Population Genetics Flashcards
Define evolution.
A change in ALLELE frequency from 1 generation to the next.
Define a gene.
A transcription unit that encodes for FUNCTIONAL RNA which will be translated into a protein.
What are the 4 evolutionary mechanisms?
- Gene flow
- Genetic drift [bottleneck, founder effect]
- Selection [natural, sexual]
- Mutation
Which evolutionary mechanism do the other mechanisms depend on?
Mutation
Why is mutation required for the other evolutionary mechanisms to work?
Mutation brings in the VARIATION that the other mechanisms rely on
Allele frequency changes lead to ________ which leads to __________.
Allele frequency changes lead to DIVERGENCE which leads to SPECIATION.
What effect does mutation have on genetic diversity?
Mutation increases genetic diversity.
Mutations can be _________.
Mutations can be DELETERIOUS.
Which evo. mechanism is mutation SLOWER than?
Selection
Which evo. mechanisms have the SAME RATE as mutation?
- Genetic drift
2. Gene flow
What are 2 causes of mutation?
- Mistakes in REPLICATION due to DNA poly not being 100% efficient.
- Environmental damage to DNA triggers DNA repair which has an error rate.
What is the PRODUCT of gene flow, drift, + selection?
Evolutionary/selective PRESSURE
To understand if allele freq. are changing over time, we need to know what 2 things?
- WHICH alleles are present.
2. The CURRENT frequency.
What is Hardy-Weinberg Equilibrium used for?
To calculate the EXPECTED allele frequencies.
Hardy-Weinberg uses the _________________ to predict the _______________ in the subsequent generation.
Hardy-Weinberg uses the ALLELE FREQUENCIES to predict the GENOTYPE FREQUENCY in the subsequent generation.
What are Punnett squares used for?
To show the possible GENOTYPES of the progeny.
What are the 3 assumptions used in H-W Equilibrium?
- Mating [fusion of gametes] is RANDOM
- Population is INFINITELY LARGE
- Evolution is NOT occurring
Why does the population need to be sufficiently large for H-W Equilibrium?
It ensures that the allele freq. changes are NOT DUE TO SAMPLING ERROR.
It shows that evolution is not occuring.
What does the assumption “evolution is not occurring” mean in H-W Equilibrium?
There are NO CHANGES in allele frequency from one generation to the next.
What happens to allele frequencies in a population bottleneck?
There is a sudden DECREASE in the # of allele copies in a population.
If a gene IS in H-W Equilibrium, what does that mean for genes at other loci?
They may or MAY NOT be in H-W Equilibrium.
What does p^2 + 2pg + q^2 provide us with?
A NULL HYPOTHESIS to compare our observed/measured data
What are 3 examples of NON RANDOM MATING?
- Inbreeding/assortative mating [like with like]
- Disassortative mating [opposites]
- Sexual selection [choosing the ‘best’ partner]
What is genetic drift?
Changes in ALLELE FREQ. due to RANDOM MATING
What is a VESTIGIAL trait?
A trait that has lost its ORIGINAL FUNCTION over evolutionary time
For a trait to be STRUCTURALLY HOMOLOGOUS, it does not need to be identical in _________, just in ____________.
For a trait to be STRUCTURALLY HOMOLOGOUS, it does not need to be identical in FUNCTION, just in CONSTRUCTION.
What are zygotes? What are their ploidy?
Fused gametes.
DIploid.
What are gametes? What are their ploidy?
Sperm or ova.
HAPloid.
Genetic drift will have a STRONGER effect on a ________ population.
Genetic drift will have a STRONGER effect on a SMALLER population
Which evolutionary mechanism is mostly caused by chance/sampling error?
Genetic drift
If a population is in H-W Equilibrium, then the allele frequencies are not changing. Why?
Because there is RANDOM MATING occuring in a SUFFICIENTLY LARGE POPULATION with NO EVOLUTIONARY MECHANISMS at work.
If a population is NOT in H-W Equilibrium, it does NOT tell us that the gene is ________. It only tells us than an ___________ has been ___________.
If a population is NOT in H-W Equilibrium, it does NOT tell us that the gene is EVOLVING. It only tells us than an ASSUMPTION has been VIOLATED.
H-W Equilibrium Step 1. \_\_\_\_\_\_\_ H-W. Step 2. \_\_\_\_\_\_\_\_ to our \_\_\_\_\_\_\_\_\_. Step 3. Has an \_\_\_\_\_\_\_\_\_\_\_ been \_\_\_\_\_\_\_? Step 4. Use your analysis to set up the \_\_\_\_\_\_\_\_\_\_.
H-W Equilibrium Step 1. CALCULATE H-W. Step 2. COMPARE to our OBSERVED. Step 3. Has an ASSUMPTION been VIOLATED? Step 4. Use your analysis to set up the ALTERNATIVE HYPOTHESIS.
What is the purpose of the Chi^2 Test?
It compares the OBSERVED data to the EXPECTED (h-w) data.
[Chi^2 and H-W] When do we REJECT the null hypothesis?
Chi > H-W
When Chi is LARGER than H-W, the population is NOT IN EQUILIBRIUM.
[Chi^2 and H-W] When do we FAIL TO REJECT the null hypothesis?
Chi < H-W
When Chi is SMALLER than H-W, the population IS in equilibrium.
