Chapter 13 Study Guide

Question 1

what is microevolution

Answer 1

small changes in allele frequencies within a populations gene pool

Question 2

what causes microevolution

Answer 2

changes in the populations gene pool over time

Question 3

what is directional selection

Answer 3

favors one extreme phenotype

Question 4

what is stabilizing selection

Answer 4

favors intermediate traits; reduces variation

Question 5

what is disruptive selection

Answer 5

favors both extremes; can split populations

Question 6

what is sexual selection

Answer 6

traits evolve because they increase mating success

Question 7

example of sexual selection

Answer 7

peacock feathers, bird songs, bright colors in males

Question 8

what is balancing selection

Answer 8

keeps different alleles in a population

Question 9

how does sickle-cell anemia show balancing selection

Answer 9

heterozygotes resist malaria–> both alleles stay common

Question 10

what is genetic drift

Answer 10

random changes in allele frequencies (chance events)

Question 11

what is a population bottleneck

Answer 11

sudden reduction in population –> loss of diversity

Question 12

what is gene flow

Answer 12

movement of genes between populations through migration

Question 13

what is speciation

Answer 13

formation of new species

Question 14

what is reproductive isolation

Answer 14

when two groups cant successfully breed

Question 15

examples of isolation mechanisms

Answer 15

behavioral isolation, hybrid inviability, hybrid sterility

Question 16

what is allopatric speciation

Answer 16

species form after geographic separation

Question 17

what is sympatric speciation

Answer 17

species form in the same area (no physical barrier)

Question 18

what is adaptive radiation

Answer 18

one species gives rise to many new species adapted to different niches

Question 19

example of adaptive radiation

Answer 19

Hawaiian honeycreepers, Darwin’s finches

Question 20

what is extinction

Answer 20

when all members of a species die out

Question 21

what is coevolution

Answer 21

two species evolve in response to each other

Question 22

what are derived traits

Answer 22

new traits that appear in recent species but not ancestors

Question 23

what is a clade

Answer 23

a group that shares a common ancestor and derived traits

Question 24

what is a cladogram

Answer 24

a branching diagram showing evolutionary relationships