1. ECOLOGY - image
2. ECOLOGY - image
3. ECOLOGY
a. The word ecology is derived from the Greek word “oikos”, or “a place to live”.
b. ECOLOGY: The study of the interrelationships of organisms with each other and with
their non-living environment.
c. Environment: consists of the abiotic and biotic components.
4. ECOLOGY
a. Abiotic: Nonliving; the abiotic portion of an ecosystem includes soil, rock, water, and the
atmosphere.
b. Biotic: Living; includes all forms of life.
c. Ecosystem: All the organisms and their non-living environment within a defined area.
5. ECOLOGY
a. Community: All interacting populations within an ecosystem.
b. Populations: All the members of a particular species within an ecosystem, found in the
same time and place and actually or potentially interbreeding.
6. POPULATION CHARACTERISTICS
a. DEMOGRAPHICS: Vital statistics of a population; e.g., size, age structure.
b. POPULATION SIZE: The total number of individuals that make up a population. Refers
to the number of individuals in a gene pool.
7. POPULATION CHARACTERISTICS
a. AGE STRUCTURE: Of a population, the way that individuals are distributed among
different age categories.
b. REPRODUCTIVE BASE: Of some population, the number of individuals already
reproducing, plus those not yet reproductively mature.
8. POPULATION CHARACTERISTICS
a. POPULATION DENSITY: Count of individuals of a population in a specified portion of a
habitat.
b. HABITAT: The type of place a species normally lives.
c. BIOME: A region that supports a characteristic type of vegetation; e.g., desert, tundra.
9. POPULATION CHARACTERISTICS
a. POPULATION DISTRIBUTION: The pattern in which the individuals of a population are
dispersed through their habitat.
b. CAPTURE-MARK-RECAPTURE METHODS: Method of estimating population size of a
mobile species. Mark animal, release, re-trap = represents population size.
10. Three factors determine whether and how much the size of a population changes:
i. BIRTHS
ii. DEATHS
iii. MIGRATION
iv. Migrate: to move from one place to another, to change location.
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v. Organisms join a population through birth or immigration and leave it through
death or emigration.
11. ECOLOGY
a. Emigration: migration of individuals out of an area.
b. Immigration: migration of individuals into an area.
c. Populations stay stable, on the average, if as many individuals leave as join.
12. ECOLOGY
a. Population growth occurs when the number of births plus immigrants exceeds the
number of deaths plus emigrants. Populations decline when the reverse occurs.
b. A simple equation for the change in population size within a given period is as follows:
i. (Births – deaths) + (immigrants – emigrants) = change in population size.
ii. BIRTH AND DEATH RATES ARE THE PRIMARY FACTORS THAT
INFLUENCE POPULATION.
13. ECOLOGY
a. THERE ARE TWO MAJOR OPPOSING FACTORS THAT DETERMINE BIRTH AND
DEATH RATES:
b. BIOTIC POTENTIAL: the maximum rate at which a population could increase, assuming
ideal conditions that allow a maximum birth rate and minimum death rate.
c. ENVIRONMENTAL RESISTANCE: any factor that tends to counteract biotic potential,
limiting population size. It can both decrease birth rates and increase death rates.
d. INTERACTION BETWEEN BIOTIC POTENTIAL AND ENVIRONMENTAL
RESISTANCE USUALLY RESULTS IN BALANCE BETWEEN POPULATION SIZE
AND AVAILABLE RESOURCES.
14. ECOLOGY
a. The growth rate (r) of a population is a measure of the change in population size per
individual per unit of time. This value is determined by subtracting the death rate (d)
from the birth rate (b).
15. ECOLOGY
a. On earth, our population is increasing.
b. The pattern of continuously accelerating increase in population size is EXPONENTIAL
GROWTH.
c. The graph of exponential population growth is often called a J-shaped curve, or just Jcurve
16. J-Curve for Eagles
17. J-CURVE WITH DEATH INCLUDED, STILL A J-CURVE
18. EXPONENTIAL GROWTH CAN NOT GO ON FOREVER:
19. ECOLOGY
a. CARRYING CAPACITY IS the maximum population size that an ecosystem can support
indefinitely; determined primarily by the availability of space, nutrients, water, and light.
b. Determined by resources: renewable and non-renewable.
20. COMPETITION FOR RESOURCES HELPS CONTROL POPULATIONS:
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a. COMPETITION: Interaction among individuals who attempt to utilize a resource (for
example food or space) that is limited relative to the demand for it.
b. Competition can be interspecific (between different species) or intraspecific (between
individuals of the same species).
21. A VERY SIGNIFICANT J-CURVE
a. Human population growth. ADVANCES OVERCOME ENVIROMENTAL RESISTANCE.
22. PROBLEMS IN COUNTRIES THAT RESTRICT POPULATION GROWTH
23. Image
24. HOW DO ECOSYSTEMS WORK?
a. The activities of life are powered by sunlight whether we consider the migration of the
salmon or the transport of molecules across the plasma membrane.
b. The molecules of life are constructed of chemical building blocks that are obtained as
nutrients from the environment.
25. TWO BASIC LAWS UNDERLIE ECOSYSTEM FUNCTION:
a. ENERGY MOVES THROUGH THE COMMUNITIES WITHIN ECOSYSTEMS IN A
CONTINUOUS ONE-WAY FLOW, NEEDING CONSTANT REPLENISHMENT FROM
THE SUN.
b. NUTRIENTS CONSTANTLY CYCLE AND RECYCLE WITHIN AND AMONG
ECOSYSTEMS.
26. ENERGY ENTERS THROUGH PHOTOSYNTHESIS
a. The sun releases tremendous quantities of energy from 93 million miles away.
b. A small amount reaches Earth in the form of electromagnetic waves, including heat,
light, and ultraviolet energy.
c. Much of the energy is reflected by the atmosphere, clouds, and Earth’s surface.
27. IT ALL STARTS WITH PHOTOSYNTHESIS
a. During photosynthesis, pigments such as chlorophyll absorb specific wavelengths of
sunlight.
b. Solar energy is then used in reactions that store energy in chemical bonds, producing
sugar and other high-energy molecules.
c. Photosynthetic organisms are called autotrophs or “producers”.
28. ECOSYSTEMS
i. The amount of life that a particular ecosystem can support is determined by the
energy captured by the producers in that ecosystem.
ii. NET PRIMARY PRODUCTIVITY: The energy stored in the autotrophs of an
ecosystem over a given period of time.
iii. Net primary productivity can be measured in units of energy - ???
29. ENERGY FLOW in ECOSYSTEMS
a. TROPHIC STRUCTURE (literally, feeding level): The different feeding relationships in
an ecosystem, which determine the route of energy flow and the pattern of chemical
cycling.
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30. TROPHIC LEVELS: AUTOTROPHS
a. TROPHIC LEVEL THAT ULTIMATELY SUPPORTS ALL OTHERS: AUTOTROPHS
b. (PRIMARY PRODUCERS)
c. Most autotrophs are photosynthetic organisms that use light energy to synthesize
sugars and other organic compounds.
d. These organisms use these materials for their own cellular respiration and growth.
31. TROPHIC LEVELS HETEROTROPH
a. PRIMARY CONSUMERS Herbivores
b. Herbivores: “plant-eaters”
c. Feed directly on plants and other primary producers.
d. Worms to giraffes.
32. TROPHIC LEVELS - HETEROTROPHS:
a. SECONDARY CONSUMERS:
b. Carnivores that eat herbivores. (Carnivores are meat-eaters.)
c. Predators that feed mostly on primary consumers.
d. PICTURED: Western garter snake eating a banana slug.
33. TROPHIC LEVELS – HETEROTROPHS
a. TERTIARY CONSUMER
b. Carnivores that eat other carnivores.
c. Are human beings tertiary consumers?
d. What level of consumer are you?
e. Omnivore: “eating-all”. Can act as primary, secondary, and occasionally tertiary
consumers.
34. TROPHIC LEVELS – HETEROTROPHS
a. Detritivores (decomposers).
b. These particular organisms get their energy from detritus (non-living organic material).
c. Many detritivores are in turn eaten by secondary and tertiary consumers.
35. FOOD WEB:
a. Natural communities rarely contain well-defined trophic levels.
b. FOOD WEB: A representation of the complex feeding relationships (in terms of
interacting food chains) within a community, including many organisms at various
trophic levels, with many of the consumers occupying more than one level
simultaneously.
36. VIP’S OF THE FOOD WEB
a. (De-trI-tus) Detritus feeder: - Meaning debris. One of a diverse group of organisms,
ranging from worms to vultures that live off the wastes and dead remains of other
organisms.
b. Decomposer: an organism, normally a fungus or bacterium, that digests organic
material by secreting digestive enzymes into the environment, in the process liberating
nutrients into the environment.
37. FACTORS THAT SHAPE COMMUNITY STRUCTURE
a. THE NICHE: Sum of activities and relationships in which individuals of a species
engage as they secure and use resources.
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38. SPECIES INTERACTIONS
a. COMMENSALISM: Interspecies interactions; one species benefits and the other is
unaffected.
b. MUTUALISM: An interspecific interaction that benefits BOTH SPECIES.
c. INTERSPECIFIC COMPETITION: Competition between members of different species.
39. SPECIES INTERACTIONS
a. PREDATION: Ecological interaction in which a free-living predator eats a prey
organism.
b. PARASITISM: Symbiotic interaction in which one species draws nutrients from another,
usually without killing it.
c. SYMBIOSIS: An interspecific interaction in which members of different species interact
closely for some or all of the life cycle; e.g., mutualism, commensalism, parasitism.
40. TROPHIC LEVEL ENERGY EFFICIENCY AND THE 10% RULE
a. ENERGY TRANSFER FROM ONE TROPHIC LEVEL TO ANOTHER IS INEFFICIENT.
b. APPROXIMATELY 10% OF THE ENERGY AT ONE TROPHIC LEVEL IS PASSED ON
TO THE NEXT TROPHIC LEVEL.
c. Only the chemical energy stored by this herbivore as biomass (growth or production of
offspring) is available as food to secondary consumers.
d. Energy is lost through cellular respiration or contained in the feces. Approximately 90%
of the energy available at one trophic level is typically not transferred to the next.
41. ENERGY TRANSFER
a. THE FIRST LAW OF THERMODYNAMICS: the principle of physics that states that
within any isolated system, energy can be neither created nor destroyed but can be
converted from one form to another.
b. THE SECOND LAW OF THERMODYNAMICS: the principle of physics that states that
any change in an isolated system causes the quantity of concentrated, useful energy to
decrease and the amount of randomness and disorder (entropy) to increase.
c. ENTROPY: a measure of the amount of randomness and disorder in a system.
42. Energy image
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