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# Population genetics pp

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### Population genetics pp

1. 1. POPULATION GENETICS
2. 2. VocabPopulation- group of organisms of theSAME species that occupies certain areaSpecies- organisms that can INTERBREEDand produce FERTILE offspringEx) Sauerman Woods Crown Point -whitetail rabbits -deer -sparrows -squirrels
3. 3. Can we capture all the whitetail rabbits in Sauerman Woods?Population Sampling- technique usespart of population to represent wholepopulationCapture 100 random rabbits– These rabbits are a representation of all the rabbits in the area.– We can study many things within this group…
4. 4. Genetics of the Population…Gene Pool- all of the genes of everyindividual in population sampleFrequency- how often something occursPopulation genetics involves studying thefrequency with which certain allelesoccur in a population’s gene pool.Frequencies can be written as:percentages, fractions, or decimals.
5. 5. Example Population Problem #1100 rabbits – “fur color” How many alleles for furtrait color are in the gene pool?B- brown fur b- white fur30 rabbits are 100 rabbits X 2 alleleshomozygous brown (BB) each=50 rabbits are 200 allelesheterozygous brown (Bb) How many dominant alleles are in the gene pool?20 rabbits are 60+50 = 110 alleles (B)homozygous white (bb) How many recessive alleles are in the gene pool? 50+40 = 90 alleles (b) What is the frequency of the dominant allele in population? 110/200= .55 or 55% What is the frequency of the recessive allele in population? 90/200= .45 or 45%
6. 6. In 50 years, will the allele frequencies be the same?Hardy-Weinberg Equilibrium Principle –“Under certain conditions, the frequencies of thedominant and recessive alleles will remain the samegeneration after generation.”
7. 7. HARDY WEINBERG 5 CONDITIONSTo keep H-W equilibrium there must be: No mutations Large population Population size remains same (no migration) Random mating No “survival of fittest”***These conditions are NEVER all met in the REAL world, so populations are always changing and NOT in H-W equilibrium.