Editing Speciation (section)

=== Sexual selection ===

[[Sexual selection]] can drive speciation in a clade, independently of [[natural selection]].<ref name=Panhuis>{{cite journal |last1=Panhuis |first1=Tami M. |last2=Butlin |first2=Roger |last3=Zuk |first3=Marlene |author-link3=Marlene Zuk |last4=Tregenza |first4=Tom |display-authors=3 |date=July 2001 |title=Sexual selection and speciation |url=http://www.selfishgene.org/Tom/Papers/TMPetal_TREE01.pdf |journal=[[Trends (journals)|Trends in Ecology & Evolution]] |volume=16 |issue=7 |pages=364–371 |pmid=11403869 |doi=10.1016/s0169-5347(01)02160-7}}</ref> However the term "speciation", in this context, tends to be used in two different, but not mutually exclusive senses. The first and most commonly used sense refers to the "birth" of new species. That is, the splitting of an existing species into two separate species, or the budding off of a new species from a parent species, both driven by a biological "fashion fad" (a preference for a feature, or features, in one or both sexes, that do not necessarily have any adaptive qualities).<ref name=Panhuis /><ref>{{cite journal |last1=Darwin |first1=Charles |author2=A. R. Wallace |title=On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection |journal=Journal of the Proceedings of the Linnean Society of London. Zoology |year=1858 |volume=3 |issue=9 |pages=46–50 |doi= 10.1111/j.1096-3642.1858.tb02500.x|doi-access=free |url=http://darwin-online.org.uk/converted/pdf/1858_species_F350.pdf}}</ref>{{sfn|Darwin|1859|loc=[http://darwin-online.org.uk/content/frameset?viewtype=side&itemID=F373&pageseq=11 "IV. Natural Selection"]|p=89}}<ref>Eberhard, W. G. (1985). Sexual Selection and Animal Genitalia. Harvard University Press, Cambridge, Massachusetts</ref> In the second sense, "speciation" refers to the wide-spread tendency of sexual creatures to be grouped into clearly defined species,{{sfn|Gould|1980|loc="A Quahog is a Quahog"|pp=[https://archive.org/details/pandasthumb000step/page/204 204–213]}}<ref name=Maynard>{{harvnb|Maynard Smith|1989|pp=275–280}}</ref> rather than forming a continuum of [[phenotype]]s both in time and space – which would be the more obvious or logical consequence of natural selection. This was indeed recognized by [[Charles Darwin|Darwin]] as problematic, and included in his ''[[On the Origin of Species]]'' (1859), under the heading "Difficulties with the Theory".<ref name="OofS"/> There are several suggestions as to how [[mate choice]] might play a significant role in resolving [[Speciation#Darwin's_dilemma:_why_do_species_exist|Darwin's dilemma]].<ref name=Maynard /><ref name="Bernstein85">{{cite journal |last1=Bernstein |first1=Harris |last2=Byerly |first2=Henry C. |last3=Hopf |first3=Frederic A. |last4=Michod |first4=Richard E. |display-authors=3 |date=December 21, 1985 |title=Sex and the emergence of species |journal=Journal of Theoretical Biology |volume=117 |issue=4 |pages=665–690 |doi=10.1016/S0022-5193(85)80246-0 |pmid=4094459|bibcode=1985JThBi.117..665B }}</ref><ref name="Koeslag, 1990">{{cite journal |last=Koeslag |first=Johan H. |date=May 10, 1990 |title=Koinophilia groups sexual creatures into species, promotes stasis, and stabilizes social behaviour |journal=[[Journal of Theoretical Biology]] |volume=144 |issue=1 |pages=15–35 |doi= 10.1016/s0022-5193(05)80297-8 |issn=0022-5193 |pmid=2200930|bibcode=1990JThBi.144...15K }}</ref><ref name="Koeslag, 1995">{{cite journal |last=Koeslag |first=Johan H. |date=December 21, 1995 |title=On the Engine of Speciation |journal=Journal of Theoretical Biology |volume=177 |issue=4 |pages=401–409 |doi=10.1006/jtbi.1995.0256 |bibcode=1995JThBi.177..401K |issn=0022-5193}}</ref><ref name="Unnikrishnan">{{cite journal |last1=Poelstra |first1=Jelmer W. |last2=Vijay |first2=Nagarjun |last3=Bossu |first3= Christen M. |last4=Lantz |first4=Henrik |last5=Ryll |first5=Bettina |last6=Müller |first6=Inge |last7=Baglione |first7=Vittorio |last8=Unneberg |first8=Per |last9=Wikelski |first9=Martin |last10=Grabherr |first10=Manfred G. |last11=Wolf |first11=Jochen B. W. |display-authors=3 |date=June 20, 2014 |title=The genomic landscape underlying phenotypic integrity in the face of gene flow in crows |journal=Science |volume=344 |issue=6190 |pages=1410–1414 |doi=10.1126/science.1253226  |pmid=24948738 |quote=The Phenotypic Differences between Carrion and Hooded Crows across the Hybridization Zone in Europe are Unlikely to be due to Assortative Mating.|url=http://nbn-resolving.de/urn:nbn:de:bsz:352-0-260687 |bibcode=2014Sci...344.1410P |s2cid=14431499 }} — Commentary by Mazhuvancherry K. Unnikrishnan and H. S. Akhila</ref><ref name="miller">{{harvnb|Miller|2013|pp=177, 395–396}}</ref> If speciation takes place in the absence of natural selection, it might be referred to as [[nonecological speciation]].<ref>{{Cite journal|last1=Rundell|first1=Rebecca J.|last2=Price|first2=Trevor D.|date=2009-07-01|title=Adaptive radiation, nonadaptive radiation, ecological speciation and nonecological speciation|url=https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(09)00126-8|journal=Trends in Ecology & Evolution|language=en|volume=24|issue=7|pages=394–399|doi=10.1016/j.tree.2009.02.007|issn=0169-5347|pmid=19409647|bibcode=2009TEcoE..24..394R }}</ref><ref>{{Cite journal|last1=Czekanski-Moir|first1=Jesse E.|last2=Rundell|first2=Rebecca J.|date=2019-05-01|title=The Ecology of Nonecological Speciation and Nonadaptive Radiations|url=https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(19)30027-8|journal=Trends in Ecology & Evolution|language=en|volume=34|issue=5|pages=400–415|doi=10.1016/j.tree.2019.01.012|issn=0169-5347|pmid=30824193|bibcode=2019TEcoE..34..400C |s2cid=73494468}}</ref>