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The Evidence for Evolution

The Evidence for Evolution

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.

What is Natural Selection?

What is Natural Selection?

Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become more common within a population or species. Naturally selected traits initially arise via random genetic mutations. In order for selection to occur, there must be variation within a population, the trait controlling the variation must be heritable, and there must be an evolutionary advantage for variation in the trait.

Viral Mutations

Viral Mutations

A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material...

Mutations

Mutations

Convergent Evolution

Convergent Evolution

Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.

Range

Range

The range is one of the measures of variation. It can be defined as the difference between a dataset's highest and lowest values. For example, in the study of seven 16-ounce soda cans, the filled volume of soda was measured, thus producing the following amount (in ounces) of soda:
15.9; 16.1; 15.2; 14.8; 15.8; 15.9; 16.0; 15.5
Measurements of the amount of soda in a 16-ounce can vary since different subjects record these measurements or since the exact amount - 16 ounces of liquid, was not...

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Related Experiment Video

Updated: Jan 23, 2026

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli

Published on: March 16, 2011

Mutational and Selective Processes Involved in Evolution during Bacterial Range Expansions.

Lars Bosshard^1,2, Stephan Peischl^2,3, Martin Ackermann^4,5

¹CMPG, Institute of Ecology an Evolution, University of Berne, Berne, Switzerland.

Molecular Biology and Evolution

|June 27, 2019

Summary

This summary is machine-generated.

Artificial selection can help bacteria overcome fitness declines during range expansions by promoting beneficial mutations. This adaptation involves loss-of-function mutations in genes regulating gene expression, aiding rapid environmental adjustment.

Keywords:

experimental evolution mutation load range expansion

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Last Updated: Jan 23, 2026

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli

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Published on: March 16, 2011

The Lambda Select cII Mutation Detection System

The Lambda Select cII Mutation Detection System

Published on: April 26, 2018

Molecular Evolution of the Tre Recombinase

Molecular Evolution of the Tre Recombinase

Published on: May 29, 2008

Area of Science:

Microbial evolution
Population genetics
Genomics

Background:

Bacterial range expansions can lead to a buildup of harmful mutations, reducing fitness.
The capacity of bacteria to adapt and counteract this mutation load through selection is not well understood.

Purpose of the Study:

To investigate whether artificial selection can mitigate the negative impacts of mutation accumulation during bacterial spatial expansions.
To understand the molecular mechanisms underlying adaptation in expanding bacterial populations.

Main Methods:

Comparison of 20 mutator bacterial lines subjected to artificial selection for rapid expansion (SEL) with 20 control lines undergoing free expansion.
Analysis of molecular evolution, focusing on mutation types and their impact on fitness and colony size.

Main Results:

SEL lines exhibited increased colony size compared to ancestral lines, unlike control lines, indicating adaptation.
Both SEL and control lines accumulated similar numbers of mutations, suggesting adaptation wasn't due to purging deleterious mutations.
Loss-of-function mutations, particularly in simple sequence repeats (SSRs) within regulatory genes, were key drivers of increased colony size in SEL lines.

Conclusions:

Artificial selection effectively counteracts fitness reduction during bacterial range expansions.
Adaptation is driven by beneficial mutations, notably loss-of-function mutations in regulatory genes, facilitating rapid adaptation to environmental changes.