Chapter 22 And 23: Descent With Modification And The Evolution Of Populations

Question 1

Descent with Modification

Answer 1

The process by which species accumulate differences from their ancestors as they adapt to different environments over time; also defined as a change in the genetic composition of a population from generation to generation

Question 2

Fossils

Answer 2

A preserved remnant or impression of an organism that lived in the past

Question 3

Strata

Answer 3

A rock layer formed when new layers of sediment cover older ones and compress them

Question 4

Paleontology

Answer 4

The scientific study of fossils

Question 5

Adaptation

Answer 5

Inherited characteristics of an organism that enhances its survival and reproduction in a specific environment

Question 6

Natural Selection

Answer 6

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Question 7

Artificial Selection

Answer 7

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits

Question 8

Homologous Structures

Answer 8

Structures in different species that are similar because of common ancestry

Question 9

Vestigial Structure

Answer 9

A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors

Question 10

Evolutionary tree

Answer 10

A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms

Question 11

Convergent Evolution

Answer 11

The evolution of similar features in independent evolutionary lineages

Question 12

Analogous

Answer 12

Having characteristics that are similar because of convergent evolution, not homology.

Question 13

Biogeography

Answer 13

The scientific study of the past and present geographic distributions of a species

Question 14

Pangaea

Answer 14

The supercontinent that formed near the end of the Paleozoic era, when plate movement brought all the land masses of earth together.

Question 15

Genetic Variation

Answer 15

Differences among individuals in the composition of their genes or other DNA sequences

Question 16

Neutral Variation

Answer 16

Genetic variation that does not provide a selective advantage or disadvantage

Question 17

Population

Answer 17

A group of individuals of the same species that live in the same area and interbreed producing fertile offspring

Question 18

Gene pool

Answer 18

The aggregate of all copies of every type of allele at all loci in every individual in a population the term is also used in a more restricted sense as the aggregate of alleles just for one or a few loci in a population

Question 19

Hardy-Weinberg Equilibrium

Answer 19

The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work

Question 20

Adaptive evolution

Answer 20

A process in which traits that enhance survival or reproduction tend to increase in frequency over time, resulting in a better match between organisms and their environment

Question 21

Genetic Drift

Answer 21

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. Effects of genetic drift are most pronounced in small populations

Question 22

Founder Effect

Answer 22

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population

Question 23

Bottleneck Effect

Answer 23

Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.

Question 24

Gene flow

Answer 24

The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes

Question 25

Relative Fitness

Answer 25

The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population

Question 26

Directional Selection

Answer 26

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes

Question 27

Disruptive Selection

Answer 27

Natural Selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes

Question 28

Stabilizing Selection

Answer 28

Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes

Question 29

Sexual Selection

Answer 29

A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates

Question 30

Sexual Dimorphism

Answer 30

Differences between the secondary sex characteristic of males and females of the same species

Question 31

Intrasexual selection

Answer 31

A form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex

Question 32

Intersexual selection

Answer 32

A form of natural selection in which individuals of one sex are choosy in selecting their mates from the other sex; also called mate choice

Question 33

Balancing Selection

Answer 33

Natural selection that maintains two or more phenotypic forms in a population

Question 34

Frequency-dependent selection

Answer 34

Selection in which the fitness of a phenotype depends on how common the phenotype is in a population

Question 35

Heterozygote Advantage

Answer 35

Greater reproductive success of heterozygous individuals compared with homozygote; tends to preserve variation in a gene pool.