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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)
1
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
(# li
ne
ag
es)
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
(# li
ne
ag
es)
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