952080
Beschreibung
Mindmap von heartsandkisses, aktualisiert more than 1 year ago
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Erstellt von heartsandkisses
vor fast 10 Jahre
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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
- Even when mutation took place, functions is the same.
Variation is neutral: non-adaptive. Not subjected to Natural
Selection
- SELECTIVE NEUTRAL
- Does not affect ability to SURVIVE &
produce VIABLE OFFSPRING
- 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
- FLAWS: 1) Does not run as smoothly
2) Some DNA change more favoured
3) E stimates older than fossil record:
high uncertainty
- 1. Estimate how long 2 related
organisms diverged from same ancestor/
Difference would be proportional to time
- Standard for measuring the absolute time of
evolutionary change at molecular level
- MOLECULAR CLOCK
- Mutations in any DNA Sequence
accumulate at absolute time of evolutionary
change. As long original function retained
- 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
- Esp. small isolated popns
- DECREASES VARIATION
- a) Bottleneck Effect
- Sudden change in environment
~> drastically reduce popn size
- Gene pool: drastic reduction
- Gene pool: drastic reduction
- Sudden change in environment
~> drastically reduce popn size
- b) Founders Effect
- Few individuals get isolated
~> Colonise a new location
- Few individuals get isolated
~> Colonise a new location
- Change in ALLELE FREQUENCY,
in small isolated POPULATION due
to PURELY CHANCE events
- New allele is added to the population/
neutral genetic changes tend to
accumulate and genomes tend to evolve
- c) Due to Genetic Drift
- b) New neutral alleles may be lost/ become fixed
- a) Variation: new alleles, not subjected to natural selection
- 1. Much evolutionary does NOT confer SELECTIVE ADVANTAGE
~> Not influenced by NATURAL SELECTION
- 3 CONCEPTS
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