Related Experiment Video
Updated: Aug 11, 2026
09:30
Genome-wide Surveillance of Transcription Errors in Eukaryotic Organisms
Published on: September 13, 2018
The evolution of gene number: are heritable and non-heritable errors equally important?
1Department of Plant Taxonomy and Ecology, Loránd Eötvös University, Budapest, Ludovika 2., H-1083, Hungary.
Heredity
|June 10, 2000
Summary
The number of genes in an organism may be limited by gene expression errors. While non-heritable errors can be frequent, their impact is less than heritable mutations unless their harmful effects are significant.
Area of Science:
- Genetics
- Evolutionary Biology
- Genomics
Background:
- Organisms face potential limits on gene number due to deleterious mutations and gene expression imprecision.
- Gene expression errors are more common than mutations but are typically non-heritable, limiting their impact on populations.
- Previous models linking error rates to gene number limits often rely on group selection arguments, which are not directly applicable to gene spread.
Purpose of the Study:
- To determine whether heritable mutations or non-heritable gene expression errors pose a greater constraint on the number of genes an organism can carry.
- To evaluate the population genetics of gene duplication in the context of error rates and genomic complexity.
- To propose a more realistic model for the limits on gene number.
Main Methods:
- Comparative analysis of the genetic load imposed by heritable mutations versus non-heritable expression failures.
- Mathematical modeling to assess the condition under which non-heritable failures outweigh mutations (p x delta > mu).
- Discussion of population genetics principles related to gene duplication and the heritability of expression errors.
Main Results:
- Non-heritable expression failures impose a higher load than heritable mutations if their impact (delta) is sufficiently large relative to their rate (p) and mutation rate (mu).
- Empirical evidence suggests common errors are often of low importance, diminishing their overall impact.
- Gene duplication can lead to heritable expression errors, suggesting a hybrid model is more realistic.
Conclusions:
- A hybrid model incorporating heritable expression errors provides the most realistic framework for understanding limits on gene number.
- The interplay between mutation rates, expression error rates, and their respective harmful effects determines genomic complexity limits.
- Understanding heritable expression errors is crucial for evolutionary genetics and the study of genome evolution.
Related Concept Videos
01:09Mutation, Gene Flow, and Genetic Drift
In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
02:05Gene Evolution - Fast or Slow?
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...
03:21Genome Size and the Evolution of New Genes
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.
02:46Genome Copying Errors
DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a long stretch of wrong bases may get added to the daughter strands. If the errors are left unchecked, cells might accumulate several mutations that might endanger their survival. Therefore, the copying errors are checked and repaired at three levels.
03:21Genome Size and the Evolution of New Genes
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.
02:05Gene Evolution - Fast or Slow?
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...