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Tempo does not correlate with mode in the fossil record
1Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway.
Evolution; International Journal of Organic Evolution
|October 18, 2016
Summary
Fossil species often appear unchanged (stasis), but this study shows significant evolution occurs even during stasis. Evolution may be more constant across geological time than previously thought.
Area of Science:
- Evolutionary biology
- Paleontology
- Macroevolutionary dynamics
Background:
- The fossil record suggests species remain largely unchanged over long periods (stasis).
- Contemporary populations show substantial evolution, creating a paradox of stasis.
- Stasis is traditionally assumed to represent minimal evolutionary change.
Purpose of the Study:
- To investigate evolutionary rates during stasis in the fossil record.
- To test the assumption that stasis equals minimal evolution.
- To re-evaluate the relationship between stasis, evolution, and speciation.
Main Methods:
- Analysis of 450 fossil time series.
- Quantification of morphological fluctuations in morphospace.
- Comparison of evolutionary distances during stasis versus directional change.
Main Results:
- Morphological fluctuations during stasis cover similar distances in morphospace as lineages with directional change.
- Lineages in stasis undergo considerable evolution, but it does not accumulate into large net changes.
- Evolutionary rates may be more homogeneous across different modes in the fossil record.
Conclusions:
- Stasis does not necessarily represent minimal evolution.
- Substantial evolution is not exclusively linked to speciation.
- Stasis provides insights into the stability of adaptive landscapes and ecological niches over macroevolutionary timescales.
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