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irreducible complexity
idea that evolution is not true because there is no such thing as an eye without all of its parts for example.
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extaptation
- adaption evolved for a different use
- ex: human leg from lizards, antennae, trans-membrane channels
- NOTE: ADH- allowed digestion of alcohol then became lens of eye
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Hardy-Weinberg Equilibrium
- evolution is not occuring because
- 1- mutation isn't occuring
- 2- natural selection isn't occuring
- 3- infinitely large population
- 4- all members of the population breed
- 5- all mating is totaly random
- 6- everyone has same number of offspring
- 7- no migration/immigration
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HWE equation
- p
=1 - p= frequency of dominant allele
- q=frequency of recessive allele
= frequency of dominant, recessive genotype
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evolution
change in an allele frequency in a population over time
-
mutation
- change to DNA base pairs/ change in genetic material not caused by recombination
- - humans have 100-200 new ones
- - most are corrected by error checking enzymes
- - most significant mutations happen in regulatory parts of genes
- - random
-
Neutral Mutation
- no affect on fitness
- - non synonymous mutations are also neutral
- - good before but useless now
-
Columbus Connection?
-looking for spices
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genetic drift
- random chance change of allele frequencies
- - population bottleneck
- - sampling error ( sometimes individuals reproduce due to chance)
- - coincidence, natural disaster
- - damaged fitness
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gene flow
migration of individuals and gamete dispersal
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fixation/fixed allele
allele is the only variant that exists in the population for that gene
-
mutation rates
- the rate at which mutations occur over time
- measured in changes per base pair
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founder effects
- - Pennsylvania Amish population
- - small population with low genetic diversity colonizes a new area in isolation
- - results in a very low genetic diversity of the new population
- -uncommon disorders become common
-
lethal equivalents
when two carriers of recessive disorders reproduce and produce offspring with that disorder
-
Why so much variation?
- - mutation
- - trade offs of same /different traits
- - hidden recessives that are passed on without being expressed
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Trade-offs
- benefit comes at a cost, finds a balance between two
- - brca gene increases fertility but with a higher risk of cancer
-
diseases?
- - dominant are hard to get out
- - recesive not a huge worry
- - any dominant disease- only needs one dom. allele
-
sickle cell example/ signifigance
- SS- fine
- Ss- carrier (small amount of disease/ resistant to malaria)
- ss- diseased
example of heterozygote advantage
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Equilibrium
different allele conditions in different conditions balance out via selection
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spatial variation
subpopulations in different areas, fragmented from whole population will have different fitness values
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temporal variation
seasons have different fitness influences
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frequency dependent selection
only genotypes alone in population
-
allele fitness?
based on rarity
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self-incompatibility
self fertilization is not possible, promotes intercourse and diversity
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why not more evolution?
- not as much variation
- gene flow
- physical laws
- evolution only works with what exists, nothing new
-
whip tailed lizard example
- all female population that clones
- once had males because of coital impersonating
-
Another way of thing about HWE?
punnet square of whole gene pool
-
example of HWE factor in real life?
coral reefs do mate almost randomly
-
when is there no selection pressure against a variant?
- little impact on fitness
- temporal/spatial variation
- old age
- somatic mutations
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somatic mutations
- mutations only in body cells that do not get passed down to offspring
- Ex: barry bonds steroid abuse
-
germ-line mutations
do get passed down
-
frequency of new genotype in population
1/N
-
frequency of new allele in population
1/2N
-
Why doesn't selection go further?
- trade-offs- too much armor slows you down
- ancestry- strange solutions stay if they are good enough to increase relative fitness
-
goal of selection
- grandbabies!
- not long term gain of species
-
conserved gene/change/phenotype and why?
- does not change based on selection because:
- 1) too risky (testicles)
- 2)not inherently bad so no need to change
- Ex: testicular structure because 4 legs were actually meant to protect it
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biggest influence on drift
population size
-
allele frequencies
change in individual populations (evolution) but alleles themselves are fixed or lost in different populations
-
mutation-drift balance
rate of mutations/rate lost
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