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Third Exam Thursday 13 May 2016
Chapters 11-15, 17-18 plus 8 readings
Energy
Money
Land
Food
Water
Sewage
Solutions
Space Travel
25th Lecture
19 April 2016
Final Exam --- 13 May 2016, 9-12 am
Janzen’s Seedling Ring Model
Dan Janzen
Pine squirrels (Tamiasciurus) and
coniferous food trees (Smith 1970)
Squirrels are very effective seed predators, stockpile cones Chris Smith
Trees reduce squirrel effectiveness in many different ways:
1. Cones difficult for squirrels to reach, open, or carry
2. Putting fewer seeds in each cone (fake cones without any seeds)
3. Increasing thickness of seed coats (seeds harder to harvest)
4. Putting less energy into each seed (smaller seeds)
5. Shedding seeds from cones early, before young squirrels forage
6. Periodic cone crop failures decimate squirrel populations
Individual trees out of synchrony would set fewer seeds and thus
be selected against.
Coevolution
Joint evolution of two (or more) taxa that have close
ecological relationships but do not exchange genes, and
in which reciprocal selective pressures operate to make
the evolution of either taxon partially dependent on the
evolution of the other.
Enterobius Pinworms and Primate Hosts Parallel Phylogenies
Some of the Suggested Correlates of Plant Apparency
_____________________________________________________________________________
Apparent Plants
Unapparent Plants
_____________________________________________________________________________
Common or conspicuous
Rare or ephemeral
Woody perennials
Herbaceous annuals
Long leaf life span
Short-lived leaves
Paul Feeny
Slow growing, competitive species
Faster growing, often fugitive species
Late stages of succession, climax
Early stages of succession, second growth
Bound to be found by herbivores
(cannot escape in time and space)
Protected from herbivores by escape in
time and space (but still encountered by
wide-ranging generalized herbivores)
Produce more expensive quantitative
(broad-based) antiherbivore defenses
(tough leaves, thorns, tannins)
Produce inexpensive qualitative chemical
defenses (poisons or toxins) to discourage
generalized herbivores
Quantitative defenses constitute
Qualitative defenses may be broken down
effective ecological barriers to herover evolutionary time by coevolution of
bivores, although perhaps only a weak
appropriate detoxification mechanisms in
evolutionary barrier unless suppleherbivores (host plant-specific herbivore
mented with qualitative defenses
species result)
_____________________________________________________________________________
Community and Ecosystem Ecology
Macrodescriptors = Aggregate Variables
Trophic structure, food webs, connectance,
rates of energy fixation and flow, ecological efficiency,
species diversity, stability, relative importance curves,
guild structure, successional stages
Bottom Line. Communities are not designed by natural selection
for smooth and efficient function, but are composed of many
gonists
(we need to attempt to understand them in terms of interactions
between individual organisms)
Energy Flow and Ecological Energetics
Gross Productivity = rate at which plants capture solar energy
Gross annual production (GAP)
Net productivity = gross productivity minus respiration losses
Net annual production (NAP)
Respiration in tropical rainforest 75-80% of GAP
Respiration in temperate forests 50-75% of GAP
In most other communities, it is 25-50 % of GAP
Only about 5-10% of plant food is harvested by animals
Remainder of NAP is consumed by decomposers
Biogeochemical cycles
Biogeochemical Cycle for Calcium
Hydrologic Cycle
Aldo Leopold, A Sand County Almanac X
Compartmentation
Trophic Levels
Autotrophs = producers
Heterotrophs = consumers & decomposers
Primary carnivores = secondary consumers
Secondary carnivores = tertiary consumers
Trophic continuum
Horizontal versus vertical interactions
Within and between trophic levels
Guild Structure
Foliage gleaning insectivorous birds
Food Webs
Subwebs, sink vs. source food webs
Connectance [n (n-1)] / 2
Energy Flow and Ecological Energetics
Energy Flow and Ecological Energetics
Energy Flow and Ecological Energetics
At equilibrium (dLi/dt = 0 for all i), energy flow in the system
portrayed in the figure may thus be represented by a set of
simple equations (with inputs on the left and rate of outflow to
the right of the equal signs):
l10 = l01 + l02 + l03 + l04
l10 = l21 + l01 + l41
l21 = l32 + l02 + l42
l32 = l03 + l43
l41 + l42 + l43 = l04
Systems Ecology
Food Web
Paine (1966)
Food Web
Bottom Line
Kirk Winemiller
Ecological Pyramids (numbers, biomass, and energy)
Pyramid of energy
Measures of standing crop versus rates of flow
Secondary Succession
Institute Woods in Princeton
Transition Matrix for Institute Woods in Princeton
Henry Horn
_________________________________________________________________________
Canopy
Sapling Species (%)
Species
BTA GB SF BG SG WO OK HI TU RM BE
Total
__________________________________________________________________________
BT Aspen
3
5
9
6
6
2
4
2
60
3
104
Gray birch 47
12
8
2
8
0
3
17
3
837
Sassafras
3
1
10
3
6
3
10
12
37 15
68
Blackgum 1
1
3
20
9
1
7
6 10
25 17
80
Sweetgum 16
0 31
0
7
7
5
27
7
662
White Oak 6
7
4
10
7
3 14
32 17
71
Red Oak
2
11
7
6
8
8
8
33 17
266
Hickory
1
3
1
3 13
4
9 49 17
223
Tuliptree
2
4
4
11
7
9 29 34
81
Red Maple 13
10
9
2
8 19
3 13 23
489
Beech
2
1
1
1
1
8
6 80
405
__________________________________________________________________________
BTA in next generation = 0.03 BTA + 0.03 SF + 0.01 BG .
Grand Total = 3286
Distributions of Trees Observed in 4 Forests and Predicted Climax
__________________________________________________________________ __________________
Age (years) BTA
GB
SF
BG
SG
WO
OK
HI TU
RM
BE
__________________________________________________________________ __________________
25
65
150
350
Predicted
climax
0
26
-
49
6
-
2
0
0
-
0
0
2
7
45
1
6
3
18
0
5
-
0
0
0
3
3
12
22
-
0
1
0
0
0
4
0
14
20
6
70
1
1
0
2
76
4
2
4
6
6
10
63
__________________________________________________________________ __________________
Data from the
Institute Woods in Princeton (Horn 1975)
Henry Horn
Diversity and Community Stability
Saturation with Individuals and with Species
Species Diversity = Biodiversity
Species Density or Species Richness
Relative Importance
Equitability
Janzen’s Seedling Ring Hypothesis
Tamiasciurus squirrel seed predation
Community and Ecosystem Ecology
Macrodescriptors = Aggregate Variables
Compartment models, trophic structure, food webs,
connectance, rates of energy fixation and flow,
biogeochemical cycles, ecological energetics,
ecological efficiency, trophic continuum, guild structure,
ecological pyramids, successional stages, transition
atrix,
species diversity, stability, relative importance curves.
Diversity and Community Stability
Saturation with Individuals and with Species
Species Diversity = Biodiversity
Species Density or Species Richness
Relative Abundance/Importance
Equitability
Species Diversity, Relative Abundance
Species
A
B
C
D
E
F
G
H
I
J
Site A
10
10
10
10
10
10
10
10
10
10
Site B
91
1
1
1
1
1
1
1
1
1
Ways two systems can differ in diversity
Relative Abundance / Importance
All 10 Sites: Total Number of lizards: 20,990
Total numbers of lizards of 67 species
collected on 10 desert study sites from
1966-2008 plotted against their ranks in
relative abundance. The 12 most common
species (blue) are named, along with 7 of
the 54 less common to rare species (red).
Samples exceed 30 for 48 of the 67 species.
Discriminant function analysis showing clear separation of rare species
based on 10 ecological variables including body size, clutch size, niche
breadths and overlaps for diet, microhabitat, and habitat.
Robert H. MacArthur
Geographical Ecology
1. Degree of Saturation
2. Range of Available Resources
3. Average Niche Breadth
4. Average Niche Overlap
Species Diversity = “Biodiversity”
Regional <—> Local <—> Point diversity
Saturation with species
Four ways in which diversity can differ
1. Range of available resources
2. Degree of saturation
3. Niche breadth
4. Degree of niche overlap
I was a mere graduate student, wet behind the ears, only 25
years old, when I wrote it. I don’t usually re-read my own
papers – but now, 5 decades later, I am pleased to find it
cerebral and fairly well written.
Latitudinal gradients in diversity
Time theories, degree of saturation with species
Climatic stability and climatic predictability, niche breadth
Spatial heterogeneity, range of available resources
Productivity and stability of productivity
Competition —> specialization, narrow niches, higher diversity
Disturbance, intermediate disturbance hypothesis, niche overlap
Predation-induced diversity (Paine’s Pisaster experiment)
Productivity Hypothesis
Intermediate Disturbance Hypothesis