Evolution of population

Question 1

microevolution

Answer 1

small scale evolution, on the level of species

Question 2

genetic variation

Answer 2

differences among individuals in the composition of their genes or other DNA segments, needed for evolution

Question 3

phenotype variation

Answer 3

depends on genetic and environmental influences

Question 4

average heterozygosity

Answer 4

the average percent of loci that are heterozygous; measure of genetic variation

Question 5

geographic variation

Answer 5

differences in the genetic composition of separate populations

Question 6

cline

Answer 6

example of geographic variation where there is a graded change in character along a geographic axis, temperature gradient, etc.

Question 7

sources of genetic variation

Answer 7

formation of new alleles (mutation), altering gene number or position (chromosomal changes), sexual reproduction (crossing over, independent assortment, fertilization)

Question 8

gene pool

Answer 8

all copies of every allele at every locus in all members of the population

Question 9

Hardy-Weinberg Equilbrium

Answer 9

describes conditions for no evolution: no mutations, random mating, no natural selection, very large population, no gene flow

Question 10

natural selection

Answer 10

organisms with traits better suited to the environment produce more offspring

Question 11

genetic drift

Answer 11

chance events cause the allele frequencies in a population to fluctuate unpredictably, important in small populations

Question 12

founder effect

Answer 12

when a few individuals become isolated from a larger population, the gene pool may differ; example of genetic drift

Question 13

bottleneck effect

Answer 13

when a sudden change in the environment (fire, flood) drastically reduces the size of a population; example of genetic drift

Question 14

gene flow

Answer 14

transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes

Question 15

relative fitness

Answer 15

average number of surviving progeny of a particular genotype compared with average number of surviving progeny of competing genotypes after a single generation

Question 16

directional selection

Answer 16

when conditions favor one extreme of a phenotype range

Question 17

disruptive selection

Answer 17

when conditions favor both extremes of a phenotype range

Question 18

stabilizing selection

Answer 18

when conditions favor intermediate phenotypes

Question 19

sexual selection

Answer 19

a form of selection in which individuals with certain inherited characteristics are more likely to obtain mates

Question 20

sexual dimorphism

Answer 20

differences between the two sexes (in size, color, ornamentation, behavior), result of sexual selection

Question 21

intrasexual selection

Answer 21

sexual selection within the same sex, individuals of the same sex compete with each other for mates of the opposite sex

Question 22

intersexual selection

Answer 22

sexual selection where individuals of one sex (usually female) are choosy in selecting mates of the opposite sex

Question 23

neutral variation

Answer 23

differences in DNA that do not confer a selective advantage or disadvantage, maintains genetic variation

Question 24

balancing selection

Answer 24

occurs when natural selection maintains two or more forms in a population (examples: heterozygote advantage, frequency-dependent selection), maintains genetic diversity

Question 25

heterozygote advantage

Answer 25

a kind of balancing selection when heterozygotes have greater fitness than homozygotes (ex. sickle-cell)

Question 26

frequency-dependent selection

Answer 26

when the fitness of a phenotype depends on how common it is in the population, balancing selection when the less common one is favored