Related Experiment Video
Updated: Aug 10, 2026
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Additive effects of environmental and demographic variation shape the repeatability of evolution across replicated
Karen Bisschop1,2,3,4,5, Meike T Wortel2,6, Ken Kraaijeveld2,7
1Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
Evolution Letters
|August 9, 2026
Summary
Evolutionary repeatability is reduced by environmental and demographic stochasticity. Understanding these factors is key for predicting evolutionary responses and developing forecasting tools.
Area of Science:
- Evolutionary biology
- Genetics
- Microbiology
Background:
- Evolutionary repeatability is crucial for understanding life's origins and developing predictive models.
- Stochasticity, defined as fitness-independent changes, limits evolutionary repeatability.
- Environmental and demographic stochasticity are key drivers of evolutionary change over short timescales.
Purpose of the Study:
- To quantify the effects of environmental and demographic stochasticity on evolutionary outcomes.
- To investigate the interaction between these stochasticity sources in driving fitness.
- To assess the repeatability of evolutionary experiments across multiple institutions.
Main Methods:
- A replicated evolutionary experiment using *Caenorhabditis elegans* was conducted across five institutes.
- Environmental variation was introduced through novel rearing conditions and divergent microbiomes.
- Demographic treatments, including population bottlenecks, were applied within institutes to explore genetic drift and draft.
Main Results:
- Significant variation in fitness outcomes was observed among institutes, partly explained by microbial differences.
- Lab-specific environmental factors accounted for most of the variation in mean fitness.
- Demographic heterogeneity, particularly population bottlenecks, strongly influenced fitness outcome repeatability.
Conclusions:
- Environmental and demographic stochasticity interact additively to reduce evolutionary repeatability.
- Understanding and statistically integrating heterogeneity is vital for accurate evolutionary forecasting.
- These findings emphasize the importance of considering stochasticity in experimental evolution studies.
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