Section 19.2 (Exam 3) Flashcards
Mutation, Selection, Gene Flow, Genetic Drift, and Nonrandom Mating Result in Evolution
Define evolution.
change in genetic makeup of populations over time
Define population.
A group of individuals of a single species that live and interbreed in a particular geographic area
How do individuals and populations differ from an evolutionary standpoint?
Individuals do not evolve; populations do evolve
What are the 4 mechanisms of evolution in addition to natural selection?
mutation
gene flow
genetic drift
nonrandom mating
What is the origin of genetic variation?
mutation
Define mutation.
any change in the nucleotide sequences of DNA
What are the three different effects mutation could have on an organism?
harmful
neutral
beneficial
What forms as a result of mutation?
alleles
Define alleles.
different forms of a gene
Define gene pool.
sum of all copies of all alleles at all loci in a population
Define allele frequency.
Proportion of an allele in the gene pool
Define genotype frequency.
Proportion of each genotype in the population
What is the calculation of the allele frequency and genotype frequency used for?
to measure evolutionary changes
How does selection produce new phenotypes?
acting on genetic variation
Define genotype.
genetic makeup of an individual
Define phenotype.
the set of observable characteristics of an individual
Define artificial selection.
Favored phenotypes are bred together by humans to produce favorable results
What organism did Darwin breed?
pigeons
What is the function of artificial or natural selection?
increases the frequency of the favored trait from one generation to the next
Define adaptation.
favored trait that spreads through a population by natural selection
What is gene flow?
results from migration of individuals and movements of gametes (e.g., pollen) between populations
How can new individuals affect a gene pool?
They can add alleles to the gene pool and changes allele frequnecies
What is genetic drift?
results from random changes in allele frequencies
What is a result of genetic drift?
Harmful alleles may increase in frequency, and rare advantageous alleles may be lost
How does genetic drift vary based on population size?
Larger populations experience less change in genetic variation, whereas smaller populations experience a greater change in genetic variation
What are two types of genetic drift?
bottleneck effect and founders effect
What is the bottleneck effect?
Environmental conditions result in the survival of only a few individuals
What is the founders effect?
small populations can colonize a new region
When does nonrandom mating occur?
When individuals choose mates with particular phenotypes
What is one example of nonrandom mating that is common in plants?
self-fertilization
What is sexual selection?
nonrandom mating that favors traits that increase the chances of reproduction
What are some examples of sexual selection?
bright colors, long tails, and elaborate courtship displays
What is experimental evidence of sexual selection?
Long-tailed widowbird males were selected by mates if they had longer tails. This inhibited their ability to fly, and made it easier for predators to catch them, but this trait still prevailed because the female long-tailed widowbirds selected the males with longer tails more often.
What can be a result of sexual selection?
significant differences between males and females of a species
