Pool Frogs Survive in Cold Climate Of Sweden

Pool frog (Pelophylax lessonae) is capable of growing at various rates depending on the changes of temperature. The new study reveals that this species have speedy growth in the warmest time of the year in Sweden. This enables the pool frog to survive the cold temperature.

Phys states that pool frog wants warm atmosphere for reproduction so its tadpoles can be fully developed. "Since Sweden has briefer periods of high temperatures than Poland and Latvia do, this increased growth capacity under warmest conditions allow this frog to take full advantage of the short periods of high temperatures," said German Orizaola, a Spanish scientist and a researcher for the department of Ecology and Genetics at Uppsala University and the co-author of the study. He also said that the frog completed its life cycle that depends deeply on warm climates like Scandinavia.

According to researchers, the pool frog begins breeding in Sweden when the pond water temperature reaches 16 degrees Celsius-probably in May, which is the breeding period of the pool frog.

The scientists visited the place that inhabited by pool frogs in the Baltic Sea in May 2006. Then, they gathered a sample of frog spawn in Poland. They also collected samples of pool frog from three Swedish areas as early as in June. This is the month wherein the species begin reproduction.

The researchers conducted their experiment in temperature-controlled rooms--that are set to 19 degrees Celsius, which is a low temperature for the pool frog and one to 26 degrees Celsius, which is a high temperature. Then, they bred the tadpoles from the various samples of frog spawn.

They also studied the degree of plasticity of the tadpoles bred at various temperatures. There is a greater difference in the development of the pool frogs. They found out that there is an increased plasticity of the pool frog tadpoles that were taken in the Swedish areas. The Swedish tadpoles are capable of growing faster than those taken from Latvia or Polish regions when displayed to high temperature, the researcher concluded.

Pool frog is also termed as European frog. It is the only amphibian species that is recognized by the UK government and protected by the Biodiversity Action Plan.