Transcript Fundamentals of Ecology

Ch. 50 Learning Objectives
1. Understand the scale of ecology
(populations – biosphere),
2. Understand the importance of
incoming solar radiation and the tilt of
the Earth in determining the distribution
of major terrestrial biomes
3. Understand the basic characteristics of
aquatic biomes.
Ch. 51: Population Ecology
1. Understand the factors influencing…
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the distribution of individuals in populations
the range of a population
The size of a population
2. Understand survivorship curves and the life
history patterns reflected therein
3. Understand r- vs. k- selection
4. Understand the components of the Logistic
Growth curve, and explain the relationship
between individuals and their immediate
environment that drives the logistic growth model.
Population Ecology
The Big Concepts.
But first, what is Population Ecology?
The study of populations in relation to the environment, including
environmental influences on density, distribution, age structure, and
variations in population size.
Density and Dispersion
Can we view Population Ecology as
“Limits to Geographic Distribution”?
What else governs a population’s size?
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According to C. Darwin: for any
species, population sizes will
increase exponetially if all
individuals that are born reproduce
successfully.
Call this biotic potential
The intrisitc rate of increase is
called “r”
Several factors influence r:
age of reproduction, number of
offspring, viability of offspring,
generation time, frequency of
mating, number of
matings/individual
r is always met by K (the carrying
capacity) aka Environmental
Resistance
Population Growth: Exponential Model
r= intrinsic rate of growth
(r = b - m)
aka: rmax > 0
Population Growth: Logistic Model
K-N
K
Narrative account?
Population Growth in Real World:
Populations oscillate around K
Using Life Tables to study Population Dynamics
Adapted from the Life Insurance Business
Life Tables help generate
Survivorship Curves
Life Histories!
Traits that affect an organism’s “schedule” of
reproduction and survival.
• Different strategies…
• Individual strategies are selected for, and those
strategies are reflected in the population
• In general, individuals in populations will exhibit:
• Semelparity: Live fast, (and you only live once!)
• Iteroparity: repeated reproductive events throughout the
course of a lifetime
r-selection vs. K-selection
• r-selection: density independent selection:
– observed in organisms that maximize reproductive
success in uncrowded environments
– maximize rate of increase: occupy a habitat
• K-selection: density-dependent selection.
– Sensitive to population increases, live near K,
maximize competition and resource utilization
near K.
– Larger, territorial organisms
• How does this relate to Survivorship curves?
• How does this relate to reproductive
strategy?
Limits on Population Growth
Density-dependent factors: negative
feedback on large populations
1. Intra_______ c_______ for resources:
2. PP:
3. DWT:
What about density independent
factors?
How are the two related?
Human Population Growth 101
• You guys will graph it.
• Has humanity been at in an exponential growth curve during
our recent history?
• Are we in one now, are are we slowing down?
• The current intrinsic rate of growth r is…
• But the world is “upside down”…
Developed Countries(MDC)
r
TFR
IMR
LE
Developing Countries (LDC)
Age Structure Pyramids:
pictures say 1000s of words
Ch 53: Community Ecology
1. Understand basic of community ecology concepts
– focus on species interactions as a win/win or
win/lose situation
2. concepts like niche, generalist and specialist
3. Understand the more dynamic, and difficult, aspects
of community ecology including Disturbance,
Succession and Island Biogeography.
4. Understand the trophic aspects of community
ecology: food webs, food chains and trophic
structure.
Community Ecology:
The Big Concepts
• Community Interactions
– Competition, Predation, Parasitism, etc.
• Trophic Interactions
– Food Webs, Trophic Levels, Top Down v. Bottom Up (Lakes)
– Functional groups
• Disturbance and Succession!
• Biodiversity, Species Richness and Island Biogeography
– Species Richness v. Relative Abundance
– Equatorial-Polar Decline in Biodiversity
– Comparison of Rates of Immigration and Extinction
• Your job…Find examples of, and write one page paragraphs
about each of the following:
– Keystone Species/Ecosystem Engineers
– Invasive Species
– A documented decline in biodiversity, the root cause of that decline, and the
potential ramifications of that decline.
Ecosystem Ecology
• Primarily focused on Energy flow through,
and material cycling within, ecosystems
(a “bottom-up” approach)
• Broader in scope: organizes trophic levels
into functional groups
– Comparison of primary productivity across
ecosystems
– Analysis of energy flow through different trophic
levels
What is a community, How are they assembled?
• Community is…
• How are communities
assembled?
– Integrative
• Rivet Theory
• “Brick Wall”
– Individualistic
• Redundancy Model
• Niches are filled by
indpendent spp.
• So, what IS an
ecological niche?
An “organismal approach” to Community Ecology:
Interspecific Interactions
Interaction
Competition
(for some resourse)
Predation/
Parasitism
()
Mutualism
(both species benefit)
Commensualism (one species
benefits, one just toleates
Code Effects on Population
Density of both
species
Example
Interspecific Competition
Fundamental Niche
vs.
Realized Niche
What is going on here?
Reductions in Interspecific Competition
• Habitat Partitioning
– Anolis Lizards in Dominican
Republic
• Character Displacement
– Galapogos Finches
– Geospiza
Predation: Lynx and Snowshoe Hare
Predator Avoidance
• Plants
– Physical Adaptations…
-- Chemical Adaptations…
• Animals
– Cryptic Coloration (camo)
– Aposematic Coloration (red)
– Batesian Mimicry,
• (read to the students)
• Coral vs. King Snakes
(snapshot)
– Muellerian Mimicry
Feeding relationships, a Common
Theme in Community Ecology
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Food Webs
Trophic Structure
Trophic Links
Keystone Predators
“Top-Down” vs. “Bottom Up” Community
Structure
• The River Continuum
Simple Food Web
A more complex Food Web
• Webs are
comprised of…
• Food Chains
• Food Chains are
comprised of
Trophic Links
Trophic Structure: Links & Levels
• Producers
• Primary Consumers
• Secondary
Consumers
• Tertiary Consumers
Community Structure Established by
Trophic Interactions
• KEYSTONE SPECIES/
KEYSTONE PREDATORS
• Robert Paine
(U. of Washington)
• Pisaster vs. Mytilus
“Bottom Up” vs. “Top Down”
Trophic Stucture is a bit more
comprehensive than the
Keystone Predator Concept
“Bottom Up” vs. “Top Down”:
Where (some of) the work was performed
“Top Down” Model can Result
in a “Trophic Cascade”
Top Predator
Top Predator
Planktivorous Fish
Planktivorous Fish
Zooplankton
Zooplankton
Phytoplankton ----- Macrophytes
Phytoplankton ----- Macrophytes
Opposing Views, but both have
real world applications
Stream Communities:
“The River Continuum”
A “Bottom-Up” Model
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Disturbance: The only thing constant is change
Disturbance is…
More Ecological Disturbances
• What is a disturbance?
• Bottom Line: Communities are in a state of
Non-equilibrium
• These disturbances allow ecologists to study
SUCCESSION:
What about the intermediate disturbance hypothesis?
Succession
• Primary Succession
• Secondary
Succession
2 Sides to Biodiversity
• Both Communities Have
the same:
Species Richness
• But Community A is more
heterogenous;
Relative Abundance is
more equitable
• Which community has
greater Biodiversity?
Species Richness
Location
# of species
Of FW Fishes
Amazon
1000+
Central
America
456
Great Lakes
(USA)
173
Lake Baikal
(Russia)
39
Bear Lake
(N. Canada)
14
• What can we say
about these data?
• Why?
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More species richness curves
Species Richness
correlates with evapotranspiration.
What’s the deal here?
How does this relate to climate?
How might this relate to climate
change?
Island Biogeography
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“Islands” make good case studies in species richness
Remember this is a dynamic equilibrium
Large v. Small:
Near v. Far:
Ch 54: Ecosystem Ecology
1.
Students should be able to recognize the different trophic levels in this
model and see that Energy flows through ecosystems and materials are
recycled within ecosystems.
Students should also understand these three nuances of ecosystems:
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the “rule of 10” Generally, only 10% of the biomass at one trophic level is converted
to biomass at the next trophic level. The other 90% is lost as heat.
the synergy between decomposers and remineralizers maintains ecosystem
function.
The energy for an ecosystem is ultimately derived from the sun, but the
remineralizers return the raw materials back to primary producers so they can
sustain the trophic pyramids.
understand community productivity and community respiration and the
difference between Gross Primary Productivity
Students should recognize the components of a biogeochemical cycle
and be able to describe (in general) how the carbon cycle, nitrogen cycle,
and hydrologic cycle. They should also be able to briefly describe how
humans have disrupted or changed a particular cycle.
Ecosystem Ecology
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Ecosystems as machines
Much of this should be review:
Trophic Levels: Detritus links it all
Microorganisms remineralize the detritus
Gross PP v. Net PP
Tropic Pyramids (Charles Elton)
Biogeochemical Cycles
Human Impacts? If we have time
An Ideal Ecosystem Model:
Nutrients:
Energy:
What about a “narrative
model”
Animals and plants in associations with each
other and with the physical factors of their
surroundings, as a fundamental ecological
system. An ecosystem. Biological and physical
parts of nature are interdependent. Plants and
animals depend on their physical surroundings,
and they contribute to the maintenance of the
physical world.
--A.G. Tansley (c. 1920)
Chapter 54, Ecosystems: The Big Ideas
Biogeochemical Cycles: Conservation of Energy)(
Detritivores and Decomposers
“10% rule”: Laws of thermodynamics
Ecological Pyramids
Energy Flow Through Ecosystems:
Eltonian Pyramids
Rule of Thumb:
Net Primary Productivity
NPP = GPP - R (gC/m2/year)
Limits to Primary Productivity
• Marine Systems:
• Freshwater Systems:
• Terrestrial Systems:
Nutrient Limits in Aquatic and
terrestrial Systems
Secondary Production
An Ideal Consumer
“A Pyramid of Numbers”
Silver Springs, FL
Biomass Pyramids
What’s
the Deal?
Ideal Biogeochemical Cycle
Material Cycling in Ecosystems
LTER: Ecosystem Manipulations
(Hubbard Brook)
LTER: Ecosystem
Manipulations (Hubbard Brook)
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LTER: Ecosystem Manipulations
(Hubbard Brook)
LTER: Ecosystem
Manipulations (Hubbard Brook)
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Name these
A diet for a small planet
An Ideal Ecosystem Model:
Nutrients:
Energy: