Giants, dwarfs and the environment - metamorphic trait plasticity in the common frog

Area of Science:

• Ecology
• Evolutionary Biology
• Herpetology

Background:

• Understanding how environmental parameters influence organismal performance and phenotypes is key to adaptation and population dynamics.
• Phenotypic plasticity allows organisms to adjust traits in response to environmental changes, impacting individual fitness.
• Amphibian larvae, like the European common frog (Rana temporaria), are known for high phenotypic plasticity in metamorphic traits.

Purpose of the Study:

• To investigate the environmental impact on realized phenotypic plasticity of metamorphic traits in a natural population of Rana temporaria.
• To assess the variability of developmental time, size, and body mass at metamorphosis within and between ponds.
• To determine the extent to which environmental factors explain observed differences in these traits.

Main Methods:

• Field study of Rana temporaria metamorphic traits across 18 ponds in 2007, with follow-up in six ponds in 2009 and 2010.
• Assessment of developmental time, size, and body mass at metamorphosis.
• Analysis of trait differences in relation to environmental parameters like predation and competition.

Main Results:

• Significant local variances in metamorphic traits were observed, with differences up to a factor of ten, both between and within ponds.
• Commonly expected environmental factors (predation, competition) did not correlate with observed trait differences.
• Divergent patterns in mass at metamorphosis were found between ponds, but no consistent pattern across years.

Conclusions:

• Environmental conditions within a single breeding pond partially explain the variability in metamorphic traits.
• The study highlights the importance of considering individual-level variability in reaction norms to fully understand within-population phenotypic variation.
• Further research is needed to elucidate the drivers of phenotypic plasticity in Rana temporaria.