9D - Speciation

Question 1

speciation

Answer 1

process by which populations genetically diverge until they form distinct species.

occurs due to the accumulation of genetic differences.

Question 2

Allopatric Speciation:

Answer 2

Caused by geographical barriers
Prevents gene flow between populations.

Different selection pressures lead to divergence

Question 3

Sympatric Speciation:

Answer 3

Occurs without geographical barriers.
Driven by selection pressures or genetic abnormalities.

Question 4

Post-reproductive (Post-zygotic) isolation mechanisms

Answer 4

Gamete Mortality: Sperm cannot fertilize ovum.

Zygote Mortality: Zygote forms but doesn’t survive.

Hybrid Sterility: Offspring survive but are infertile.

Question 5

Pre-reproductive (Pre-zygotic) isolating mechanisms

Answer 5

Geographical: Physical barriers (e.g., rivers).

Ecological: Different habitats or niches.

Temporal: Breeding at different times.

Behavioural: Different mating behaviors.

Structural: Physical differences prevent mating

Question 6

example of Allopatric Speciation

Answer 6

Galápagos Finches:
Islands separated by ocean (geographical barrier).
Different selection pressures (e.g., food sources).
Beak shapes adapted to specific diets.

Question 7

Example of Sympatric Speciation

Answer 7

Howea Palms on Lord Howe Island:
Selection Pressure: Soil pH differences.
Reproductive Isolation: Changes in flowering time.
Resulted in two species: Howea belmoreana and Howea forsteriana.

Question 8

Speciation Requirements

Answer 8

Lack of Gene Flow: Essential for divergence.

Selection Pressures: Drive genetic differences.

Reproductive Isolation: Prevents interbreeding of diverged populations.