Themangrove rivulusormangrove killifish,Kryptolebias marmoratus(syn.Rivulus marmoratus),[2][3]is a species ofkillifishin thefamilyRivulidae.It lives inbrackishand marine waters (less frequently in fresh water) along the coasts ofFlorida,through theAntilles,and along the eastern and northern Atlantic coasts of Mexico, Central America and South America (south to Brazil).[1][2]It has a very wide tolerance of bothsalinity(0–68)[4]and temperature (12–38 °C or 54–100 °F),[5]can survive for about two months on land,[6]and mostly breeds byself-fertilization.[7]It is typically found in areas withred mangroveand sometimes lives in burrows ofCardisoma guanhumicrabs.[5]

Mangrove rivulus
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Rivulidae
Genus: Kryptolebias
Species:
K. marmoratus
Binomial name
Kryptolebias marmoratus
(Poey,1880)
Synonyms[2]
  • Rivulus marmoratusPoey, 1880
  • Rivulus heyeiNichols,1914
  • Rivulus bonairensisHoedeman,1958
  • Rivulus garciaide la Cruz & Dubitsky, 1976

The mangrove rivulus is up to 7.5 cm (3.0 in) long,[2]but most individuals are 1–3.8 cm (0.4–1.5 in).[4]

Overall the mangrove rivulus is widespread and not threatened,[1]but in the United States it is considered aSpecies of Concernby theNational Marine Fisheries Service.[8]

Ecology

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Land living

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The mangrove rivulus can spend up to 66 consecutive days out of water, which it typically spends inside fallen logs, breathing air through its skin.[6][9]It enters burrows created by insects inside trees where it relaxes its territorial, aggressive behavior. During this time, it alters itsgillsso it can retain water and nutrients, whilenitrogenwaste is excreted through the skin. The change is reversed once it re-enters the water.[6]

When jumping on land, the mangrove rivulus does a "tail flip", flipping its head over its body towards the tail end. The rivulus' jumping technique gives it an ability to direct its jumps on land and to make relatively forceful jumps. A team of scientists associated with theSociety for Experimental Biologyreleased a video in 2013 showing the jumping technique.[10]

Breeding

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Mangrove rivulus inGuadeloupe

Spawninghas not yet been observed in the wild in the mangrove rivulus, but captive studies show that the eggs are positioned in shallow water, sometimes even in places that periodically are on land during low tide. The eggs can continue their development when out of water, but once they are ready to hatch this is delayed until again submerged.[11][12]

The species consists mostly of hermaphrodites which are known to reproduce byself-fertilization,but males do exist,[7]and strong genetic evidence indicates occasionaloutcrossing.[13]The concentration of males to hermaphrodites can vary depending on the local requirement for genetic diversity (for example, if an increase in the local parasite population occurred, secondary male numbers might increase).[14]In Florida, almost all (>99%) arehomozygousclones,but in highly colonized South and Central American pools males typically are 3 to 8% of the population, and in offshore cays inBelize20 to 25% are males.[5]

K. marmoratusproduces eggs and sperm bymeiosisand routinely reproduces by self-fertilization.[15]Each individual hermaphrodite normally fertilizes itself when an egg and sperm that it has produced by an internal organ unite inside the fish's body.[16]In nature, this mode of reproduction can yield highly homozygous lines composed of individuals so genetically uniform as to be, in effect, identical to one another.[17][18]The capacity for self-fertilization in these fishes has apparently persisted for at least several hundred thousand years.[19]Meioses that lead to self-fertilization can reduce genetic fitness by causinginbreeding depression.However, self-fertilization does provide the benefit of "fertilization assurance" (reproductive assurance) at each generation.[17]Meiosis can also provide the adaptive benefit of efficient recombinational repair of DNA damages during formation ofgerm cellsat each generation.[20]This benefit may have prevented the evolutionary replacement of meiosis and selfing by a simpler type of clonal reproduction such as ameiotic or apomicticparthenogenesis.Adults may cannibalize juveniles, but only unrelated offspring.[21]

Epigenetic studies

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BecauseK. marmoratuscan reproduce consistently by self-fertilization, it gives rise to isogenic lineages. These lineages afford the opportunity to explicitly investigateepigeneticphenotypiceffects ingeneticallyidentical individuals.[22]Epigenetic changes due toDNA methylationwere studied, and specific patterns of DNA methylation atCpG sitesin adults and during development were found to occur.[22]

Conservation

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Overall the mangrove rivulus is widespread and not threatened,[1]but in the United States it is considered aSpecies of Concernby theNational Marine Fisheries Service.[8]It is considered a species ofLeast Concernby theIUCN,[1]and was formerly listed as a species of special concern in Florida, but has since been delisted.[4]It was formerly often overlooked and considered rare in Florida, but surveys have revealed that it is locally common in this state and abundant in theFlorida Keys.[1]It is considered vulnerable by the American Fisheries Society.[citation needed]

The mangrove rivulus is considered to have potential as abioindicatorspecies ofestuaryhabitats.[1]

See also

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References

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  1. ^abcdefgNatureServe; Lyons, T.J. (2019)."Kryptolebias marmoratus".IUCN Red List of Threatened Species.2019:e.T19735A131005753.doi:10.2305/IUCN.UK.2019-2.RLTS.T19735A131005753.en.Retrieved16 November2021.
  2. ^abcdFroese, Rainer;Pauly, Daniel (eds.)."Kryptolebias marmoratus".FishBase.February 2023 version.
  3. ^Ong, K. J.; Stevens, E. D.; Wright, P. A. (2007). "Gill morphology of the mangrove killifish (Kryptolebias marmoratus) is plastic and changes in response to terrestrial air exposure ".Journal of Experimental Biology.210(7): 1109–15.doi:10.1242/jeb.002238.PMID17371909.
  4. ^abcBester, C:Mangrove Rivulus.Florida Museum. Retrieved 6 May 2017.
  5. ^abcHill, K:Rivulus marmoratus.Smithsonian Marine Station at Fort Pierce. Retrieved 6 May 2017.
  6. ^abc"Tropical fish can live for months out of water",Reuters, Wed Nov 14, 2007 9:05pm GMT
  7. ^abLublnski, B. A.; Davis, W. P.; Taylor, D. S.; Turner, B. J. (1995). "Outcrossing in a natural population of a self-fertilizing hermaphroditic fish".Journal of Heredity.86(6): 469–473.doi:10.1093/oxfordjournals.jhered.a111623.
  8. ^abNational Marine Fisheries Service (23 February 2017).Species of Concern List.Retrieved 6 May 2017.
  9. ^Taylor, D. Scott; Turner, Bruce J.; Davis, William P.; Chapman, Ben B. (February 2008). "A novel terrestrial fish habitat inside emergent logs".The American Naturalist.171(2): 263–6.doi:10.1086/524960.hdl:10919/49125.ISSN1537-5323.PMID18197778.S2CID46035347.
  10. ^Tail-Flipping Fish Hops on LandonYouTube
  11. ^Taylor, D.S. (2012)."Twenty-four years in the mud: what have we learned about the natural history and ecology of the mangrove rivulus,Kryptolebias marmoratus?".Integrative and Comparative Biology.52(6): 724–736.doi:10.1093/icb/ics062.PMC3501094.PMID22576816.
  12. ^Martin, K.L.; A.L. Carter (2013)."Brave new propagules: terrestrial embryos in anamniotic eggs".Integrative and Comparative Biology.53(2): 233–247.doi:10.1093/icb/ict018.PMID23604618.
  13. ^MacKiewicz, M.; Tatarenkov, A.; Turner, B. J.; Avise, J. C. (2006)."A mixed-mating strategy in a hermaphroditic vertebrate".Proceedings of the Royal Society B: Biological Sciences.273(1600): 2449–52.doi:10.1098/rspb.2006.3594.PMC1634907.PMID16959634.
  14. ^Cole, Kathleen S.; Noakes, David L. G. (1 January 1997). "Gonadal development and sexual allocation in mangrove killifish,Rivulus marmoratus(Pisces: Atherinomorpha) ".Copeia.1997(3): 596–600.doi:10.2307/1447566.JSTOR1447566.
  15. ^Harrington, Robert W. (1963-10-01)."Twenty-four-hour rhythms of internal self-fertilization and of oviposition by hermaphrodites ofRivulus marmoratus".Physiological Zoology.36(4): 325–341.doi:10.1086/physzool.36.4.30152746.S2CID85957196.
  16. ^Sakakura, Yoshitaka; Soyano, Kiyoshi; Noakes, David L.G.; Hagiwara, Atsushi (2006). "Gonadal morphology in the self-fertilizing mangrove killifish,Kryptolebias marmoratus".Ichthyological Research.53(4): 427–430.Bibcode:2006IchtR..53..427S.doi:10.1007/s10228-006-0362-2.hdl:10069/35713.S2CID9474211.
  17. ^abAvise JC, Tatarenkov A (November 2012)."Allard's argument versus Baker's contention for the adaptive significance of selfing in a hermaphroditic fish".Proceedings of the National Academy of Sciences of the United States of America.109(46): 18862–7.Bibcode:2012PNAS..10918862A.doi:10.1073/pnas.1217202109.PMC3503157.PMID23112206.
  18. ^Earley RL, Hanninen AF, Fuller A, Garcia MJ, Lee EA (December 2012)."Phenotypic plasticity and integration in the mangrove rivulus (Kryptolebias marmoratus): a prospectus ".Integrative and Comparative Biology.52(6): 814–827.doi:10.1093/icb/ics118.PMC3501102.PMID22990587.
  19. ^Tatarenkov A, Lima SM, Taylor DS, Avise JC (August 2009)."Long-term retention of self-fertilization in a fish clade".Proceedings of the National Academy of Sciences of the United States of America.106(34): 14456–9.Bibcode:2009PNAS..10614456T.doi:10.1073/pnas.0907852106.PMC2732792.PMID19706532.
  20. ^Bernstein H, Byerly HC, Hopf FA, Michod RE (September 1985). "Genetic damage, mutation, and the evolution of sex".Science.229(4719): 1277–81.Bibcode:1985Sci...229.1277B.doi:10.1126/science.3898363.PMID3898363.
  21. ^Wells, Michael W.; Wright, Patricia A. (2017-10-01). "Do not eat your kids: embryonic kin recognition in an amphibious fish".Behavioral Ecology and Sociobiology.71(10): 140.Bibcode:2017BEcoS..71..140W.doi:10.1007/s00265-017-2360-y.ISSN0340-5443.S2CID34001850.
  22. ^abFellous A, Labed-Veydert T, Locrel M, Voisin AS, Earley RL, Silvestre F (June 2018)."DNA methylation in adults and during development of the self-fertilizing mangrove rivulus,Kryptolebias marmoratus".Ecol Evol.8(12): 6016–33.Bibcode:2018EcoEv...8.6016F.doi:10.1002/ece3.4141.PMC6024129.PMID29988456.
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