Ground Rules, exams, etc. (no

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Exploitation vs. interference competition Lotka-Vo
lterra Competition equations Assumptions linear
response to crowding both within and between
species, no lag in response to change in
density, r, K, a constant Competition
coefficients aij, i is species affected and j is
the species having the effect Solving
for zero isoclines, resultant vector
analyses Point attractors, saddle points, stable
and unstable equilibria Four cases, depending on
K/as compared to Ks Sp. 1 wins, sp. 2 wins,
either/or, or coexistence Gauses and Parks
competition experiments Mutualism equations,
conditions for stability Intraspecific self
damping must be stronger than interspecific
positive mutualistic effects.
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The ecological niche, function of a species in
the community Resource utilization functions
(RUFs) Competitive communities in equilibrium
with their resources Hutchinsons n-dimensional
hypervolume concept Euclidean distances in n-
space (Greek mathematician, 300 BC) Fundamental
versus Realized Niches
3
Resource matrices of utilization
coefficients Niche dynamics Niche
dimensionality and diffuse competition Complement
arity of niche dimensions Niche Breadth
Specialization versus generalization. Similar
resources favor specialists, different resources
favor generalists Periodic table of lizard
niches (many dimensions) Thermoregulatory axis
thermoconformers gt thermoregulators
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Experimental Ecology Controls Manipulation
Replicates Pseudoreplication Rocky Intertidal
Space Limited System Paines Pisaster removal
experiment Connell Balanus and
Chthamalus Menges Leptasterias and Pisaster
experiment Dunhams Big Bend saxicolous
lizards Browns Seed Predation
experiments Simberloff-Wilsons defaunation
experiment
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R. T. Paine (1966)
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Joseph Connell (1961)
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Bruce Menge (1972)
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Menge 1972
Bruce Menge
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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
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James Brown
Pogonomyrmex harvester ants
Dipodomys kangaroo rats
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Experimental Design of Seed Predation in the
Chihuahuan Desert________________________________
___________________

Plots Treatments__________
_________________________________________


11,14 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 pulse5,24 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 ants10,23 All seed-eating rodents
plus all seed-eating ants________________________
___________________________________Munger, J.
C. and J. H. Brown. 1981. Competition in desert
rodents an experiment with semipermeable
enclosures. Science 211 510-512.
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open circles rodents removed solid circles
controls
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Defaunation Experiments in the Florida
Keys Islands of mangrove trees were surveyed
and numbers of arthropod species
recorded Islands then covered in plastic
tents and fumigated with methyl bromide Islands
then resurveyed at intervals to document
recolonization
Simberloff and Wilson 1970
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Simberloff and Wilson 1970
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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__________________________
__________________________________________________
___________

E1 9 (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)ST2 7 (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)E9 12 (7) 1 (0) 1 (1) 2 (2) 6 (5) 13
(10) 2 (3) 0 (1) 37 (29)Totals 55 (55) 7 (5)
13 (8) 8 (6) 32 (23) 36 (31)
12 (9) 1 (3) 164 (140)
__________________________________________________
_____________________________________H
herbivoreS scavengerD detritus feederW
wood borerA antC carnivorous predator?
undetermined
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Wilson 1969
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Predation and Parasitism
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Predator-Prey Experiments
Georgii F. Gause
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Predator-Prey Experiments
Georgii F. Gause
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Predator-Prey Experiments
Georgii F. Gause
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Lotka-Volterra Predation
Equations coefficients of
predation, p1 and p2 dN1 /dt r1 N1
p1 N1 N2 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 J. Lotka
Vito Volterra
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Vectors spiral in closed loops
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Neutral Stability (Vectors spiral in closed loops)
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Vectors spiral inwards (Damped
Oscillations)
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Damped Oscillations
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Functional response rate at which Individual
predators capture and eat more prey per unit
time as prey density increases
C. S. Holling
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Numerical response increased prey density
raises the predatorspopulation size and a
greater number of predators consume An
increased number of prey