Topic 3: Inbreeding Flashcards
What is the most basic definition of inbreeding?
The mating of closely related individuals
How do we calculate the number of ancestors?
- 2^t ancestors, where t is the number of generations in the past
- ex. 10 generations, 2^10 = 1024 ancestors
Inbreeding will depend on ……
population size
“Inbreeding does not directly change the ______ ___ ___ ________, and is therefore not an __________ _________.”
“Inbreeding does not directly change the frequency of an allele, and is therefore not an evolutionary force.”
How come inbreeding is not considered an evolutionary force?
- With inbreeding, allele frequency do not change. Inbreeding only increases the frequency of homozygosity in a population
- As evolution is a change in allele frequency over time, these definitions contradict one another.
inbreeding affects _________ frequencies, but not _______ frequencies
inbreeding affects genotype frequencies, but not allele frequencies
if there is a loop in a pedigree, this is indicative of ______
inbreeding!
What is Wright’s coefficient of inbreeding?
- a statistic to estimate the level of inbreeding for a particular individual
- estimates the probability that a specific allele came from a specific ancestor.
- “the probability that two alleles in an individual were both descended from a single allele in an ancestor”
What is identity by descent?
- where two alleles that are identical are descended from the same recent ancestral allele
- can be traced back to a common ancestor
What is identity by state?
- where two alleles have identical DNA sequences or amino acid sequences
- NOT identical because they have a common ancestor. Just happen to be the same allele (gained separately)
What is the difference between identity by descent vs. identity by state?
- identity by descent must have 2 identical alleles that are genetically related, while identity by state has 2 alleles that are identical, but not necessarily related.
Alleles that are identical by descent will always be identical in_______, but not all alleles identical by state will be identical by ________.
Alleles that are identical by descent will always be identical in state, but not all alleles identical by state will be identical by descent.
How can an inbreeding coefficient increase?
if the common ancestors are also inbred.
What hierarchical levels can we measure inbreeding at?
- individual level
- population level
describe the individual and population level measuring of inbreeding
individual: measures the extent to which an individual is inbred relative to the random mating in their population. F = the probability that two alleles are identical by descent.
population: measures the average rate of inbreeding in a population relative to random mating. F= proportion of the population that have alleles that are identical by descent