1. Experimental Ecology. Controls. Manipulation. Replicates
Experimental Ecology Controls Manipulation Replicates Pseudoreplication Rocky Intertidal Space Limited System Paine’s Pisaster removal experiment Connell: Balanus and Chthamalus Menge’s Leptasterias and Pisaster experiment Dunham’s Big Bend saxicolous lizards Brown’s Seed Predation experiments

2. R. T. Paine
(1966)

3. Joseph Connell
(1961)

4. Bruce Menge
(1972)

5. Menge 1972
Bruce Menge

6. Grapevine Hills, Big Bend National Park
Sceloporus merriami and Urosaurus ornatus
Six rocky outcrops: 2 controls, 2 Sceloporus removal
plots and 2 Urosaurus removal areas.
========================================
4 year study: 2 wet and 2 dry: insect abundances
Monitored density, feeding success, growth rates, body weights, survival, lipid levels
Urosaurus removal did not effect Sceloporus density
No effects during wet years (insect food plentiful)
Insects scarce during dry years: Urosaurus growth and survival
was higher on Sceloporus removal plots
Arthur Dunham

7. James Brown

8. Experimental Design of Seed Predation in the Chihuahuan Desert ___________________________________________________ Plots Treatments ___________________________________________________ ,14 Controls 6,13 Seed addition, large seeds, constant rate 2,22 Seed addition, small seeds, constant rate 9,20 Seed addition, mixed seeds, constant rate 1,18 Seed addition, mixed seeds, temporal pulse 5,24 Rodent removal, Dipodomys spectabilis (largest kangaroo rat) 15,21 Rodent removal, all Dipodomys species (kangaroo rats) 7,16 Rodent removal, all seed-eating rodents 8,12 Pogonomyrmex harvester ants 4,17 All seed-eating ants 3,19 All Dipodomys plus Pogonomyrmex ants 10,23 All seed-eating rodents plus all seed-eating ants ___________________________________________________________ Munger, J. C. and J. H. Brown Competition in desert rodents: an experiment with semipermeable enclosures. Science 211:

9. open circles =
rodents removed
solid circles =
controls

11. Simberloff and Wilson 1970

12. Evidence for Stability of Trophic Structure
Evidence for Stability of Trophic Structure? First number is the number of species before defaunation, second in parentheses is the number after _____________________________________________________________________________ Trophic Classes ____________________________________________________________ Island H S D W A C P ? Total _____________________________________________________________________________ E (7) 1 (0) 3 (2) 0 (0) 3 (0) 2 (1) 2 (1) 0 (0) 20 (11) E2 11 (15) 2 (2) 2 (1) 2 (2) 7 (4) 9 (4) 3 (0) 0 (1) 36 (29) E3 7 (10) 1 (2) 3 (2) 2 (0) 5 (6) 3 (4) 2 (2) 0 (0) 23 (26) ST (6) 1 (1) 2 (1) 1 (0) 6 (5) 5 (4) 2 (1) 1 (0) 25 (18) E7 9 (10) 1 (0) 2 (1) 1 (2) 5 (3) 4 (8) 1 (2) 0 (1) 23 (27) E (7) 1 (0) 1 (1) 2 (2) 6 (5) (10) 2 (3) 0 (1) 37 (29) Totals 55 (55) 7 (5) (8) 8 (6) (23) (31) (9) (3) (140) _____________________________________________________________________________ H = herbivore S = scavenger D = detritus feeder W = wood borer A = ant C = carnivorous predator ? = undetermined

13. Wilson 1969

15. Predation and Parasitism

17. Predator-Prey Experiments
Georgii F. Gause

18. Predator-Prey Experiments
Georgii F. Gause

19. Predator-Prey Experiments
Georgii F. Gause

20. Predation Equations coefficients of predation,
Lotka-Volterra
Predation Equations coefficients of predation,
p1 and p2
dN1 /dt = r1 N1 – p1 N1 N dN2 /dt = p2 N1 N2 – d2 N2
No self damping (no density dependence) dN1 /dt = 0 when r1 = p1 N2 or N2 = r1 / p1 dN2 /dt = 0 when p2 N1 = d2 or N1 = d2 / p2
Alfred Lotka Vito Volterra