Edible Frog

Pond Frog ( Pelophylax " esculentus " )

The Pond Frog ( Pelophylax kl. Esculentus, Pelophylax " esculentus " or Rana " esculenta " ), also known as accurate water frog, heard within the order of Anura to the family of the Real frogs ( Ranidae ). In addition, he is expected to follow appearance, biology and distribution of the water frogs that have recently been questioned by many authors in a separate genus Pelophylax. Within this hard to looking taxonomic complex is near a pond frog not a biological species in the classical sense, but rather a hybrid of hybridogenetische the marsh frog ( Pelophylax ridibundus) and the little water frog ( Pelophylax lessonae). Due to special genetic circumstances, however, the pond frog can exist without backcross with the parent species and reproduce.

Features

The physical characteristics of the pond frog ideally lie intermediate between those of its parent species Pool Frog and marsh. Depending on the genetic disposition may resemble either more of one or the other kind of an individual as well. This concerns both the body size and the color and pattern of the top of the abdomen and limbs, or even, for example, the length of the lower leg in relation to the head-body length. Even for the hock on the rear inner toe applies to this intermediate position. When pond frog is the callus internus called hock and raised in relation to the toe length greater than in the marsh, but smaller and more asymmetric than the little water frog.

Specimens with genetic proximity to the marsh up to nine inches (male ) or eleven inches (females ) long. In the " normal case", the top is colored green grass - but occasionally brown - and of a light green line along the center back (from the tip of the snout to vent ), and two clearly protruding back glands bars marked. Also, dark spots and stains can often be identified.

Even convey the vocalizations between the parental species: The mating calls are not as buzzing as Pelophylax lessonae, but for the human ear a little more noticeable in their individual melodies, but less choppy than the " quacks " of the Seefrosches. Like all water frogs owns the pond frog two external vocal sacs, which are located in the lateral corners of the mouth and to read him call empowering. With him, they are usually whitish- gray in color ( the darker gray marsh frog, the little water frog white). The " croaking " area calls are assigned to the different taxa but not accurate.

Genetic peculiarities

A hybrid is usually either infertile or at least not very vital and dependent for reproduction in the next generation to the recombination of parental genes. When Teichfrosch this also takes place, at least if one of the two parental species syntopically, ie in the same habitat lives (see also hybridogenesis ). In particular, in Northern Germany however, it is more the rule that pond frogs occur in pure populations Bastard - Pelophylax lessonae and P. ridibundus then that is missing in the same habitat. Nevertheless, the pond frog can there exist long-term and multiply. He achieves this by also occur in addition to such "normal " individuals with double ( diploid ) set of chromosomes, which have three sets of chromosomes. These animals are called triploid; they wear so that the full genetic information of one of the two parental species in itself. Often, they are also particularly vital and therefore play the reproductive events a crucial role.

Since triploid specimens have less " stolen " a set of chromosomes of the parent species, the frog pond after a proposal by the herpetologists Dubois & Günther (1982 ) is not kind, but is Klepton ( neuter participle to Greek κλέπτω klepto "steal" ) called. This is sometimes referred to by the abbreviation "kl. " Between the scientific genus and species names - however, this notation is not accepted by all scientists (alternatively the Artnamensteil example, in quotes ). This inheritance biological specificity also explains the variability described above, the physical characteristics of the pond frog: While diploid specimens phenotypically are exactly between the two parent species because they each have a set of chromosomes from both triploid animals resemble each of the parent species from which they have two sets of chromosomes. This circumstance leads to the field of biological research to the fact that triploid pond frogs are sometimes externally very difficult to distinguish from that of parental species, which is dominant in their genes.

Among the mentioned genetic peculiarities is the fact that the genome of the pond frog a huge proportion (77 %) of transposable elements. This also " jumping genes " called DNA segments may be responsible and will therefore be discussed today as a driving evolutionary force for certain mutations occurring in the organism ( chromosomal rearrangements ).

Habitat, lifestyle and dissemination

The Frog Pond is open year relatively closely tied to water, but again not as much as the marsh: So the animals also take longer ashore and hibernate probably predominantly terrestrial ( in Erdhohlräumen etc.). As spawning and living waters perennial ( permanent water-bearing ), open standing water are preferred, especially ponds and natural ponds where the frogs sun sitting on the shore edge or on lily leaves and can look out for insects. In case of danger they jump in typical water frog style with a wide set into the water and hide in the mud. The mating season is in May and June in particular - in the spawning calendar of amphibians in Central Europe which Pond Frog is the latest. For characteristics of spawning and tadpoles for example compare Pool Frog. For food range includes besides insects and other invertebrates ( spiders, worms, snails, etc.), but sometimes even small amphibians.

The pond frog is spread from France to northern Italy and central Europe to the Baltic states, Ukraine and the south-western edge of Russia. The " type " is missing naturally in the Mediterranean, the British Isles and Scandinavia (except Denmark and the southern tip of Sweden ). In Germany, Austria and Switzerland, there is a nearly wide dissemination; larger gaps exist only in the extreme north- west of Germany (especially in East Frisia ) and in some middle and high mountain areas. Pond frogs are - generally much more likely than their parent species - almost everywhere present where Seefrösche or Small water frogs are, moreover, but also in many other "pure " stocks.

Threats and conservation

Pond frogs seem to be less of a threat because of their adaptability and their relatively stationary lifestyle than most other amphibian species. ( Should have but at least reeds entangled bank ) Even in some fish ponds can they survive better than the other amphibians ( with the exception of the common toad ).

Legal protection status (selection)

• Fauna-Flora -Habitat Directive (FFH Directive): Annex V (Article may be subject to management measures )
• Federal Species Protection Ordinance ( BArtSchV ): specially protected

National Red List classifications (selection)

• Red List Federal Republic of Germany: not threatened
• Red List of Austria: NT ( Near Threatened )
• Red List of Switzerland: NT ( Near Threatened )

Trivia

An old term for these animals is railings. The dictionary of the Brothers Grimm can be inferred:

The term is now entirely uncommon, but has received the railings ( TWV 51/a4 ) in Georg Philipp Telemann's A Major Violin Concerto.