Directional selection
. The type of selection that favors phenotypes at one extreme of a trait’s range; causes a shift in a population’s phenotypic distribution; an extreme phenotype that was once rare in a population becomes more common; mean value of a trait shifts in the direction of the more advantageous phenotype.
Which of the following types of selection favors one extreme of a phenotypic distribution?
A type of selection that favors phenotypes at one extreme of a trait’s range is called
directional selection
.
When two or more extreme phenotypes are favored over an intermediate phenotype?
Disruptive selection, also called diversifying selection
, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.
What is it called when evolution favors the extremes of a phenotype?
Stabilizing selection
When individuals with intermediate phenotypes are favoured and extreme phenotypes are selected against, the selection is said to be stabilizing. (See the left column of the figure.) The range and distribution of phenotypes then remains approximately the same from one generation to another.
When an extreme phenotype is favored and the distribution curve moves toward that extreme this would demonstrate a type of natural selection called?
Directional selection
occurs when one extreme phenotype is favored by natural selection. During stabilizing selection, the intermediate phenotype is favored and becomes more common in the population.
What are 3 ways natural selection can change a distribution of traits?
There are three modes of selection:
directional, disruptive, and stabilizing
. Natural selection can alter the frequency distribution of heritable traits in three ways, depending on which phenotypes in a population are favored. The three modes of selection are called directional, disruptive, and stabilizing selection.
What is an example of an extreme phenotype?
An extreme phenotype that was once rare in a population becomes more common. Examples:
The rise of drug-resistant bacteria
provides a classic example of this type of selection. examples: One example of this type of selection involves feather color in male lazuli buntings, a bird species native to North America.
What are the 4 types of natural selection?
Stabilizing, Directional, and Diversifying Selection
. Stabilizing, directional, and diversifying selection either decrease, shift, or increase the genetic variance of a population.
What occurs when an intermediate phenotype is favored?
the intermediate phenotype is favored and
becomes more common in the population
. The distribution becomes stable at the intermediate phenotype rather than shifting toward one of the extremes.
What is an extreme phenotype?
We define a person as having an extreme phenotype
if the observed phenotype is above a specified threshold or below a specified threshold
. We consider a model where these thresholds can be tailored to each individual. The classical extreme sampling design is to set equal thresholds for all individuals.
What are 3 types of evolution by natural selection?
- Stabilizing Selection.
- Directional Selection.
- Disruptive Selection.
What are the two phases of speciation quizlet?
What are the two phases of speciation?
There is a normal distribution of traits seen in natural selection
, where the medium trait is favored. However, the distribution of traits is altered when factors in the environment change and influence natural selection.
What are the four kinds of evidence that evolution has occurred?
Evidence for evolution:
anatomy, molecular biology, biogeography, fossils, & direct observation
.
What can you learn from looking at phenotypic distribution?
What can you learn from looking at a phenotypic distribution?
An intermediate phenotype is favored
and becomes more common. Both extreme phenotypes are favored while individuals with intermediate phenotypes are selected against by something in nature.
What is the difference between natural selection and survival of the fittest?
Natural selection refers to the process by which organisms evolve. There are
selective pressures
in their environment that affect reproductive success. … “Survival of the fittest” is a phrase that is related to this idea of reproductive fitness, but doesn’t really mean what most people that use it think.
What is natural selection and what are its effects on allele frequencies?
Natural selection
can cause microevolution (change in allele frequencies)
, with fitness-increasing alleles becoming more common in the population. Fitness is a measure of reproductive success (how many offspring an organism leaves in the next generation, relative to others in the group).
