Editing Parasitism (section)

=== Trait loss ===

Parasites can exploit their hosts to carry out a number of functions that they would otherwise have to carry out for themselves. Parasites which lose those functions then have a selective advantage, as they can divert resources to reproduction. Many insect ectoparasites including [[Cimex|bedbugs]], [[Polyctenidae|batbugs]], [[lice]] and [[flea]]s have lost their [[insect flight|ability to fly]], relying instead on their hosts for transport.<ref>{{cite book |last=Alexander |first=David E. |title=On the Wing: Insects, Pterosaurs, Birds, Bats and the Evolution of Animal Flight |url=https://books.google.com/books?id=H6xUCgAAQBAJ&pg=PT119 |year=2015 |publisher=Oxford University Press |isbn=978-0-19-999679-7 |page=119}}</ref> Trait loss more generally is widespread among parasites.<ref>{{cite journal |last=Poulin |first=Robert |author-link=Robert Poulin (zoologist) |url=http://faculty.uml.edu/rhochberg/hochberglab/Courses/Parasite/PDF%20Papers/Parasitology%20Papers/Myths-Realities%20Parasite%20life%20histories.pdf |title=Evolution of parasite life history traits: myths and reality |journal=Parasitology Today |date=September 1995 |volume=11 |issue=9 |pages=342–345 |pmid=15275316 |doi=10.1016/0169-4758(95)80187-1|archive-url=https://web.archive.org/web/20120216194337/http://faculty.uml.edu/rhochberg/hochberglab/Courses/Parasite/PDF%20Papers/Parasitology%20Papers/Myths-Realities%20Parasite%20life%20histories.pdf |archive-date=16 February 2012 }}</ref> An extreme example is the [[myxosporea]]n ''[[Henneguya zschokkei]]'', an ectoparasite of fish and the only animal known to have lost the ability to respire aerobically: its cells lack [[mitochondria]].<ref name="PNAS">{{Cite journal |last1=Yahalom |first1=Dayana |last2=Atkinson |first2=Stephen D.|last3=Neuhof |first3=Moran |last4=Chang |first4=E. Sally |last5=Philippe |first5=Hervé |last6=Cartwright |first6=Paulyn |last7=Bartholomew |first7=Jerri L. |last8=Huchon |first8=Dorothée |date=19 February 2020 |title=A cnidarian parasite of salmon (Myxozoa: Henneguya) lacks a mitochondrial genome |journal=Proceedings of the National Academy of Sciences |volume=117 |issue=10 |pages=5358–5363 |doi=10.1073/pnas.1909907117 |pmid=32094163|pmc=7071853 |bibcode=2020PNAS..117.5358Y |doi-access=free }}</ref>