5 Mechanism of Speciation

Question 1

What is a species?

Answer 1

Population whose members can interbreed & produce viable, fertile offspring.

Question 2

a process by which two species that could otherwise produce hybrid offspring are prevented from doing so.

Answer 2

ISOLATION

Question 3

• are mechanisms that prevent closely related species from interbreeding.
• Stops two species from producing viable, fertile offspring.

Answer 3

Reproductive Barriers

Question 4

• Also known as pre - reproductive barrier
• prevent mating between two closely related species.

Answer 4

Prezygotic Barrier

Question 5

6 types of Prezygotic Barrier/Isolation

Answer 5

Geographic Isolation
Ecological isolation
Temporal isolation
Behavioral isolation
Mechanical isolation
Gametic isolation

Question 6

• Physical barrier separate ancestral species.
• New species appear in different areas.

Answer 6

Geographic Isolation

Question 7

Species occur in same region, but occupy different habitats so they rarely encounter each other

Answer 7

Ecological isolation

Question 8

Two closely related species reproduce at different times of the day, season, or year.

Answer 8

Temporal “time” isolation

Question 9

Unique behavioral patterns & rituals isolate species.

Answer 9

Behavioral isolation/ Ethological isolation

Question 10

• Morphological differences can prevent successful mating
• differences in their reproductive organs prevent interbreeding

Answer 10

Mechanical isolation

Question 11

• A mechanism of reproductive isolation which inhibits mating between two distinct species, by ensuring that their gametes don’t interact with each other.
• Sperm of one species may not be able to fertilize eggs of another species

Answer 11

Gametic isolation

Question 12

Sperm cannot penetrate egg because of receptor recognition malfunction or lock & key between egg & sperm is disrupted

Answer 12

Biochemical barrier

Question 13

Sperm cannot survive in female reproductive tract.

Answer 13

Chemical Incompatibility

Question 14

Prevent hybrid offspring from developing into a viable, fertile adult.

Answer 14

Postzygotic barriers

Question 15

3 Types of Postzygotic Barriers/Isolation

Answer 15

Hybrid sterility
Hybrid viability
Hybrid Breakdown

Question 16

Chromosomes of parents differ in number or structure thus meiosis in hybrids will fail to produce a normal gametes.

Answer 16

Hybrid sterility

Question 17

Genes of different parents can impair or stop the development of the hybrid.

Answer 17

Hybrid viability

Question 18

• First generation of hybrids are fertile and viable
• Succeeding generations are sterile.

Answer 18

Hybrid Breakdown

Question 19

2 MODE OF SPECIATION

Answer 19

• GEOGRAPHIC ISOLATION
• GENETIC ISOLATION/ ECOLOGICAL ISOLATION

Question 20

MODE OF SPECIATION
l
- GEOGRAPHIC ISOLATION

Answer 20

• ALLOPATRIC
• PERIPATRIC

Question 21

MODE OF SPECIATION
l
- GENETIC ISOLATION/ ECOLOGICAL ISOLATION

Answer 21

• SYMPATRIC
• PARAPATRIC

Question 22

• Geographical barrier
• Separate two large populations.

Answer 22

Allopatric

Question 23

• Geographical barrier
• Separate a small number of species from the whole population.

Answer 23

Peripatric

Question 24

• No geographical barrier
• Leave in the same habitat
• the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.

Answer 24

Sympatric

Question 25

• No geographical barrier
• Leave within the same habitat.
• Slight difference in the habitat, new niche.
• a species is spread out over a large geographic area

Answer 25

Parapatric