Related Experiment Video
Updated: Jul 7, 2026
07:34
Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients
Published on: August 22, 2018
Quantifying variability of avian colours: are signalling traits more variable?
1Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Radolfzell, Germany. delhey@orn.mpg.de
Plos One
|February 28, 2008
Summary
Sexual selection theory predicts increased trait variability, especially in bright coloration. This study confirms higher color variability in sexually selected traits but finds no general increase in male or dimorphic color variability, challenging some evolutionary assumptions.
Area of Science:
- Evolutionary biology
- Animal coloration
- Sexual selection
Background:
- Condition-dependent handicap models posit that trait variability, particularly in sexually selected ornaments, is maintained by individual quality.
- These models predict amplified variability in sexually selected traits, greater male than female variability, and higher variability in sexually dimorphic traits.
- Previous tests focused on metric traits, neglecting bright coloration, a prominent sexual trait, due to measurement challenges.
Purpose of the Study:
- To develop a method for quantifying perceived color variation in animal coloration.
- To test predictions of sexual selection theory regarding trait variability in bird coloration.
- To investigate the relationship between sexual selection, condition-dependence, and color variability.
Main Methods:
- Developed a novel index to quantify chromatic color variation based on avian color vision models.
- Compared color variability in ornamental and non-ornamental patches across six bird species.
- Analyzed variability in relation to sexual selection and sexual dimorphism.
Main Results:
- Confirmed that sexually selected or quality-indicating colored patches exhibit increased chromatic variability.
- Found no general support for increased variability in males compared to females.
- Observed no association between sexual dichromatism and increased color variability.
Conclusions:
- Demonstrated a viable method for estimating perceived color variability, applicable to traits difficult to quantify otherwise.
- Provided evidence supporting sexual selection theory's prediction of increased variability in selected colors.
- Highlighted that sexual differences in variability may not always be driven by the same selective forces, particularly concerning sex differences and dimorphism.
Related Concept Videos
01:20Mate Choice
Mate choice—the decision about whom to mate with—is a type of natural selection, since animals must reproduce to pass down their genes. Mate choice is also called intersexual selection because the behavior occurs between the sexes.
01:21Testing a Claim about Mean: Unknown Population SD
A complete procedure of testing a hypothesis about a population mean when the population standard deviation is unknown is explained here.
Estimating a population mean requires the samples to be approximately normally distributed. The data should be collected from the randomly selected samples having no sampling bias. There is no specific requirement for sample size. But if the sample size is less than 30, and we don't know the population standard deviation, a different approach is used; instead...
Estimating a population mean requires the samples to be approximately normally distributed. The data should be collected from the randomly selected samples having no sampling bias. There is no specific requirement for sample size. But if the sample size is less than 30, and we don't know the population standard deviation, a different approach is used; instead...
00:49Complementation Tests
A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes.
Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...
Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...
01:39Epistasis
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
01:11Variability: Analysis
Measures of variability are statistical metrics that reveal the dispersion pattern within a dataset. They are pivotal in biostatistics, providing insights into the heterogeneity within health and biological data. Variability signifies the degree to which data points diverge from one another, helping researchers understand the potential range of values and associated uncertainty within the data.
The range is a simple measure of variability, indicating the difference between the highest and...
The range is a simple measure of variability, indicating the difference between the highest and...
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...