Size-density scaling in protists and the links between consumer-resource interaction parameters.

Area of Science:

• Ecology
• Macroecology
• Theoretical Ecology

Background:

• Body-size-dependent demographic processes can generate macroecological patterns.
• The scaling of population density with body size is a key macroecological pattern.

Purpose of the Study:

• Evaluate if body-size-dependent interactions generate macroecological patterns in grazing protists.
• Test for correlations between demographic parameters after controlling for body size.
• Assess resource use dependence on body size and prey size selection.

Main Methods:

• Compiled laboratory data on heterotrophic protists grazing algae.
• Used nested dynamic models to predict size-density scaling.
• Controlled for consumer size and assessed links between model parameters.

Main Results:

• Predicted size-density scaling closely matched observed patterns; simple models sufficed.
• Prey productivity and capture area influence variation, not prey size selection.
• Correlated consumer-resource parameters, including prey size selection and conversion efficiency.

Conclusions:

• Widespread community patterns are explained by simple, consistent population models.
• Ecological parameter space is structured, limiting realistic system dynamics.
• Predator-prey size ratios have minimal influence on population size and fitness.