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Natural Selection, genetic drift, and gene flow
In your own words, describe the difference between Genetic Variation and Evolution
Differences in genotypes found in a population.
Changes of a population over time.
The following: natural selection, genetic drift, and gene flow are all methods for what?
*Only natural selection causes adaptive evolution
is the change in allele frequencies in a population over generations
can lead to Evolution on a larger scale
VITAL for evolution
can be measured at a molecular level
Sources: mutation, gene duplication, and sexual reproduction
There was a specific population of rabbits. They only contained the genes that expressed a brown coat. One rabbit was accidently exposed to radiation. The rabbit mated with another brown rabbit. One white baby was produced. What agent of evolutionary change is this?
None of the above
Rates generally low
Other evolutionary processes usually more important in changing allele frequency
Ultimate source of genetic variation
Makes evolution possible
Duplication of Genes
Chromosomal rearrangements that lead to an expanded genome
Example: sense of smell
Rate of reproduction correlates with mutation rates
Sexual reproduction shuffles alleles through:
What is the point of this equation?
Helps one to predict genotype frequencies!
p2 + 2pq + q2 = 1
p + q = 1
Hardy-Weinberg Equilibrium occurs if what conditions are met?
No mutation takes place
No genes are transferred to or from other sources (no immigration or emigration takes place)
Random mating is occurring
The population size is very large
No selection occurs
What part of this equation refers to heterozygous frequency?
None of it
Which of the following sets of alleles frequencies would produce the greatest proportions of heterozygotes?
P=.5; q= .2
P=.5; q= .5
P=.8; q= .2
Can’t be determined
What is the frequency of homozygous recessive if you were given the following information?
P=.9 and Q= .1
If all assumptions of the Hardy-Weinberg equilibrium were met, what would happen to the frequency of the recessive allele after many generations?
Remain the same
Would decrease slowly
Would increase exponentially
Would not be passed on after many generations due to it being bred out.
Which of the following equations refer to an allelic frequency?
Homozygous Dominant genotype frequency= 0.55
What is the frequency of homozygous recessive genotype?
p + q = 1 p2 + 2pq + q2 = 1
I need help
In a population of red (dominant) or white flowers in Hardy-Weinberg equilibrium, the frequency of red flowers is 91%. What is the frequency of the red allele?
p + q = 1 p2 + 2pq + q2 = 1
Red short-horned cattle are homozygous for the red allele, white cattle are homozygous for the white allele, and roan cattle are heterozygotes. Population A consists of 36% red, 16% white, and 48% roan cattle. What are the allele frequencies?
red = 0.36, white = 0.16
red = 0.6, white = 0.4
red = 0.84, white = 0.16
red = 0.5, white = 0.5
Allele frequencies cannot be determined unless the population is in equilibrium.
If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be
There is not enough information to say unless the population is in equilibrium.
Mamma turtle is a green sea turtle and laid eggs in the sand next to the shore. The season had unexpected high tides, and washed into the nest. The eggs were washed up onto a nearby island shore. The nearby island shore only had loggerhead sea turtles. Many years later tourists were drawn to this island to see a rare species of green loggerhead sea turtles. What evolutionary agent was this?
Movement of alleles from one population to another
Animal physically moves into new population
Drifting of gametes or immature stages into an area
Mating of individuals from adjacent populations
Darwin is studying his favorite animal, finches! He is specifically monitoring one population whose diets consist of only red berries. This population currently has genetic variation of blue feathers and gold feathers. One season the island experiences a terrible drought. The berries are very scarce. Half of the finch population dies off. Coincidently, all of the blue feathered finches died off except for one. Generations later, Darwin is unable to observe any blue finches What is this evolutionary agent?
In small populations, allele frequency may change by chance alone
Magnitude of genetic drift is negatively related to population size
Genetic drift can lead to the loss of alleles in isolated populations
Alleles that initially are uncommon are particularly vulnerable
Sometimes one or a few individuals leave a population and “find” their own isolated area.
Cause drastic changes in allelic frequency, some may disappear or a rare one may increase.
Josie’s cat, Mittens, had a $*&?% ton of kittens. The kittens had a hard time with surviving, however. Birds would swoop up the kittens leaving behind nothing but tufts of cute kitten fur, or the raccoons would kill off the kittens because that was competition for their cat food. Only a few kittens survived out of 20 or so. These kittens were of brown coloring, and blended in the fields well. They were also larger, and stronger than their deceased siblings. These kittens then bred and led to population of cats that were all large and brown. What is this an example of?
Some individuals leave behind more progeny than others, and the rate at which they do so is affected by phenotype and behavior
3 conditions for natural selection to occur and to result in evolutionary change:
Variation must exist among individuals in a population
Variation among individuals must result in differences in the number of offspring surviving in the next generation
Variation must be genetically inheritedp2 + 2pq + q2 = 1