Editing Biodiversity (section)

===Hybridization and genetic pollution===
[[File:Wheat selection k10183-1.jpg|right|thumb|The Yecoro [[wheat]] (right) [[cultivar]] is sensitive to salinity, plants resulting from a hybrid cross with cultivar W4910 (left) show greater tolerance to high salinity]]Endemic species can be threatened with [[extinction]]<ref>{{cite journal |last1=Mooney |first1=H. A. |last2=Cleland |first2=EE |year=2001 |title=The evolutionary impact of invasive species |journal=Proceedings of the National Academy of Sciences |volume=98 |issue=10 |pages=5446–5451 |bibcode=2001PNAS...98.5446M |doi=10.1073/pnas.091093398 |pmc=33232 |pmid=11344292 |doi-access=free}}</ref> through the process of [[genetic pollution]], i.e. uncontrolled [[Hybrid (biology)|hybridization]], [[introgression]] and genetic swamping. Genetic pollution leads to homogenization or replacement of local [[genomes]] as a result of either a numerical and/or [[Fitness (biology)|fitness]] advantage of an introduced species.<ref>{{cite report |last1=Aubry |first1=Carol |last2=Shoal |first2=Robin |last3=Erickson |first3=Vicky |date=January 2005 |title=Grass cultivars: Their origins, development, and use on national forests and grasslands in the Pacific Northwest |publisher=USDA Forest Service |url=https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev7_015644.pdf }}</ref>
Hybridization and introgression are side-effects of introduction and invasion. These phenomena can be especially detrimental to [[rare species]] that come into contact with more abundant ones. The abundant species can interbreed with the rare species, swamping its [[gene pool]]. This problem is not always apparent from [[morphology (biology)|morphological]] (outward appearance) observations alone. Some degree of [[gene flow]] is normal adaptation and not all [[gene]] and [[genotype]] constellations can be preserved. However, hybridization with or without introgression may, nevertheless, threaten a rare species' existence.<ref>{{cite journal |last1=Rhymer |first1=Judith M. |last2=Simberloff |first2=Daniel |year=1996 |title=Extinction by Hybridization and Introgression |journal=Annual Review of Ecology and Systematics |volume=27 |issue=1 |pages=83–109 |doi=10.1146/annurev.ecolsys.27.1.83 |jstor=2097230|bibcode=1996AnRES..27...83R }}</ref><ref name="PottsBarbour2001">{{cite book |last1=Potts |first1=Bradley Michael |last2=Barbour |first2=Robert C. |last3=Hingston |first3=Andrew B. |title=Genetic Pollution from Farm Forestry Using Eucalypt Species and Hydrids: A Report for the RIRDC/L & WA/FWPRDC Joint Venture Agroforestry Program |date=2001 |publisher=RIRDC |isbn=978-0-642-58336-9 }}{{pn|date=October 2024}}</ref><!--this argument seems circular. hybridization is bad because...it limits future hybridization. so...the more genetic engineering the better to limit future hybridization? just sayin'...-->