Related Experiment Videos
Directionality theory and the evolution of body size.
1Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA. ldemetr@oeb.harvard.edu
Proceedings. Biological Sciences
|January 2, 2001
Summary
Directionality theory explains evolutionary patterns using evolutionary entropy, a measure of age variability in reproducing individuals. This dynamic theory links micro-evolutionary processes to macro-evolutionary trends in body size.
Area of Science:
- Evolutionary biology
- Population genetics
- Demography
Background:
- Directionality theory integrates population genetics and demography.
- It is based on evolutionary entropy, measuring age variability in reproducing individuals.
Purpose of the Study:
- To explain empirical patterns in body size evolution using directionality theory.
- To link micro-evolutionary dynamics with macro-evolutionary changes.
Main Methods:
- Applying three principles of directionality theory relating ecological constraints to entropy trends.
- Utilizing an allometric relationship between entropy and body size.
Main Results:
- Directionality principles explain Cope's rule (phyletic size increase).
- Directionality principles explain the island rule (size changes in island colonization).
- Directionality principles explain Bergmann's rule (size increase with latitude).
Conclusions:
- Evolutionary entropy serves as a unifying concept in evolutionary biology.
- Directionality theory successfully links micro- and macro-evolutionary processes.
- The theory provides a framework for understanding body size evolution across different ecological contexts.