Ecology:

The study of Interactions among
Organisms and its environment
including:
Abiotic factors are nonliving factors
such as temp. soil, air, rocks
 Biotic Factors are living parts of the
ecosystem

Populations vs. Communities:


A population is a group of organisms
of the same species living in a certain
area
All populations interacting together in
a given area is a community

Ex. Frogs + fish + algae = community
Habitats are:
Place in the ecosystem where an
organism lives
 Determined by both biotic and
abiotic factors


Ex. Earthworm = moist soil, dead organic
material
Niche:
The role of the organism in its
environment
 Includes feeding habits,
reproduction, habitat, and what it
contributes to its surrounding

Ecosystem is a
community and its
physical environment
including biotic and
abiotic factors
Autotrophic
and
Heterotrophic
Nutrition:
Autotrophs:



Make their own food PRODUCERS
Provide food to consumers
Most carry out photosynthesis (solar light
energy being converted into food
glucose!!)


Ex. Green Plants!!
Some producers are chemosynthetic –
ability to create food by using energy stored
in inorganic molecules
Autotrophs:
Heterotrophs:
Are also known as consumers
 Cannot make their own food
 Must obtain their food from
their environment

Heterotrophs:
Types of Heterotrophs include:
Herbivores
eat only
plants
Types of Heterotrophs include:
carnivores eat only meat

predators- kill and eat their prey

prey - the animal that is killed and
eaten
scavengers feed on dead and
decaying meat
 ex. Buzzards, crows, hyenas

Types of Heterotrophs include:
omnivores – eat both plant and
animals

ex. US!!, bears and…???
Types of Heterotrophs include:
Decomposers
(aka. saprobes)
get nutrients
from breaking
down dead
plants
& animals

Ex. bacteria, fungus, mushrooms
Symbiosis
(Symbiotic Relationships):
2 organisms living
together where at
least 1 organism
benefits
3 types of symbiotic
relationships:
Mutualism
2. Commensalism
3. Parasitism
1.
Mutualism




mutualism - both organisms
benefit from the association
Ex. Humans and bacteria in the
digestive track
Ex. Fish in sea anemones
Ex. Flower and the bee
Commensalism



Commensalism - one organism
benefits the other is not effected
(not harmed, no benefit)
ex. Remora fish and sharks
ex. Orchids/moss living in tree
Parasitism:



Parasitism - one organism
benefits at the cost of the
other (host)
ex. parasites living in
animals (tapeworm, tick)
often cause disease
Energy Flow in an Ecosystem:
Includes:
 producers (Autotrophs ) make their
own food
 consumers (heterotrophs) obtain or
eat their food from the environment
 Decomposers (a.k.a saprobes ) break
down left over remains of plants and
animals
FOOD CHAINS:


Are a transfer or 1
pathway of energy
through an ecosystem
Solar Energy from the
sun is converted by
producers
(photosynthesis) into
chemical energy or
FOOD
FOOD CHAINS cont…

Show the relationship b/w Producers and
Consumers



Energy is transferred from the producer to the
consumer that eats it.
Herbivores are first order consumers gaining the
most energy from the producers
Omnivores and Carnivores are secondary
consumers getting left over energy
FOOD CHAINS cont…


The feeding relationship shows the transfer
of energy which forms a food chain
The transfer of energy moves from producer
to consumer to decomposers

Ex. Sun plant  grasshopper  bird  cat
Decomposers
Examples of food chains:
Producers
(plants)
consumers
(1st level)
consumers
(2nd level)
Grass grasshoppers robins 
consumers
(3rd level)
hawk
FOOD WEB


food chains (1 pathway of energy)
which are interconnected = food webs
Food webs are many food chains
interacting together
Each arrow in the food web means
consumed (EATEN) by…
FOOD WEB
Energy Pyramids ARE:
Another way
of showing
the flow of
energy in an
ecosystem
Energy Pyramids
Each step in a feeding relationship is
called a trophic level
1st trophic level = producers
 2nd trophic level = primary
consumers
 3rd trophic level = secondary
consumers

The greatest amount of energy is at
the bottom of the pyramid
(producers), the least amount of
energy is at the top.
90% of
Energy is lost
moving at
each level,
only 10% is
transferred to
the next level
Some of the Energy is used in cell
activities (growth, cell division), the
rest is lost as heat
The Carbon Cycle:

An exchange of materials
(carbon dioxide, oxygen)
between autotrophs and
heterotrophs
The Carbon Cycle:
Cycles in Nature:

Autotrophs:
use the sun’s energy to produce their
own food in a process called
photosynthesis
 In photosynthesis CO2 is absorbed
(taken in) from the environment and
O2 (Oxygen) is released as a waste.

Cycles in Nature:

Heterotrophs:
take in the Oxygen and use it for
cellular activities
 Releases CO2 into the environment as a
waste
 The process is called cellular

respiration
The Carbon Cycle:
The Carbon Cycle is a balance between
Carbon Dioxide and Oxygen in the air.
Remember…
A population is a group of
organisms of the same
species living in a certain
area
Discussion on Populations:




change over time
Most stabilize rather than continuously
grow
As populations increase in #, it puts
more demand on the resources available
such as food, shelter, and water
Environmental factors that limit the size
of a population are called limiting factors.
Limiting Factors:
Environmental factors that
limit the size of a population
 The availability of resources


Ex. Food, water, shelter,
oxygen, sun
Density-Dependent Factors:

limit the growth of a population when the
population reaches a certain size


Ex. Disease, competition, predators, and
food
Population Density
The number of organisms in a given area
 Predation, competition, and the spread of
disease all are influenced by population
density

Question:
what happens to the level of
competition when the population
density increases?
Predation?
Disease?
Population Cont.

predator- prey population cycles
Density Independent Limiting
Factors:
limit growth in a population
regardless of size
 These factors are often climatic
events
 Ex. Extreme temp, drought,
volcanoes flooding

Carrying Capacity:


The largest number of organisms (of one
species) that can be supported for an
unlimited amount of time
Occurs when # of deaths and births are about
equal


If a population goes over the carrying capacity the
number of deaths is greater than the # of births
If the population is under the carrying capacity
then…
Carrying Capacity
Population Growth Rate Involves:

Birth and Death rate influences
the population growth
 Life expectancy of humans


Man-72 years
Woman-79 years
Population Growth Rate Involve:
Immigration-movement of
individuals into a population
 Emigration -movement of
individuals out of a population

Graphs & Populations
Exponential Model:
 Describes a population that
increases rapidly
after only a few generations
 The larger the population
gets, the faster it grows
 “J” shaped curve
Logistic Model:





Takes Limiting factors into account
Includes carrying capacity -the number of
individuals the environment can support over a
period of time
Increased birth rates causes growth rates to
increase
Growth will decrease when a population reaches
the carrying capacity.
Birth rate = Death rate when a population
reaches carrying capacity therefore GROWTH
Logistic Population Growth
After discussing topics in ecology
such as: the flow of energy, balance
among organisms and populations,
what type of impact do you feel
humans have on the environment?
Why?