Related Experiment Video
Updated: May 31, 2026
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Rapid recent human evolution and the accumulation of balanced genetic polymorphisms
1University of California, San Diego, Biological Sciences Department, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA. cwills@ucsd.edu
High Altitude Medicine & Biology
|July 2, 2011
Summary
Evolutionary changes are driven by allele frequency shifts. Recent studies successfully disentangle natural selection
Area of Science:
- Population genetics
- Evolutionary biology
- Human genomics
Background:
- Evolutionary change is fundamentally driven by alterations in allele frequencies within populations over time.
- Massive-scale DNA sequencing allows tracking genetic divergence and adaptation during human evolution and migration.
- Disentangling the effects of natural selection from other evolutionary forces (mutation, recombination, drift, gene flow) is challenging.
Purpose of the Study:
- To review recent studies that have successfully identified the role of natural selection in human and Drosophila evolution.
- To summarize findings on the extent of allele fixation during recent human evolution.
- To explore the significance of genetic polymorphisms, particularly those maintained by negative frequency dependence, in human evolution.
Main Methods:
- Analysis of large-scale DNA sequencing data.
- Examination of studies investigating rapid evolutionary changes, such as adaptation to high altitudes in Tibetan and Andean populations.
- Review of data on allele fixation and polymorphism patterns.
Main Results:
- Natural selection has driven rapid trait evolution, with some alleles nearing fixation in just a few thousand years.
- Remarkably few alleles have reached complete fixation during recent human evolution.
- Evidence suggests that many polymorphisms, potentially maintained by balancing selection and negative frequency dependence, play a crucial role in adaptation.
Conclusions:
- Natural selection is a powerful force shaping populations, capable of rapid allele frequency shifts.
- Recent human evolution is characterized by limited allele fixation, with ongoing balancing selection maintaining genetic diversity.
- Genetic polymorphisms are vital for species' adaptability to changing environments, and methods are proposed to quantify their contribution.
Related Concept Videos
02:37Gene Duplication and Divergence
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
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...
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...
02:31Synteny and Evolution
John H. Renwick first coined the term “synteny” in 1971, which refers to the genes present on the same chromosomes, even if they are not genetically linked. The species with common ancestry tend to show conserved syntenic regions. Therefore, the concept of synteny is nowadays used to describe the evolutionary relationship between species.
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
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).
02:16Genetics of Speciation
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.