4. What Is An Ecosystem
An ecosystem is a natural unit
consisting of all plants, animals and
micro-organisms (biotic factors) in an
area functioning together with all of
the non-living physical (abiotic)
factors of the environment.
5. Types Of Ecosystem
Natural
1.Terrestrial ecosystems (grasslands, forests,
desert ecosystems)
2.Aquatic ecosystem
a. Lentic (Stagnant water) like lake, ponds
b. Lotic (Flowing water) like river, ocean.
Artificial
1.A crop land, garden, aquarium, park,
kitchen garden.
6. Components
Abiotic or Non-living components.
1. Inorganic substances
2. Organic compounds
3. Climatic factors
Biotic or Living components.
1. Autotrophs or Producers
2. Heterotrophs or Consumers
3. Decomposers or Saprotrophs
7. Ecosystem and Organism Interactions
An ecosystem is a defined space in which interactions
take place between a community, with all its complex
interrelationships, and the physical environment.
A community is an assemblage of all interacting
species of organisms in an area.
Organisms Populations Community
Comuni
8. The particular place where a population of a
living thing lives is called its habitat. A
population is a group of animals from the
same species that lives in the same space,
such as a population of gorillas in a mountain
range. A habitat can be as big as a rainforest
or as small as a burrow, depending on how
much space the population needs.
A niche is a set of conditions
within which an organism
can maintain a viable popultion
10. It is a struggle between organisms as they attempt to
use the same limited resource
Occurs when two species occupy
the same niche
Why can’t two species occupy the same niche?
If two species occupy the same niche, they will
compete directly against each other and one
species will eventually die off
11. Competition
It occurs when two or
more individuals seek
to utilize the same
limited resource
An example is the
African driver ants
(Hymenoptera) that out
compete and consume
everything that crosses
its path.
12. Competition
Competition is a kind of interaction in which two
organisms strive to obtain the same limited resource.
Intraspecific competition is competition between
members of same species.
Interspecific competition is competition between
members of different species.
13. Competition
The competitive
exclusion principle
holds that no two
species can occupy
the same ecological
niche in the same
place at the same
time.
Less-fit species
must evolve into
a slightly
different niche.
14. Complete competitors cannot coexist
Competitive exclusion is reached more slowly with
higher resource abundances
Stable coexistence requires niche differentiation,
such that members of each species compete more
strongly among themselves than with members of
the other species.
Therefore the level of intraspecific competition is
always greater than interspecific competition
15. Symbiosis
Symbiosis is a close
ecological relationship
between the individuals
of two or more species.
Sometimes a symbiotic
relationship benefits both
species
Mutualism,
commensalism,
parasitism, cooperation
Bees (Hymenoptera) and
Plants
16. Symbiotic Relationships
Symbiosis is a close, long-lasting, physical relationship
between two different species. At least one species
derives benefit from the interaction.
There are three categories of symbiotic relationships:
Parasitism
Commensalism
Mutualism
17. Symbiotic Relationships
Parasitism is a relationship in which one organism
(parasite) lives in or on another organism (host), from
which it derives nourishment.
Ecto-parasites live on the host’s surface.
Fleas, lice, molds, mildews
Endo-parasites live inside the body of the host.
Tapeworms, malaria parasites, bacteria, fungi
18. Symbiotic Relationships
Commensalism is a relationship in which one
organism benefits while the other is not affected.
Remoras and sharks
Mutualism is a relationship in which both species
benefit. The relationship is obligatory in many
cases, as neither can exist without the other.
Mycorrhizae
19. Mutualism and Symbiosis
Mutualism is an association
between organisms of two
different species in which
each member benefits.
Ants (Hymenoptera) protect
the aphids (Aphididae) and
the aphids provide
honeydew for the ants
20. Commensalism and Symbiosis
Commensalism is a symbiotic
relationship between two organisms
of different species in which one
derives some benefit while the
other is unaffected.
E.g. remoras and shark
21. Parasitism and Symbiosis
Parasitism is a form of symbiosis in which one species
benefits at the expense of another species; similar to
predation, but acts more slowly than predators and may
not always kill the host.
Tapeworms in the intestine of humans, transmitted
through infected food.
22. Symbionts
These are organisms that live in or on other organisms.
More than half of the millions of species that live on Earth
are symbionts.
Human body is a habitat to many micro species.
23. Predator and Prey
Predation describes an
interaction where a
predator species kills and
eats other organisms, known
as prey.
Sometimes, predators
themselves become preys
e.g. when a praying mantis
captures grasshopper and
the anole captures and eats
praying mantis.
25. Producers provide energy for other
organisms in an ecosystem.
Producers = Plants
Producers are also
known as autotrophs.
Producers need sunlight
to make food.
The sun is their main
source of energy.
Consumers = Everything else!
Consumers are also
known as heterotrophs.
Energy flows from
producers to consumers.
30. Almost all producers obtain energy from
sunlight.
Chemosynthesis
In 1977, scientists
discovered the first
prokaryotes (archaea)
that did NOT need
sunlight to make food.
Instead, these
prokaryotes utilized
the chemicals in the
water to form
carbohydrates—this is
called
chemosynthesis.
32. Food Chains
A food chain is a
sequence that links
species by their
feeding
relationships.
33. Types of Consumers
Herbivores
Eat only plants
Carnivores
Eat only meat (includes insects)
Omnivores
Eat both plants and animals
(includes insects)
Detritivores
Eat detritus, or dead organic
matter
Decomposers
Are detritivores that break
down organic matter into
simpler compounds
34. Types of Consumers
Specialist
A consumer that
primarily eats
one specific
organism or
feed on a very
small number of
organisms.
Generalist
Consumers that
have a varying
diet.
Giant Pandas are
specialists. Over
95% of their diet
comes from bamboo.
If bamboo became
scarce, the Panda
would be in danger of
extinction.
Raccoons are
generalists.
They can live
almost
anywhere, and
eat almost
anything.
36. Trophic Levels
Producers
Basis of all trophic levels.
Primary consumers
herbivores
Secondary consumers
carnivores that eat
herbivores.
Tertiary consumers
carnivores that eat
secondary consumers.
Omnivores
May be listed at different
trophic levels in different
food chains.
37. food webs
A food web is a model
that shows the complex
network of feeding
relationships and the
flow of energy within
and sometimes beyond
an ecosystems.
At each link in a
food web, some
energy is stored
within an organism,
and some energy is
dissipated into the
environment.
38. Food Webs
The stability of any food
web depends on the
presence of producers,
as they form the base of
the food web.
The mouse is both a primary
and secondary consumer
because it eats both plants and
insects in this food web.
40. An energy pyramid shows the distribution of
energy among trophic levels.
Sunlight provides the energy for photosynthesis,
and that energy flows up the food chain. Along the
way, some of the energy is dissipated, or lost.
41. Loss of Available Energy
Biomass is a measure of the total mass of organisms in a given area.
When a consumer incorporates the biomass of a producer to its own
biomass, a great deal of energy is lost in the process as heat and
waste.
The dissipation, or loss, of energy from one trophic level to the
next may be as much as 90%.
Only 10% of the available energy is left to transfer from one
trophic level to the next.
42. Energy Pyramids
Because energy is lost at each
stage of a food chain, the
longer the chain is, the more
energy is lost overall.
The total energy used by
producers far exceeds the
energy used by the
consumers they support.
An energy pyramid is a
diagram that compares the
energy used by producers,
primary consumers, and
other trophic levels.
43. Other pyramid models illustrate an
ecosystem’s biomass and distribution of
organisms.
Biomass pyramid
Diagram that compares the
biomass of different trophic
levels within an ecosystem.
Pyramid of numbers
Shows the number of individual
organisms at each trophic level in
an ecosystem.
5,000,0000
500,000
5,000
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