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Measuring starvation resistance in the field?. Kim van der Linde Supervisors: Jan Sevenster, Bas Zwaan, Paul Brakefield Institute for Evolutionary and Ecological Sciences Leiden University The Netherlands. Habitat changes. Vegetation change Microclimatic changes Higher day temperatures
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Measuring starvation resistance in the field? Kim van der Linde Supervisors: Jan Sevenster, Bas Zwaan, Paul Brakefield Institute for Evolutionary and Ecological Sciences Leiden University The Netherlands
Habitat changes • Vegetation change • Microclimatic changes • Higher day temperatures • Dryer overall • What is the effect on starvation resistance?
What do we know? • ….. lots about large scale clines • Not much on a local scale, but….
Variation in life history traits over large clines Latitude (ºN) • Parkash, R., and A. K. Munjal. 1999. Journal of Zoological systematics and evolutionary research 37:195-202.
Complications long clines • Large distances, so: • large changes in macro-climate • large changes in vegetation • related microclimatic variation? • differences in genetic background • No conclusive patterns • Common environment experiments
Aim • What is the variation in starvation resistance between species and habitats under natural circumstances? • And what is the role of the genetic variation? • Are there GxE interactions?
Where? • Panama Canal • Two transects • Each transect with three habitats: • Forest • Intermediate • Grassland • Distance between habitats (1-2 km) within a transect smaller then distance between transects (10 km)
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
Experiments • Field experiment 1: Expression of life-history traits in the original habitat: • 12 species, 5941 individuals • Field experiment 2: Transplantation experiment. • 4 species, 5629 individuals
Robustness • Jack-knifing shows that none of the species has a overly large effect on the overall outcome
Conclusions first field experiment • Habitat and location effect on starvation resistance • Habitat and transect effect on body size • Large differences between species, but overall very consistent result
Second field experiment Univariate Tests of Significance for STAR_RES Sigma-restricted parameterization Effective hypothesis decomposition Degr. of SS Freedom MS F p Intercept .0673 1 .067 .330 .565475 TRANSECT 1.3706 1 1.370 6.730 .009523 OR .8766 2 .438 2.152 .116390 EX 26.9426 2 13.471 66.157 0.000000 TRANSECT*OR 3.4590 2 1.729 8.493 .000210 TRANSECT*EX 1.1549 2 .577 2.835 .058835 OR*EX 8.6395 4 2.159 10.607 .000000 TRANSECT*OR*EX 7.3454 4 1.836 9.018 .000000 Error 593.5638 2915 0.203
Robustness Univariate Tests of Significance for STAR_RES Sigma-restricted parameterization Effective hypothesis decomposition Degr. of SS Freedom MS F p Intercept .0673 1 .067 .330 .565475 TRANSECT 1.3706 1 1.370 6.730 .009523 OR .8766 2 .438 2.152 .116390 EX 26.9426 2 13.471 66.157 0.000000 TRANSECT*OR 3.4590 2 1.729 8.493 .000210 TRANSECT*EX 1.1549 2 .577 2.835 .058835 OR*EX 8.6395 4 2.159 10.607 .000000 TRANSECT*OR*EX 7.3454 4 1.836 9.018 .000000 Error 593.5638 2915 0.203
Conclusions second field experiment • Experimental habitat effect indicates strong environmental impact • Transect effect could indicate large scale differences • Original by experimental location effect indicates GxE interaction for 4 species at population level
Preliminary conclusions • Starvation resistances can be measured in the field • Species show consistent results • The GxE interaction factor indicates genetic differentiation between collection locations • Extrapolating the results from one common environment to general conclusions is tricky