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Genome Size and the Evolution of New Genes

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While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.

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Related Experiment Video

Updated: Sep 1, 2025

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Published on: February 3, 2023

Gene-influx-driven evolution.

David B Saakian¹, Eugene V Koonin²

¹A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, 2 Alikhanian Brothers St., Yerevan 375036, Armenia.

Physical Review. E

|August 17, 2022

Summary

This summary is machine-generated.

Continuous influx of low-fitness genotypes can drive out high-fitness ones, altering evolutionary trajectories. This influx-driven evolution impacts finite populations and is crucial for understanding microbial and viral evolution.

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Area of Science:

Evolutionary biology
Population genetics
Mathematical modeling

Background:

Understanding evolutionary dynamics in habitats with limited resources.
Investigating the impact of external genotype influx on established populations.

Purpose of the Study:

To analyze evolutionary processes under continuous influx of sub-maximum fitness genotypes.
To determine conditions under which low-fitness genotypes can outcompete and replace high-fitness genotypes.
To model the extinction dynamics of high-fitness genotypes due to external influx.

Main Methods:

Development and analysis of a mathematical model for genotype competition.
Calculation of extinction times for high-fitness genotypes in finite populations.
Application of the quasispecies model to single-peak and symmetric fitness landscapes.

Main Results:

Strong influx of low-fitness genotypes can lead to the extinction of higher-fitness genotypes.
Conditions for genotype transition driven by external influx were mathematically derived.
Nonperturbative effects observed in symmetric landscapes, where minimal influx drastically alters fitness distribution and allele fixation times.

Conclusions:

Influx-driven evolution is a significant factor in population dynamics, capable of overriding fitness advantages.
This phenomenon is broadly applicable to biological systems, particularly prokaryotes and viruses.
External gene flow can fundamentally reshape evolutionary outcomes and genetic diversity.