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Rates of evolution on the time scale of the evolutionary process
1Department of Geological Sciences, Museum of Paleontology, The University of Michigan, Ann Arbor 49109-1079, USA.
Genetica
|February 13, 2002
Summary
Evolutionary rates are best measured per generation, revealing high short-term change despite long-term stability. This suggests evolution operates within narrow morphological constraints over vast timescales.
Area of Science:
- Evolutionary biology
- Quantitative genetics
Background:
- Natural selection operates on a generational timescale.
- Microevolutionary and macroevolutionary patterns reflect evolutionary processes over extended periods.
- Rates of evolution can be quantified using Haldane units (H), representing standard deviations per generation.
Purpose of the Study:
- To analyze the relationship between evolutionary rates and time intervals using rate-interval (RI) and log rate-log interval (LRI) scaling.
- To reconcile the apparent paradox between long-term stationary scaling and high short-term evolutionary rates.
- To investigate the morphological constraints on evolutionary change.
Main Methods:
- Analysis of rates from replicated selection experiments and simulations.
- Examination of empirical microevolutionary and macroevolutionary data.
- Modeling evolutionary dynamics using an heuristic time-form evolutionary lattice.
Main Results:
- Empirical data exhibit stationary scaling, indicating consistent evolutionary patterns over time.
- Generational rates of evolution (H0) are estimated to be approximately 0.2 standard deviations per generation.
- Cenozoic mammals demonstrate a time-form evolutionary lattice significantly longer in time than in morphological width.
Conclusions:
- The evolutionary process is dynamic, characterized by substantial generational change.
- Evolutionary change is constrained within relatively narrow morphological limits despite ample time.
- Stationary scaling over long intervals coexists with high rates of change on a generational scale.
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