Lecture 6 Flashcards
(21 cards)
Why would we not get HWE in finite populations?
Due to chance events. But in populations that are infinite in size, then you would get perfect proportions, but not for finite
What does genetic drift result from?
random sampling
When is sampling error higher?
with a smaller sample
What does population bottleneck cause?
genetic drift
What is genetic drift?
the change in frequency of an existing gene variant in the population due to random chance
What does a genetic bottleneck result in?
in a non representative set of alleles for subsequent populations, even after the population size rebounds
What is population bottleneck?
When a population goes through a shrinking phase, and during the process of declining, very few individuals survive. This would result in very strong genetic drift
What does the founder effect cause?
genetic drift
What is the founder effect?
a type of genetic bottleneck resulting from a small number of individuals colonizing a new, isolated habitat. The allele frequencies among colonists are not repersentative of source population
Does founder effect cause a change in allele frequencies with short or long lasting effects?
causes long lasting effects
What are the changes like in small populations?
the changes are less predictable in small populations
What is the presence of alleles like in smaller populations?
alleles are lost more rapidly in small populations
Where are rare alleles most likely to be lost?
in a population bottleneck
Can the direction of change in allele frequency be predicted?
No, the direction of change in allele frequency can not be predicted (if it goes up or down can not be predicted)
What does it mean if an allele is fixed?
The allele has a frequency of one, everybody carries the allele
What happens to the alleles in terms of the proporties of genetic drift?
one allele will eventually become fixed, the other eliminated.
What does genetic drift tend to remove?
genetic variation. because if a population only has one allele it is not variable
What is the probability than an allele will eventually become fixed or lost?
the probability is proportional to its frequency in the population. This will happen over enough time in any finite population
Where are rare alleles mainly found?
in heterozygotes
Why do different populations have different frequencies?
due to drift
What are the main features (3) of genetic drift?
- a loss of genetic variation results within populations (because one allele will eventually be lost or fixed)
- genetic divergence results between populations (populations become more differeny by chance)
- drift causes evolution (allele frequencies change) but not adaptive evolution
