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Spatial-Scale Evolutionary Bias Sheds Light on the Latitudinal Diversity Gradient
Haoyuan Wu1, Donghui Xu1, Yonghua Wu1,2
1School of Life Sciences Northeast Normal University Changchun China.
Ecology and Evolution
|July 31, 2026
Summary
Spatial-scale evolutionary bias (SSEB) drives species towards higher fitness gains. This bias may explain the latitudinal diversity gradient by promoting adaptation towards lower latitudes.
Area of Science:
- Evolutionary Biology
- Ecology
Background:
- The latitudinal diversity gradient (LDG) describes decreasing species richness from the equator to the poles.
- The underlying causes of the LDG are complex and debated within ecological and evolutionary research.
Purpose of the Study:
- To experimentally investigate the existence of spatial-scale evolutionary bias (SSEB).
- To determine if SSEB contributes to the latitudinal diversity gradient (LDG).
Main Methods:
- Utilized *Escherichia coli* as a model organism for experimental evolution.
- Conducted competition assays between high-fitness-gain and low-fitness-gain populations.
- Performed experimental evolution assays to observe adaptive spatial spread.
Main Results:
- High-fitness-gain populations exhibited significantly faster spatial expansion.
- Gene flow promoted competitive exclusion of low-fitness-gain populations by high-fitness-gain populations.
- Experimental populations preferentially evolved and spread towards regions offering higher fitness gains.
Conclusions:
- Empirical evidence supports the occurrence of spatial-scale evolutionary bias (SSEB).
- SSEB can drive biased adaptation towards lower latitudes, potentially explaining the latitudinal diversity gradient.
- SSEB offers a novel evolutionary mechanism contributing to the observed patterns of biodiversity across latitudes.
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