Dynamic landscapes driving diversity

T. Janzen, R.S. Etienne Community and Conservation Ecology Group

University of Groningen

Picture courtesy Jen Reynolds

Dynamic landscapes & diversity

• Diversity mainly driven by speciation– Sympatric speciation– Allopatric speciation

• Slow changes in landscape– Mountain ridges– Formation of lakes– Drifting of continents

Dynamic landscapes

• Fast (repetitive) changes in landscape:– Glaciation– Islands and changing sea levels– Fluctuating lake levels– On a different spatio-temporal scale:

• Predators• Dispersal and expansion

• Alternating periods of allopatry and sympatry

Aguilée et al. 2010

Aguilée et al. 2010

Aguilée et al 2010

Focal system

Lake Tanganyika

Million years ago

Wat

er e

lvel

bel

ow p

rese

nt

Eretmodini

Ruber et al. 1999 PNAS

Summary and aims

• Changes in landscapes can be relatively fast

• Lake Tanganyika has experienced dramatic changes in water level

• Have these changes in waterlevel driven the current diversity in cichlids?

The model

| 10

Lineages-through-time plots (LTT)

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10

100

-20 -15 -10 -5 0

time (My)

# lin

eag

es

Slide by R. S. Etienne

Lamprologini

Sturmbauer et al. 2010

Typical run

-7 -6 -5 -4 -3 -2 -1 0

0.0

0.5

1.0

1.5

2.0

MY ago

log

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Simulation

Empirical data

Water level

Stochasticity

-7 -6 -5 -4 -3 -2 -1 0

0.0

0.5

1.0

1.5

2.0

2.5

MY ago

log

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Extinction rate Speciation rate Rate of water level fluctuation

Found estimates

Model Empirical

Speciation events / MY0.87±0.25 0.7-1.1

Extinction events / MY5.00E-06 NA

Average time to Water level change

100ky±30k 61ky±13k

Spec rate: Coyne & Orr 2004Waterlevel: Lezzar 1996, Cohen 1997, Scholz 2003

Conclusion & Perspectives

• Dynamic landscapes are important in shaping diversity

• Estimates of this model are well in line with empirical estimates

• Fit this model to similar systems

Thanks to:

• Rampal Etienne• Lucas Molleman• Hanno Hildenbrandt• Stephan Koblmüller

Picture courtesy T. Janzen