski|first4=Ilkka|date=July 2000|title=Forest fragmentation truncates a food chain based on an old-growth forest bracket fungus|journal=Oikos|language=en|volume=90|issue=1|pages=119–126|doi=10.1034/j.1600-0706.2000.900112.x|bibcode=2000Oikos..90..119K |issn=0030-1299}}</ref> Furthermore, edge effects have been shown to result in significantly varied [[Microenvironment (ecology)|microenvironments]] compared to interior forest due to variations in light availability, presence of wind, changes in precipitation, and overall moisture content of leaf litter.<ref>{{Cite journal|last=Matlack|first=Glenn R.|date=1993|title=Microenvironment variation within and among forest edge sites in the eastern United States|journal=Biological Conservation|language=en|volume=66|issue=3|pages=185–194|doi=10.1016/0006-3207(93)90004-K|bibcode=1993BCons..66..185M }}</ref> These microenvironments are often not conducive to overall forest health as they enable [[Generalist and specialist species|generalist]] species to thrive at the expense of [[Generalist and specialist species|specialists]] that depend on specific environments.<ref name="Nordén2013" />

=== Effect on mutualistic and antagonistic relationships ===
A [[metadata]] analysis has found that habitat fragmentation greatly affects [[Mutualism (biology)|mutualistic]] relationships while affecting antagonistic relationships, such as [[predation]] and [[Herbivore|herbivory]], to a less degree.<ref>{{Cite journal |last1=Magrach |first1=Ainhoa |last2=Laurance |first2=William F. |last3=Larrinaga |first3=Asier R. |last4=Santamaria |first4=Luis |date=October 2014 |title=Meta-Analysis of the Effects of Forest Fragmentation on Interspecific Interactions: Forest Fragmentation and Interspecific Interactions |url=https://onlinelibrary.wiley.com/doi/10.1111/cobi.12304 |journal=Conservation Biology |language=en |volume=28 |issue=5 |pages=1342–1348 |doi=10.1111/cobi.12304|pmid=24725007 |s2cid=5526322 |url-access=subscription }}</ref> For example, the mutualistic relationship between ''[[Mesogyne insignis]]'' and ''[[Megachile]]''. A study has found greater [[pollination]] and increased fruit production of ''M. insignis'' in unfragmented forests verses fragmented forests.<ref>{{Cite journal |last1=Olotu |first1=Moses I. |last2=Ndangalasi |first2=Henry J. |last3=Nyundo |first3=Bruno A. |date=March 2012 |title=Effects of forest fragmentation on pollination of Mesogyne insignis (Moraceae) in Amani Nature Reserve forests, Tanzania: Effects of forest fragmentation on pollination of Mesogyne insignis |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2028.2011.01302.x |journal=African Journal of Ecology |language=en |volume=50 |issue=1 |pages=109–116 |doi=10.1111/j.1365-2028.2011.01302.x|url-access=subscription }}</ref>  As for an example of an antagonistic relationship of nest predation, a study found that there is no increase in nest predation on fragmented forests - thus not supporting the [[Edge effects|edge effect]] hypothesis.<ref>{{Cite journal |last1=Carlson |first1=Allan |last2=Hartman |first2=Göran |date=2001 |title=Tropical forest fragmentation and nest predation – an experimental study in an Eastern Arc montane forest, Tanzania |url=http://link.springer.com/10.1023/A:1016649731062 |journal=Biodiversity and Conservation |volume=10 |issue=7 |pages=1077–1085 |doi=10.1023/A:1016649731062|bibcode=2001BiCon..10.1077C |s2cid=20971928 |url-access=subscription }}</ref>

=== Effect on ecosystem services ===
Habitat fragmentation has profound effects on [[ecosystem service]]s, impacting nutrient retention, species richness, and local biophysical conditions. Fragmentation-mediated processes cause generalizable responses at the [[population]], [[Community (ecology)|community]], and [[ecosystem]] levels, resulting in decreased nutrient retention.<ref>{{Cite journal |last1=Li |first1=Dehuan |last2=Yang |first2=Yixuan |last3=Xia |first3=Fan |last4=Sun |first4=Wei |last5=Li |first5=Xiao |last6=Xie |first6=Yujing |date=2022-11-01 |title=Exploring the influences of different processes of habitat fragmentation on ecosystem services |url=https://doi.org/10.1016/j.landurbplan.2022.104544 |journal=Landscape and Urban Planning |volume=227 |pages=104544 |doi=10.1016/j.landurbplan.2022.104544 |bibcode=2022LUrbP.22704544L |issn=0169-2046|url-access=subscription }}</ref> Furthermore, habitat fragmentation alters relationships between biodiversity and ecosystem functioning across multiple scales, affecting both the local loss of [[biodiversity]] and the local loss of function.<ref name="ReferenceA"/> Moreover, fragmentation can change the [[microclimate]] at both local and regional scales, influencing biodiversity through interactions with anthropogenic [[climate change]].<ref>{{Cite journal |last1=Wilson |first1=Maxwell C. |last2=Chen |first2=Xiao-Yong |last3=Corlett |first3=Richard T. |last4=Didham |first4=Raphael K. |last5=Ding |first5=Ping |last6=Holt |first6=Robert D. |last7=Holyoak |first7=Marcel |last8=Hu |first8=Guang |last9=Hughes |first9=Alice C. |last10=Jiang |first10=Lin |last11=Laurance |first11=William F. |last12=Liu |first12=Jiajia |last13=Pimm |first13=Stuart L. |last14=Robinson |first14=Scott K. |last15=Russo |first15=Sabrina E. |date=2016-02-01 |title=Habitat fragmentation and biodiversity conservation: key findings and future challenges |url=https://doi.org/10.1007/s10980-015-0312-3 |journal=Landscape Ecology |language=en |volume=31 |issue=2 |pages=219–227 |doi=10.1007/s10980-015-0312-3 |bibcode=2016LaEco..31..219W |issn=1572-9761}}</ref> Overall, habitat fragmentation significantly disrupts ecosystem services by altering nutrient retention, biodiversity, and ecosystem functioning at various spatial and temporal scales.