Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
gene pool
|
combined genetic information of all the members of a particular population
|
|
relative frequency
|
the number of times that allele occurs in a gene pool compared with the number of times other alleles occur
|
|
single-gene trait
|
controlled by a single gene that has two alleles
|
|
polygenic trait
|
often has two or more alleles
|
|
What two processes can lead to inherited variation in populations?
|
the two main sources of genetic variation are mutaitons and the genetic shuffling that results from sexual reproduction
|
|
How does the range of phenotypes differ between single-gene traits and polygenic traits?
|
The number of phenotypes produced for a given trait depends on how many genes control the trait.
|
|
directional selection
|
individuals at one end of the curve have higher fitness than individuals in the middle or other end; evolution causes an increase in the number of individuals with the trait at one end of the curve
|
|
stabilizing selection
|
the curve have higher fitness than individuals at either end of the curve; keeps center of curve same but narrows overall graph
|
|
disruptive selection
|
individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle; selection creates two distinct phenotypes
|
|
genetic drift
|
random change in allele frequency
|
|
founder effect
|
situation in which allele frequencies change as a result of the migration of a small subgroup of a population
|
|
Hardy-Weinberg principle
|
states allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change
|
|
genetic equilibrium
|
allele frequencies remain constant; if no change then they don't evolve
|
|
describe how natural selection can affect traits controlled by single genes.
|
natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution
|
|
describe three patterns of natural selection on polygenic traits. which one leads to two distinct phenotypes?
|
natural selection can affect the distributions of phenotypes in any of three ways: directional selection, stabilizing selection, or disruptive selection. disruptive selection
|
|
how does genetic drift lead to a change in a population's gene pool?
|
in small populations, individuals that carry a particular allele may leave more descendants than other individuals, just by chance. over time, a series of chance occurrences of this type can cause an allele to become common in a population
|
|
what is the Hardy-Weinberg principle?
|
Five conditions are required to maintain genetic equilibrium from generation to generation:
-there must be random mating; -the population must be very large; -and there can be no movement into or out of the population, -no mutations, -no natural selection |
|
speciation
|
formation of new species
|
|
reproductive isolation
|
when the members of two populations cannot interbreed and produce fertile offspring
|
|
behavioral isolation
|
when two populations are capable of interbreeding but have differences in courtship rituals or other types of behavior
|
|
geographic isolation
|
two populations are separated by geographic barriers such as rivers, mountains or bodies of water
|
|
temporal isolation
|
two or more species reproduce at different times
|
|
how is reproductive isolation related to the formation of new species?
|
as new species evolve, populations become reproductively isolated from each other
|
|
what type of isolating mechanism was important in the formation of different Galapagos finch species?
|
speciation in the Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population's gene pool, reproductive isolation and ecological competition.
|