Relative Fitness
Relative Fitness - Related Videos
04:31
An Assay for Measuring the Relative Replication Fitness of Viral Strains
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2026
Source: Manocheewa, S., et al. Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses. J. Vis. Exp. (2015)The video demonstrates the procedure for a growth competition assay to measure the relative replication fitness of two viral strains by comparing their replication in human immune cells.
01:13
Induced-fit Model
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2019
Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon. Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
11:39
A Quantitative Fitness Analysis Workflow
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Cited by 25 •
2012
Quantitative Fitness Analysis (QFA) is a complementary series of experimental and computational methods for estimating microbial culture fitnesses. QFA estimates the effect of genetic mutations, drugs or other applied treatments on microbe growth. Experiments scaling from focussed analysis of single cultures to thousands of parallel cultures can be designed.
01:16
Goodness-of-Fit Test
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2025
The goodness-of-fit test is a type of hypothesis test which determines whether the data "fits" a particular distribution. For example, one may suspect that some anonymous data may fit a binomial distribution. A chi-square test (meaning the distribution for the hypothesis test is chi-square) can be used to determine if there is a fit. The null and alternative hypotheses may be written in sentences or stated as equations or inequalities. The test statistic for a goodness-of-fit test is given as...
00:57
Inclusive Fitness
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2025
Most altruistic behavior—in which one animal helps another at a cost to themselves—occurs between relatives. Scientists think these altruistic behaviors evolved because they increase the inclusive fitness of the animal providing help. Inclusive fitness is an individual’s ability to pass down their genes—both through their offspring and the offspring of close relatives with shared genes. If an animal helps a close relative improve their reproductive success, this increases the animal’s...
FAQs
Relative fitness must be interpreted within a particular population and set of environmental conditions. A genotype that produces more viable offspring in one setting may not have the same advantage when pressures change, because survival, mating success, and reproduction are shaped by context. This makes fitness a comparative, rather than universally fixed, measure.
Differences in relative fitness can arise at several stages of reproduction. An organism may survive longer, achieve greater mating success, or produce more viable offspring. Considering these contributions separately helps biologists identify which trait differences are associated with greater reproductive success than alternatives in the same population.
When organisms carrying one allele or genotype leave more viable offspring than others, their associated genetic variants can become more common across generations. Natural selection therefore links differences in reproductive success with changes in allele and genotype frequencies. Tracking this shift helps biologists evaluate how selection produces evolutionary change in populations.
Biologists compare genotypes within the same population by examining outcomes such as survival, mating success, and the production of viable offspring. They then assess which variants contribute more successfully to the next generation under the relevant conditions. This comparison provides a basis for identifying likely fitness differences without treating success as an absolute property.
Relative fitness helps biologists investigate whether population traits are associated with improved success under particular environmental pressures. If variants linked with greater survival or reproduction become more frequent over generations, the pattern can support an analysis of adaptation. The measure also helps connect observed trait differences with predicted evolutionary changes in the population.
By comparing the reproductive success of genotypes, researchers can anticipate how genotype and allele frequencies may change across generations. Variants with higher relative fitness are expected to contribute more genetic material to later populations, whereas less successful variants may decline. These predictions are especially informative when environmental conditions impose identifiable selection pressures.