Chapter 22

Question 1

What is the biological species concept?

Answer 1

It defines species as groups of populations that have the potential to interbreed and that are reproductively isolated from other groups.

Question 1

What is sympatric speciation?

Answer 1

Differentiation of populations within a common geographic area into species

Question 2

What do gene pools have?

Answer 2

All alleles present in a species

Question 3

What the definition of a reproductive isolating mechanism?

Answer 3

Any barrier that prevents genetic exchange between species

Question 4

What are prezygotic isolating mechanisms?

Answer 4

The formation of the zygote is prevented.

Question 5

What are Postzygotic isolating mechanisms?

Answer 5

the zygote is formed but the offspring can not reproduce (infertile)

Question 6

What is the ecological species concept?

Answer 6

Distinctions among species are maintained by natural selection

Question 7

Why is the ecological species concept difficult to apply?

Answer 7

Because populations are geographically separated in nature

Question 8

How does is reproductive isolation reinforced?

Answer 8

In speciation, the process by which reproductive isolation between populations is increased by selection against mating between members of the two population eventually resulting in reproductive isolation.

Question 9

What are the two possible outcomes when two populations that are partially reproductively isolated become sympatric?

Answer 9

1. gene flow occurs between them
2. hybrids reproduce with other members of the population and they will serve as a means of genetic exchange.

Question 10

What is the effect of genetic drift on a population?

Answer 10

Random change in small populations, founder effects, and population bottlenecks all may lead to changes in traits that cause reproductive isolation.

Question 11

How can genetic drift and natural selection lead to speciation?

Answer 11

Natural selection causes them to accumulate many differences to adapt leading to reproductive isolation.

Question 12

What is allopatric speciation?

Answer 12

It takes place when populations are geographically isolated

Question 13

What is polyploidy?

Answer 13

a condition in which one or more entire sets of chromosomes instantaneously is added to the diploid genome.

Question 14

autopolyploidy?

Answer 14

results in meotic error

Question 15

What is allopolyploid

Answer 15

it is contains genomes of two or more species

Question 16

What is distrubtive selection?

Answer 16

It causes populations to have two different phenotypes

Question 17

What is adaptive radiation

Answer 17

The evolution of several divergent from a primitive and unspecialized ancestor

Question 18

What is key innovation

Answer 18

Allows members to use a new resource from an adaptation

Question 19

What is stasis?

Answer 19

A period of time during which little evolutionary change occurs

Question 20

What is gradual evolutionary change?

Answer 20

The view that species change very slowly in ways that may be imperceptible from one generation to the next but that accumulate and lead to major changes over thousands or millions of years.

Question 21

What is the punctual equilibrium hypothesis?

Answer 21

A hypothesis about the mechanisms of evolutionary change proposing that long periods of little or no change are punctuated by periods of rapid evolution.

Question 22

Define mass extinction

Answer 22

a relatively sharp decline in the number of species.