Rana arvalis

The moor frog (Rana arvalis) is a slim, reddish-brown, semiaquatic amphibian native to Europe and Asia. It is a member of the family Ranidae, or true frogs. The family the moor frog belongs to, Ranidae, is a broad group containing 605 species. The family is like a “catch-all” for ranoid frogs that do not belong to any other families. Since this is the case, the characteristics that define them are more general, and the frogs are found all throughout the world, on every continent but Antarctica. The moor frog’s genus, Rana, is a little more specific. Frogs of this genus are found in Europe, Asia, South America, and North America. The moor frog is not found in either of the Americas, unlike the foothill yellow-legged frog, Cascades frog, and Columbia spotted frog, which are all found in North America. The moor frog’s scientific name, Rana arvalis means 'frog of the fields'. It is also called the Altai brown frog because frogs from the Altai Mountains in Asia have been included in the R. arvalis species. The Altai frogs have some different characteristics such as shorter shins, but currently there is no official distinction and all frogs are placed under Rana arvalis. The taxonomy may be more defined in the future. This is a small frog, characterized by an unspotted belly, a large, dark ear spot, and — often, not always — a pale stripe down the center of the back. They are generally described as a reddish-brown, but can also be yellow, gray, or light olive. Their bellies are white or yellow and they have a 'bandit-like' black stripe going from their nose to their ears. They vary from 5.5 to 6.0 cm long, but can reach up to 7.0 cm in length, and their heads are more tapered than those of the Common frog (Rana temporaria). The skin on their flanks and thighs is smooth, and the posterior part of their tongues is forked and free. They have horizontal pupils, their feet are partially webbed, and their back legs are shorter than those of other species of frogs. The males are different from the females because of the nuptial pads on their first fingers and their paired guttural vocal sacs. The species has an extensive distribution across Europe. It can be found inhabiting an area stretching from the lowlands of Central and Southern Europe to Siberia, in Austria, Belarus, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Latvia, Lithuania, Moldova, Netherlands, Norway, Poland, Romania, Russian Federation, Slovakia, Slovenia, Sweden, Switzerland, and Ukraine. However, they are believed to be extirpated in Switzerland and possibly in Siberia as well; the records of frogs being in Siberia at all may have been in error. Alsace, France, constitutes the western boundary of their territory. Moor frogs were also confirmed to have been present in East Anglia in the UK, after archaeological remains were found. The types of land they can inhabit are greatly varied. They live in tundra, forest tundra, forest, forest steppe, and steppe, forest edges and glades, semideserts, swamps, meadows, fields, bush lands, and gardens. They prefer areas untouched by humans, such as damp meadows and bogs, but they still may be able to live in agricultural and urban areas. Moor frogs provide a good model for studying local adaptation as they experience a wide range of environments and are relatively limited in their movements. Their restriction in movements implies limited gene flow and facilitates evolution through adaptive genetic differentiation among populations.