Rana temporaria Linnaeus, 1758
The European common frog (R. temporaria) is a widespread species. In the Iberian Peninsula it is restricted to a small area at the north: the Cantabrian ridge and the Pyrenees mountains (Fig. 1).
Recently it has been shown that the most substantial genetic and morphological differentiation within R. temporaria is found in the northers Iberia. Indeed, Sequeira and Nicieza (unpublished data) have detected four highly diverged mtDNA evolutionary lineages, corresponding to populations from Galicia, Asturias, Basque Country, and Pyrenees.
In the Cantabrian ridge it can be found close to streams (in beech and fir forests), as well as in lakes, flooded areas, bogs, streams, wet meadows, and rocky areas. Further, it is distributed from 350 to 2950 meters AMSL (above mean see level).
The European common frog is a big robust frog (40-70 mm) with a coloration that goes from reddish to dark brown (sometimes yellow or greenish). They have a lifespan of 2-12 years and they reach the sexual maturity within three years. The time of reproduction varies depending on the altitude/latitude and the reproductive active days last for 10-35 or 5-15 days, depending on the altitude/latitude.
Common frogs lay between 480 and 2680 eggs and tadpoles hatch in 3-4 weeks. Tadpoles reach a snout-vent length of 15-40 mm. Besides, tadpoles of R. temporaria possess an elevated degree of phenotypic plasticity (e.g. in growth strategies; Dahl et al. 2012).
The wide distribution of this species makes it a unique system to examine the geographical variation (across altitude and latitude) in thermal tolerance, life-history traits, etc.