ECOSYSTEMS
•An ECOSYSTEM is made of all the
living & nonliving things that interact in
a particular area
•Ecosystems can be
large or small
FACTORS THAT AFFECT THE GROWTH OF A
POPULATION
When conditions are good, a
population will generally increase.
But a population does not keep
growing forever. Eventually some
factor in its environment causes
the population to stop growing.
LIMITING FACTORS
• LIMITING FACTORS: Biotic and abiotic
factors that prevents a population from
increasing.
– Food
– Water
– Living space
– Temperature
– Predation
– Competition
Limiting Factors
• Environmental abiotic and biotic factors can
also be termed "Limiting Factors."
• They are limiting in that they tend to have the
least affect on those organisms which have
the best tolerance, or adaptation to the factor.
• At different times of the year, some abiotic
factors take on more importance than others.
These factors help to keep a population at or
below carrying capacity.
LIMITING FACTORS
FOOD & WATER
-When food is scarce, the
population numbers will
decrease from
starvation or low birth
numbers.
-When food if plentiful,
numbers increase because
of low death rates and high
birth rates.
LIMITING FACTORS
SPACE
-If the plant or animal does not have
enough room to reproduce and grow,
the numbers will decrease.
-When space is
plentiful, the population will increase.
LIMITING FACTORS
CLIMATE
-Conditions such as drought and temperature
changes can limit the population growth.
-Too cold, too hot, too wet, too dry all affect
population growth. Early frost can kill many
insects and plants.
-Favorable weather
conditions such as
seasonable temps,
rainfall etc, can
increase populations.
Predation
• Predation is the type of feeding relationship
in which one animal captures and eats
another animal for its food.
• Prey – is eaten
• Predator – captures and eats prey.
LIMITING FACTORS
Predator/Prey Relationship
Predation has a huge effect on the size and growth of a
population.
-If there are more predators or they are more efficient
at hunting techniques, then the prey species goes
down.
Predator/Prey Continued
-Predators affect prey species numbers and
prey species affect predators numbers.
• As predator numbers decrease, the prey
species numbers will increase due to less
predators in the
area.
PREDATOR/PREY RELATIONSHIP
Predators directly affect the population
of their prey and the prey directly affect
the population of the predator.
How is this possible?
PREDATOR/PREY RELATIONSHIP
25
20
DEER
15
10
MOUNTAIN
LIONS
5
YEARS
15
13
11
9
7
5
3
0
1
NUMBER OF DEER
OR MT LIONS
Deer & Mt Lions Population Over 15
Years
What is the carrying capacity of this ecosystem for
the rabbits? Fox?
Name the carrying capacity of this environment for
the wolves and the moose.
PREDATOR/PREY RELATIONSHIP
25
20
DEER
15
10
MOUNTAIN
LIONS
5
YEARS
15
13
11
9
7
5
3
0
1
NUMBER OF DEER
OR MT LIONS
Deer & Mt Lions Population Over 15
Years
PREDATOR/PREY RELATIONSHIP
Remember, when the prey species
goes up, the predator goes up
SHORTLY THEREAFTER.
When the prey species goes down,
the predators go down, SHORTLY
THEREAFTER.
LIMITING FACTORS
COMPETITION
-When two or more individuals or populations try
to use the same resources. Can occur within
populations or between populations
Limiting Factors
- When competition for resources is high (many
organisms fighting for the same one), populations
will decrease.
- When competition for resources is low, populations
will increase.
Competition
• Competition – occurs whenever more than
one individual or populations tries to make
use of the same limited resources.
LIMITING FACTORS
DISEASE
-When disease (fungal, parasitic, bacterial, viral)
is introduced to a population, population
numbers are affected. Only the strongest
individuals overcome the disease and survive.-
Limiting Factors
Introduced Species
Humans sometimes move organisms
to a location where they do not
belong. Sometimes they die, but
often they prosper. If the organism
has no predators, then its population
will grow.
• An example of this occurring is
the kudzu plant. It was
transplanted to America and
nothing eats it here.
• So, it grows out of control. This
causes native plants to loose the
space, sunlight and water supply
Brown Tree Snake
• Shortly after World War II, and before 1952, the brown
Treesnake was accidentally transported from its native
range in the South Pacific to Guam, probably as a
stowaway in ship cargo. As a result of abundant prey to
eat on Guam and the absence of natural predators and other
population controls, brown Treesnake populations grew.
Snakes caused the loss of most of the native forest
vertebrate species; thousands of power outages affecting
private, commercial, and military activities; widespread
loss of domestic birds and pets. Most songbirds of Guam
have gone extinct.
Brown Tree Snake
Cane Toad
Cane Toad
• Cane toads, introduced into Australia to control
beetles that were destroying sugarcane crops, are
still spreading across Australia. They failed to
control the cane beetles, and became a major pest
themselves. Cane toads can harm native wildlife
by eating small animals and poisoning larger
predators that try to eat them. Household pets are
also at risk from poisoning. So far, there is no
known way to control cane toads across large
areas, but scientists are searching for a biological
control agent that is specific to the toads.
Name the limiting factors in the pictures below:
CARRYING CAPACITY
• The maximum number of organisms an
ecosystem can successfully support.
Symbiosis
• Any close relationship between species.
Individuals in the relationship are either:
1. Helped 2. Unaffected 3. Harmed
Mutualism
• A relationship in which both species benefit
Zebra & oxpecker
Cleaner fish
www.orn.mpg.de
Lichens: algae + fungus
Commensalism
• A relationship in which one species benefits
and the other is neither helped nor harmed
Barnacles on whale
Shark & remora
Parasitism
• A relationship in which one organisms
benefits and the other is harmed. The
individual that benefits is called the
parasite, the one harmed is called the
host.
Tick
Mistletoe
Coevolution
The evolution of two species totally dependent on
each other. Coevolution is an extreme example of
mutualism.
Yucca flowers are a
certain shape so only
that tiny moth can
pollinate them. The
moths lay their eggs in
the yucca flowers and
the larvae (caterpillars)
live in the developing
ovary and eat yucca
seeds.
Yucca moths and yucca plants
Acacias are small, trees
that have large, hollow
thorns. The acacia ants
live in the thorns. On the
tips of its leaflets, the plant
makes a substance used
by the ants as food. The
ants defend the tree from
herbivores by
attacking/stinging any
animal that even
accidentally brushes up
against the plant. The ants
also prune off seedlings of
any other plants that sprout
under “their” tree
Acacia ants and acacia trees
Coevolution is often seen in a
number of species of flowering
plants that coevolved
with specific pollinators (insects,
bats, etc).
The pollinator gets a
reward such as nectar for
pollinating the plant.
Insects (beetles) on the
plant found this
protein/sugar mix and
used it as food.
Insects became dependent
on this food source and
started carrying pollen
from plant to plant.
Beetle-pollination must
have been more efficient
than wind for some
species, so there was
natural selection for
plants that attracted
insects.
Examples of Symbiosis
Examples of Symbiosis
Examples of Symbiosis
Tapeworm
Dustmite
Botfly
Limiting Factors ORQ Proficient
• 1. 900
• 2. Food, water, space, disease, competition,
predators, intro. New species, climate,
natural disaster. You must DECSRIBE how
the factors affected the population. NOT
list.
• 3.The adding of a new species would
decrease the squirrel population because
they would use all of the resources.
• 4. Yes the Earth has a carrying capacity
because the Earth has a limited number of
resources
Limiting Factors ORQ App. Or
Novice
1. Got the number wrong makes it a 1 or 2.
2. If they just listed – food, water, disease,
climate, intro new species, disaster, space.
If they just listed with no discussion or only
listed one or incorrect. 1 or a 2.
3. They did not say it went down. If they said
it went up or blank, it is a 1.
4. If they said the Earth had not capacity – 1
If they did not explain why - 2