Chapter 19 Part 2

Question 1

natural selection acts on ____

Answer 1

phenotype

Question 2

fitness

Answer 2

reproductive contribution of a phenotype to subsequent generations relative to other phenotypes

Question 3

changes in relative success of different phenotypes lead to change in ____

Answer 3

allele frequencies

Question 4

fitness of a phenotype is determined by the rates of ____ and _____ of individuals with that phenotype.

Answer 4

survival and reproduction

Question 5

qualitative trait

Answer 5

influenced by alleles only at one locus; categories.

Question 6

quantitative traits

Answer 6

show continuous variation. influenced by alleles at more than 1 locus. bell shape.

Question 7

natural selection can act on quantitative traits in three ways

Answer 7

-stabilizing selection
-directional selection
-disruptive selection

Question 8

stabilizing selection preserves the ___ phenotype. reduces variation but does not change the mean.

Answer 8

average phenotype

Question 9

_____ selection favors individuals that vary in one direction away from the mean. one extreme is more successful.

Answer 9

directional

Question 10

directional selection results in an ____ of frequencies of ___ that produce the favored phenotype at one extreme.

Answer 10

-increase
-alleles

Question 11

disruptive selection

Answer 11

favors individuals that vary in both directions- more successful than average.

Question 12

disruptive selection and directional selection increase ___

Answer 12

variation

Question 13

if the allele for a given trait does not exist in a population, that trait ___ evolve.

Answer 13

cannot

Question 14

during tradeoffs, the benefit must ___ the cost

Answer 14

outweigh

Question 15

cell size and organism size, protein folding, laws of thermodynamics are ____ that limit selection

Answer 15

universal constraints

Question 16

stabilizing selection ___ variation

Answer 16

deceases