Related Experiment Video
Updated: Apr 2, 2026
15:00
Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli
Published on: August 18, 2023
4.6K
Non-ergodicity in ecology and evolution
Teemu Kuosmanen1, Alexandre Minetto1, Ville Mustonen1
1Department of Computer Science, Organismal and Evolutionary Research Programme, University of Helsinki, Helsinki 00014, Finland.
Summary
Biological systems often exhibit non-ergodicity, meaning typical outcomes differ from averages. This study explores how non-ergodicity in ecological and evolutionary dynamics impacts population growth, fitness, and cooperation.
Area of Science:
- Ecology and Evolutionary Biology
- Theoretical Biology
- Mathematical Biology
Background:
- Stochasticity is crucial in biological systems, but standard ensemble averaging assumes ergodicity.
- Ergodicity implies that system trajectories mirror ensemble statistics over time.
- Non-ergodicity, where trajectories diverge from ensemble averages, may be common in real biological systems.
Purpose of the Study:
- To investigate the implications of non-ergodicity for eco-evolutionary dynamics.
- To challenge the assumption of ergodicity in biological modeling.
- To provide a framework for understanding systems where typical outcomes differ from mean statistics.
Main Methods:
- Analysis of demographic stochasticity and its impact on growth rates.
- Modeling of environmental stochasticity and eco-evolutionary feedbacks.
- Examination of metapopulation dynamics and subpopulation evolutionary trajectories.
Main Results:
- Demographic stochasticity can cause ergodicity breaking, making growth rates dependent on initial conditions and defining a mutant establishment threshold.
- Eco-evolutionary feedbacks under environmental stochasticity lead to non-ergodic dynamics, precluding simple averaging of genotype fitness.
- Metapopulation dynamics can exhibit deviations from ensemble averages, explaining cooperation's evolution despite fitness costs.
Conclusions:
- Non-ergodicity is prevalent in biological systems and significantly alters eco-evolutionary dynamics.
- Standard averaging methods may fail to capture typical outcomes in many ecological and evolutionary contexts.
- Understanding non-ergodicity is essential for accurately modeling population dynamics, fitness landscapes, and the evolution of complex traits like cooperation.
Related Concept Videos
03:33Genetic Drift
45.2K
Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.
45.2K
00:57Population Growth
29.5K
Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.
29.5K
01:25Modeling with Differential Equations
249
Population dynamics can be described mathematically by considering the population size P(t) as a function of time. The rate of change of the population is then represented by the derivative of P(t). A simple assumption is that the rate of growth is proportional to the size of the population itself. This leads to an exponential growth model, where the population increases rapidly without bound. While this is a useful first approximation, it does not reflect realistic long-term...
249
02:55The Evidence for Evolution
50.1K
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.
50.1K
01:49Hardy-Weinberg Principle
77.4K
Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.
77.4K
01:24Evolution of New Traits in Microbes
114
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
114