Gerris

{{Short description|Genus of true bugs}} {{Automatic taxobox | image = Gerris.lacustris.couple.jpg | image_caption = A pair of common water striders (''Gerris lacustris'') copulating | taxon = Gerris | authority = Fabricius, 1794 | subdivision_ranks = Species | subdivision = See text }}

'''''Gerris''''' is an insect genus in the family Gerridae (water striders).<ref>{{EOL|38453001|Gerris (Gerris) Fabricius 1794}}</ref><ref>{{Cite web|title=Taxon profile: genus ''Gerris'' Fabricius, 1794|publisher=BioLib|url=https://www.biolib.cz/en/taxon/id71301/}}</ref>

==Species== The genus ''Gerris'' contains 44 species in 3 subgenera:<ref>{{cite journal |first1=Jakob |last1=Damgaard |first2=Felipe Ferraz Figuiredo |last2=Moreira |first3=Tom A. |last3=Weir |first4=Herbert |last4=Zettel |title=Molecular phylogeny of the pond skaters (Gerrinae), discussion of the fossil record and a checklist of species assigned to the subfamily (Hemiptera: Heteroptera: Gerridae) |year=2014 |journal=Insect Systematics & Evolution |volume=45 |issue=3 |pages=251–281 |doi=10.1163/1876312X-44042105}}</ref>

===Subgenus ''Gerris''=== {{Columns-list|colwidth=30em| * ''Gerris alacris'' Hussey, 1921 * ''Gerris angulatus'' Lundblad, 1934 * ''Gerris argentatus'' Schummel, 1832 * ''Gerris argenticollis'' Parshley, 1916 * ''Gerris babai'' Miyamoto, 1958 * ''Gerris brasili'' Poisson, 1941 * ''Gerris buenoi'' Kirkaldy, 1911 * ''Gerris caucasicus'' Kanyukova, 1982 * ''Gerris comatus'' Drake and Hottes, 1925 * ''Gerris costae'' (Herrich-Schäffer, 1850) * ''Gerris curvus'' Tran & J.T. Polhemus, 2012 * ''Gerris firmus'' Drake and Harris, 1938 * ''Gerris gibbifer'' Schummel, 1832 * ''Gerris gillettei'' Lethierry and Severin, 1896 * ''Gerris gobanus'' Poisson, 1940 * ''Gerris incognitus'' Drake and Hottes, 1925 * ''Gerris incurvatus'' Drake and Hottes, 1925 * ''Gerris insperatus'' Drake and Hottes, 1925 * ''Gerris kabaishanus'' Linnavuori, 1998 * ''Gerris lacustris'' (Linnaeus, 1758) * ''Gerris latiabdominis'' Miyamoto, 1958 * ''Gerris lobatus'' Andersen and Chen, 1993 * ''Gerris maculatus'' Tamanini, 1946 * ''Gerris marginatus'' Say, 1832 * ''Gerris nepalensis'' Distant, 1910 * ''Gerris odontogaster'' (Zetterstedt, 1828) * ''Gerris pingreensis'' Drake and Hottes, 1925 * ''Gerris sphagnetorum'' Gaunitz, 1947 * ''Gerris swakopensis'' (Stal, 1858) * ''Gerris thoracicus'' Schummel, 1832 * ''Gerris xizangensis'' Zhang, Leng, and Ye, 2026 * ''Gerris zuqualanus'' Poisson, 1940 }}

===Subgenus ''Gerriselloides''=== * ''Gerris asper'' (Fieber, 1860) * ''Gerris brachynotus'' Horváth, 1907 * ''Gerris kiritshenkoi'' Kanyukova, 1979 * ''Gerris lateralis'' Schummel, 1832

===Subgenus ''Macrogerris''=== * ''Gerris cui'' Esaki, 1925 * ''Gerris gracilicornis'' Horváth, 1879 * ''Gerris insularis'' Motschulsky, 1866 * ''Gerris issikii'' Miyamoto, 1961 * ''Gerris lundbladi'' Andersen and Chen, 1993 * ''Gerris tigrinus'' Brown, 1949 * ''Gerris yezoensis'' Miyamoto, 1958

==Mating system== thumb|Male grappling on top of the female in an attempt to force copulation Species of genus ''Gerris'' demonstrate a high degree of female control over most aspects of mating and there is significant evidence that supports antagonistic coevolution, and the convenience polyandry hypothesis of multiple matings.<ref name = rowe1991>{{cite journal|last1=Rowe|first1=Locke|title=Convenience polyandry in a water strider: foraging conflicts and female control of copulation frequency and guarding duration|journal=Animal Behaviour|date=19 September 1991|volume=44|pages=189–202|doi=10.1016/0003-3472(92)90025-5|s2cid=53185546}}</ref><ref name = rowe2001>{{cite journal|last1=Rowe|first1=Locke|last2=Arnqvist|first2=Goran|title=Sexually Antagonistic Coevolution in a Mating System: Combining Experimental and Comparative Approaches to Address Evolutionary Processes|journal=Evolution|date=2002|volume=56|issue=4|pages=754–767|doi=10.1111/j.0014-3820.2002.tb01386.x|pmid=12038533|doi-access=free}}</ref> There is evidence to suggest that the post-copulatory guarding exhibited by ''Gerris buenoi'' - and other species of ''Gerris'' - is a form of a direct (material) benefit that females take advantage of to reduce superfluous matings.<ref>{{cite journal|last1=Pandey|first1=Omkar P.|title=Benefits of polyandry in Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae)|journal=Journal of Asia-Pacific Entomology|date=2010|volume=13|issue=2|pages=151–155|doi=10.1016/j.aspen.2010.01.001}}</ref><ref name="rowe1991" /> [[File:Surface waves and water striders.JPG|thumb|"Moving of mating Water Striders (''Gerris argentatus''), weigh about 0.00002 lb created surface waves (Ripples) in a pond. The striders are out of focus (on purpose), but you could see their shadows, the hairs at their legs and the sun reflected from their footprints" - Brocken Inaglory. The ripples attract predators.|221x221px]] Male persistence is often detrimental to female fitness as male species of ''Gerris'' harass females.<ref name="rowe1991" /><ref name="rowe2001" /> This is believed to be the result of males having a lower number of available mates and therefore, have a reduced fitness.<ref name = arnqvist1992>{{cite journal|last1=Arnqvist|first1=Goran|title=Pre-copulatory fighting in a water strider - inter-sexual conflict or mate assessment|journal=Animal Behaviour|date=1992|volume=43|issue=4|pages=559–567|doi=10.1016/s0003-3472(05)81016-4|s2cid=53173218}}</ref> Females are at risk of predation during mating attempts as males mount the female in an attempt to mate and tap their legs on the surface of the water to attract predators.<ref>{{cite journal|last1=Han|first1=Chang S.|last2=Jablonski|first2=Piotr G.|title=Male water striders attract predators to intimidate females into copulation|journal=Nature Communications|date=2010|volume=1|page=52|doi=10.1038/ncomms1051 |pmid=20975717|pmc=2964456|doi-access=free}}</ref> Females respond in turn, creating a pre-copulatory struggle in which they try to perform backwards somersault-like movements to break free of the male grapple.<ref name = arnqvist1989>{{cite journal|last1=Arnqvist|first1=Goran|title=Sexual selection in a water strider: the function, nature of selection and heritability of a male grasping apparatus|journal=Oikos|date=1989|volume=56|pages=344–350|doi=10.2307/3565619|jstor=3565619}}</ref> If unsuccessful, female species of ''Gerris'' will resort to mating with the male as the cost of rejecting the male advances (death by predation) outweighs the cost of mating out of convenience.<ref name="rowe1991" /><ref name="arnqvist1989" /> thumb|220x220px|An example of genitalia shielding and the courting that males do instead of the usual forced copulation attempts. As a result of the tactics employed by both species there is evidence of rapid evolution between the sexes in a persistence-resistance form of sexual conflict.<ref name="rowe2001" /> The sexes of species of genus ''Gerris'' compete between each other in an "arms race" behaviour where males and females have varying traits that serve to increase their own fitness over the other.<ref name="rowe2001" /> Males evolved to harass females by chasing and lunging in an attempt to grapple the female for copulation, and females evolved mechanisms such as genital shielding, evasive maneuvers, and attempting to fight even when grappled. However, evading and fighting are quite costly for females and will give in if the costs of resistance outweigh the cost of mating.<ref name="rowe2001" /><ref name="rowe1991" /> Genital shielding can best be seen in ''G. gracilicornis'' and a male will have a hard time at inserting his genitalia unless the female protrudes her genitalia out.<ref name =han2009>{{cite journal|last1=Han|first1=Chang S.|last2=Jablonski|first2=Piotr G.|title=Female Genitalia Concealment Promotes Intimate Male Courtship in a Water Strider|journal=PLOS ONE|date=2009|volume=4|issue=6|article-number=e5793|doi=10.1371/journal.pone.0005793 |pmid=19516886|pmc=2686155|doi-access=free}}</ref> Males have evolved to overcome this mechanism by attempting an intimate courtship instead of forceful mating, as well as a more hostile approach: attracting predators to force mating with females.<ref name="rowe1991" /><ref name="han2009" /><ref name="rowe2001" /> The rationale behind attracting predators to force mating is due to how copulation occurs: a male will attempt to mount a female on the surface water; it is the female that is at most risk from insect-eating fish and water dwelling predators.<ref name="rowe1991" /><ref name="han2009" /><ref name="rowe2001" /><ref name="arnqvist1989" />

After copulation, males continue to rest on top of females for some period of time - this is what is known as guarding duration.<ref name="rowe1991" /><ref name="arnqvist1992" /> It can be hypothesized that when superfluous matings are plenty, females will extend this guarding duration by allowing the male to rest upon her for some time which in turn prevents harassment from other males. This also incurs costs for the female as they must exert energetic costs to compensate for the passive male on her back, and that this might not be an effective tactic for females in the long run.<ref name="arnqvist1992" /><ref>{{cite journal|last1=Arnqvist|first1=Goran|title=Arnqvist, G. 1989b. Multiple mating in a water strider: mutual benefits or intersexual conflict?|journal=Animal Behaviour|date=1989|volume=38|pages=749–856|doi=10.1016/s0003-3472(89)80107-1|s2cid=54254489}}</ref>

Water striders, and more specifically those that fall under the genus ''Gerris'' are a model organism for studying sexual conflict as they have clear costs associated with their actions. They have great use as a control group when comparing to other organisms where it is more unclear as what is occurring.

==Former species== * ''Gerris ampla'' reclassified as ''Aquarius amplus'' (Drake and Harris, 1938) * ''Gerris canaliculatus'' reclassified as ''Limnoporus canaliculatus'' (Say, 1832) * ''Gerris conformis'' reclassified as ''Aquarius conformis'' (Uhler, 1878) * ''Gerris dissortis'' reclassified as ''Limnoporus dissortis'' (Drake and Harris, 1930) * ''Gerris mantis'' reclassified as ''Emesa mantis'' (Fabricius, 1794) * ''Gerris najas'' reclassified as ''Aquarius najas'' (De Geer, 1773) * ''Gerris nebularis'' reclassified as ''Aquarius nebularis'' (Drake and Hottes, 1925) * ''Gerris nyctalis'' reclassified as ''Aquarius nyctalis'' (Drake and Hottes, 1925) (now synonymized with ''A. remigis'') * ''Gerris remigis'' reclassified as ''Aquarius remigis'' (Say, 1832) * ''Gerris rufoscutellatus'' reclassified as ''Limnoporus rufoscutellatus'' (Latreille, 1807)

== References == {{Commons}} {{Wikispecies}} {{Reflist}}

Category:Gerrini Category:Gerromorpha genera