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  1. 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.

  2. Deforestation The beginning…... …. and the end

  3. 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 • ...

  4. 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?

  5. 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

  6. Which model system? • Panamanian Drosophila • Ecologically well studied: Sevenster (1987-1992), Krijger (1996-2000) • Many species:30+ 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

  7. 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

  8. 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

  9. Starvationresistance

  10. Field experiment 1: original environment Overall variation

  11. 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:

  12. Stocks Transect 1 Transect 2 Grass- land Forest Inter- mediate Forest Inter- mediate Grass- land Experiment Transect 1 Transect 2 Grass- land Forest Inter- mediate Forest Inter- mediate Grass- land Field experiment 2: transplantation

  13. 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 <0.001 Transect*OR 3.4590 2 1.729 8.493 <0.001 Transect*EX 1.1549 2 .577 2.835 0.06 OR*EX 8.6395 4 2.159 10.607 <0.001 Transect*OR*EX 7.3454 4 1.836 9.018 <0.001 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 <0.001 Transect*OR 3.4590 2 1.729 8.493 <0.001 Transect*EX 1.1549 2 .577 2.835 0.06 OR*EX 8.6395 4 2.159 10.607 <0.001 Transect*OR*EX 7.3454 4 1.836 9.018 <0.001 Error 593.5638 2915 0.203

  14. Field experiment 2: transplantation Original versus experimental habitat

  15. Field experiment 2: transplantation Subdivision into components

  16. 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:

  17. Common environment experiment Overall variation

  18. 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

  19. Comparison with other traits

  20. 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

  21. 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