Transcript Ecology - Humble ISD

Ecology
Ecosystems and Communities
Chapter 4
Populations are affected by both abiotic and
biotic ecological pressures.
Habitat- The area in which an organism lives
Niche: The organism’s place or role it takes in
the ecosystem.
No two species can
share the exact
same niche in a
habitat!
Shaded areas show
where each species
feeds (one factor
that defines a niche).
Symbiosis:

Describes a close relationship between 2
organisms, in which at least one of the
organisms involved benefits.
Types of Symbiosis:
1. Mutualism
2.
Parasitism
3.
Commensalism
Mutualism

Both organisms benefit from the relationship.
A).Clown fish is provided a
protective home and the sea
anemone is provided food
as the clownfish lures other
fish toward the sea
anemone.
B). Bees receive food (nectar),
while the flower’s pollen is
spread for reproduction.
Parasitism

One organism benefits, and the other is
harmed (host).
A).Ticks feed on the blood of the host in which they
live. The closer together organisms live, the easier
these parasites can spread through the population.
B). Make up one of your own
Commensalism

One organism benefits, and the other is
neither helped nor harmed.
A). Barnacles live and grow on the bodies of various
ocean organisms like whales. However, they do not
help or cause any harm to them.
B). Make up one of your own.
Aphids feed on
sugary sap from the
plant.
-Parasitism
Aphids are herded
and protected by
the ants because
the ants feed on
sugary excretions
the aphids produce.
-Mutualism
4. PREDATION:
An interaction in which one
organism captures and feeds on
another organism
5. COMPETITION:
Could be over a
mate, food,
space, water
etc. Anything
that would
affect survival.
when organisms attempt to use
an ecological resource in the
same place at the same time.
The Carbon Cycle: a process through which the
element carbon cycles through the environment.
1. In photosynthesis, producers
Draw this in your notes.
remove CO2 gas from the
atmosphere to make organic
molecules (sugars)
2. Animals get organic molecules from
plants & return CO2 gas to the
atmosphere through respiration.
3. When plants and animals die in an
ecosystem, CO2 gas is returned to
the atmosphere during
decomposition.
3. Fossil fuels (Coal, oil, natural gas
which were once living organic
material) when burned produce CO2
gas and this is returned to the
atmosphere and increases the
amount of CO2 gas in the air.
The Nitrogen Cycle
1.
2.
Draw this in your notes.
3.
4.
5.
Producers (plants) absorb these
forms through their roots.
Nitrogen fixation: actions by
some bacteria & lightning change
N2 gas into ammonia (NH4+) and
nitrate ions (NO3-).
Consumers (herbivores) obtain
nitrogen from the plants they
eat.
Decomposers break down animal
waste, dead animals, & dead
plant material & return the
nitrogen to the soil.
Other bacteria return nitrogen in
the soil back to the atmosphere
(denitrification)
Ecological Succession
Ecological Succession

The gradual replacement of an existing
environment by another.
Primary Succession: when
a community develops where
there was none before.

Pioneer Organisms/Species : The first species to
populate an area.
Secondary Succession: when an existing
community is disturbed or destroyed without
removing the soil and a new community begins.
Populations
Chapter 5
Three Characteristics of a
Population
1. Geographic Distribution – describes area
inhabited by a population
2. Density : # of individuals per unit area
3. Growth Rate : rate at which population
changes in size
Factors that affect Size of a
Population
1.Birth Rate
2.Death Rate
3.Immigration – People moving into an area
4.Emigration – People moving out of an area
Limits to a Population


1. Carrying Capacity: the number of
organisms that an enviroment can
support.
2. Limiting Factors: something that
could cause a population growth to
decrease. There are 2 types of
limiting factors – Density-Dependent
and Density-Independent.
Density-dependent Factors
(affect larger populations)
1.Competition
2.Predation
3.Parasitism
4.Disease brought on not
only by bacteria but also
by stress, overcrowding
etc.
(ex: Indian tigers fighting over land as
it becomes less available, causes
stress and they won’t mate)
Density-Independent Factors
1. Unusual Weather (drought, freeze)
2. Natural Disasters (Tsunami, Earthquake, Forest Fires,
Floods)
3. Seasonal Cycles (Hurricanes)
4. Human Activities (deforestation, pollution, overhunting, industrial growth, urban dev.)
Renewable & Non-Renewable Resources
Renewable: can be
regenerated or replenished
but not necessarily unlimited.
Ex: trees, water

Non-Renewable: can’t
be replenished
Ex: fossil fuels such as
coal, oil and
natural gas
Biodiversity
The variety of organisms in the biosphere
Has provided us with a variety of foods, industrial
products and medicines inc. painkillers,
antibiotics, heart medications, antidepressants
and anticancer drugs.
Threats to the Biodiversity can lead to species
becoming endangered even extinct.
Examples of threats are altering habitats,
overhunting, introduction toxic compounds into
food webs and introduction of foreign species to
new environments.