15. Evolutionary Hotspots

Question 1

What are, broadly speaking, the 3 most productive hotspots of evolutionary change? (geographically)

Answer 1

Islands/archipelagos
Lakes
High parts of mountain ranges

Question 2

What are some examples of evolutionary productive lakes/lake systems?

Answer 2

East African lakes, crater lakes, Canadian post-glacial lakes

Question 3

Where are honeycreepers endemic to? What did they possibly evolve from?

Answer 3

Hawaii, possible adaptation of the Rose finch

Question 4

What are the effects of spatial isolation that make islands ideal for adaptation/evolution?

Answer 4

1. Restricts gene flow and creates reproductive isolation and thus new species
2. Keeps islands depauperate, therefore with many vacant niches which lead to adaptations and new species

Question 5

Why are oceanic islands better for speciation than continental islands?

Answer 5

Continental islands have too strong a gene flow and are non depauperate enough.

Question 6

What is the meaning of depauperate?

Answer 6

Lacking in numbers or varieties of species

Question 7

What sort of environment is the East African Rift Valley?

Answer 7

A series of disconnected, tropical, lowland, isolated, large lakes

Question 8

What fish species has seen vast adaptations in the East African Rift Valley?

Answer 8

Cichlid fish - with >200 species in some lakes

Question 9

What plant species has seen extensive speciation in the high Andes?

Answer 9

Lupins

Question 10

In what unique way are mountain areas isolated?

Answer 10

They are spatially isolated, not from other ground, but from other regions of the same altitude.
- also more depauperate due to restricted gene flow and dispersal barriers

Question 11

Explain why serpentinites are significant in studying speciation.

Answer 11

Chemically unusual rocks such as serpentinites see evolutionary explosions by specific plants as their soil is toxic to most plants
- Not spatially isolated but they are depauperate

Question 12

Are evolutionary hotspots usually ‘spots’ within time or geography? Where/when are they?

Answer 12

Larger scale hotspots seen over time, usually after mass extinctions

Question 13

When is spatial isolation not a factor in high rates of speciation?

Answer 13

On ultramafic rock outcrops, or after mass extinction events

Question 14

Where is a fierce selection process a factor in high rates of speciation? Where isn’t it?

Answer 14

Fierce selection process on unusual rocks, but not after mass extinctions or on islands/lakes

Question 15

What one factor links all types of evolutionary hotspot?

Answer 15

Depauperacy

Question 16

Why are some lakes often depauperate?

Answer 16

Difficult for species to disperse to isolated lakes

Question 17

What factors come together to encourage high species radiation of lupins in the Andes?

Answer 17

Large area, fragmented gaps between altitudes, high resource diversity