Editing Selfish genetic element (section)

=== Rule 2: Presence is often revealed in hybrids ===
The presence of selfish genetic elements can be difficult to detect in natural populations. Instead, their phenotypic consequences often become apparent in hybrids. The first reason for this is that some selfish genetic elements rapidly sweep to fixation, and the phenotypic effects will therefore not be segregating in the population. Hybridization events, however, will produce offspring with and without the selfish genetic elements and so reveal their presence. The second reason is that host genomes have evolved mechanisms to suppress the activity of the selfish genetic elements, for example the small RNA administered silencing of transposable elements.<ref>{{cite journal | vauthors = Aravin AA, Hannon GJ, Brennecke J | title = The Piwi-piRNA pathway provides an adaptive defense in the transposon arms race | journal = Science | volume = 318 | issue = 5851 | pages = 761–4 | date = November 2007 | pmid = 17975059 | doi = 10.1126/science.1146484 | bibcode = 2007Sci...318..761A | s2cid = 8532459 | doi-access =  | url = https://resolver.caltech.edu/CaltechAUTHORS:20190509-083948927 }}</ref> The co-evolution between selfish genetic elements and their suppressors can be rapid, and follow a [[Red Queen hypothesis|Red Queen dynamics]], which may mask the presence of selfish genetic elements in a population. Hybrid offspring, on the other hand, may &nbsp;inherit a given selfish genetic element, but not the corresponding suppressor and so reveal the phenotypic effect of the selfish genetic element.<ref name=":9">{{cite journal | vauthors = Crespi B, Nosil P | title = Conflictual speciation: species formation via genomic conflict | journal = Trends in Ecology & Evolution | volume = 28 | issue = 1 | pages = 48–57 | date = January 2013 | pmid = 22995895 | doi = 10.1016/j.tree.2012.08.015 }}</ref><ref name=":10">{{cite journal | vauthors = Ågren JA | title = Selfish genes and plant speciation. | journal = Evolutionary Biology | date = September 2013 | volume = 40 | issue = 3 | pages = 439–449 | doi = 10.1007/s11692-012-9216-1 | bibcode = 2013EvBio..40..439A | s2cid = 19018593 }}</ref>