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952080
Evolution (Neutral Theory)
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Mind Map on Evolution (Neutral Theory), created by heartsandkisses on 30/05/2014.
Mind Map by
heartsandkisses
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heartsandkisses
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Resource summary
Evolution (Neutral Theory)
FOCUS: Molecular level/ e.g. N substitutions in DNA and AA substitutions in Proteins
3 CONCEPTS
1. Much evolutionary does NOT confer SELECTIVE ADVANTAGE ~> Not influenced by NATURAL SELECTION
Does not affect ability to SURVIVE & produce VIABLE OFFSPRING
SELECTIVE NEUTRAL
a) Genetic Code is DEGENERATE
b) SILENT MUTATION
Even when mutation took place, functions is the same. Variation is neutral: non-adaptive. Not subjected to Natural Selection
2. RATE of mutation is CONSTANT
Mutations in any DNA Sequence accumulate at absolute time of evolutionary change. As long original function retained
MOLECULAR CLOCK
Standard for measuring the absolute time of evolutionary change at molecular level
Assumption: DNA seq mutates at constant rates.
1. Estimate how long 2 related organisms diverged from same ancestor/ Difference would be proportional to time
FLAWS: 1) Does not run as smoothly 2) Some DNA change more favoured 3) E stimates older than fossil record: high uncertainty
3. Most evolutionary change in populations is the result of Genetic Drift
a) Variation: new alleles, not subjected to natural selection
b) New neutral alleles may be lost/ become fixed
c) Due to Genetic Drift
New allele is added to the population/ neutral genetic changes tend to accumulate and genomes tend to evolve
GENETIC DRIFT
Change in ALLELE FREQUENCY, in small isolated POPULATION due to PURELY CHANCE events
Allele can be eliminated, beneficial or not
DECREASES VARIATION
Esp. small isolated popns
a) Bottleneck Effect
Sudden change in environment ~> drastically reduce popn size
Gene pool: drastic reduction
b) Founders Effect
Few individuals get isolated ~> Colonise a new location
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