Related Experiment Video
Updated: Jun 14, 2025
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
927
Evolution of GC-biased gene conversion by natural selection.
Augustin Clessin1, Julien Joseph1, Nicolas Lartillot1
1Laboratoire de Biométrie et Biologie Evolutive, Universite Claude Bernard Lyon 1, UMR 5558, CNRS VAS, Villeurbanne F-69622, France.
Genetics
|June 13, 2025
Summary
GC-biased gene conversion (gBGC) influences genome composition and can increase harmful mutations. This study shows gBGC evolves under weak positive selection, not to minimize genetic load, potentially explaining its presence in humans.
Area of Science:
- Evolutionary biology
- Population genetics
- Molecular evolution
Background:
- GC-biased gene conversion (gBGC) drives human genome base composition variation.
- gBGC can lead to a significant burden of deleterious GC alleles.
- The evolutionary origins and interspecies intensity variations of gBGC are poorly understood.
Purpose of the Study:
- Investigate the evolutionary dynamics of gBGC as a quantitative trait.
- Determine the role of mutation, drift, and natural selection on gBGC evolution.
- Clarify why gBGC persists and varies across species, particularly in humans.
Main Methods:
- Simulations of evolutionary processes.
- Semi-analytical approximations.
- Modeling gBGC as a trait under mutation, drift, and selection.
Main Results:
- In finite populations with deleterious mutations, gBGC is under weak stabilizing selection.
- Evolved gBGC levels depend on mutational bias and genomic selective constraints.
- Selected gBGC levels do not minimize but can increase genetic load, especially in high recombination regions.
Conclusions:
- The observed levels of gBGC in humans may have been positively selected.
- Natural selection on gBGC does not optimize for minimal genetic load.
- gBGC's persistence may be due to weak positive selection despite potential fitness costs.
Related Concept Videos
02:08Gene Conversion
9.7K
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
9.7K
03:21Genome Size and the Evolution of New Genes
7.9K
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.
7.9K
02:05Gene Evolution - Fast or Slow?
7.1K
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
7.1K
02:32Exon Recombination
3.6K
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon...
Exon shuffling follows “splice frame rules.” Each exon...
3.6K
02:16Genetics of Speciation
19.1K
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.
19.1K
03:33Genetic Drift
39.6K
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.
39.6K