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16 Cards in this Set
- Front
- Back
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What is microevolution? |
Microevolution is the study of evolutionary events within a species,
Rather than the ancestral tree ( evolution on a grand scale) |
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What is macroevolution, how is microevolution linked to this? |
Macroevolution is evolution on grand scale, above the level of a species.
Microevolution gives rise to macroevolution |
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Definition of microevolution? |
Changes in the gene pool over time,
Where the gene pool is all alternate forms of alleles in all individuals in a population |
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Genetic basis of evolutionary change? |
1) Diferential reproductive success
2) Genetic differences between individuals ( genetic variation)
Evolution changes genetic structure of a population or species |
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What is the study of microevolution called?
What can it tell us... |
Population genetics
Amount of genetic diversity present in a population
Response of population to change |
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How do population geneticist study gene pool? |
Impractical to study entire gene pool as too large, they look at one or a few genes at a time.
most often single gene locus model |
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What is measured in the gene pool? |
Allele frequency
Genotype frequency |
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How is allele frequency measured? |
Allele freq is;
number of allele of one type/ total number of alleles
Where each individuals have 2 alleles at each gene locus |
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Genotype frequency?
How measured? |
Genotype frequency is portion of a genotype in the population
= Number of each genotype/ total number of individuals |
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What happens to allele and genotype frequecies over time? |
They reach hardy weinberg equilibrium, and stay constant providing no changes.
The equation is measured in allele freq |
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When does the Hardy-weinberg equilibrium only apply? |
Population size is large
mating random
No migration from other populations
No selection
No mutation: this will always occur but is ignored over short term |
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If a population not a HW equilibrium, what does it indicate? |
Something is happening in the population to change it...
Genetic drift, non-random mating, migration (gene flow), selection due to different pressures....ect |
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If a species is diploid, how many genotpes could it have at a single gene locus? |
3
AA aa Aa |
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What is temporal variation? |
Change of allele/ Genetic frequencies over time |
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Discuss non-random mating causes |
One example is sexual selection ( individuals picking mates based on certain characteristics)
Assortive mating
individuals mate with those with similar genotypes as themselves (positive assortive mating)
Positive assorting mating increases homozygosity (decreasing hetero)
Or individuals mating with individuals with an opposite genotype, such as a tall man mating with short women. called Negative assortive mating
Negative assortive mating increases heterozygosity (decreasing homozy)
Assortive mating, whether positive or negative changes proportion of homo or hetero only for the gene loci that is being chosen
Inbreeding is a particualar example of positive assortive mating. Where individuals mate with related individuals.
Inbreeding increases homoztgosity for all gene loci,
The increase in homo can cause inbreeding depression, a reduction in fitness due to expression of harmful alleles
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What is puryfying selection? |
Puryfying selection/ Negative selection is where an allele is being selected against, and will ultimately lead to allele being lost,
The opposite is positive selection, where an allele is being selected for and may eventually become fixed in the population. |
