Edible frog – Pelophylax esculentus

Mainly, the distribution of the edible frog follows that of the pool frog. There are only some distinct populations of pool frogs in which the edible frog is absent. On the other hand, the uniform distribution area of the edible frog covers Denmark, and Skåne in Sweden, of which both the pool and lake frogs are absent.

In Finland, the edible frog was first observed in 2008 in Ruissalo in Turku. By 2013, it had been found in around 50 ponds in the Turku region, stretching from Naantali to Paimio and from Vahto to Kaarina. The spread seems to have occured rapidly.

In Finland, the morphology of the captured and studied individuals suggests that there might be triploid individuals of both the type LRR and the type LLR, but this needs to be confirmed by further research. Also, no individuals of either parent species have been found in edible frog populations, which suggests that triploid individuals are involved. Reportedly, the populations closest to Finland containing triploid individuals of edible frogs are in Skåne in Sweden, in the Danish islands, and in Poland and northern Germany. At least in Denmark, both triploid types LLR and LRR are commonly found as well as the diploid type LR.

In Finland, it is likely that the edible frogs originate from the southernmost parts of the Baltic Sea from where they have migrated to Finland, possibly by marine traffic. The deliberate planting of the pool frog is also a possiblity which cannot be ruled out either in this case.