The science of genetic change in populations. Population- interbreeding single-species group ...
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![Page 1: The science of genetic change in populations. Population- interbreeding single-species group individuals of the same species, living in the same.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649f1b5503460f94c30dbe/html5/thumbnails/1.jpg)
POPULATION GENETICS
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POPULATION GENETICS The science of genetic change in
populations. Population- interbreeding single-
species group individuals of the same species, living in
the same place at the same time Populations are the smallest unit that
can evolve.
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HOW CAN WE MEASURE EVOLUTION? As a change in the prevalence of certain
traits in a population over several generations
Evolution is only apparent when a population is tracked over time
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HOW DOES IT HAPPEN?Spontaneous mutations may produce new
traitsSegregation & independent assortment
produce variations in gametes & offspringGenes are passed through gametes from
parents to offspring
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MODERN SYNTHESIS Theory developed in the 1940’s Includes genetics and evolution
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MICROEVOLUTION GENE POOL = where all members of the next generation get their genes!
When allele frequencies in a population change over generations, evolution is occurring at its smallest scale.
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WHERE THE SPECIES LIVE MATTERS! Species distributed over a geographic range –> have different gene pool
THAN Species localized due to water, islands, mountains etc.!!!
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THERE ARE SEVERAL POTENTIAL CAUSE OF MICROEVOLUTION:
1. genetic drift2. bottleneck effect
3. founder effect4. gene flow5. mutation
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GENETIC DRIFT A change in the gene pool of a small population due to chance!
Ex: flipping coin 10X
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BOTTLENECK EFFECT
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THE FOUNDER EFFECT Type of genetic drift -colonization of a new location by a small number of individuals small size, less representative of the gene pool.
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GENE FLOW Fertile individuals move into or out of a
population Gametes are transferred between
populations.
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HARDY-WEINBERG EQUILIBRIUM
Allele frequency with ONLY sexual reproduction involved!
NO OUTSIDE AGENTS
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VARIABLESp = dominantq = recessive2pq = heterozygousp + q = 1p2 + 2pq + q2 = 1
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5 CONDITIONS ARE REQUIRED FOR HARDY-WEINBERG EQUILIBRIUM
1. very large population
2. population is isolated
3. mutations (changes in genes) do not alter the gene pool
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CONTINUE… 4. mating is random 5. all indiv. Are equal in reproductive success NO NATURAL SELECTION OCCURS!
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HARDY-WEINBERG EQUILLIBRIUM
Conditions rarely met by a natural population
Gives us a basis to compare nonevolving population vs. actual ones with gene pools that are changing!