Download Ecology

An Introduction To Ecology
Chapter 18
18.1
Ecology – study of interactions
between organisms and
environment.
 Consists of abiotic (nonliving;
i.e. temperature, light, etc) and
biotic (living) factors.

Levels of Organization
The levels of
organization are
designed to allow
scientists to
understand and
study relationships
more easily
Levels of Organization
all
one
all
smallest
large
group
interacting
organisms
living
individual
region
of
unit
and
populations
of
similar
with
living
different
nonliving
of
organs
the
living
typical
thing
same
cellsin
an
organized
kind
plants
kinds
working
ecosystem
things
living
and
of to
in
work
animals
interacting
one
together
tissues
together
area
that
within
includes
workinga
certain
together
several
area
ecosystems
cell
Species – a group of organisms
that can breed and produce fertile
offspring
Populations – groups of
individuals that are the same
species and living in the same area
Communities – a group of
organisms of different species living
together in the same area
Ecosystems – all the populations
living together with the nonliving
environment
Biomes – groups of similar
ecosystems that have similar
climates and similar communities
Biosphere – combines all the
parts of the earth in which life
exists
Ecology
18.2 Components of an Ecosystem
Abiotic – the nonliving components of an ecosystem
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Light – affects photosynthesis
Temperature – affects metabolism
Water supply
Oxygen supply
Minerals
Soil/Rocks
pH
Examples of Abiotic
Factors
Biotic – the living components of
an ecosystem

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Plants
Animals
Protists
Fungus
Bacteria
Examples of Biotic
Factors
Organisms in a changing
environment

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Each organism can survive within a limited
range of environmental conditions
Tolerance curve- a graph of performance
versus values of an environmental variable
such as temperature
Acclimation- the process of an organism
adjusting tolerance to abiotic factors
Organsims can survive unfavorable
environmental conditions through:
Dormancy- entering a state of reduced
activity
Migration-moving to a favorable habitat

Structure
Habitat – the physical area in which an
organism lives (includes climate,
topography, soil and water chemistry,
plant and animal life, etc.)
Niche – the way of life of a species
(includes its habitat, feeding habits,
reproductive behavior, etc.)
species can be generalists (broad
niche) or specialists (narrow niche)
18.3 Energy Transfer
All energy comes from the sun
Plants harness the sun’s
energy in which process?
Plants need light for
photosynthesis, what else do they
need?
We call plants producers
because they produce
energy from the sun
Measuring productivity
Gross primary productivity-rate at
which producers in an ecosystem
capture energy of sunlight by
producing organic compounds
Biomass-organic material produced in
an ecosystem
Net primary productivity-rate at which
biomass accumulates
Primary Producers (Autotrophs)
 Energy
from the sun is captured
by plants, algae, or bacteria
through photosynthesis.
 Energy
from chemicals is
captured by some bacteria
through chemosynthesis.
 Capture
energy from the sun or
from chemicals and store it in
the bonds of sugars, making it
available to the rest of the
community
Did You Know? Deep-sea vents, far from sunlight,
support entire communities of fish, clams, and
other sea animals, which depend on energy
converted through chemosynthesis.
Consumers (Heterotrophs)
Rely
on other organisms for energy
and nutrients
Use
oxygen to break bonds in sugar
and release its energy through cellular
respiration (primary producers do this,
too)
Types
of Consumers:
 Herbivores:
plant-eaters
 Carnivores:
meat-eaters
 Omnivores:
combination-eaters
 Detritivores
and decomposers:
recycle nutrients within the
ecosystem by breaking down
nonliving organic matter
California Condor
Did You Know? Scavengers, such as
vultures and condors, are just large
detritivores.
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When one organisms eats another,
molecules are metabolized and energy is
transferred
An organism’s trophic level indicates the
organism’s position in a sequence of
energy transfers
Trophic Levels
Lesson 5.3 Ecological Communities
Energy in Communities
An organism’s rank in a
feeding hierarchy is its trophic
level.
 Primary producers always
occupy the first trophic level of
any community.
 In general, only about
10% of the energy available at
any trophic level is passed to
the next; most of the rest is
lost to the environment as
heat.

Pyramid of Energy
What is a food chain?

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Food chain: Linear series
of feeding relationships
A Basic Food Chain
Plants absorb light from the
sun, which is turned into
energy to grow. We call
these producers.
The vegetarian animals eat
the plants, they are called
primary consumers.
Secondary consumers
prey on primary
consumers.
Food Web- interrelated food chains in an ecosystem
MATTER CYCLING IN
ECOSYSTEMS
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Nutrient Cycles: Global Recycling
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Global Cycles recycle nutrients through the
earth’s air, land, water, and living organisms.
Nutrients are the elements and compounds
that organisms need to live, grow, and
reproduce.
Biogeochemical cycles move these substances
through air, water, soil, rock and living
organisms.
Covered in Photo/Resp. Chapter!
Water Cycle Key Terms:
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Ground water-water found in soil or in
underground formations of porous rock
Transpiration-process by which water
evaporates from leaves of plants in
terrestrial ecosystems
Evaporation-adds water to the atmopshere
Precipitation-the process by which water
leaves the atmosphere
Water Cycle
Carbon Cycle
 Fourth
most abundant element in universe
 Building block of all living things
 Main Pathway– in and out of living matter
Key Terms
Carbon Cycle- Circulation of carbon
through ecosystems
Carbon- A non-metallic element found in
coal, petroleum and natural gas. Major
component of life.
Soil Respiration- Carbohydrates are
oxidized and returned to the air by soil
microorganisms that decompose dead
animals
Key Terms Continued
Atmosphere- layer of gasses
Fossil Fuels- Carbon-rich fuel from ancient
animals and plants
Photosynthesis- Energy (sun)+ Water+
Carbon dioxide Carbohydrates+ Oxygen
Cellular Respiration- Glucose+ Oxygen
CO2+ H20+ Energy (ATP)
Decomposition- breakdown of matter by
bacteria and fungi
Biological Importance of Carbon
 All
living organisms contain carbon
 CO2 is found in all living organisms
 Plants use carbon dioxide and water to
form simple sugars (photosynthesis)
 Carbon is needed for life
 Carbon dioxide is a greenhouse gas
 Carbon is necessary for life, but carbon
dioxide can be harmful
Carbon Cycle
Nitrogen cycle
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Organisms need nitrogen to make proteins and
nucleic acids
Nitrogen gas makes up 78% of the atmosphere
Most plants can only use nitrogen in the form of
nitrate
Nitrogen fixation- process of converting nitrogen
gas into nitrate
Nitrogen fixing bacteria transform nitrogen into
a usable form
Recycling nitrogen
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Decomposers break down decaying organisms
and release the nitrogen they contain as NH3
Ammonification- changing NH3 (ammonia) into
NH4 +(ammonium)
Nitrification-soil bacteria take up ammonium and
oxidize it into (nitrites) NO2-and (nitrates) NO3Denitrification-process where anaerobic bacteria
break down nitrates and release nitrogen gas
into the atmosphere
Nitrogen Cycle
Importance of the Phosphorus
cycle
 Phosphorus
is an essential nutrient for
plants and animals
 It is a part of DNA-molecules and RNAmolecules, molecules that store energy
(ATP and ADP)
 Phosphorus is also a building block of
certain parts of the human and animal
body, such as the bones and teeth.
Difference in the Phosphorus cycle
 The
phosphorus cycle differs from the
nitrogen and carbon cycles because
phosphorus is unable to achieve the
gaseous state in the atmosphere.
Phosphorus is mainly found in water, soil
and sediments. In the atmosphere,
phosphorus is found as fine dust particles.
By: Jermaine Loutin (Jose Marti Six Form
Envi.)
The Phosphorus Cycle
Ch 19 Populations
19.1 Understanding populations
 Population ecology: studies changes in population size
and the factors that regulate populations over time
A. Populations are affected by size, density and dispersion
1. Population size- number of individuals
2. Population density: the number of individuals of a
species per unit area or volume
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Ex: number of earthworms per cubic meter of soil
Normally determined by sampling
Estimates are more accurate for larger populations
3. Population dispersion
a. Clumped dispersion pattern: individuals are
grouped in patches
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Most common in nature
Due to unequal distribution of
resources in the environment
b. Uniform dispersion pattern: even spreading
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Usually results from interaction
between individuals
Ex: territories
c. Random dispersion pattern: unpredictable
spacing
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Ex: plants grown from
windblown seeds
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B. Population dynamics: interactions between biotic
and abiotic factors that cause variation in population
size
1. Population growth
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Population increases occur through birth (natality)and
immigration
Immigration-movement of individuals into a population
Population decreases occur through death (mortality) and
emigration
Populations are also affected by life expectancy or how
long and individual is expected to live
Emigration-movement of individuals out of a population
May be influenced by factors such as food availability and water
quality
2. Age structure-distribution of individuals
among different ages in a population
3. Patterns of mortality
Survivorship: the chance of an individual in
a given population surviving to various
ages
 Survivorship curves: plot survivorship as
the proportion of individuals from an initial
population that are alive at each age

Allows for species comparison
a. Type I survivorship: animals
that produce few offspring and
nurture them to maturity
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Ex: humans and other large
mammals
b. Type III curve: opposite of a
Type I
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Many offspring are produced
but few make it to maturity
Ex: many invertebrates
c. Type II curve: survivorship is
constant over the lifespan
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Individuals are equally
vulnerable at every stage of
the life cycle
Ex: lizards and rodents
19.2 Measuring Populations
A. Population size
 Determined by the following equation:
 Growth rate =(individuals added)- (individuals
subtracted)
or
 (birthrate + immigration rate) – (death rate + emigration
rate)
 Growing populations have a positive growth rate;
shrinking populations have a negative growth rate.
 Usually expressed in terms of individuals per 1000
 Population changes are expressed as percentages:
 Growth rateX100= % growth
B. Exponential growth model:
the rate of population
growth under ideal
conditions
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As the population size grows,
more individuals are added
during each interval
Graphing this data gives a Jshape curve
Exponential growth can NOT
continue indefinitely
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Eventually, one or more
environmental factors will
limit growth
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Ex: space and food supply
C. Logistic growth model: idealized
population growth that is slowed by
limiting factors as the population size
increases
 Results in formation of an S-shape
curve
 K is the carrying capacity - maximum
population size that a particular
environment can sustain
 K varies depending on the species
and the resources available
 Influenced by predators, parasites,
food sources, and abiotic factors
 Emphasizes that resources are finite
 At low populations, resources are
abundant and the population is able
to grow nearly exponentially

Population stabilizes at the carrying
capacity when the birth rate equals the
death rate
D. Population Regulations
Density-independent factors- factors that reduce the
population by the same proportion. Influence does not
change with population density.
 These are usually abiotic factors
 They include natural phenomena, such as weather
events
 Drought, flooding, extreme, heat or cold, tornadoes,
hurricanes, fires, etc.
Density-dependent factors- Influence changes with
population density.
 Any factor in the environment that depends on the
number of members in a population per unit area
 Usually biotic factors, these include:
 Predation, Disease, Parasites, Competition