View
213
Download
0
Category
Tags:
Preview:
Citation preview
Paradox of the Cichlidsoutline of my PhD project
Thijs JanzenSupervisor: Rampal Etienne
Picture courtesy Jen Reynolds
Cichlids
The success of the cichlids
• Pharyngeal jaw
• Mouthbrooding
Barlow 2000
Oliver 2010
The African Rift Lakes
Differences between the lakes
Lake
Victoria
Lake
Malawi
Lake
Tanganyika
Age (My) 0.25-0.75
3 – 5 9 – 12
# Species ~700 ~700 ~250
Area (km2)
68 635 29 600 32 893
Depth 83 m 706 m 1 471 m
Lake Victoria Lake Tanganyika Lake Malawi
Why should there be more?
• Age
• Water level
• Bathymetry
Waterlevel
• Water level changes frequently– King Mwangonde (1820)
Owen 1990, Barlow 2000, Salzburger 2002
Why should there be more?
• Age
• Water level
• Bathymetry
BathymetryTanganyikaMalawi
Talling 1969, Scholz et al. 2007
Victoria
Water level
Water level:
0 m
Water level
Water level:
-100 m
Water level
Water level:
-250 m
Water level
Water level
-300 m
Water level:
-300 m
Water level
Water level:
-400 m
Water level
Water level:
-600 m
Water level
Water level:
-1000 m
Effects of water level changes
• Decrease in lake size
• Splitting in proto lakes
• Merging of sub-populations after water level rise
Summary of possible causes
• Age
• Water level
• Bathymetry
Research Questions
• What external factors determine the differences in biodiversity between the African Rift Lakes?
• How does biogeography influence biodiversity?
Approach
• Standard neutral model– Influence of environment size
– Spatiality
– Environmental change
– Cyclic environment change
– Splitting and merging of communities
– Repeated splitting and merging
ApproachTailored model
• Check predictions with a tailored version– Correct size of lakes
– Include explicit bathymetry
– Remodel water level changes
The end
• Questions?• Suggestions?
Conformism
Local variability
Picture courtesy Jen Reynolds
Picture courtesy Jen Reynolds
Other stuff to do
• Time-scale difference between speciation and environmental change
• Interaction between tectonic drift and biodiversity
Recommended