Paradox of the Cichlids outline of my PhD project Thijs Janzen Supervisor: 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) – 59 – 12 # Species~700 ~250 Area (km 2 ) Depth83 m706 m1 471 m

Lake VictoriaLake TanganyikaLake 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

TanganyikaMalawi Talling 1969, Scholz et al Victoria

Water level Water level: 0 m

Water level Water level: -100 m

Water level Water level: -250 m

Water level -300 m Water level: -300 m

Water level Water level: -400 m

Water level Water level: -600 m

Water level Water level: 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

Approach Tailored 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

Other stuff to do Time-scale difference between speciation and environmental change Interaction between tectonic drift and biodiversity