Population Genetics Flashcards
Define probability:
The method for determining the likelihood of something uncertain happening.
What is the equation for P(event)?
P(event) = (number of times an event occurs) / (total number of observations)
There is a 500 head cow herd.
400 are black
50 are red
50 are white
What are the probabilities for each color to occur?
400/500 = 0.8 black
50/500 = 0.1 red
50/500 = 0.1 white
Probability ranges from ___ to ___.
0 ; 1
What are the two types of probability?
Theoretical and Experimental
What is Theoretical Probability based on?
The knowledge from previous experiences or events
What is Experimental Probability based on?
How frequently something (actually) happens in an experiment.
___________ confidence level = smaller confidence range =
\_\_\_\_\_\_\_\_ likely to be correct!
Higher ; more
Define Confidence Range:
How much we trust the probability to be correct
Is a high probability but low confidence range good or bad?
Not good. Without a high confidence range, the probability is not as dependable.
What are the three types of (probability) events?
Independent
Mutually Exclusive
Joint
What is an Independent Event?
The probability that one event occurs that not influenced by the occurrence of a second event.
What is a Mutually Exclusive Event?
The occurrence of one event precludes the occurrence of another event.
Uses OR
Ex.: male OR female
What is a Joint Probability Event?
The occurrence of one or more events happening together or in sequence.
Uses AND
Ex.: A cow having twins. One is red AND one is black
What is z?
A value that corresponds to a desired confidence level
A ____________ event will be calculated with the SUM of probabilities
Mutually Exclusive
A ____________ event will be calculated with the PRODUCT of probabilities
Joint probability
What is a Conditional Probability?
A measure of the probability of an event occurring, given that another event has already occurred.
An example of conditional probability is in cats with the Manx phenotype. Having the phenotype is dependent on what occurrence happening or not happening?
Firstly, the cat cannot have the mm genotype, because this would kill it (lethal). Therefore, the cat must first survive, THEN show the Manx phenotype.
Define Population Genetics:
The study of allele and genotype frequencies and what happens to them generation to generation.
Who were the original founders of Theoretical Population Genetics?
Robert A. Fisher
Sewall Wright
J. B. S. Haldene
What is genotypic frequency?
Relative frequency of a particular genotype for one locus in a population
Define Allele (or gene) Frequency
Relative frequency of a particular allele in a population
What is Relative Frequency?
Fraction or proportion of times a value occurs
What does P mean population genetics?
The frequency of homozygous dominant genotypes. P = f(AA)
What does H in population genetics mean?
The frequency of the heterozygous genotypes. H = f(Aa)
What does Q in population genetics mean?
The frequency of homozygous recessive genotypes. Q = f(aa)
P + H + Q = __________
ONE
What does p stand for in population genetics?
p = f(A).
The frequency of the dominant allele.
What does q mean in populations genetics?
q = f(a)
The frequency of the recessive allele.
p + q = ________
ONE
What are two ways to calculate p?
p = P + (1/2)H
p = 1 - q
What are two ways to calculate q?
q = Q + (1/2)H
q = 1 - p
Define fixation.
When a particular allele becomes the only locus in a population
What are the five assumptions of the Hard-Weinberg Law?
(You should know this very well)
Large population
Random mating
No migration
No selection
No mutation
Define mutation.
A permanent, heritable change in a DNA sequence
Define migration.
Movement of breeding animals from one population to another
Is the use of AI (artificial insemination) and embryo transfer considered migration?
YES
What are the two mating strategies?
Random and Non-random
Define random mating
Each breeding animal has an equal opportunity to breed
What are the two types of non-random mating?
Positive assortative and negative assortative
___________ mating is between organisms with similar phenotypes
Positive assortative
Negative assortative ___________ is between organisms with __________ phenotypes
mating ; different
