Term
| Why can't adaptation be explained by mutation and drift alone? |
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Definition
Adaptations are tied closely to natural selection--these variations that consistently enhance their survival or reproduction replace less favorable traits
-FITNESS! |
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Term
| What is fitness and what does it include? |
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Definition
Fitness is the average per capita rate of increase in numbers and includes:
-Probability of survival to various reproductive ages
-Average number of offspring via female function
-Average number of offspring produced via male function |
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Term
| Why is historical perspective necessary when defining an adaptation? |
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Definition
| The definition emphasizing the present time suggests that it results in the highest fitness in a given environment. The past emphasis suggests that it must be a derived character that evolved in response to a selective agent. |
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Term
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Definition
| Guarantees passing on to next generation, but decreases fitness of the individual carrying it |
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Term
| What is linkage disequlibrium? |
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Definition
| certain alleles of each gene are inherited together more often than would be expected by chance |
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Term
| How can you test whether or not a trait is an adaptation? Give examples |
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Definition
Experiment on short lived organisms, observe natural phenomenon, experimental manipulation of putatively adaptive trait
-Bird tails
-Guppy spots
-Bees and flowers |
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Term
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Definition
R = response to selection
h = heritability
s = selection differential |
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Term
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Definition
VP = total phenotypic variance
VG = genetic variance
VE = environmental variance |
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Term
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Definition
| the proportion of phenotypic variance that is from genetic sources |
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Term
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Definition
| phenotypic plasticity--altering one's phenotype in response to changes in the environment |
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Term
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Definition
Distribution shifts away from mean
Increases the proportion of genotypes with a more extreme value of the trait |
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Term
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Definition
Thinner distribution
Does not alter the mean, but may reduce variance |
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Term
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Definition
Bumpy distribution
Unlikely to be exactly symmetrical, therefore shifting mean slightly. |
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Term
| Real life example of directional selection |
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Definition
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Term
| Real life example of stabilizing selection |
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Definition
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Term
| Real life example of disruptive selection |
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Definition
| Beak dimensions in black-bellied seed cracker |
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Term
| Inverse frequency dependent selection |
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Definition
Rare genotype favored
Increases frequency till no longer rare
Once common, fitness declines |
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Term
| Positive frequency dependent selection |
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Definition
Common genotype favored
Whichever allele or morph is initially more fit will rapidly be fixed |
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Term
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Definition
Generally increases genetic variation within populations
Reduces genetic differences between populations |
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