Chapter 17

Question 1

Dimorphic

Answer 1

Two distinct forms in the same species (like male and female).

Question 2

Polymorphic

Answer 2

Many different forms or types in a population.

Question 3

Gene pool

Answer 3

All the genes in a population.

Question 4

Microevolution

Answer 4

Small changes in a population over time.

Question 5

Directional selection

Answer 5

Favors one extreme form of a trait.

Question 6

Stabilizing selection

Answer 6

Favors the average form of a trait.

Question 7

Balancing selection

Answer 7

Keeps different traits in a population.

Question 8

Disruptive selection

Answer 8

Favors both extreme forms, not the average.

Question 9

Sexual selection

Answer 9

Traits that help an organism attract mates are favored.

Question 10

Sexual dimorphism

Answer 10

Males and females look very different in a species.

Question 11

Balanced polymorphism

Answer 11

Two or more traits stay common in a population.

Question 12

Frequency-dependent selection

Answer 12

A trait’s success depends on how common or rare it is.

Question 13

Bottleneck effect

Answer 13

A big drop in population size reduces genetic diversity.

Question 14

Founder effect

Answer 14

A few individuals start a new population with limited genes.

Question 15

Immigration

Answer 15

Organisms move into a population.

Question 16

Emigration

Answer 16

Organisms move out of a population.

Question 17

Gene flow

Answer 17

Movement of genes between populations (through immigration/emigration).

Question 18

Speciation

Answer 18

When one species splits into two.

Question 19

Habitat isolation

Answer 19

Two species live in different places and don’t meet.

Question 20

Temporal isolation

Answer 20

Two species breed at different times.

Question 21

Behavioral isolation

Answer 21

Two species have different mating behaviors.

Question 22

Mechanical isolation

Answer 22

Physical differences prevent mating.

Question 23

Gamete isolation

Answer 23

Eggs and sperm can’t combine.

Question 24

Gamete incompatibility

Answer 24

Sperm can’t survive or fertilize the egg.

Question 25

Zygote mortality

Answer 25

A fertilized egg (zygote) dies early.

Question 26

Hybrid sterility

Answer 26

A hybrid grows up but can’t have babies (e.g., mule).

Question 27

F2 fitness

Answer 27

The hybrid’s offspring (F2 generation) are weak or sterile.

Question 28

Allopatric speciation

Answer 28

Species form after being separated by geography.

Question 29

Adaptive radiation

Answer 29

One species quickly evolves into many new species.

Question 30

Sympatric speciation

Answer 30

Species form in the same area without physical separation.

Question 31

Parapatric speciation

Answer 31

Species form in neighboring areas with only partial separation.

Question 32

Polyploidy

Answer 32

Having extra sets of chromosomes (common in plants).

Question 33

Macroevolution

Answer 33

Big evolutionary changes, like the rise of new species.

Question 34

Stasis

Answer 34

Long periods where a species doesn’t change much.

Question 35

Exaptation

Answer 35

A trait that evolves for one use but gets used for something else.

Question 36

Mass extinction

Answer 36

Many species die out at once.

Question 37

Coevolution

Answer 37

Two species evolve together by affecting each other.

Question 38

Phylogeny

Answer 38

The evolutionary history of a species.

Question 39

Cladistics

Answer 39

Grouping organisms based on shared traits.

Question 40

Cladogram

Answer 40

A diagram showing evolutionary relationships.