Size and survival in a stochastic environment

Area of Science:

• Ecology
• Evolutionary Biology
• Population Dynamics

Background:

• Environmental conditions exhibit spatial and temporal variability.
• This variability can influence body size fluctuations in populations.
• Factors like size-dependent mortality and dispersal costs are key.

Purpose of the Study:

• To model the effects of environmental variability on body size.
• To compare the impact of temporal versus spatial variability.
• To evaluate different modeling approaches for studying trait evolution in variable environments.

Main Methods:

• Development of a theoretical model assuming innate capacity for increase (r_m) as a fitness measure.
• Analysis of the model's predictions regarding spatial and temporal environmental heterogeneity.
• Presentation and discussion of an alternative approach using parent-offspring regression.

Main Results:

• Temporal environmental variability has a greater effect on body size fluctuations than spatial variability.
• The model highlights the significance of size-dependent mortality and dispersal costs.
• Limitations of the r_m-based model are identified.

Conclusions:

• Parent-offspring regression models are more appropriate for studying continuous trait evolution in variable environments.
• These models avoid assumptions of optimizing a specific fitness measure.
• They offer greater insight into the rates of character change.