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Evolution 3
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Natural Selection
-differential survival and reproduction (fitness) of individuals based on genetic differences in some trait (adaptation)
-affects fitness of a single individual in a population depending on traits
-causes frequencies of genes in populations to change
for adaptations to evolve
-differences in the trait must cause differences in fitness
-differences in the trait must be heritable
-fitness depends on local environment
selection
-some individuals have more offspring than others
-causes change in allele frequency
testing for adaptation
-reciprocal transplant experiment
-colored guppies w/ no predators moved to area where drap guppies with predators environment. colored get eaten.
adaptation
-characteristic that enhances likelihood of reporduction and survival
-individuals becoming better suited to their environment
sexual selection
-differential repoduction as a result of variation in the ability to obtain mates
tradeoffs
Malaria
-people with good blood are good hosts
-causes death
-homozygous recessive
-therefore Ss is best genotype because not good hosts and not infected.
natural selection does NOT:
-perfection
: a genotype needs to be a bit better than another in order to survive
-lack of genetic variation
: selection cannot act on mutations that have not happened yet
-developmental constraint
: no way to get from here to there
-trade off (ex big heads to be smarter, or birth conditions)
phenotypic plasticity
-a genotype producing multiple phenotypes depending on the environment
-ex. worm that has bristles, is smooth, and fuzzy
-ex. barnacle and penis size (reaching mates and controling penises)
Author
Chloe
ID
7471
Card Set
Evolution 3
Description
natural selection, fitness, selection pressure
Updated
2010-02-20T20:54:41Z
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