High latitude species (and populations within species) are adapted to their unique environment. They often have high growth and development rates to fully utilize the short growing season and mature before winter. Within the concept of ecological stoichiometry theory, this study combines ecology with evolution by relating latitudinal life history adaptations to their molecular consequences in body nutrient composition.
In laboratory experiments using the common frog Rana temporaria, we manipulated temperature (18°C and 23°C), food quality (high and low) and region of origin (Arctic and Boreal) in a fully factorial design. We determined tadpole growth rate, development rate, body size and nutrient content, to test if: 1) tadpoles with higher growth rates have higher phosphorus content, 2) Arctic and Boreal tadpoles differ in their stoichiometric reaction to temperature changes, and 3) Arctic tadpoles need higher (than Boreal) quality food to reach full growth potential.
Results/Conclusions
We found that P content was not positively correlated to growth rate but increased with temperature and that Arctic and Boreal tadpoles differed in their stoichiometric reaction to temperature treatment, likely due to temperature adaptations. Furthermore, Arctic tadpole development rates were more limited by food quality than Boreal tadpoles.
Overall, temperature had a strong effect on tadpole nutrient stoichiometry, thus climate change (e.g. predicted temperature increase) is likely to influence the nutrient stoichiometry and will thus have consequences for nutrient requirements and nutrient cycling in these consumers. Furthermore, this is likely to lead to a northward migration of genotypes as the optimal conditions for these genotypes shift northwards. It is therefore ostensible that altered nutrient dynamics and nutrient limitation scenarios will have severe consequences for Arctic food web dynamics.