Speciation and Macroevolution

Question 1

How does speciation and macroevolution occur?

Answer 1

An accumulation of microevolutionary changes over time.

Question 2

What are the four patterns of diversification between species?

Answer 2

-Divergent (Closely related species diverges to have different traits due to selection pressure e.g. Darwin’s Finches, homologous structure)
-Convergent (Distantly related species evolve to have similarly functioning traits e.g. bat and bird wing, analogous structures)
-Parallel (independent species acquire similar characteristics while evolving together at the same time and space e.g. pattern and colouration of butterfly wings)
-Coevolution (When the evolution of one species directly impacts the evolution of another e.g. speeds of rabbit and foxes)

Question 3

Describe the modes of speciation.

Answer 3

Allopatric- Geological barrier isolates populations of an ancestorial species and they speciate.
Sympatric- Speciation in the same geographical area through niche differentiation (different habitats) or polyploidy (error in meiosis, typically plants)
Parapatric- No direct barrier but populations are more likely to breed with those in their geographic area

Question 4

What mechanisms of isolation influence gene flow?

Answer 4

-geographic (environmental disasters, habitat fragmentation)
-reproductive
-spatial
-temporal

Question 5

Explain how populations with reduced genetic diversity face an increased risk of extinction

Answer 5

Without genetic diversity populations are at a greater risk of extinction as if an event occurs such as a disease it may wipe out the entire population as there is no variation in genes to give some a grater chance at survival.