Chapter 23 Flashcards
Evolution on its smallest scale
Change in allele frequencies in a population over generations
Microevolution
During the drought of Daqhne Major, did the beak of any individual finch get larger?
No
Name a heritable trait
Height
Are all individuals in a population identical with respect to a heritable trait?
No
Differences in a population
Provides the raw material for evolution
Genetic variation
Name a phenotype that is not heritable
Big muscles
Would you expect two populations of the same species in different locations to have identical genetic compositions?
No
A gradual change in genetic composition along a geographic gradient is called a
Cline
New alleles arise through the process of
Mutation
Genetic variation can also arise through errors __ genes or ___ them around
Duplicate, move
Most of the time, changes to genes is
Harmful
What population would accumulate the most mutations in a year
Virus
Genetic variation is also increased through
Sexual reproduction
A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
Population
When a population has only one allele for a particular locus, that allele is considered to be __ in the gene pool of that population
Fixed
Imagine a population of wildflowers with 500 individuals. There are 20 plants with red flowers, 160 with pink flowers, and 320 with white flowers. What is the percent of the Cr allele? And Cw?
20% and 80%
The Hardy-Weinberg principle applies to populations that __ evolving with respect to that particular trait
Are not
If you know the proportion of two alleles in a population, you can predict the frequency of each of the three possible genotype a by using the
Multiplication rule
What is the formula for the Hardy-Weinberg equation?
P2 + 2pq + q2 = 1
What are the 5 assumptions that must be met for the population to be considered to be in a Hardy-Weinberg equilibrium?
No mutations Random mating No natural selection Extremely large population size No gene flow
When there is selection against both extremes and in favor of the intermediate phenotype
Stabilizing selection
When both extremes are favored over the intermediate phenotype
Disruptive selection
When selection favors one extreme phenotype over the other
Directional selection
Which selection affected the soapberry bug?
Directional
Two ways in which mating is not random?
Only mating with a spouse
An individual preferring a certain phenotype and mating with individuals with the phenotype
In diploid organisms __ alleles can be maintained over time even if they are harmful, because they are preserved in heterozygous individuals
Recessive
How does sickle cell disease relate to heterozygous advantage?
Those with the heterozygote for sickle cell have protections against malaria
Many predators form a “search image”, which allows them to spot prey more easily. Typically, they will match this search image to whatever color of prey is most abundant. Therefore, prey with the most common color are more likely to get eaten. This results in
Frequency selection
Three reasons why natural selection doesn’t create perfect organisms
Selection can only act on existing variation
Evolution is limited by historical constraints
Adaptions are often comrpomises
