Principles of Ecology

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Principles of Ecology

• Chapter 18

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Ecology Study of relationships between living
things their environment. All life all
nonliving factors affect each other. Environment
All the living (biotic) nonliving (abiotic)
things that surrounds a living thing. Biotic
Examples lion, tigers, bears, trees, venus
flytrap, starflower, candy flower, bacteria,
yeast, amoebas, insects, humans, fungus, moss,
mushrooms, worms, etc.... Abiotic Examples
Rocks, soil, water, air, sand, dirt, ice
(glaciers), fossils, buildings, roads, cars,
etc...
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Niche versus habitat
Nichethe role where it feeds, is it a producer,
predator, scavenger,etc. Habitatwhere it lives.
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Resource Partitioning in the Niche
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• LEVELS OF ORGANIZATION IN THE ENVIRONMENT
• 1. Organism One living thing. (Ex.--1 zebra.)
• 2. Population A group of similar life forms
  in an area. (Ex- Herd of zebras.)
• 3. Community A group of populations that
  interact with each other the environment.
  (Ex.--zebras, lions, antelopes, hyaenas,
  giraffes, bushes, trees, grass, soil, water, air,
  etc......)
• 4. Ecosystem A group of communities
  interacting with each other their non-living
  surroundings. (All the grassland communities of
  Africa, or all the desert communities of USA,
  etc...)
• 5. Biosphere All the earth's ecosystems
  interacting with the physical environment. This
  includes all ife as well as the earth itself and
  the atmosphere. This it what we call spaceship
  earth.

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Populations One female herring (a small fish)
can lay one million eggs in a single year. If all
the eggs hatched and all the offspring survived,
what would soon happen to the earth? The fish
would overpopulate the world and they would then
deplete the resources they need. Other animals
would be affected, and perhaps, eventually, many
species would die off. Population A group of
individuals of the same species (humans, tigers,
dandelions, bacteria, etc) that live in a
particular area.
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Birth and immigration add to a population.
Death and emigration subtract individuals to a
population Immigration Individuals moving into
an area Emigration Individuals moving out of an
area What causes creatures to immigrate/emigrate?
Lack of resources (food, water shelter), lack
of mates, lack of breeding territory, poor
weather, too many predators, etc.. Population
Increases when of births of immigrants gt
of deaths of emigrants Population
Decreases when of deaths of emigrants gt
of births of immigrants
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Most organisms produce more offspring than can
survive to grow up and reproduce. Why do they
need to produce so many young? To ensure that
some survive to breeding age!
                          Biotic Potential The
rate at which a population would grow if every
new individual survived to adulthood and
reproduced at its maximum capacity. When a
population grows at its maximum rate, it does so
exponentially. This is shown by a J-shaped curve
on a graph (see graph at right). Some biotic
potentials Humans 6 per year (population
doubles every 11 years) Rats 1.5 per day (400
per year) (pop. doubles every 47 days) Bacteria
250 per hour (doubles every 15-30 minutes)
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Dispersal Patterns Clumped Random
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uniform dispersion
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Density Dependent Factors Intraspecific
competitionsame organisms competing for
food. Build up of toxic wastes.
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Density Independent Factors Not directly
related to population numbers. Deer may
freeze to death in the snow. Related to starving
even though food may be hard to find.
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Age Structure of Three Countries
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Generation Times
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• Reproductive Strategies
• r-selected (opportunistic) populations -
  characterized by exponential growth and sudden
  crashes-- High intrinsic rate of growth (r)--
  Reproduce early, have many offspring-- Offspring
  are small, mature rapidly, receive little
  parental care-- Generations are relatively
  short, large brood size-- Examples dandelions,
  aphids, mice, cockroaches
• K-selected (equilibrial) populations -
  Populations with sigmoid growth curves limited by
  carrying capacity (K)-- Include relatively
  slow-breeding organisms-- Tend to live in
  stable, predictable habitats
• -- Reproduce late, have small broods-- Offspring
  are large, mature slowly-- Receive intensive
  parental care-- Generations are relatively
  long-- Examples oaks, humans, whales
• Many organisms are intermediate

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Camouflage to remain hidden from predators
organisms blend in with their surrounds. Warning
coloration serves to convey a message of
avoidance to potential predators. In general,
predators tend to avoid animals with coloration
that they associate with pain, illness or other
unpleasant experiences. Mimicry adapting
coloration of a more dangerous species to avoid
being preyed upon. It is of great benefit to the
mimic. Batesian mimicry involves a harmless
animal imitating a dangerous one. Mullerian
mimicry involves two or more dangerous species
evolving similar color patterns.
                                                  
                                      Web
Activity
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Succession Succession is a series of changes that
take place in a community as it gets older.
Often, smaller, less competitive plants get
replaced by larger more competitive plants which
take up all the water from the ground and shade
the smaller ones. The change in plants in the
community as succession occurs thus determines
what animals live there. Community All the
populations of plants and naimals that live in a
certain area. Climax Community The last or
final stage of succession in a community. This
stage is often called "old growth" in the Pacific
Northwest. In Pacific Northwest forests, the old
growth trees might be Douglas Fir and Red Cedar,
while in the sagebrush desert east of the
Cascades, the old growth might consist of
sagebrush or juniper.
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Primary Succession Succession that occurs on an
area that never had life on it before. The soil
in such areas is bare rock (recently exposed by
volcanic action, or exposed by the melting of
glaciers). Therefore, soil must develop before
plants can live there. Pioneer Plants Pioneer
plants are the 1st plants that livein an area
after a disturbance. Their seeds are carried to
the area by the wind, by the action of water, or
accidentily in the guano (birdy doo doo) of birds
or stuck to the feathers or fur of animals
(remember some seeds have stickery outer coats to
help move them to new areas!).
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During primary succession, the first plants to
live on bare rock include bacteria and blue-green
algae (where moist), and lichens. Lichens are
common pioneer plants on rock. They are an
example of 2 creatures that live together and
help each other (mutualism). One is a fungus
which provides a home on the rock and absorbs
minerals and water from the rock. The other is an
algae which lives inside the fungus and makes
food via photosynthesis. Lichens help break down
rock by releasing carbon dioxide which makes an
acid when mixed with water. This acid dissolves
rock particles, and breaks big rocks down into
sand. The wind then blows the sand grains into
cracks where it collects. As pieces of lichen
die, they are blown into the cracks too, mixed
with sand, and these then make soil which larger
plants may live in.
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Secondary Succession Succession where the
community of plants that exists in an area is
changed after a disturbance. Such changes
include fires (including natural forest fires),
floods, earthquakes, landslides, and such human
caused phenomena as farming, logging, road
building, and home or building construction. The
key factor in secondary succession is that the
soil already exists, so that succession can
quickly resume and rebuild the area with plants
and animals. The pioneer plants after
disturbances during secondary succession include
mosses, grasses, and weeds.
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Fire and Succession   Fires, both natural and
human-caused are important events which interrupt
the cycle of succession and create areas within
the community which are at different stages of
succession. In many cases, fires eliminate duff
(old leaves and conifer needles), logs, or
branches which collect on the ground and could
create a larger fire (one that leap into the
lower branches of trees) that would endanger the
trees and shrubs. In addition, fire recycles
the nutrients and minerals in dead materials back
into fertilizer which can be used by young
plants. In some cases, a fire might remove old,
diseased trees and shrubs, making the forest more
healthy. Some trees and shrubs need a fire to
kill the older part of the plant so that the
roots can send new shoots into growth. These not
only revitalize the community with their growth,
but also they provide food for many browsing
animals. Finally, many conifers need fire to
open the cones and release the seeds to the
fertilized ground.
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