Chapter 13 - How Populations Evolve

Question 1

Natural selection

Answer 1

A process in which individuals with certain inherited traits are more likely to survive and reproduce than are individuals that do not have those traits.

Question 2

Adaptation

Answer 2

An inherited character that enhances an organism’s ability to survive and reproduce in a particular environment.

Question 3

Theory

Answer 3

A widely accepted explanatory idea that is broader in scope than a hypothesis, generates new hypotheses, and is supported by a large body of evidence.

Question 4

Evolution

Answer 4

Descent with modification; the idea that living species are descendants of ancestral species that were different from present-day ones; also, the genetic changes in a population from generation to generation.

Question 5

Fossil

Answer 5

A preserved remnant or impression of an organism.

Question 6

Fossil record

Answer 6

The chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in rock strata.

Question 7

Paleontologist

Answer 7

A scientist who studies fossils.

Question 8

Stratum

Answer 8

(plural, strata) Rock layer formed when a new layer of sediment covers an older one and compresses it.

Question 9

Homology (Homo = Similarity)

Answer 9

Similarity in characters resulting from a shared ancestry.

Question 10

Homologous structures

Answer 10

Structures in different species that are similar because of common ancestry.

Question 11

Molecular biology

Answer 11

The study of biological structures, functions, and heredity at the molecular level.

Question 12

Vestigial structure

Answer 12

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

Question 13

Evolutionary tree

Answer 13

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

Question 14

Artificial selection

Answer 14

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

Question 15

Mutation

Answer 15

A change in the genetic information of a cell; the ultimate source of genetic diversity. A mutation also can occur in the DNA or RNA of a virus.

PS: Most mutations don’t become more common because they are not advantageous

Question 16

Sexual reproduction

Answer 16

The creation of genetically unique offspring by the fusion of two haploid sex cells (gametes), forming a diploid zygote.

Question 17

Population

Answer 17

A group of individuals belonging to one species and living in the same geographic area.

(All of the same species)

Question 18

Gene pool

Answer 18

All copies of every type of allele at every locus in all members of the population.

Question 19

Microevolution

Answer 19

A change in a population’s gene pool over generations.

Question 20

Hardy-Weinberg equilibrium

Answer 20

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

Question 21

Genetic drift

Answer 21

A change in the gene pool of a population due to chance. Effects of genetic drift are most pronounced in small populations.

Question 22

Bottleneck effect

Answer 22

Genetic drift resulting from a drastic reduction in population size. Typically, the surviving population is no longer genetically representative of the original population.

Question 23

Founder effect

Answer 23

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

Question 24

Gene flow

Answer 24

The transfer of alleles from one population to another as a result of the movement of 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 and reproduce more successfully than do other individuals.

Question 27

Stabilizing selection

Answer 27

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Question 28

Disruptive selection

Answer 28

Natural selection in which individuals on both extremes of a phenotypic range are favored over intermediate phenotypes.

Question 29

Sexual selection

Answer 29

A form of natural selection in which individuals with certain inherited traits are more likely than other individuals to obtain mates.

Question 30

Sexual dimorphism

Answer 30

Marked differences between the secondary sex characteristics of males and females.

Question 31

Balancing selection

Answer 31

Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.

Question 32

Heterozygote advantage

Answer 32

Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in gene pools.