Editing Speciation (section)

=== Hybrid speciation ===
{{Main|Hybrid speciation}}

Hybridization between two different species sometimes leads to a distinct [[phenotype]]. This phenotype can also be fitter than the parental lineage and as such natural selection may then favor these individuals. Eventually, if reproductive isolation is achieved, it may lead to a separate species. However, reproductive isolation between hybrids and their parents is particularly difficult to achieve and thus hybrid speciation is considered an extremely rare event. The [[Mariana mallard]] is thought to have arisen from hybrid speciation.{{Citation needed|date=November 2023}}

Hybridization is an important means of speciation in plants, since [[polyploid]]y (having more than two copies of each [[chromosome]]) is tolerated in plants more readily than in animals.<ref name=Wendel>{{cite journal |last=Wendel |first=Jonathan F. |date=January 2000 |title=Genome evolution in polyploids |journal=Plant Molecular Biology |volume=42 |issue=1 |pages=225–249 |doi=10.1023/A:1006392424384 |pmid=10688139|s2cid=14856314 }}</ref><ref name=Semon>{{cite journal |last1=Sémon |first1=Marie |last2=Wolfe |first2=Kenneth H. |date=December 2007 |title=Consequences of genome duplication |journal=[[Current Opinion (Elsevier)|Current Opinion in Genetics & Development]] |volume=17 |issue=6 |pages=505–512 |doi=10.1016/j.gde.2007.09.007 |pmid=18006297}}</ref> Polyploidy is important in hybrids as it allows reproduction, with the two different sets of chromosomes each being able to pair with an identical partner during meiosis.<ref name="Comai_2005"/> Polyploids also have more genetic diversity, which allows them to avoid [[inbreeding depression]] in small populations.<ref>{{cite journal |last1=Soltis |first1=Pamela S. |author-link1=Pamela S. Soltis |last2=Soltis |first2=Douglas E. |date=June 20, 2000 |title=The role of genetic and genomic attributes in the success of polyploids |journal=PNAS |volume=97 |issue=13 |pages=7051–7057 |doi=10.1073/pnas.97.13.7051 |pmc=34383 |pmid=10860970 |bibcode=2000PNAS...97.7051S|doi-access=free }}</ref>

Hybridization without change in chromosome number is called homoploid hybrid speciation. It is considered very rare but has been shown in ''[[Heliconius]]'' [[butterfly|butterflies]]<ref name="Mavarez2006">{{cite journal |last1=Mavarez |first1=Jesús |last2=Salazar |first2=Camilo A. |last3=Bermingham |first3=Eldredge |last4=Salcedo |first4=Christian |last5=Jiggins |first5=Chris D. |last6=Linares |first6=Mauricio |display-authors=3 |date=June 15, 2006 |title=Speciation by hybridization in ''Heliconius'' butterflies |journal=[[Nature (journal)|Nature]] |volume=441 |issue=7095 |pages=868–871 |doi=10.1038/nature04738 |pmid=16778888 |bibcode=2006Natur.441..868M|s2cid=2457445 }}</ref> and [[sunflower]]s. Polyploid speciation, which involves changes in chromosome number, is a more common phenomenon, especially in plant species. {{Citation needed|date=November 2023}}