Chapter 17 Flashcards
Members of a population share a common group of genes called
gene pool
The number of times an allele occurs in a gene pool compared with the number of times other alleles for the same gene occur
allele frequency
Three main sources of genetic variations are
mutations
genetic recombination during sexual reproduction
horizontal gene transfer
A ________ is any change in a sequence of DNA
mutation
Most hereditable differences are due to ____________ _________
genetic recombination
__________ __________ ________ is the passing of genes from one organism to another that is not its offspring
lateral gene transfer
____ _____ _____ is controlled by one gene. AN example in snails is the presence or absence of dark bands on their shells.
single-gene trait
_______ _________ is controlled by two or more genes, and each gene often has two or more alleles.
polygenetic gene
The combination of different alleles is an individuals ________.
genotype
Natural selection acts on _________, not _________.
phenotype
genotype
___________ ______ takes place when individuals at one end of the bell curve have higher fitness that those near the middle or at the other end of the curve.
Directional selection
_________ ________takes place when individuals near the middle of the curve have higher fitness than individuals at either end
Stabilizing selection
_________ ___________ takes place when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle.
Disruptive selection
3 types of selection
directional selection
stabilizing selection
disruptive selection
Allele frequencies in a population gene pool does not change thus no evolution occurs (stays constant)
genetic equilibrium
Allele frequency in a population should remain constant unless 1 or more factors cause frequencies to change
Hardy-Weinberg Principle
Random change in frequency of alleles in a gene pool is called _________ __________.
genetic drift
Change in allele frequency following a dramatic loss of population is call __________
bottleneck effect
Change in allele frequency that results from a small group starting a new population
founder effect
disruption of genetic equilibrium
gene flow
list 5 conditions that disturb genetic equilibrium and cause evolution to occur
non-random mating
small population size
immigration/emmigration
mutations
natural selection
Formation of a new species is called
speciation
When two populations can no longer mate and produce offspring, __________ _________ has occured
reproductive isolation
When populations are separated by a barrier such as a river, mountains, or ocean, __________ _________ can occur.
geographic isolation
If two interbreeding populations develop different behaviors, such as different mating dances, then __________ _____________
behavioral isolation
____________ _____________ happens when populations that live in the same habitat reproduce at different times`
Temporal isolation
A _________ ______________ uses mutation rates in DNA to estimate how long ago two organisms shared a common ancestor. ( few mutations shared ancestor recently, many mutations shared an ancestor long ago)
molecular clock
