Biology Chapter 19: Genes within populations
Why does selection occur?
-Because some individuals in a population possess more favorable phenotypes than others.
What is the founder effect?
-Changes in allele frequencies that result from the colonization of a new location by a small group of individuals from a larger population
Which of the following agents of evolutionary change occurs when alleles move from one population to another?
-Gene flow
Select the statement that describes nonrandom mating.
-Genetically similar individuals preferentially mate with each other.
In a large population that is not subject to mutation, migration, selection, or nonrandom mating, the proportions of genotypes are stable and the population is said to be in __________- __________ equilibrium, named after the scientists who described this principle.
-Hardy- Wienberg
How does gene flow affect allele frequencies among populations?
-It tends to decrease differences in allele frequencies.
What is gene flow?
-The movement of alleles into or out of a population.
What is fitness?
-The relative likelihood that a phenotype will produce the most offspring
Select all of the following criteria that must be present for natural selection to occur and cause evolutionary change in a population.
-Variation must result in differences in the number of offspring surviving in the next generation. -Variation must have a genetic basis. -Variation must exist among individuals.
The allele frequency is calculated by dividing the number of copies of a given _______ in a population by the total number of ______ in that population.
-allele -alleles
The number of copies of an allele in a population divided by the total number of all alleles for that gene in a population is the..
-allele frequency
The bottleneck effect occurs when allele frequencies change due to..
-an event that drastically reduces population size
In what type of selection does a breeder select for desirable characteristics in organisms?
-artificial selection
In artificial selection, the ______ selects individuals with desired characteristics to produce offspring, and in natural selection, the ______ selects which individuals will produce the most offspring.
-breeder -environment
Sexual selection is a type of natural selection in which the evolution of certain traits is driven by which of the following types of competition?
-competition for mates
Natural selection can lead to __________ if variation is genetically based.
-evolution
The accumulation of differences in species that causes new species to arise from existing ones is a process called ......
-evolution
The word _______ is used to refer to how an entity, such as a species, changes over time.
-evolution
What term quantifies reproductive success of a phenotype?
-fitness
For natural selection to occur, variation in traits must be which of the following?
-genetic and heritable
What evolutionary mechanism results in random changes in allele frequencies from one generation to the next?
-genetic drift
The processes that lead to evolutionary change are mutations, natural selection, _______ drift, gene flow and _________ mating.
-genetic drift -nonrandom mating
Select all of the following that are true of antibiotic resistance.
-increased resistance is due to selection -agents that target cellular proteins will lead to the evolution of resistance
Which theory proposes that variation among individuals is created by experience, not by preexisting genetic differences.
-inheritance of acquired characteristics
Consider population 1 in which the frequency of allele A = 0.1 and population 2 in which the frequency of allele A = 0.7. What will happen to the frequency of A in population 1 if individuals from population 2 move into population 1?
-it will increase
What is the ultimate source of all new alleles?
-mutation
__________ is the ultimate source of genetic variation.
-mutation
Antibiotic resistance in bacteria is an example of...
-natural selection
The theory of _________ _________ proposes that variation among individuals is not created by experience, but is the result of preexisting genetic differences.
-natural selection
What evolutionary process is occurring if individuals with certain genotypes mate with each other more commonly than would be expected on a random basis?
-nonrandom mating
In a population that is in Hardy-Weinberg equilibrium, proportions of genotypes are....
-not changing
Selection occurs because some individuals in a population have more favorable __________ than others in the same population and leave more progeny than others.
-phenotypes
If population 1 is in Hardy-Weinberg equilibrium such that p = 0.7 and q = 0.3, select all of the following that would result if mating began to occur with the adjacent population 2 in which p = 0.1 and q = 0.9.
-population 1 will shift out of the hardy weinberg equilibrium -in population 1, q will increase -in population 2, p will increase
The field of study that examines the properties of genes in populations is called...
-population genetics
___________ selection is a type of natural selection in which competition for mates drives the evolution of certain traits.
-sexual
A dramatic reduction in population size due to a natural disaster or destruction of habitat and the resulting change in the allele frequencies of the new population is called..
-the bottleneck effect
True or false: Genetic drift, mutations, and nonrandom mating are three agents that can act to produce evolutionary changes in a population.
-true
What is genetic drift?
random change in allele frequency of a population over time
What is population genetics?
study of properties of genes in a population