Genetic differences on a local scale

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Genetic differences on a local scale
Kim van der Linde

• Testing Drosophila life-history in the field

Paul M. Brakefield Jan G. Sevenster Jacques J.M.
van Alphen Bas J. Zwaan
Leiden University, Institute for
Biology, Sections Animal Ecology Evolutionary
Biology, The Netherlands.
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Deforestation
The beginning...
. and the end
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Habitat change local effects

• Abiotic microclimatic changes
• Higher day temperatures
• Dryer
• Higher light intensity at the forest floor
• ...
• Biotic
• Vegetation composition and structure
• Resource abundance
• Species composition
• ...

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Research questions

• Does variation between habitats over short
  distances result in local adaptation in the
  resident populations?
• And if so, what is the relative importance of
• Genetic differences?
• Environmental variation?
• GxE interactions?

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Where?

• Panama canal zone
• Easy access
• Established situation
• Two transects with each three habitats
• Forest
• Intermediate
• Grassland

• Distance between habitats within a transect 1-2
  km
• Distance between transects 10 km

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Which model system?

• Panamanian Drosophila
• Ecologically well studied Sevenster (1987-1992),
  Krijger (1996-2000)
• Many species30 within Panama canal zone, 12
  used in this experiment
• Elimination of lucky choice
• Robustness of effect
• Short generation time 8-15 days
• Easy to collect and culture
• Three ecological relevant life-history traits
• Body size
• Development time
• Starvation resistance

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Field set-up

• Large roofed cages to work in
• Small cages with fine netting for development
  times
• Petridishes with agar and covered with fine
  netting for starvation resistance
• Dead flies for body size

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Experiments

• Collection of flies
• Maintained in open air laboratory for several
  generations
• Field experiment 1 expression of life-history
  traits in the original collection habitat
• 12 species, 5941 individuals
• Field experiment 2 transplantation experiment
• 4 species, 5629 individuals
• Common environment experiment expression of
  life-history traits in the laboratory environment
• 12 species, 15802 individuals

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Starvationresistance
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Overall variation
Field experiment 1 original environment
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Conclusions

• First field experiment (original environment)
• Habitat and location effect on starvation
  resistance
• Forest populations do better then grassland
  populations
• Second field experiment (transplantation
  experiment)
• Common environment experiment

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Field experiment 2 transplantation
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Field experiment 2 transplantation
Degree of SS Freedom
MS F p Intercept .0673 1 .067
.330 0.56 Transect 1.3706 1 1.370 6.730
0.01 Origin (OR) .8766 2 .438 2.152
0.12 Experimental (EX) 26.9426 2 13.471 66.157 lt0.
001 TransectOR 3.4590 2 1.729 8.493
lt0.001 TransectEX 1.1549 2 .577 2.835
0.06 OREX 8.6395 4 2.159 10.607
lt0.001 TransectOREX 7.3454 4 1.836 9.018
lt0.001 Error 593.5638 2915 0.203
Degree of SS Freedom
MS F p Intercept .0673 1 .067
.330 0.56 Transect 1.3706 1 1.370 6.730
0.01 Origin (OR) .8766 2 .438 2.152
0.12 Experimental (EX) 26.9426 2 13.471 66.157 lt0.
001 TransectOR 3.4590 2 1.729 8.493
lt0.001 TransectEX 1.1549 2 .577 2.835
0.06 OREX 8.6395 4 2.159 10.607
lt0.001 TransectOREX 7.3454 4 1.836 9.018
lt0.001 Error 593.5638 2915 0.203
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Original versus experimental habitat
Field experiment 2 transplantation
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Subdivision into components
Field experiment 2 transplantation
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Summary of conclusions

• First field experiment (original environment)
• Habitat and location effect on starvation
  resistance
• Forest populations do better then grassland
  populations
• Second field experiment (transplantation)
• Strong environmental impact
• Original by experimental location effect
  indicates gxe interaction for 4 species at
  population level
• Common environment experiment

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Overall variation
Common environment experiment
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Summary of conclusions

• First field experiment (original environment)
• Habitat and location effect on starvation
  resistance
• Forest populations do better then grassland
  populations
• Second field experiment (transplantation)
• Strong environmental impact
• Original by experimental location effect
  indicates GxE interaction for 4 species at
  population level
• Common environment experiment
• Habitat and location related genetic differences
• Grassland population are better adapted to stress

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Comparison with other traits
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Final conclusions

• Local adaptation does take place
• The results are robust and are duplicated between
  species
• Extensive GxE interaction present in all three
  traits
• Extrapolating the results from one common
  environment to general conclusions about the
  field is tricky

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Questions?

• van der linde, K. 2003. Testing Drosophila
  life-history theory in the field local
  adaptation in body size, development time and
  starvation resistance. Ph.D.-Thesis. Leiden
  university, Leiden