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Related Concept Videos

Formation of Species01:31

Formation of Species

Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.Allopatric SpeciationIn allopatric speciation, gene flow between two populations of the same species is prevented by a geographic barrier, like...
Understanding Species and Reproductive Barriers01:17

Understanding Species and Reproductive Barriers

A species is a group of organisms that interbreed and produce fertile offspring. Typically, individuals of the same species appear similar and share common characteristics due to their highly similar genomes. However, not all organisms that look alike are members of the same species. Various mechanisms keep most species discrete. While some mechanisms prevent reproductive behavior and fertilization (pre-zygotic isolation), others prevent the production of fertile offspring after mating has...
Speciation Rates01:07

Speciation Rates

Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
Phylogenetic Species Concept in Microbiology01:22

Phylogenetic Species Concept in Microbiology

The phylogenetic species concept (PSC) is a framework used to delineate species based on evolutionary relationships, emphasizing shared ancestry and diagnosable genetic traits. Unlike morphological or biological species concepts, the PSC is particularly advantageous for microbial taxonomy, where traditional reproductive or phenotypic criteria often fall short due to the prevalence of asexual reproduction, minimal morphological differentiation, and widespread horizontal gene transfer among...
Genetics of Speciation02:16

Genetics of Speciation

Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.The genetics of speciation involves the different traits or isolating mechanisms preventing gene exchange, leading to reproductive isolation. Reproductive isolation can be due to reproductive barriers that have effects either before or after the formation of a zygote. Pre-zygotic mechanisms prevent fertilization from occurring, and post-zygotic mechanisms...
Viral Recombination00:57

Viral Recombination

Cells are sometimes infected by more than one virus at once. When two viruses disassemble to expose their genomes for replication in the same cell, similar regions of their genomes can pair together and exchange sequences in a process called recombination. Alternatively, viruses with segmented genomes can swap segments in a process called reassortment.

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Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples
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Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples

Published on: October 25, 2018

What is a quasispecies?

M A Nowak1

  • 1Martin Nowak is at the Dept of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.

Trends in Ecology & Evolution
|January 18, 2011
PubMed
Summary
This summary is machine-generated.

A quasispecies, a distribution of mutants shaped by mutation and selection, acts as a single unit under evolutionary pressure. This concept is crucial for understanding viral evolution, including human immunodeficiency viruses (HIV) and acquired immunodeficiency syndrome (AIDS) pathogenesis.

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Area of Science:

  • Evolutionary Biology
  • Virology
  • Genetics

Background:

  • A quasispecies is defined as a distribution of mutants arising from mutation and selection.
  • Selection acts on the entire quasispecies, not individual mutants.
  • Extensive genetic heterogeneity in virus populations, such as HIV-1 and HIV-2, is characterized as a quasispecies.

Purpose of the Study:

  • To explore the concept of quasispecies.
  • To discuss the implications of quasispecies in evolutionary biology.
  • To examine the role of quasispecies in virology, particularly in the context of HIV and AIDS.

Main Methods:

  • Review of theoretical frameworks defining quasispecies.
  • Analysis of experimental systems designed to study quasispecies evolution.
  • Examination of viral population genetics, focusing on HIV.

Main Results:

  • Quasispecies represent a fundamental unit of selection in systems with high mutation rates.
  • The quasispecies model provides insights into the pathogenesis of diseases like AIDS.
  • Viral genetic heterogeneity is a key characteristic explained by the quasispecies concept.

Conclusions:

  • The quasispecies concept is vital for understanding evolutionary dynamics in populations with high mutation rates.
  • Understanding quasispecies is essential for developing strategies against rapidly evolving viruses like HIV.
  • This concept bridges theoretical evolutionary biology with practical applications in virology and disease mechanisms.