Hotspots of Evolution Flashcards
What are the most productive and renowned geographic hotspots of evolutionary change
- Some islands/archipelagos
- Some lakes/lake systems
- (Higher) parts of many mountains
Why is it some island (e.g. Galapogos) have high levels of evolutionary change but other (e.g. UK) do not
Different islands have different degrees of separation from the mainland
This is how many vacant niches there are which a species can evolve into
What is spatial isolation and its consequence
- Spatial isolation: restricts gene flow to islands, leading to reproductive isolation and new species
- It keeps islands improverished - vacant niches, leading to adaptive change and new species
If an island is close to the mainland, what affect does this have on evolutionary change
- Islands which are close to the mainland, are swamped by gene flow which inhibits evoutionary change
- There are more species which can move across laving fewer vacant niches
What is special about the Rift Valley
- It is a ‘failed rift’ - Eaastern part attempting to rift away from the rest of Africa - but failing
- It is pretty isolated and lakes are not connected to rivers
- There is huge colour and morphological variety in these fish, with very high endemism - almost like an oceanic island
What is special about the Crater Lakes in Cameroon
Isolated Crater lakes in Cameroon have radiations of cichlids, showing a lot og colour variation and in some cases great morphological variation
The collapsed crater filled with water and are highly isolated due to little inflow and outflow
These fish can create about 10 endemic species per lake
What do the Crater lakes of Cameroon and the Rift Valley demonstrate
Isolation seems to be driving evolution
What are post glacial lakes
How do they form
A postglacial lake forms when a glacier erodes a large depression, then melts
May of these lakes are spatially isolated
What seem to be the two main drivers of evolution
- Isolation (limited gene flow) and depauperacy (opportunity)
- Shown through these isolated bodies of water
The Lupin Family is not endemic to the Andes, but lupins are very diverse there, and many of the species are endemic
What is special about the Lupins Habitat
Lupins are staggeringly diverse in the vegetated zone above the treeline; much less so below it
But could well be the depauperacy (lacking other species) of the vegetation above the tree line
What are volcanic islands
Volcanic mountains tops start with nothing on them and may be very young (recent uplift and/or outpouring of lava)
What is Serpentinite and how has it effected evolution
- Serpentinite is uncommon on the surface of continent - fragments of oceanic crust that have accreted to the side of continental landmasses as oceanic and continetal plates come together and often thrusted onto continents
- Oceanic crust is chemically very different from continetal crust, so serpentinites are toxic to most continetal plant
- Has promoted extensive diversification among plants that have managed to colonise these environments
Serpentines are….
Depauperate (vacant niche) but not spatially isolated
It has lead to the fastest speciation we know of (apart from polyploidy)
Serpentines are….
Depauperate (vacant niche) but not spatially isolated
It has lead to the fastest speciation we know of (apart from polyploidy)
Previously, it was talked about how the aftermath of a mass extinction event seems to promote accelerated diversification of life - due to depauperacy
Again this is an event where
There is no change is spatial isolation but increase in depauperacy
