Chapter 24 The Origins Of Species

Question 1

The origin of new species, is at the focal point of evolutionary theory

Answer 1

Speciation

Question 2

Consist of changes in allele frequency in a population over time

Answer 2

Microevolution

Question 3

Refers to broad patterns of evolutionary change above the species level

Answer 3

Macroevolution

Question 4

Group of populations whose members have the potential to interbreed in nature

Produce viable, fertile offspring

Do not breed successfully with other populations

Answer 4

Species

Question 5

____________ between populations holds the phenotype of a population together

Answer 5

Gene flow

Question 6

• The existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
• can be classified by whether factors occur before or after fertilization

Answer 6

Reproductive isolation

Question 7

What does reproductive limitation limit the formation of?

Answer 7

Hybrids

Question 8

What are the reproductive barriers?

Answer 8

• habitat isolation
• temporal isolation
• behavioral isolation
• mechanical isolation
• gametic isolation
• reduce hybrid viability
• reduced hybrid fertility
• hybrid breakdown

Question 9

Block fertilization from occurring by

• impeding different species from attempting to mate
• preventing the successful completion of mating
• hindering fertilization if mating is successful

Answer 9

Prezygotic barriers

Question 10

Species that breed at different times of the day, different seasons or different years cannot mix their gametes

Answer 10

Temporel isolation

Question 11

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

Answer 11

Habitat isolation

Question 12

Courtship rituals and other behaviors unique to a species are effective barriers

Answer 12

Behavioral isolation

Question 13

Morphological differences can prevent successful mating

Answer 13

Mechanical isolation

Question 14

Sperm of one species may not be able to fertilize eggs of another species

Answer 14

Gametic isolation

Question 15

Prevents the hybrid from developing into a viable, fertile adult:

• reduce hybrid viability
• reduced hybrid fertility
• hybrid breakdown

Answer 15

Postzygotic barriers

Question 16

Genes of the different parent species may interact and impair the hybrids development

Answer 16

Reduced hybrid viability

Question 17

Even if hybrids are Vigorous, they may be sterile

Answer 17

Reduced hybrid fertility

Question 18

Some first generation hybrids are fertile, but when they mate with another species or with either parent species offspring of the next generation are feeble or sterile

Answer 18

Hybrid breakdown

Question 19

Cannot be applied to fossils or asexual organisms (prokaryotes)

Emphasizes absence of Gene flow

Ex: growler bear?

Answer 19

Biological species concept

Question 20

Can Gene flow occur between distinct species?

Answer 20

Yes

Question 21

Applies to sexual and asexual species but relies on subjective criteria

Appearances

Answer 21

Morphological species concept

Question 22

Applies to sexual and asexual species and emphasizes the role of disruptive selection. Where they live, food sources.

Answer 22

Ecological species concept

Question 23

Defined as a species as the smallest Group of individuals on a phylogenetic tree

It applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species

Answer 23

Phylogenetic species concept

Question 24

Can speciation take place with or without geographic separation?

Answer 24

Yes

Question 25

Speciation can occur in what two ways ?

Answer 25

- allopatric speciation | - sympatric speciation

Question 26

How do the numbers of geographic barriers affect the numbers of species in the area?

Answer 26

More variety of species

Question 27

What can result as the distance between populations increase?

Answer 27

Reproductive isolation

Question 28

Speciation takes place in graphically overlapping populations More common In plants

Answer 28

Sympatric speciation

Question 29

What are the three ways sympatric speciation can occur?

Answer 29

- polyploidy - habitat differentiation - sexual selection

Question 30

The presence of extra sets of chromosomes due to accidents during cell division Much more common in plants than in animals

Answer 30

Polyploidy

Question 31

An individual with more than two chromosomes sets derived from one species

Answer 31

Autopolyploid

Question 32

A species with multiple sets of chromosomes derived from different species Sterile hybrid

Answer 32

Allopolyploid

Question 33

* An individual with more than two chromosome sets | - derive from one species

Answer 33

Autoployploid

Question 34

Can drive sympatric speciation Sexual selection for mates Ex: speciation in Cichlid fish in lake Victoria

Answer 34

Sexual selection

Question 35

A reproductive barrier isolates a subset of a population without geographic separation from the Parent species Can result from polyploidy, natural selection, or sexual selection

Answer 35

Sympatric speciation

Question 36

Geographic isolation restricts gene flow between populations reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations -even if contact is restored between populations, interbreeding is prevented

Answer 36

Allopatric speciation

Question 37

the area where two species meet and mate to form hybrids

Answer 37

Hybrid zone

Question 38

The result of mating between species with incomplete reproductive barriers

Answer 38

Hybrids

Question 39

What is the level of fitness in hybrids compared with the parent species?

Answer 39

Lower

Question 40

What are the three possible outcomes when closely related species meet in a hybrid zone?

Answer 40

- reinforcement - Fusion - stability

Question 41

Occurs when hybrids are less fit than the parent species. This reinforces natural selection and barriers between them.

Answer 41

Reinforcement: Strengthening reproductive barriers****

Question 42

Does reinforcement strengthen or weaken reproductive barriers?

Answer 42

Strengthen

Question 43

Are reproductive barriers stronger in allopatric or sympatric species?

Answer 43

Sympatric Ex: birds that look the same in allopatric speciation Birds that look completely different in sympatric speciation, no attempts to mate

Question 44

Fusion (strengthens or weakens) reproductive barriers?

Answer 44

Weakens

Question 45

In hybrids zones, Reproductive barriers weaken until the two species become one. Ex: cichlids

Answer 45

Fusion

Question 46

Hybrid survive or reproduce better than the parent species Continues formation of hybrid individuals

Answer 46

Stability *Not common

Question 47

- each new species evolves continuously over long spans of time - large phenotypic differences that produce new species are due to the accumulation of many small genetic changes

Answer 47

Gradualism

Question 48

Species in equilibrium (stasis) for long periods and then short rapid burst of change

Answer 48

Punctuated Equilibrium

Question 49

The _____________ in the fossil record and evidence from lab studies suggest that speciation can be rapid

Answer 49

Punctuated pattern