Transcript Ecology - Images

ECOLOGY
“Ecology” – the scientific study of
interactions among organisms and between
organisms and their environment, or
surroundings.
The Biosphere & Ecology
The biosphere contains the combined
portions of the planet in which all life exists.
This includes the land, air, and water.
Levels of Organization
The levels of organization that pertain to
ecology are:
Species/Organism –
Population – a group of the same species that live in the
same area.
Community – the various populations that exist in a
defined area.
Ecosystem – a collection of all the organisms
(communities) of a particular place together with their
nonliving or physical environment.
Biome – a group of ecosystems that have the same
climate, and similar dominant communities.
Methods of Ecological Study:
1. Observation
2. Experimentation
3. Modeling – since many ecological
studies may involve long periods of time, or
large spaces, ecologists can make models
based on observation and experiments, and
from there can make predictions.
Energy Flow in Ecosystems:
“Without a constant input of energy, living
systems cannot function.”
Producer : Autotroph : : Consumer : Heterotroph
Autotrophs/Producers:
-Sunlight is the main energy source for life
on Earth.
-Plants, some algae, and few bacteria are
able to capture the sun’s energy and
produce food. (mainly through
photosynthesis)
These organisms are called autotrophs (or
producers).
Heterotrophs/Consumers:
-Heterotrophs (or consumers) rely on other
organisms as their energy & food supply..
Types of heterotrophs:
Herbivores – obtain energy by eating plants (cows,
caterpillar, deer)
Carnivores – eat animals (snakes, dogs, owls)
Omnivores – eat both plants and animals (humans,
bears, crows)
Detritivores – feed on dead plant and animal matter
(mites, worms)
Feeding Relationships
Energy flows in an ecosystem in one
direction:
The Sun → autotrophs → heterotrophs
Food Chain – The way energy stored by producers is
passed through an ecosystem. It is the way organisms
transfer the energy by eating, or being eaten.
Food web – Links all the food chains in an ecosystem
together.
Trophic Levels – Represents each step in a food chain.
Producers are the 1st level, consumers are the 2nd, 3rd, or
higher levels.
Pyramid showing freshwater ecosystem trophic levels
Energy pyramid – shows the energy stored in one
level, and what is available for the next level.
Only about 10% in one level is transferred to the next level.
Cycles of Matter:
Unlike one-way energy flow → , matter is
recycled
in and between ecosystems.
The Water Cycle – Evaporation, Condensation,
Precipitation, Runoff, Infiltration, Transpiration
Nutrient cycles – Carbon, Nitrogen, Phosphorus,
etc.
Ecosystems: factors and interactions
Biotic factors - all of the living parts of an
ecosystem, with which an organism may interact.
Abiotic factors – non-living factors which shape
an ecosystem. Examples are temperature,
precipitation, humidity, wind, soil type, sunlight.
(see worksheet)
Habitat & Niche:
The area in which an organism lives is
called its habitat. A habitat includes both
biotic/abiotic factors.
A niche is the full range of physical and
biological conditions in which an organism
lives. No two species can occupy the same
niche in an ecosystem.
“If a habitat is an organisms address in an ecosystem,
then the niche is its occupation. “
Community interactions:
Competition – organisms compete for resources
in an ecosystem. A resource is a necessity of life
(water, food, etc).
Predation – Interaction where one organism
captures and feeds on another. The one doing the
killing is the predator. The one getting eaten is the
prey.
Symbiosis – Relationships where 2 organisms
live closely together. There are 3 main classes of
symbiosis:
The 3 main classes of symbiosis:
Mutualism – both species benefit from the
relationship. (insects, and flowers)
Commensalism – one organism benefits, and the
other is not harmed or helped (barnacles &
whales)
Parasitism – one organism lives on, or inside
another, and harms it. They generally weaken, but
do not kill the host. (tapeworms, or ticks).
Ecological succession:
Ecosystems are constantly changing in response
to natural and human disturbance. The series of
predictable changes which occurs in an ecosystem
over time is called ecological succession.
Primary succession – occurs on surfaces where no soil
exists. Examples are on bare rock left by melting glaciers,
or recent lava flows. The first species to populate these
areas are called pioneer species. (usually mosses &
lichens)
Secondary succession – occurs following a disturbance
of a community without removing the soil. Examples are
tilled farm lands, or areas of recent fires.
Biomes
Biomes are determined by abiotic factors, such as
climate.
A few examples of land biomes are; desert, tundra,
rainforest, shrubland, and prairie.
Other land areas that do not fit into the major biomes are
the polar ice caps, and mountain ranges.
Biome precipitation
Biome data
Aquatic Ecosystems:
Aquatic ecosystems are determined by depth,
flow, temperature, and chemistry of the overlying
water. A few examples are described below:
Freshwater ecosystems can be flowing water, or freestanding water.
Freshwater wetlands water covers the soil for all or most
of the year.
Estuaries are wetlands formed where rivers meet the sea.
These include salt-marshes and mangrove swamps.
Marine ecosystems are within the ocean. They can be
photic (receiving sunlight)
aphotic (in the dark)
Populations:
Population size can be affected by:
birth rate, death rate, emigration/immigration
How Populations Grow
3 characteristics of a population are:
1. geographic distribution
2. density (# / area)
3. growth (2 types)
2 types of population growth:
• Exponential Growth - occurs when individuals
reproduce at a constant rate. Under ideal
conditions, with unlimited resources, a
population will grow exponentially. (J curve)
• Logistic Growth - occurs when a population's
growth slows or stops following a period of
exponential growth. This is a result of resources
becoming less available. (S curve).
Carrying Capacity - the largest # of
individuals that an ecosystem can support.
(top part of the S curve).
Exponential Growth
J curve
Logistic Growth
S curve
Carrying capacity approx. 650
Limiting factora factor causing population's growth to
decrease.
Density-dependent limiting factor - based on # of
individuals in area.
3 factors include: Competition, predation,
parasitism.
Density-independent limiting factor - affect all
populations in similar ways.
Examples are: unusual weather, seasonal
cycles, and human activity.
Human Population Growth
"The scientific study of human
populations is called demography".
Demographic transition - a dramatic change
in birth and death rates. As countries
become advanced in medicine, nutrition,
and sanitation the death rate lowers, and
demographic transition begins.
Renewable & nonrenewable
resources:
Renewable resources - can regenerate, and
are replaceable. They may however,
become limited.
Examples: Land, Forests, Ocean, Air, Water
Nonrenewable resources - cannot be
replenished by natural processes. Fossil
fuels are an example.
Biodiversity
Biodiversity - is the sum total of the
genetically based variety of organisms in the
biosphere.
Threats to biodiversity –
Extinction- when a species disappears from all or
part of its range.
Endangered species - a species whose population
size is declining, and is in danger of extinction.
Habitat fragmentation - when an ecosystem splits
into pieces.
Hunting
Pollution - such as biological magnification where a
toxin is concentrated to higher amounts as you move
higher in a food chain.
Invasive species - non-native species introduced into
a habitat which tend to reproduce rapidly.
Other Ecology Vocabulary
• Smog - a mixture of chemicals that appears as a graybrown haze in the atmosphere.
• Pollutant - a harmful material that can enter the
biosphere through air, land, or water.
• Acid Rain - acidic gases are released by the burning of
fossil fuels. These gases combine with water vapor to
form drops of nitric and sulfuric acid. These can kill
plants, and damage soil chemistry.
• Deforestation - the loss of a forest, due to over use of
raw materials. Results in loss of habitat, and soil erosion.
• Desertification - areas which were once productive, but
are not anymore due to farming, overgrazing, and
drought.
Other Ecology Topics
• Ozone Depletion - the ozone layer absorbs a lot of UV
radiation from the sun before it reaches Earth's surface.
Satellites have shown a hole in our ozone layer over part
of Antarctica, and more recently a hole over the Arctic
appeared.
– CFC's (chlorofluorocarbons) - cause the reduction of ozone as
they break apart the ozone molecules (O3). Once widely used in
aerosols and refrigerants, they are now under better control in
most parts of the world.
• Global Warming - the increase in the average
temperature of the biosphere. Thought to be caused by
too much Carbon dioxide in the atmosphere (a result of
burning fossil fuels). If predictions are correct it could
cause substantial melting of the polar ice caps and
cause flooding. Also insect populations may increase.