Unit 8

Question 1

Artificial Selection

Answer 1

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

Question 2

Allopathic speciation

Answer 2

A mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations

Question 3

Adaptive radiation

Answer 3

The emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new opportunities and problems

Question 4

Biogeography

Answer 4

The study of the past and present distribution of species

Question 5

Bottleneck effect

Answer 5

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population

Question 6

Balancing selection

Answer 6

Natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism)

Question 7

Balanced polymorphism

Answer 7

The ability of natural selection to maintain diversity in a population

Question 8

Catastrophism

Answer 8

The hypothesis by Georges Cuvier that each boundary between strata corresponded in time to a catastrophe, such as a flood or drought, that had destroyed many of the species living there at that time

Question 9

Cline

Answer 9

A graded variation in a trait that parallels a gradient in the environment

Question 10

Descent with modification

Answer 10

Darwin’s initial phrase for the general process of evolution

Question 11

Directional selection

Answer 11

Natural selection that favors individuals at one end of the phenotypic range

Question 12

Disruptive selection

Answer 12

Natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes

Question 13

Evolutionary adaptation

Answer 13

An accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments

Question 14

Evolution

Answer 14

All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today

Question 15

Founder effect

Answer 15

Genetic drift that occurs when a few individuals become isolated from a population, with the result that the new population’s gene pool is not reflective of the original population

Question 16

Fitness

Answer 16

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

Question 17

Gradualism

Answer 17

A view of earth’s history that attributes profound change to the cumulative product of slow but continuous processes

Question 18

Gene pool

Answer 18

The total aggregate of genes in a population at any one time

Question 19

Genetic drift

Answer 19

Unpredictable fluctuations in allele frequencies from one generation to the next because of a population’s finite size

Question 20

Gene flow

Answer 20

Genetic additions to or subtractions from a population resulting from the movement of fertile individuals or gametes

Question 21

Genetic polymorphism

Answer 21

The existence of two or more distinct alleles at a given locus in a population’s gene pool

Question 22

Homology

Answer 22

Similarity in characteristics resulting from a shared ancestry

Question 23

Homologous structures

Answer 23

Structures in different species that are similar because of common ancestry

Question 24

Hardy-Weinberg Theorem

Answer 24

The principle that 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 25

Hardy-Weinberg equilibrium

Answer 25

The condition describing a non-evolving population (one that is in genetic equilibrium)

Question 26

Heterozygote advantage

Answer 26

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

Question 27

Microevolutuon

Answer 27

Evolutionary change below the species level; change in the genetic makeup of a population from generation to generation

Question 28

Mutations

Answer 28

A change in the DNA of a gene, ultimately creating genetic diversity

Question 29

Natural Selection

Answer 29

Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in relative frequencies of alleles in the gene pool

Question 30

Population genetics

Answer 30

The study of how populations change genetically over time

Question 31

Population

Answer 31

A localized group of individuals that belong to the same biological species (that are capable of interbreeding and producing fertile offspring)

Question 32

Phenotypic polymorphism

Answer 32

The existence of two or more distinct morphs (discrete forms), each represented in a population in high enough frequencies to be readily noticeable

Question 33

Prezygotic barriers

Answer 33

A reproductive barrier that impedes mating between species or hinders fertilization of ova if interspecific mating is attempted

Question 34

Postzygotic barriers

Answer 34

Any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults

Question 35

Punctuated equilibrium

Answer 35

In evolutionary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change

Question 36

Relative fitness

Answer 36

The contribution of one genotype to the next generation compared to that of alternative genotypes for the same locus

Question 37

Reproductive isolation

Answer 37

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids

Question 38

Sexual selection

Answer 38

Natural selection for mating success

Question 39

Sexual dimorphism

Answer 39

A special case of polymorphism based on the distinction between the secondary sex characteristics of males and females

Question 40

Stabilizing selection

Answer 40

Natural selection that favors intermediate variants by acting against extreme phenotypes

Question 41

Taxonomy

Answer 41

Ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences, leading to a classification scheme; the branch of biology concerned with naming and classifying the diverse forms of life

Question 42

Vestigial organs

Answer 42

A structure of marginal, if any, importance to an organism. Vestigial organs are historical remnants of structures that had important functions in ancestors