Download Introduction to Ecology

Introduction to Ecology
Chapter 18
Ecology
Section 18.1
Definition:
• The study of the interactions between
organisms and their environment
• Interdependence of organisms and
their environment
Levels of Organization
1. Biosphere
2. Ecosystem
3. Community
4. Population
5. Organism
Biosphere
• The Earth & the atmosphere
• “Thin film of life covering a
lifeless planet”
Ecosystem
•All organisms & nonliving
environment in a given place
–Organisms + water, pH, minerals, etc.
Community
• All of the organisms in an
ecosystem
– Living things only!
Population
• All the members of ONE species
living in one place at one time
Organism
• ONE member of ONE species
living in one place at one time
Ecology of Organisms
Section 18.2
Habitat
• Where organisms live
• Contains abiotic and biotic factors
– Abiotic: nonliving components
• Ex) sunlight, water, soil
– Biotic: living components
• Ex) plants, animals, predators
Tolerance Range
• The range of abiotic conditions
where the organism can still
perform all activities for life
Acclimation
•When an organism adjusts
its tolerance to an abiotic
factor
•Ex) Moving from room to
room with different
temperatures
Control of Internal Conditions
• Conformers: organisms that DO
NOT regulate their internal
environment
– “cold blooded”
• Regulators: organisms that DO
regulate their internal environment
– “warm blooded”
Escape from the Habitat
• Dormancy: a state of reduced
activity for the organism
– Hibernation
• Migration: movement of organism
to a favorable habitat
– Immigration: movement into a
habitat
– Emigration: movement out of a
habitat
Niche
• The way of life for a species
• The role the species plays on its
environment
Niche includes:
•
•
•
•
•
Tolerable conditions for organism
Methods to obtain resources
Number of offspring per year
Time of reproduction
Any other interactions with the
environment
• ETC.
2 Types of Niches
• Fundamental Niche: the range of
conditions a species could
POTENTIALLY tolerate and the
range of resources it could
POTENTIALLY use.
• Realized Niche: the range of
conditions and resources the
species ACTUALLY tolerates and
uses.
Questions:
• Which niche is larger?
• Why?
Niche Differences
• A species’ niche can change
within its lifespan
• Generalist: species with a broad
niche
• Specialist: species with a narrow
niche
Specialist
Generalist
Question:
•Which type can adapt to a
changing environment better?
–Generalist or specialist?
•Why?
18-3 Energy Transfer
Energy
Why do organisms need energy?
Maintain HOMEOSTASIS,
growth, reproduction, etc.
How does energy affect an
ecosystem?
Determines how many and what
kind of organisms live in an
ecosystem.
Energy Flow:
• The sun is the ultimate source of
energy
• The PRODUCERS use this energy to
make “food” energy for themselves
and for the CONSUMERS
Trophic Levels
The organism’s
position in the
sequence of energy
transfers.
A.K.A. Trophic
Level is a group of
organisms whose
feeding source is
the same number
of steps from the
Sun.
Common Trophic Levels:
•First = Producers (Autotrophs)
–LARGEST
•Second = Herbivores (Heterotrophs,
Consumers)
•Third and above = All other consumers
(Heterotrophs, Omnivores, Carnivores,
Decomposers)
–SMALLEST
• Omnivores (Humans)
– Eat Plants & Animals
• Detritivores (Scavengers)
– Feed On Dead Plant & Animal Remains
(buzzards)
• Decomposers
– Fungi & Bacteria
Consumers
Heterotrophs eat other organisms to
obtain energy. (e.g. animals)
• Herbivores
– Eat Only Plants
• Carnivores
– Eat Only Other Animals
Energy Gain by Trophic Levels:
• At each trophic level, the energy stored in an
organism is about 1/10 that of the level below
it (10%).
Implications on the ecosystem:
 Because energy diminishes at each
successive trophic level, few ecosystems
can contain more than 4 or 5 trophic levels.
 Organisms at higher levels (large
carnivores) tend to be fewer in number than
those at lower levels (producers).
Food Chain
• A single pathway of feeding (and
energy transfer) relationships
among organisms in an
ecosystem.
Ex) Food chain
Food Web
• A diagram of the
interrelated food
chains in an
ecosystem.
• More accurate
description of
the ecosystem.
Can you now answer these questions?
1. Contrast between producers and
consumers.
2. Explain the important role of
decomposers in an ecosystem.
3. Explain why an ecosystem usually
contains only a few trophic levels.
4. What is the difference between an
organism’s niche and its habitat?
5. List 2 sources that add carbon to the
carbon cycle.
Energy flows through an
ecosystem and nutrients cycle
in an ecosystem.
Ecosystem Recycling (18.4)
Water Cycle Steps:

EVAPORATION
from lakes, rivers,
and oceans.

TRANSPIRATION
from plants and trees.

CONDENSATION –
Cloud Formation



PRECIPITATION –
Rain, Snow, Sleet,
Hail.
RUN OFF, or
RETURNED back into
the Cycle.
Groundwater- water in
soil or in underground
formations of porous
rock.
The Water Cycle
The Carbon Cycle

Cellular
Respiration

Photosynthesis

Combustion

Death and
decomposition
Human Influences

Atmospheric CO2 has risen more than
30% in the past 150 years.
Burning of fossil fuels- coal, oil,
and natural gas
 Burning down the tropical rain
forest

The Nitrogen Cycle
Nitrogen Fixation: the process of converting atmospheric
nitrogen (N2) into nitrate, its useable form.
Key Terms
Nitrogen-fixing bacteria:
turn nitrogen gas into a
useable form. Located in
soil and the roots of some
plants.
Ammonification: bacteria
decompose dead matter
and release the nitrogen
they contain as ammonia
So… How do plants and animals get nitrogen?
Phosphorous Cycle



obtained by plants from water and soil, and
animals from the food they eat
used to form bones, teeth, and molecules such
as DNA and RNA
Source: erosion of rocks into the soil or water,
decomposition of organisms, and fertilizers