Editing Cladistics (section)

=== Hybridization, interbreeding ===
Anything having to do with biology and sex is complicated and messy, and cladistics is no exception.<ref>{{Cite web |title=Introduction to Cladistics |url=https://ucmp.berkeley.edu/clad/clad1.html |access-date=2022-05-08 |website=ucmp.berkeley.edu}}</ref> Many species reproduce sexually, and are capable of interbreeding for millions of years. Worse, during such a period, many branches may have radiated, and it may take hundreds of millions of years for them to have whittled down to just two.<ref>{{Cite journal |last1=Harrison |first1=Richard G. |last2=Larson |first2=Erica L. |date=2014-01-01 |title=Hybridization, Introgression, and the Nature of Species Boundaries |journal=Journal of Heredity |volume=105 |issue=S1 |pages=795–809 |doi=10.1093/jhered/esu033 |pmid=25149255 |issn=0022-1503|doi-access=free }}</ref> Only then one can theoretically assign proper last common ancestors of groupings which do not inadvertently include earlier branches.<ref name="Hörandl-2010">{{Cite journal |last1=Hörandl |first1=Elvira |last2=Stuessy |first2=Tod F. |date=2010 |title=Paraphyletic groups as natural units of biological classification |url=https://www.jstor.org/stable/41059863 |journal=Taxon |volume=59 |issue=6 |pages=1641–1653 |doi=10.1002/tax.596001 |jstor=41059863 |issn=0040-0262}}</ref> The process of true cladistic bifurcation can thus take a much more extended time than one is usually aware of.<ref>{{Cite journal |last1=Mehta |first1=Rohan S. |last2=Rosenberg |first2=Noah A. |date=2019-10-01 |title=The probability of reciprocal monophyly of gene lineages in three and four species |journal=Theoretical Population Biology |language=en |volume=129 |pages=133–147 |doi=10.1016/j.tpb.2018.04.004|pmid=29729946 |pmc=6215533 |bibcode=2019TPBio.129..133M }}</ref> In practice, for recent radiations, cladistically guided findings only give a coarse impression of the complexity. A more detailed account will give details about fractions of introgressions between groupings, and even geographic variations thereof. This has been used as an argument for the use of paraphyletic  groupings,<ref name="Hörandl-2010" /> but typically other reasons are quoted.