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Related Concept Videos

Natural Selection and Adaptation01:15

Natural Selection and Adaptation

Natural selection, a fundamental concept in evolutionary biology, is the mechanism by which evolution is driven, favoring organisms that are best adapted to their environments. This process enhances their chances of survival and reproduction. Adaptation, a key outcome of this process, involves genetic modifications that optimize an organism's functionality under specific environmental challenges, such as extreme cold or thinner air at high altitudes.
Beyond physical adaptations, psychological...
Limits to Natural Selection01:38

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...
What is Natural Selection?01:32

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.The Theory of Natural...
Evolution of New Traits in Microbes01:24

Evolution of New Traits in Microbes

Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
Types of Selection01:46

Types of Selection

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural selection can be directional, stabilizing, or disruptive. Directional selection favors one extreme trait and shifts the population towards that phenotype while selecting against individuals displaying alternate traits. Stabilizing selection favors an intermediate trait with a narrow range of variation. Deviation from the optimal phenotype towards an...
Natural Selection and Mating Preferences01:06

Natural Selection and Mating Preferences

The principle of natural selection posits that organisms better adapted to their environment are more likely to survive and reproduce. This principle is closely intertwined with mating preferences, a key aspect of sexual selection, which evolutionary psychologists believe is driven by instincts to propagate one's genes. Such instincts significantly influence mating behaviors and preferences between genders.
Females, due to their biological roles in conception, pregnancy, and nursing, inherently...

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Visualizing Visual Adaptation
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Adaptation and Natural Selection revisited.

E Sober1, D S Wilson

  • 1Department of Philosophy, University of Wisconsin, Madison, WI, USA.

Journal of Evolutionary Biology
|January 14, 2011
PubMed
Summary
This summary is machine-generated.

George C. Williams linked adaptation and selection levels. This paper explores multilevel selection theory to define adaptation, examining conditions beyond mere selection for traits to be considered adaptations.

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Area of Science:

  • Evolutionary biology
  • Theoretical biology

Background:

  • George C. Williams' Principle posits that adaptation at a given level necessitates selection at that same level.
  • The distinction between group and individual adaptation is historically linked to group and individual selection.

Purpose of the Study:

  • To elucidate the necessary and sufficient conditions for adaptation within multilevel selection theory.
  • To examine the requirements for a trait to be classified as an adaptation beyond the presence of selection at its level.
  • To discuss an alternative framework for defining units of adaptation that challenges Williams' Principle.

Main Methods:

  • Review and synthesis of concepts within multilevel selection theory.
  • Conceptual analysis of adaptation and selection at different hierarchical levels.
  • Exploration of theoretical frameworks for defining units of adaptation.

Main Results:

  • Multilevel selection theory provides a framework for understanding the conditions required for adaptation.
  • Williams' Principle is a necessary but not sufficient condition for adaptation; further criteria are needed.
  • An alternative framework exists that deviates from Williams' Principle in defining units of adaptation.

Conclusions:

  • Defining adaptation requires more than just the presence of selection at a given level.
  • Multilevel selection theory offers a nuanced understanding of adaptation across different scales.
  • The study highlights ongoing theoretical developments in defining units of adaptation.