Editing Sexual selection (section)

=== Multiple models ===

{{Further|Sexy son hypothesis|Sexual conflict|Mate choice}}

More recently, the field has grown to include other areas of study, not all of which fit Darwin's definition of sexual selection. A "bewildering"<ref name="Kokko Jennions 2006"/> range of models variously attempt to relate sexual selection not only to the fundamental<ref name="Kokko Jennions 2006"/> questions of [[anisogamy]] and parental roles, but also to mechanisms such as [[sex ratio]]s – governed by [[Fisher's principle]],<ref name="Hamilton 1967">{{cite journal |last=Hamilton |first=W. D. |author-link=W. D. Hamilton |year=1967 |title=Extraordinary sex ratios |journal=Science |volume=156 |issue=3774 |pages=477–488 |bibcode=1967Sci...156..477H |pmid=6021675 |doi=10.1126/science.156.3774.477}}</ref> parental care, [[Sexy son hypothesis|investing in sexy sons]], [[sexual conflict]], and the "most-debated effect",<ref name="Kokko Jennions 2006"/> namely [[mate choice]].<ref name="Kokko Jennions 2006">{{cite journal |last1=Kokko |first1=Hanna |last2=Jennions |first2=Michael D. |last3=Brooks |first3=Robert |title=Unifying and Testing Models of Sexual Selection |journal=Annual Review of Ecology, Evolution, and Systematics |volume=37 |issue=1 |year=2006 |pages=43–66 |doi=10.1146/annurev.ecolsys.37.091305.110259 |url=https://www.researchgate.net/profile/Michael_Jennions/publication/261950187_Unifying_and_Testing_Models_of_Sexual_Selection/links/550775830cf2d7a281257def.pdf<!--not a copyvio as it's the author, and not redundant to the DOI either--> |hdl=1885/22652 |hdl-access=free }}</ref> Elaborated characteristics that might seem costly, like the tail of the Montezuma swordfish (''[[Xiphophorus montezumae]]''), do not always have an energetics, performance or even survival cost; this may be because "compensatory traits" have evolved in concert with the sexually selected traits.<ref name="Oufiero 2015">{{cite web |last=Oufiero |first=Christopher E. |title=Sexual Selection, Costs, and Compensation |date=May 2015<!--updated, presumably--> |publisher=University of California Riverside |url=http://idea.ucr.edu/documents/flash/sexual_selection_costs/story.htm |archive-url=https://web.archive.org/web/20140606234023/http://idea.ucr.edu/documents/flash/sexual_selection_costs/story.htm |archive-date=6 June 2014}}</ref>