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Third Exam Thursday 3 December 2015Chapters 11-15, 17-18 plus 8 readings

Final Exam -- 9 December -- 2-5 PM

25th Lecture19 November 2015

Dan Janzen

Janzen’s Seedling Ring Model

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 carry2. 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 forage6. Periodic cone crop failures decimate squirrel populations

Individual trees out of synchrony would set fewer seeds and thusbe 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 ephemeralWoody perennials Herbaceous annualsLong leaf life span Short-lived leavesSlow growing, competitive species Faster growing, often fugitive speciesLate stages of succession, climax Early stages of succession, second growth

Bound to be found by herbivores Protected from herbivores by escape in (cannot escape in time and space) time and space (but still encountered by

wide-ranging generalized herbivores)

Produce more expensive quantitative Produce inexpensive qualitative chemical(broad-based) antiherbivore defenses defenses (poisons or toxins) to discourage(tough leaves, thorns, tannins) generalized herbivores

Quantitative defenses constitute Qualitative defenses may be broken downeffective ecological barriers to her- over evolutionary time by coevolution ofbivores, although perhaps only a weak appropriate detoxification mechanisms inevolutionary barrier unless supple- herbivores (host plant-specific herbivoremented with qualitative defenses species result)_____________________________________________________________________________

Paul Feeny

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

antagonists

(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

Hydrologic Cycle

Biogeochemical Cycle for Calcium

Aldo Leopold, A Sand County Almanac X

CompartmentationTrophic Levels

Autotrophs = producers

Heterotrophs = consumers & decomposersPrimary carnivores = secondary consumersSecondary carnivores = tertiary consumersTrophic continuumHorizontal versus vertical interactionsWithin and between trophic levels

Guild StructureFoliage gleaning insectivorous birds

Food WebsSubwebs, 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 (di/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):

10 = 01 + 02 + 03 + 04

10 = 21 + 01 + 41

21 = 32 + 02 + 42

32 = 03 + 43

41 + 42 + 43 = 04

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

_________________________________________________________________________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 104Gray birch - - 47 12 8 2 8 0 3 17 3 837Sassafras 3 1 10 3 6 3 10 12 - 37 15 68Blackgum 1 1 3 20 9 1 7 6 10 25 17 80Sweetgum - - 16 0 31 0 7 7 5 27 7 662White Oak - - 6 7 4 10 7 3 14 32 17 71Red Oak - - 2 11 7 6 8 8 8 33 17 266Hickory - - 1 3 1 3 13 4 9 49 17 223Tuliptree - - 2 4 4 - 11 7 9 29 34 81Red Maple - - 13 10 9 2 8 19 3 13 23 489Beech - - - 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

Henry Horn

Distributions of Trees Observed in 4 Forests and Predicted Climax__________________________________________________________________ __________________ Age (years) BTA GB SF BG SG WO OK HI TU RM BE __________________________________________________________________ __________________

25 0 49 2 7 18 0 3 0 0 20 1 65 26 6 0 45 0 0 12 1 4 6 0 150 - - 0 1 5 0 22 0 0 70 2 350 - - - 6 - 3 - 0 14 1 76

Predicted climax 0 0 2 3 4 2 4 6 6 10 63__________________________________________________________________ __________________

Data from theInstitute 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

matrix,

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 Site A Site B A 10 91 B 10 1 C 10 1 D 10 1 E 10 1 F 10 1 G 10 1 H 10 1 I 10 1 J 10 1

Relative Abundance / Importance

Ways two systems can differ in diversity

All 10 Sites: Total Number of lizards: 20,990

Total numbers of lizards of 67 species collected on 10 desert study sites from1966-2008 plotted against their ranks inrelative 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