Edible frog

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Edible frog
Rana esculenta on Nymphaea edit.JPG
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Ranidae
Genus: Pelophylax
Species: P. lessonae × P. ridibundus
Binomial name
Pelophylax kl. esculentus
(Linnaeus, 1758)

Pelophylax esculentus (Linnaeus, 1758)
Rana esculenta Linnaeus, 1758

The edible frog (Pelophylax kl. esculentus) [1][2] is a name for a common European frog, also known as the common water frog or green frog (however, this latter term is also used for the North American species Rana clamitans).

It is used for food, particularly in France for the delicacy frog legs. Females are between 5 to 9 cm long, males between 6 to 11 cm.


P. esculentus is endemic to Europe. It naturally occurs from the northern half of France to western Russia, and from Estonia and Denmark to Bulgaria and northern Italy. It is introduced in Spain and the United Kingdom. The natural range is nearly identical to that of P. lessonae.[3]


Pelophylax kl. esculentus is the fertile hybrid of the pool frog (Pelophylax lessonae) and the marsh frog (Pelophylax ridibundus).

It reproduces by hybridogenesis (hemiclonally).[4][5][6][7][8]

Hybridogenesis implies that hybrids (RL genotype) during gametogenesis exclude one parental genome (L or R) and produce gametes with unrecombined genome of second parental species (R or L respectively), instead of containing mixed recombined parental genomes.[5][6][8]

And that the hybrid populations are propagated usually by mating (backcrosses) with sympatric one of the parental species - P. lessonae (LL) or P. ridibundus (RR) providing second, discarded parental genome (L or R respectively).[5][6][8]

So hybridogenesis is a hemiclonal mode of reproduction - half of genome is transmitted to the next generation clonally, unrecombined (intact), other half sexually, recombined.[9][7][8]

For example, in the most widespread so called L–E system edible frogs Pelophylax kl. esculentus (RE) produce gametes of the marsh frog P. ridibundus (R) and mate with coexisting with them pool frogs Pelophylax lessonae (L gametes) – see below in the middle.[5][8]

Example crosses between pool frog (Pelophylax lessonae), marsh frog (P. ridibundus) and their hybrid - edible frog (P. kl. esculentus). First one is the primary hybridisation generating hybrid, second one is most widespread type of hybridogenesis.[5][7]

Because this hybrid requires other taxon as sexual host to reproduce, usually one of parental species, it is klepton[10][11][12]. Hence the addition of the "kl." (for klepton) in the species name.[13]

There are known also all-hybrid populations, where diploid hybrids (LR) coexist with triploid (LLR or LRR) hybrids providing L or R genomes respectively. Diploid hybrids (LR) generate here not only haploid R or L gametes, but also not reduced diploid gametes (RL) needed to recreate triploids.[5][6]


  1. ^ Frost, Darrel R. (2006). "Amphibian Species of the World: an Online Reference. Version 4". American Museum of Natural History, New York, USA. Retrieved 17 August 2006. 
  2. ^ Frost, Grant, Faivovich, Bain, Haas, Haddad, de Sá, Channing, Wilkinson, Donnellan, Raxworthy, Campbell, Blotto, Moler, Drewes, Nussbaum, Lynch, Green, and Wheeler 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History. Number 297. New York. Issued March 15, 2006.
  3. ^ "Pelophylax esculentus, Edible Frog". AmphibiaWeb. Retrieved 28 January 2014. 
  4. ^ Berger, L. (1970). "Some characteristics of the crossess within Rana esculenta complex in postlarval development". Ann. Zool. 27: 374–416. 
  5. ^ a b c d e f Holsbeek, G.; Jooris, R. (2010). "Potential impact of genome exclusion by alien species in the hybridogenetic water frogs (Pelophylax esculentus complex)" (PDF). Biol Invasions (Springer Netherlands) 12: 1–13. doi:10.1007/s10530-009-9427-2. ISSN 1387-3547. Retrieved 2015-06-21. 
  6. ^ a b c d Christiansen D. G. (2009). "Gamete types, sex determination and stable equilibria of all-hybrid populations of diploid and triploid edible frogs (Pelophylax esculentus) Rana esculenta as deduced from mtDNA analyses.". BMC Evolutionary Biology 9 (135). doi:10.1186/1471-2148-9-135. Retrieved 2012-07-25. 
  7. ^ a b c Vorburger, Christoph; Reyer, Heinz-Ulrich (2003). "A genetic mechanism of species replacement in European waterfrogs?" (PDF). Conservation Genetics (Kluwer Academic Publishers) 4: 141–155. doi:10.1023/A:1023346824722. ISSN 1566-0621. Retrieved 2015-06-21. 
  8. ^ a b c d e Ragghianti M, Bucci S, Marracci S, Casola C, Mancino G, Hotz H, Guex GD, Plötner J, Uzzell T. (February 2007). "Gametogenesis of intergroup hybrids of hemiclonal frogs." (PDF). Genet Res. 89 (1): 39–45. doi:10.1017/S0016672307008610. Retrieved 2012-07-25. 
  9. ^ Simon J.-C., Delmotte F., Rispe C., Crease T. (2003). "Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals." (PDF). Biological Journal of the Linnean Society 79: 151–163. doi:10.1046/j.1095-8312.2003.00175.x. Retrieved 2012-07-30. 
  10. ^ Dubois, Alain (2009). "Asexual and metasexual vertebrates. Book review" (PDF). Alytes (ISSCA (International Society for the Study and Conservation of Amphibians)) 27 (2): 62–66. Retrieved 2015-06-22. John C. Avise, 2008.–Clonality. The genetics, ecology, and evolution of sexual abstinence in vertebrate animals. New York, Oxford University Press: i-xi + 1-237. ISBN 978-0-19-536967-0. 
  11. ^ Dubois, A.; Günther, R. (1982). "Klepton and synklepton: two new evolutionary systematics categories in zoology". Zool. Jahrb. Syst. (Zoologische Jahrbücher. Abteilung für Systematik, Ökologie und Geographie der Tiere) (Jena; Stuttgart; New York.: Gustav Fischer Verlag) 109: 290–305. ISSN 0044-5193. 
  12. ^ Polls Pelaz, Manuel (October 1990). "The Biological Klepton Concept (BKC)". Alytes (ISSCA (International Society for the Study and Conservation of Amphibians)) 8 (3): 75–89. Retrieved 2015-06-22. 
  13. ^ Dubois, Alain (October 1990). "Nomenclature of parthenogenetic, gynogenetic and hybridogenetic vertebrate taxons: new proposals". Alytes (ISSCA (International Society for the Study and Conservation of Amphibians)) 8 (3): 61–74. Retrieved 2015-06-22. 

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