Ch09Cont
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What is an adaptive landscape?
A tri-dimensional considering the relationship between fitness & multiple phenotypes
list the interactions among genes
• Pleiotropy • Epistasis • Norms of reaction • Dominance • Multiple pathways
at the population or species levels what are multiple fitness peaks called & what are they seperated by?
• adaptive peaks - fitness valleys
why do selection prevents populations from “going down” into the low fitness valleys?
A large population typically moves “myopically” uphill to a local fitness maximum
what can help small populations move from a local fitness peak to a global fitness maximum?
genetic drift by decreasing fitness
what can “teleport” a population from one part of a adaptive landscape to another?
mutations
Why is it hard to reverse compensated antibiotic resistance?
a reversal decreases fitness, & selection act against this
phenotype results from the interaction among what?
• genes • environment • development
what does quantitative genetics enables us to do?
track the variation in the phenotype within a population considering mean & variance of characters
define broad sense heritability
The total fraction of variation that can be attributed to genetic causes *hard to determine
define narrow sense heritability
The fraction of variation that is accessible to natural selection
what does narrow sense heritability reflects?
how much offspring resemble their parents in a population
define Selection differential (S)
difference between mean trait value of reproducing individuals & all individuals in the population
define selection Response (R)
difference between mean trait value of offspring population & parent population
Estimated h2 is not …
• a characteristic of a species • the same for different populations • the same across generations