Measuring starvation resistance in the field?

1
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

2
Habitat changes

• Vegetation change
• Microclimatic changes
• Higher day temperatures
• Dryer overall
• What is the effect on starvation resistance?

3
What do we know?

• Not much on a local scale, but.

• .. lots about large scale clines

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Variation in life history traits over large clines
Latitude (ºN)
Parkash, R., and A. K. Munjal. 1999. Journal of
Zoological systematics and evolutionary research
37195-202.
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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

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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?

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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)

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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

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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

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First field experiment
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Robustness

• Jack-knifing shows that none of the species has a
  overly large effect on the overall outcome

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Species
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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

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Second field experiment
Univariate Tests of Significance for
STAR_RES Sigma-restricted parameterization Effecti
ve 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 TRANSECTOR 3.4590
2 1.729 8.493 .000210 TRANSECTEX
1.1549 2 .577 2.835 .058835 OREX
8.6395 4 2.159 10.607 .000000 TRANSECTOR
EX 7.3454 4 1.836 9.018
.000000 Error 593.5638 2915
0.203
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Second field experiment
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Robustness
Univariate Tests of Significance for
STAR_RES Sigma-restricted parameterization Effecti
ve 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 TRANSECTOR 3.4590
2 1.729 8.493 .000210 TRANSECTEX
1.1549 2 .577 2.835 .058835 OREX
8.6395 4 2.159 10.607 .000000 TRANSECTOR
EX 7.3454 4 1.836 9.018
.000000 Error 593.5638 2915
0.203
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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

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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