Calculations
A rare disease which is due to a recessive allele (a) that is lethal when homozygous, occurs within a specific population at a frequency of one in a million. How many individuals in a town with a population of 14,000 can be expected to carry this allele?
q2 = 1/1,000,000 = 0.000001 so q = 0.001.
p + q = 1; p = 0.999.
Carriers are heterozygous; 2pq = 0.00099, now multiply that number by 14,000 to get the number of individuals that are carriers = 28 individuals.
What is the Bottleneck effect caused by? What does the Founder Effect affect?
Massive die off
Newly established populations
Is genetic drift fast or slow in small populations?
Describe allopatric and sympatric speciation.
Allopatric: most prevalent method, occurs when some members of a species become geographically separated. This also means having different fathers.
Sympatric: New species arise form within a single population, ways include polyploidy, adaption to local environments, and sexual selection. This also means having the same fathers.
Define adaptive radiation.
SINGLE SPECIES EVOLVES INTO ARRAY OF DESCENDENTS THAT DIFFER GREATLY IN HABITAT, FORM OR BEHAVIOR. COMMON ON ISLAND CHAINS.
In the US, approximately one child in every 10,000 is born with PKU, a syndrome that affects individuals homozygous for the recessive allele (aa). Calculate the frequency of this allele in the population, the frequency of the normal allele, and the percentage of carriers of the trait within the population.
q2 = 1/10,000 = 0.0001. q = 0.01.
p + q = 1; p = 0.99.
Heterozygotes are the carriers, so 2pq = 0.0198. Multiply this by 10,000 to get the number of carriers in the population = 198.
Are all of our traits in equilibrium? If no, why?
No, because if all of our traits were in equilibrium, we would not be able to evolve.
List the causes of microevolution.
Genetic drift (founder effect, bottleneck effect), movement of individuals (gene flow), mutations (new alleles), natural selection (differential reproductive success), nonrandom mating (favors some alleles over others).
What are the two ways that geographic isolation occurs? Describe the two.
Dispersal: a few leave, a population moves to a new habitat, colonizes, and forms a new population.
Vicariance: a physical barrier that splits a widespread population into a subgroup that are physically isolated from each other.
What are sympatric speciation due to?
Due to disruptive selection and chromosomal mutations.
An allele W, for white wool, is dominant over allele w, for black wool. In a sample of 900 sheep, 891 are white and 9 are black. Calculate the allele frequencies within this population, assuming that the population is in H-W equilibrium.
The allelic frequency of w is represented by the q term, and the allelic frequency of W is represented by the p term. We are given the number of homozygous recessive individuals (9/900) which equates to q2.
q2 = 9/900 = 0.01 so q = 0.1.
We also know that p + q = 1, so we can use that equation to find that p = 0.9.
Final answer: Frequency of W = 90% and frequency of w = 10%.
What is speciation?
What is an example of allopatric speciation by vicariance?
The pork fish near South America. They both look very similar, but are different because they were separated by the isthmus of Panama.
What are the two parts to the Biological Species Concept?
REPRODUCTIVE ISOLATION AND TWO INDIV. ARE OF THE SAME SPECIES IF THEY CAN INTERBREED AND PRODUCE FERTILE OFFSPRING.
The frequency of two alleles in a gene pool is 0.19 and 0.81. Assume the population is in Hardy-Weinberg equilibrium. Calculate the percentage of heterozygous individuals in the population.
Heterozygotes are represented by 2pq, so therefore you take (2)(0.19)(0.81) = 0.31 or 31%.
What are the four steps to determine if the Hardy-Weinberg principle hold true?
Estimate genotype frequencies
Calculate observed allele frequencies from the observed genotype frequencies
Use the observed allele frequencies to calculate the genotypes expected according to the Hardy–Weinberg principle
Compare the observed and expected values
What is the morphospecies concept? What is an example of a problem with this concept?
Shape, size morphology determines species.
Jaguars vs panthers because even though they are the same species, they are different according to the morphospecies concept because they are a different color.
What are the differences between autopolyploid and allopolyploid?
Auto: deals with individual produced when a mutations results in a doubling of the chromosome number and those chromosomes come from the same species.
Allo: deals with the individual that are created when parents belong to different species and produce offspring with different sets of chromosomes.
Species can be defined in what three different ways?
Biological
Morphological
Phylogenetic
Two Siamese and three Persian cats survive a shipwreck and are carried on driftwood to a previously uninhabited tropical island. Al five cats have normal ears, but one carries recessive allele f for folded ears (he is Ff). Calculate the frequencies of alleles F and f in the cat population of this island.
We know that the genotype for the carrier is Ff, so the other four cats are not carriers and must have a genotype of FF. There are 10 total alleles in this population (because there are 5 cats with two alleles each), 9 are F alleles and 1 is f allele.
Therefore, 9/10 = 0.9 for the F allele
1/10 = 0.1 for the f allele.
Lets fill out the Hardy Weinburg Table together!
You all get the points :)
List of the types of mechanisms of Reproductive Isolation and if they are pre or post zygotic.
PRE: TEMPORAL, HABITAT, BEHAVIORAL, GAMETIC BARRIER, MECHANICAL
POST: HYBRID VIABILITY, HYBRID STERILITY.
What is a hybrid zone? What are the variations of them?
It is a geographic area where interbreeding between two populations occurs and hybrid offspring are common.
They can be narrow or wide. Long or short-lived.
What are the five possible outcomes of secondary contact between populations?
-FUSION OF POPULATIONS: OCCURS WHEN POPULATIONS OF THE SPECIES COME INTO CONTACT.
-REINFORCEMENT OF DIVERGENCE. THIS HAPPENS TO BE COMMON FOR DISTINCT POPULATIONS THAT OCCUPY THE SAME GEOGRAPHIC AREA. PREVENTION OF INTERBREEDING
-HYBRID ZONE OF FORMATION: OCCURS IN A WELL DEFINED GEOGRAPHIC AREA. THIS AREA BAY MOVE OVER TIME OR BE STABLE.
-EXTINCTION OF ON POPULATION: ONE SPECIES IS BETTER AT COMPETING AND GAINING RESOURCES AND BUTTS OUT THE OTHER.
-FORMATION OF A NEW SPECIES: COMBO OF GENES CREATE AN OFFSPRING THAT IS A HYBRID AND CREATES SOMETHING NEW.