I. Competition

1
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue
   
 
2
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue 1. Ideally, we want to
harvest from a po without decreasing its
size This is the "Maximum Sustainable Yield" and
it equals the new organisms that will be added to
a population in a given interval.
   
 
3
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue 1. Ideally, we want to
harvest from a po without decreasing its
size This is the "Maximum Sustainable Yield" and
it equals the new organisms that will be added to
a population in a given interval. 2. MSY
rN
   
 
4
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue 1. Ideally, we want to
harvest from a po without decreasing its
size This is the "Maximum Sustainable Yield" and
it equals the new organisms that will be added to
a population in a given interval. 2. MSY
rN 3. Suppose the Maximal Sustainable Yield is
1000 fish from a population of 10,000 (N
10,000, r 0.1, so rN 1000). But, suppose 1500
are taken. Now, the population is only 9500 (a
catch of 1000 would have left the population
intact at 10,000, but an extra 500 were taken
from the population). Now, the MSY 950. Folks
work harder to get the 1500 fish they need, and
that depresses the population by 550 to 8950.
Each time the same number of fish are taken from
a progressively smaller population, so the
debilitating effects are more pronounced each
year. Eating the principle, not just the
interest.
   
 
5
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory
Experiments
   
 
6
E. Laboratory Experiments 1. Gauss P.
caudatum (prey) and Didinium nasutum (predator)

   
 
7
E. Laboratory Experiments 1. Gauss P.
caudatum (prey) and Didinium nasutum (predator)
In initial experiments, Paramecium populations
would increase, followed by a pulse of Didinium,
and then they would crash.
   
 
8
E. Laboratory Experiments 1. Gauss P.
caudatum (prey) and Didinium nasutum (predator)
In initial experiments, Paramecium populations
would increase, followed by a pulse of Didinium,
and then they would crash. He added oats to
the bottom, creating a REFUGE that the predator
did not enter.
   
 
9
E. Laboratory Experiments 1. Gauss He
induced oscillations by adding Paramecium as
'immigrants'
   
 
10
E. Laboratory Experiments 1. Gauss 2. Huffaker
six-spotted mite (Eotetranychus sexmaculatus)
was prey - SSM Predatory mite (Typhlodromus
occidentalis) was predator - PM
   
 
11
E. Laboratory Experiments 1. Gauss 2. Huffaker
six-spotted mite (Eotetranychus sexmaculatus)
was prey - SSM Predatory mite (Typhlodromus
occidentalis) was predator - PM The six spot
feeds on citrus fruits, so Huffaker created tray
with 40 depressions that could each receive an
orange. He covered all but the top of the orange
with wax, so there was only a small area of
available resource. He then distributed oranges
and rubber balls throughout the grid, and could
create 'walls' between the stations with
petroleum jelly.
   
 
12
E. Laboratory Experiments 1. Gauss 2. Huffaker
six-spotted mite (Eotetranychus sexmaculatus)
was prey - SSM Predatory mite (Typhlodromus
occidentalis) was predator - PM The six spot
feeds on citrus fruits, so Huffaker created tray
with 40 depressions that could each receive an
orange. He covered all but the top of the orange
with wax, so there was only a small area of
available resource. He then distributed oranges
and rubber balls throughout the grid, and could
create 'walls' between the stations with
petroleum jelly. The prey "balloons" on
silk The predator has to walk from orange to
orange
   
 
13
E. Laboratory Experiments 1. Gauss 2. Huffaker
six-spotted mite (Eotetranychus sexmaculatus)
was prey - SSM Predatory mite (Typhlodromus
occidentalis) was predator - PM The six spot
feeds on citrus fruits, so Huffaker created tray
with 40 depressions that could each receive an
orange. Then, he covered all but the top of the
orange with wax, so there was only a small area
of available resource. He then distributed
oranges and rubber balls throughout the grid, and
could create 'walls' between the stations with
petroleum jelly. Found that 1. Increase of
oranges, increase of oscillations and
coexistence 2. Increase dispersion, increase
coexistence 3. Increase barriers (bigger effect
on PM), increase coexistence
   
 
14
Found that 1. Increase of oranges, increase
of oscillations and coexistence 2. Increase
dispersion, increase coexistence 3. Increase
barriers (bigger effect on PM), increase
coexistence
   
 
15
E. Laboratory Experiments 1. Gauss 2. Huffaker
3. Holyoak and Lawler-1996
   
 
16
E. Laboratory Experiments 1. Gauss 2. Huffaker
3. Holyoak and Lawler-1996 Used a bacteriovore
ciliate, Colpidium striatum as the prey and our
old friend Didinium nasutum as the predator.

   
 
17
E. Laboratory Experiments 1. Gauss 2. Huffaker
3. Holyoak and Lawler-1996 Used a bacteriovore
ciliate, Colpidium striatum as the prey and our
old friend Didinium nasutum as the predator. Set
up replicate 30mL bottles, linked together by
tubes, and single flask systems.
   
 
18
Found that Subdivided systems persisted 2X as
long as single systems.
   
 
19
Found that Subdivided systems persisted 2X as
long as single systems. Persistence was due to
metapopulation dynamics the populations in the
bottles were all out of phase with each other,
suggesting that migration rates were low. But,
migration was high enough for prey to repopulate
flasks where extinction had occurred.
   
 
20
Found that Subdivided systems persisted 2X as
long as single systems. Persistence was due to
metapopulation dynamics the populations in the
bottles were all out of phase with each other,
suggesting that migration rates were low. But,
migration was high enough for prey to repopulate
flasks where extinction had occurred. Indeed,
dispersal was more rapid from sites containing
predators than from sites without. A key
difference is that there is no permanent refuge
the prey just stays ahead by recolonizing at a
fester rate. Preds don't disperse if prey are
present.
   
 
21
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments
   
 
22
F. Natural Experiments A. Kelp and Urchins
In 1940's
   
 
23
F. Natural Experiments A. Kelp and Urchins
In 1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly.
   
 
24
F. Natural Experiments A. Kelp and Urchins
In 1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly. It turns out that urchins, which are
the major predators of kelp, can also feed on
suspended particulates (sewage). So, the sewage
provided an alternative food resource, raising
the K for the urchins, whcih them exerted a
greater predation pressure on kelp.
   
 
25
F. Natural Experiments A. Kelp and Urchins
In 1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly. It turns out that urchins, which are
the major predators of kelp, can also feed on
suspended particulates (sewage). So, the sewage
provided an alternative food resource, raising
the K for the urchins, whcih them exerted a
greater predation pressure on kelp. Urchins could
stay abundant even while kelp continued to
decline.
   
 
26
F. Natural Experiments A. Kelp and Urchins
In 1940's B. Moose and Wolves - Isle
Royale
   
 
27
F. Natural Experiments A. Kelp and Urchins
In 1940's B. Moose and Wolves - Isle
Royale 1930's - Moose population about 2400 on
Isle Royale
   
 
28
F. Natural Experiments A. Kelp and Urchins
In 1940's B. Moose and Wolves - Isle
Royale 1930's - Moose population about 2400 on
Isle Royale 1949 - Wolves cross on an ice bridge
studied since 1958
   
 
29
F. Natural Experiments A. Kelp and Urchins
In 1940's B. Moose and Wolves - Isle
Royale 1930's - Moose population about 2400 on
Isle Royale 1949 - Wolves cross on an ice bridge
studied since 1958
   
 
30
F. Natural Experiments A. Kelp and Urchins
In 1940's B. Moose and Wolves - Isle
Royale 1930's - Moose population about 2400 on
Isle Royale 1949 - Wolves cross on an ice bridge
studied since 1958
   
 
Predator populations affected by moose, but also
by parasites (viral die-off in 1980), and
climate. Warming seems to have reduced predator
success rates.
31
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary of
Effects
   
 
32
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence
   
 
33
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence 1. Prey refugia

   
 
34
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence 1. Prey refugia 2.
Specialist predators (that can't switch to
alternate prey when primary prey decline)

   
 
35
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence 1. Prey refugia 2.
Specialist predators (that can't switch to
alternate prey when primary prey decline) 3.
Prey with greater r than predators
   
 
36
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence 1. Prey refugia 2.
Specialist predators (that can't switch to
alternate prey when primary prey decline) 3.
Prey with greater r than predators 4.
Subdivided habitats and greater prey dispersal

   
 
37
I. Competition II. Predation A. Lotka-Volterra
Models B. Major Criticisms and Modified
Models C. Multiple State States D. The
Optimal Yield Issue E. Laboratory Experiments
F. Natural Experiments G. Summary
Mechanisms of Coexistence 1. Prey refugia 2.
Specialist predators (that can't switch to
alternate prey when primary prey decline) 3.
Prey with greater r than predators 4.
Subdivided habitats and greater prey dispersal
5. Metapopulation dynamics semi-isolated
systems fluctuate independently, with
migration retarding population decline or
repopulating after local extinctions