Editing Invasive species (section)

== Causes ==
Typically, an introduced species must survive at low population densities before it becomes invasive in a new location.<ref name="tilm">{{cite journal |last=Tilman |first=D. |year=2004 |title=Niche tradeoffs, neutrality, and community structure: A stochastic theory of resource competition, invasion, and community assembly |journal=[[Proceedings of the National Academy of Sciences]] |volume=101 |pages=10854–10861 |doi=10.1073/pnas.0403458101 |pmid=15243158 |issue=30 |pmc=503710 |bibcode=2004PNAS..10110854T |doi-access=free }}</ref> At low population densities, it can be difficult for the introduced species to reproduce and maintain itself in a new location, so a species might need to reach a location multiple times before it becomes established. Repeated patterns of human movement, such as ships sailing to and from ports or cars driving up and down highways, offer repeated opportunities for establishment (a high [[propagule pressure]]).<ref name="verl">{{cite journal |last=Verling |first=E. |year=2005 |title=Supply-side invasion ecology: characterizing propagule pressure in coastal ecosystems |journal=[[Proceedings of the Royal Society B]] |volume=272 |pages=1249–1256 |doi=10.1098/rspb.2005.3090 |pmid=16024389 |issue=1569 |pmc=1564104}}</ref> 

=== Ecosystem-based mechanisms ===
In [[ecosystem]]s, the availability of resources determines the impact of additional species on the ecosystem. Stable ecosystems have a resource equilibrium, which can be changed fundamentally by the arrival of invasive species.<ref name="Byers 2002">{{cite journal |last1=Byers |first1=James E. |title=Impact of non-indigenous species on natives enhanced by anthropogenic alteration of selection regimes |journal=Oikos |date=June 2002 |volume=97 |issue=3 |pages=449–458 |doi=10.1034/j.1600-0706.2002.970316.x |bibcode=2002Oikos..97..449B }}</ref> When changes such as a [[forest fire]] occur, normal [[ecological succession]] favors native [[Graminoid|grasses]] and [[forb]]s. An introduced species that can spread faster than natives can outcompete native species for food, squeezing them out. [[Nitrogen]] and [[phosphorus]] are often the limiting factors in these situations.<ref name="Davis 2000 528–534">{{cite journal |last1=Davis |first1=M.A. |last2=Grime |first2=J.P. |last3=Thompson |first3=K. |s2cid=14573817 |year=2000 |title=Fluctuating resources in plant communities: A general theory of invisibility |journal=[[Journal of Ecology]] |volume=88 |issue=3 |pages=528–534 |doi=10.1046/j.1365-2745.2000.00473.x|doi-access=free |bibcode=2000JEcol..88..528D }}</ref> Every species occupies an [[ecological niche]] in its native ecosystem; some species fill large and varied roles, while others are highly specialized. Invading species may occupy unused niches, or create new ones.<ref>{{Cite book |last=Fath |first=Brian D. |title=Encyclopedia of Ecology |url=https://archive.org/details/encyclopediaecol00jorg |url-access=limited |publisher=Elsevier Science |edition=1st |year=2008 |isbn=978-0444520333 |location=Amsterdam, the Netherlands |page=[https://archive.org/details/encyclopediaecol00jorg/page/n1122 1089]}}</ref> For example, [[edge effect]]s describe what happens when part of an ecosystem is disturbed, as in when land is cleared for [[agriculture]]. The boundary between the remaining undisturbed habitat and the newly cleared land itself forms a distinct habitat, creating new winners and losers and possibly hosting species that would not thrive outside the boundary habitat.<ref>{{Cite journal |last1=Alverson |first1=William S. |last2=Waller |first2=Donald M. |last3=Solheim |first3=Stephen L. |date=1988 |title=Forests Too Deer: Edge Effects in Northern Wisconsin |journal=[[Conservation Biology (journal)|Conservation Biology]] |volume=2 |issue=4 |pages=348–358 |doi=10.1111/j.1523-1739.1988.tb00199.x |jstor=2386294|bibcode=1988ConBi...2..348A }}</ref>

In 1958, [[Charles S. Elton]] claimed that ecosystems with higher [[species diversity]] were less subject to invasive species because fewer niches remained unoccupied.<ref name="elton">{{cite book |last=Elton |first=C.S. |others=Foreword by Daniel Simberloff |title=The Ecology of Invasions by Animals and Plants |orig-date=1958 |year=2000 |publisher=University of Chicago Press |location=Chicago |isbn=978-0-226-20638-7 |page=196}}</ref> Other ecologists later pointed to highly diverse, but heavily invaded ecosystems, arguing that ecosystems with high species diversity were more susceptible to invasion.<ref name=Schell>{{cite journal |last1=Stohlgren |first1=Thomas J. |last2=Binkley |first2=Dan |last3=Chong |first3=Geneva W. |last4=Kalkhan |first4=Mohammed A. |last5=Schell |first5=Lisa D. |last6=Bull |first6=Kelly A. |last7=Otsuki |first7=Yuka |last8=Newman |first8=Gregory |last9=Bashkin |first9=Michael |last10=Son |first10=Yowhan |display-authors=6 |title=Exotic Plant Species Invade Hot Spots of Native Plant Diversity |journal=Ecological Monographs |date=February 1999 |volume=69 |issue=1 |pages=25–46 |doi=10.1890/0012-9615(1999)069[0025:EPSIHS]2.0.CO;2 }}</ref> This debate hinged on the [[Scale (spatial)|spatial scale]] of invasion studies. Small-scale studies tended to show a negative relationship between [[Biodiversity|diversity]] and invasion, while large-scale studies tended to show the reverse, perhaps a side-effect of invasives' ability to capitalize on increased resource availability and weaker species interactions that are more common when larger samples are considered.<ref>{{cite journal |last1=Byers |first1=James E. |last2=Noonburg |first2=Erik G. |title=Scale Dependent Effects of Biotic Resistance to Biological Invasion |journal=Ecology |date=June 2003 |volume=84 |issue=6 |pages=1428–1433 |doi=10.1890/02-3131 |bibcode=2003Ecol...84.1428B }}</ref><ref>{{cite journal |last1=Levine |first1=Jonathan M. |title=Species Diversity and Biological Invasions: Relating Local Process to Community Pattern |journal=Science |date=5 May 2000 |volume=288 |issue=5467 |pages=852–854 |doi=10.1126/science.288.5467.852 |pmid=10797006 |bibcode=2000Sci...288..852L }}</ref> However, this pattern does not seem to hold true for invasive vertebrates.{{r|ivey2019}}

[[File:Brown tree snake (Boiga irregularis) (8387580552).jpg|thumb|right|The [[brown tree snake]] has had an impact on the native bird population of the island ecosystem of Guam.]]

[[Island ecosystem]]s may be more prone to invasion because their species face few strong competitors and predators, and because their distance from colonizing species populations makes them more likely to have "open" niches.<ref name="stach">{{cite book |last=Stachowicz |first=J.J. |editor=D.F. Sax |editor2=J.J. Stachowicz |editor3=S.D. Gaines |title=Species Invasions: Insights into Ecology, Evolution, and Biogeography |publisher=Sinauer Associates |location=Sunderland, Massachusetts |isbn=978-0-87893-811-7 |chapter=Species invasions and the relationships between species diversity, community saturation, and ecosystem functioning |year=2005 |url-access=registration |url=https://archive.org/details/speciesinvasions0000unse }}</ref> For example, native bird populations on [[Guam]] have been decimated by the invasive [[brown tree snake]].<ref>{{Cite web |title=Brown Tree Snake |url=https://www.invasivespeciesinfo.gov/profile/brown-tree-snake |url-status=live |archive-url=https://web.archive.org/web/20190824120114/https://www.invasivespeciesinfo.gov/profile/brown-tree-snake |archive-date=24 August 2019 |website=USDA National Invasive Species Information Center}}</ref> 

In [[Invasive species in New Zealand|New Zealand]] the first invasive species were the dogs and [[Polynesian rat|rats]] brought by Polynesian settlers around 1300. These and other introductions devastated endemic New Zealand species.<ref>{{cite book |last=Howe |first=K. R. |title=The Quest for Origins |year=2003 |page=179 |publisher=Penguin Books |isbn=0-14-301857-4}}</ref><ref>{{Cite news |date=4 June 2008 |title=Rat remains help date New Zealand's colonisation |work=New Scientist |url=https://www.newscientist.com/article/mg19826595-200-rat-remains-help-date-new-zealands-colonisation/?ignored=irrelevant |url-status=live |url-access=subscription |access-date=23 June 2008 |archive-url=https://web.archive.org/web/20220611120716/https://www.newscientist.com/article/mg19826595-200-rat-remains-help-date-new-zealands-colonisation/?ignored=irrelevant |archive-date=11 June 2022}}</ref> The colonization of [[Madagascar]] brought similar harm to its ecosystems.<ref>{{cite journal |last1=Goodman |first1=Steven M. |date=1997 |title=The birds of southeastern Madagascar |journal=Fieldiana |issue=87 |doi=10.5962/bhl.title.3415 |doi-access=free}}</ref> Logging has caused harm directly by destroying habitat, and has allowed non-native species such as [[Opuntia|prickly pear]] and [[Acacia dealbata|silver wattle]] to invade.<ref>{{cite journal |last1=Brown |first1=Kerry A. |last2=Gurevitch |first2=Jessica |title=Long-term impacts of logging on forest diversity in Madagascar |journal=Proceedings of the National Academy of Sciences |date=20 April 2004 |volume=101 |issue=16 |pages=6045–6049 |doi=10.1073/pnas.0401456101 |pmid=15067121 |pmc=395920 |bibcode=2004PNAS..101.6045B |doi-access=free }}</ref><ref>{{cite journal |last1=Kull |first1=Ca |last2=Tassin |first2=J |last3=Carriere |first3=Sm |title=Approaching invasive species in Madagascar |journal=Madagascar Conservation & Development |date=26 February 2015 |volume=9 |issue=2 |pages=60 |doi=10.4314/mcd.v9i2.2 |doi-access=free }}</ref> The [[Eichhornia crassipes|water hyacinth]] forms dense mats on water surfaces, limiting light penetration and hence harming aquatic organisms, and causing substantial management costs.<ref>{{cite journal |last1=Villamagna |first1=A. M. |last2=Murphy |first2=B. R. |title=Ecological and socio-economic impacts of invasive water hyacinth (''Eichhornia crassipes''): a review |journal=Freshwater Biology |date=February 2010 |volume=55 |issue=2 |pages=282–298 |doi=10.1111/j.1365-2427.2009.02294.x |bibcode=2010FrBio..55..282V }}</ref><ref name="Rakotoarisoa 365–379">{{cite journal |last1=Rakotoarisoa |first1=T. F. |last2=Richter |first2=T. |last3=Rakotondramanana |first3=H. |last4=Mantilla-Contreras |first4=J. |title=Turning a Problem Into Profit: Using Water Hyacinth (''Eichhornia crassipes'') for Making Handicrafts at Lake Alaotra, Madagascar |journal=Economic Botany |date=December 2016 |volume=70 |issue=4 |pages=365–379 |doi=10.1007/s12231-016-9362-y |bibcode=2016EcBot..70..365R |s2cid=255557151 |id = {{s2cid|18820290}} }}</ref> The shrub lantana (''[[Lantana camara]]'') is now considered invasive in over 60 countries, and has invaded large geographies in several countries prompting aggressive federal efforts at attempting to control it.<ref>{{Cite journal |last1=Bhagwat |first1=Shonil A. |last2=Breman |first2=Elinor |last3=Thekaekara |first3=Tarsh |last4=Thornton |first4=Thomas F. |last5=Willis |first5=Katherine J. |date=2012 |title=A Battle Lost? Report on Two Centuries of Invasion and Management of Lantana camara L. in Australia, India and South Africa |journal=PLOS ONE |language=en |volume=7 |issue=3 |pages=e32407 |doi=10.1371/journal.pone.0032407 |doi-access=free |pmc=3293794 |pmid=22403653|bibcode=2012PLoSO...732407B }}</ref><ref>{{Cite journal |last1=Mungi |first1=Ninad Avinash |last2=Qureshi |first2=Qamar |last3=Jhala |first3=Yadvendradev V. |date=2020 |title=Expanding niche and degrading forests: Key to the successful global invasion of Lantana camara (sensu lato) |journal=Global Ecology and Conservation |volume=23 |pages=e01080 |doi=10.1016/j.gecco.2020.e01080 |doi-access=free |bibcode=2020GEcoC..2301080M }}</ref>  

Primary geomorphological effects of invasive plants are bioconstruction and bioprotection. For example, kudzu (''[[Pueraria montana]]''), a vine native to Asia, was widely introduced in the [[Southeastern US|southeastern United States]] in the early 20th century to control [[soil erosion]]. The primary geomorphological effects of invasive animals are [[bioturbation]], [[bioerosion]], and bioconstruction. For example, invasions of the Chinese mitten crab (''[[Eriocheir sinensis]]'') have resulted in higher bioturbation and bioerosion rates.<ref>{{cite journal |last1=Fei |first1=Songlin |last2=Phillips |first2=Jonathan |last3=Shouse |first3=Michael |title=Biogeomorphic Impacts of Invasive Species |journal=Annual Review of Ecology, Evolution, and Systematics |date=23 November 2014 |volume=45 |issue=1 |pages=69–87 |doi=10.1146/annurev-ecolsys-120213-091928 |doi-access=free }}</ref>

A native species can become harmful and effectively invasive to its native environment after human alterations to its [[food web]]. This has been the case with the purple sea urchin (''[[Strongylocentrotus purpuratus]]''), which has decimated kelp forests along the northern California coast due to overharvesting of its natural predator, the California sea otter (''[[Sea otter|Enhydra lutris]]'').<ref>{{Cite web |title=Plague of purple sea urchins ravages California's offshore ecosystem, heads to Oregon |website=[[Los Angeles Times]]|date=October 24, 2019|url=https://www.latimes.com/california/story/2019-10-24/purple-sea-urchins-california-oregon-coasts|access-date=July 14, 2021 |archive-date=July 14, 2021 |archive-url=https://web.archive.org/web/20210714030639/https://www.latimes.com/california/story/2019-10-24/purple-sea-urchins-california-oregon-coasts |url-status=live}}</ref>

===Species-based mechanisms===
[[File:Riesenknoeterich.jpg|right|thumb|Japanese knotweed (''[[Reynoutria japonica]]'') is considered one of the [[100 of the World's Worst Invasive Alien Species|world's worst invasive species]].]]
[[File:Ocicat-woodpecker.jpg|upright|thumb|Cats (here, killing a [[woodpecker]]) are [[Cats in Australia|considered invasive species]] in Australia and [[Cat predation on wildlife|negatively impact wildlife]] worldwide.]]

Invasive species appear to have specific traits or specific combinations of traits that allow them to outcompete [[native species]]. In some cases, the competition is about rates of growth and reproduction. In other cases, species interact with each other more directly. One study found that 86% of invasive species could be identified from such traits alone.<ref name="kolar">{{cite journal |last=Kolar |first=C.S. |year=2001 |title=Progress in invasion biology: predicting invaders|journal=[[Trends in Ecology & Evolution]] |volume=16 |issue=4 |pages=199–204 |doi=10.1016/S0169-5347(01)02101-2 |pmid=11245943|s2cid=5796978 }}</ref> Another study found that invasive species often had only a few of the traits, and that noninvasive species had these also.<ref name="kolar"/><ref name="theb">{{cite journal |last=Thebaud |first=C. |year=1996 |title=Assessing why two introduced Conyza differ in their ability to invade Mediterranean old fields |journal=Ecology |volume=77 |issue=3 |pages=791–804 |doi=10.2307/2265502 |jstor=2265502 |bibcode=1996Ecol...77..791T }}</ref><ref name="reichard">{{cite journal |last=Reichard |first=S.H. |s2cid=29816498 |year=1997 |title=Predicting invasions of woody plants introduced into North America |journal=[[Conservation Biology (journal)|Conservation Biology]] |volume=11 |issue=1 |pages=193–203 |doi=10.1046/j.1523-1739.1997.95473.x |pmc=7162396}}</ref> Common invasive species traits include fast growth and rapid [[reproduction]], such as [[vegetative reproduction]] in plants;<ref name="kolar"/><!--high [[Biological dispersal|dispersal]] ability;--><!--[[Phenotypic plasticity|Phenotype plasticity]];--><!--[[ecological competence]];--><!--[[Generalist and specialist species|generalist]];--> association with humans;<ref name="Williams">{{cite book |last=Williams |first=J. D. |year=1998 |chapter=Non-indigenous Species |title=Status and Trends of the Nation's Biological Resources |location=[[Reston, Virginia]] |pages=117–29 |publisher=[[United States Geological Survey]] |isbn=978-0-16-053285-6 |id={{DTIC|ADA368849}} }}</ref> and prior successful invasions.<ref name="ewell">{{cite journal |last=Ewell |first=J.J. |year=1999 |title=Deliberate introductions of species: Research needs – Benefits can be reaped, but risks are high |journal=[[BioScience]] |volume=49 |pages=619–630 |doi=10.2307/1313438 |jstor=1313438 |issue=8 |doi-access=free |bibcode=1999BiSci..49..619E }}</ref> [[Domestic cat]]s are effective predators; they have become feral and invasive in places such as the [[Florida Keys]].<ref name="Cove Gardner 2018">{{cite journal |last1=Cove |first1=Michael V. |last2=Gardner |first2=Beth |last3=Simons |first3=Theodore R. |last4=Kays |first4=Roland |last5=O'Connell |first5=Allan F. |s2cid=3536174 |date=February 1, 2018 |title=Free-ranging domestic cats (''Felis catus'') on public lands: estimating density, activity, and diet in the Florida Keys |journal=[[Biological Invasions]] |volume=20 |issue=2 |pages=333–344 |doi=10.1007/s10530-017-1534-x|bibcode=2018BiInv..20..333C }}</ref>

An introduced species might become invasive if it can outcompete native species for resources. If these species evolved under great [[Competition (biology)|competition]] or [[predation]], then the new environment may host fewer able competitors, allowing the invader to proliferate. [[Ecosystem]]s used to their fullest capacity by native species can be modeled as [[zero-sum]] systems, in which any gain for the invader is a loss for the native. However, such [[unilateral]] competitive superiority (and extinction of native species with increased populations of the invader) is not the rule.<ref name="Schell"/><ref name="sax">{{cite journal |last1=Sax |first1=Dov F. |last2=Gaines |first2=Steven D. |last3=Brown |first3=James H. |title=Species Invasions Exceed Extinctions on Islands Worldwide: A Comparative Study of Plants and Birds |journal=The American Naturalist |date=December 2002 |volume=160 |issue=6 |pages=766–783 |doi=10.1086/343877 |pmid=18707464 |s2cid=8628360 }}</ref> 

[[File:Lantana Invasion of abandoned citrus plantation Sdey Hemed Israel.JPG|right|thumb|upright=1.8|[[Lantana]], abandoned [[citrus grove|citrus]], [[Sdei Hemed]]]]

An invasive species might be able to use resources previously unavailable to native species, such as deep water accessed by a long [[taproot]], or to live on previously uninhabited soil types. For example, [[Aegilops triuncialis|barbed goatgrass]] was introduced to [[California]] on [[serpentine soil]]s, which have low water-retention, low nutrient levels, a high [[magnesium]]/[[calcium]] ratio, and possible [[Heavy metal (chemistry)|heavy metal]] toxicity. Plant populations on these soils tend to show low density, but goatgrass can form dense stands on these soils and crowd out native species.<ref>{{cite journal |last1=Huenneke |first1=Laura Foster |last2=Hamburg |first2=Steven P. |last3=Koide |first3=Roger |last4=Mooney |first4=Harold A. |last5=Vitousek |first5=Peter M. |title=Effects of Soil Resources on Plant Invasion and Community Structure in Californian Serpentine Grassland |journal=Ecology |date=1990 |volume=71 |issue=2 |pages=478–491 |doi=10.2307/1940302 |jstor=1940302 |bibcode=1990Ecol...71..478H }}</ref>

Invasive species might alter their environment by releasing chemical compounds, modifying [[abiotic]] factors, or affecting the behaviour of [[herbivore]]s, impacting on other species. Some, like ''[[Bryophyllum daigremontianum|Kalanchoe daigremontana]]'', produce [[allelopathy|allelopathic compounds]] that inhibit competitors.<ref name="HERRERAFERRER-PARIS2018">{{cite journal |title=An Invasive Succulent Plant (Kalanchoe daigremontiana) Influences Soil Carbon and Nitrogen Mineralization in a Neotropical Semiarid Zone |journal=[[Pedosphere]] |volume=28 |issue=4 |year=2018 |pages=632–643 |doi=10.1016/S1002-0160(18)60029-3 |last1=Herrera |first1=Ileana |last2=Ferrer-Paris |first2=José R. |last3=Benzo |first3=Diana |last4=Flores |first4=Saúl |last5=García |first5=Belkis |last6=Nassar |first6=Jafet M. |bibcode=2018Pedos..28..632H |hdl=1959.4/unsworks_64013 |s2cid=104843296|url=https://unsworks.unsw.edu.au/bitstreams/12acbbad-8af9-444b-a478-e7dc9d941d9b/download |hdl-access=free }}</ref> Others like ''[[Stapelia gigantea]]'' [[ecological facilitation|facilitate]] the growth of seedlings of other species in arid environments by providing appropriate [[microclimate]]s and preventing herbivores from eating seedlings.<ref>{{cite journal |last1=Herrera |first1=Ileana |last2=Ferrer-Paris |first2=José R. |last3=Hernández-Rosas |first3=José I. |last4=Nassar |first4=Jafet M. |title=Impact of two invasive succulents on native-seedling recruitment in Neotropical arid environments |journal=[[Journal of Arid Environments]] |date=2016 |volume=132 |pages=15–25 |doi=10.1016/j.jaridenv.2016.04.007 |bibcode=2016JArEn.132...15H}}</ref>

Changes in [[fire regime]]ns are another form of facilitation. ''[[Bromus tectorum]]'', originally from Eurasia, is highly fire-adapted. It spreads rapidly after burning, and increases the frequency and intensity of fires by providing large amounts of dry [[detritus]] during the fire season in western North America. Where it is widespread, it has altered the local fire regimen so much that native plants cannot survive the frequent fires, allowing it to become dominant in its introduced range.<ref name="Brooks 2004 677–688">{{cite journal |last1=Brooks |first1=Matthew L. |last2=D'Antonio |first2=Carla M. |last3=Richardson |first3=David M. |last4=Grace |first4=James B. |last5=Keeley |first5=Jon E. |last6=DiTOMASO |first6=Joseph M. |last7=Hobbs |first7=Richard J. |last8=Pellant |first8=Mike |last9=Pyke |first9=David |title=Effects of Invasive Alien Plants on Fire Regimes |journal=BioScience |date=2004 |volume=54 |issue=7 |pages=677 |doi=10.1641/0006-3568(2004)054[0677:EOIAPO]2.0.CO;2 |s2cid=13769125 |doi-access=free }}</ref>

[[Ecological facilitation]] occurs where one species physically modifies a habitat in ways advantageous to other species. For example, [[zebra mussel]]s increase habitat complexity on lake floors, providing crevices in which [[invertebrate]]s live. This increase in complexity, together with the nutrition provided by the waste products of mussel [[filter feeder|filter-feeding]], increases the density and diversity of [[Benthic zone|benthic]] invertebrate communities.<ref name="silv">{{cite journal |last1=Silver Botts |first1=P. |last2=Patterson |first2=B.A. |last3=Schlosser |first3=D. |year=1996 |title=Zebra mussel effects on benthic invertebrates: Physical or biotic? |journal=[[Journal of the North American Benthological Society]] |issue=2 |volume=15 |doi=10.2307/1467947 |jstor=1467947 |pages=179–184 |s2cid=84660670 }}</ref>

Introduced species may spread rapidly and unpredictably.<ref>{{Cite book |last=Keddy |first=Paul A. |url=https://books.google.com/books?id=ncloDgAAQBAJ&q=Plant+Ecology |title=Plant Ecology |publisher=Cambridge University Press |year=2017 |isbn=978-1-107-11423-4 |pages=343 |access-date=October 6, 2020 |archive-date=August 16, 2021 |archive-url=https://web.archive.org/web/20210816224645/https://books.google.com/books?id=ncloDgAAQBAJ&q=Plant+Ecology |url-status=live}}</ref> When [[Population bottleneck|bottlenecks]] and [[founder effect]]s cause a great decrease in the population size and may constrict [[genetic variation]],<ref>{{Cite journal |last1=Xu |first1=Cheng-Yuan |last2=Tang |first2=Shaoqing |last3=Fatemi |first3=Mohammad |last4=Gross |first4=Caroline L. |last5=Julien |first5=Mic H. |last6=Curtis |first6=Caitlin |last7=van Klinken |first7=Rieks D. |date=September 1, 2015 |title=Population structure and genetic diversity of invasive Phyla canescens: implications for the evolutionary potential |journal=[[Ecosphere (journal)|Ecosphere]] |volume=6 |issue=9 |pages=art162 |doi=10.1890/ES14-00374.1 |doi-access=free}}</ref> the individuals begin to show additive variance as opposed to epistatic variance. This conversion can lead to increased variance in the founding populations, which permits [[rapid evolution]].<ref name="Prentis 2008 288-294">{{cite journal |last=Prentis |first=Peter |title=Adaptive evolution in invasive species |journal=[[Trends in Plant Science]]|volume=13 |issue=6 |pages=288–294 |doi=10.1016/j.tplants.2008.03.004 |pmid=18467157 |year=2008|bibcode=2008TPS....13..288P |hdl=10019.1/112332 |hdl-access=free }}</ref> Selection may then act on the capacity to disperse as well as on physiological tolerance to new stressors in the environment, such as changed temperature and different predators and prey.<ref name="Eunmi 2002 386-391">{{cite journal |last=Lee |first=Carol Eunmi |title=Evolutionary genetics of invasive species |journal=[[Trends in Ecology & Evolution]]|volume=17 |issue=8 |pages=386–391 |doi=10.1016/s0169-5347(02)02554-5 |year=2002}}</ref> 

Rapid adaptive evolution through intraspecific phenotypic plasticity, [[Exaptation|pre-adaptation]] and post-introduction evolution lead to offspring that have higher fitness. Critically, plasticity permits changes to better suit the individual to its environment. Pre-adaptations and evolution after the introduction reinforce the success of the introduced species.<ref name="Zenni 2013 635-644">{{cite journal |last=Zenni |first=R.D. |title=Adaptive Evolution and Phenotypic Plasticity During Naturalization and Spread of Invasive Species: Implications for Tree Invasion Biology |journal=[[Biological Invasions]] |year=2013 |volume=16 |issue=3 |pages=635–644 |doi=10.1007/s10530-013-0607-8 |s2cid=82590}}</ref>

The [[enemy release hypothesis]] states that evolution leads to ecological balance in every ecosystem. No single species can occupy a majority of an ecosystem due to the presences of competitors, predators, and diseases. Introduced species moved to a novel habitat can become invasive, with rapid population growth, when these controls do not exist in the new ecosystem.{{r|amstutz2018}}