Lesson 4.2

Question 1

A group of individuals of the same species that occupy a given area at the same time and share a common set of genes

Answer 1

population

Question 2

What characterizes a population

Answer 2

The frequency of alleles for a given trait

Question 3

The sum of all the alleles for all traits in a sexually reproducing population.

Answer 3

gene pool

Question 4

What is the potential for genetic variation in populations

Answer 4

Virtually unlimited

Question 5

What causes variation within gene pools

Answer 5

Independent assortment of chromosomes.

Crossing over.

Chance fertilization.

Chromosome rearrangements.

Mutations of existing alleles.

Question 6

When does evolution occur in relation to alleles?

Answer 6

When relative allele frequencies change across generations

Question 7

Mixing of alleles at meiosis and recombination does not change allele frequencies in future generations (no evolution).

Answer 7

Hardy-Weinberg Theorem

Question 8

What are the assumptions of the Hardy-Weinberg Theorem

Answer 8

Large population size.

No migration.

No mutations or mutational equilibrium.

Random mating (no natural selection).

Question 9

When does evolution occur according to Hardy-Weinberg

Answer 9

When any one of the assumptions is not met.

Question 10

What are the four main mechanisms of evolutionary change

Answer 10

Genetic drift, gene flow, mutation, and natural selection

Question 11

Random events that change allele frequencies in populations

Answer 11

genetic drift

Question 12

In which populations is genetic drift most important?

Answer 12

Small populations

Question 13

What are the two special cases of genetic drift

Answer 13

Founder effect and bottleneck effect

Question 14

Example of bottleneck effect

Answer 14

Northern elephant seals, which have very low genetic diversity due to overhunting

Question 15

Changes in allele frequency due to migration of individuals

Answer 15

gene flow

Question 16

How does gene flow affect populations

Answer 16

In both directions: makes populations more similar.

Absence: makes evolutionary change less likely

Question 17

Example of gene flow restriction

Answer 17

African elephants (Loxodonta africana vs. Loxodonta cyclotis) with little gene flow, now considered separate species

Question 18

What is the origin of all new alleles

Answer 18

Mutation

Question 19

Are most mutations beneficial or harmful

Answer 19

Most are neutral or detrimental

Question 20

When are mutations most influential

Answer 20

At the gamete level.

Question 21

What upsets Hardy-Weinberg equilibrium

Answer 21

Natural selection

Question 22

The tendency for natural selection to occur

Answer 22

selection pressure

Question 23

What are the three types of selection

Answer 23

Directional selection.

Disruptive (diversifying) selection.

Stabilizing selection

Question 24

Example of directional selection

Answer 24

Peppered moth (Biston betularia)

Question 25

Example of disruptive selection

Answer 25

Plainfin midshipman (Porichthys notatus) with two subpopulations of males

Question 26

What does sexual selection often result in?

Answer 26

Extreme morphology such as antlers, bright colors, or exaggerated traits.

Question 27

What does stabilizing selection do

Answer 27

Selects against both extremes, narrows the phenotypic range

Question 28

What is the biological species concept?

Answer 28

Populations in which genes are exchanged through interbreeding

Question 29

What are the problems with the biological species concept

Answer 29

Taxonomists often rely on morphology. Some species are asexual. Fossil species can’t be tested. Difficult for geographically isolated groups

Question 30

What is the phylogenetic species concept

Answer 30

Groups of populations that evolved independently of others

Question 31

The formation of new species through reproductive isolation

Answer 31

speciation

Question 32

What mechanisms cause reproductive isolation

Answer 32

Geographical barriers, behavioral differences, physiological differences, hybrid non-viability

Question 33

Speciation due to geographic isolation (e.g., Galapagos finches).

Answer 33

allopatric speciation

Question 34

Speciation in small local populations with relative isolation (rare, no documented examples).

Answer 34

parapatric speciation

Question 35

Speciation within a single population due to reproductive isolation (e.g., African indigo birds, Felidae resource partitioning).

Answer 35

sympatric speciation

Question 36

Slow evolutionary change over millions of years.

Answer 36

phyletic gradualism

Question 37

Long stasis interrupted by short rapid change (10,000–100,000 years).

Answer 37

punctuated equilibrium

Question 38

What is the basis of all evolutionary change?

Answer 38

Changes in DNA and protein

Question 39

What are conserved genes/proteins useful for?

Answer 39

Tracing relationships among distantly related organisms.

Question 40

What are less conserved DNA regions useful for?

Answer 40

Studying closely related organisms

Question 41

Example of a conserved gene used in evolution studies?

Answer 41

Cytochrome C

Question 42

Accidental duplication of a gene on a chromosome

Answer 42

gene duplication

Question 43

Why is gene duplication important

Answer 43

One copy can mutate into a new allele while the other maintains original function

Question 44

Example of gene duplication products in vertebrates

Answer 44

Hemoglobin and myoglobin

Question 45

Different parts of a species evolve at different rates

Answer 45

mosaic evolution

Question 46

Example of mosaic evolution in birds

Answer 46

Conserved: bills, wings, feathers