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We will give an overview on the interrelations of organisms with their environment upon which determine distribution and abundance of organisms.
1.
Introduction to Ecology
2.
Organism
An individual living thing
Species
A group of the same organisms that
are able to breed and produce fertile
organisms.
3.
Ecology
The study of organisms and their
interrelationships with their
environment (biotic and abiotic)
upon which determine distribution
and abundance of organisms.
4.
Habitat
A place where an organism lives or
can be found.
5.
Ecosystem
An interacting system that consists
of groups of organisms and their
non-living environment with in a
boundary.
6.
Two parts of an Ecosystem
Biotic and Abiotic
Biotic –
– factors that are or were alive/living in
an ecosystem.
Examples: animals, plants, insects,
bacteria, fungi, and dead organisms.
7.
Abiotic
Factors in an environment that are
not or never were alive.
Examples: rock island, gases, water,
sun, minerals and temperature.
8.
Levels of Biological Organization
It is important to remember that all
parts of an ecosystem are interrelated.
Each part is affected by all other parts.
If we remove one species from an
ecosystem, there could be severe
consequences for that ecosystem.
9.
Cont.
Ifwe remove all the spiders from a
given ecosystem, the insect
population will grow rapidly and
destroy forest and crops.
Who do you think would benefit?
What would happen to their
population?
Who would be affected then?
10.
Levels of Organization
Ecologists tend to label groups of
organisms.
Let’s look at a familiar setting for
example: Your house is part of a
town, this is part of a state, which is
part of a country, which is part of a
continent.
11.
Levels of Organization Cont.
No individual organism lives
completely on its own. It may live
with other individuals of the same
species to form a population.
Several populations living together
make up a community.
Several communities in a given area
make up a biome.
12.
Organization Cont.
Collectively, all the biomes of the planet earth
make up the biosphere.
Again, the most basic level of
ecological organization is the individual/species.
A group of individuals of the
same species make up a population.
A community is all the
populations of living
organisms in an area.
13.
Organization Cont.
A biome is a large geographical area
with a similar climate.
14.
Biosphere
The
biosphere is the region on Earth
where all life exists.
Biodiversity is the degree of variation
of life.
It is a measure of the variety of organisms present in
different ecosystems.
This can refer to genetic variation, ecosystem variation, or
species variation (number of species) within an area,
biome, or planet.
15.
Habitat and Niche
Each organism confronts the
challenge of survival in a different
way.
The niche an organism occupies is
the sum of all the ways it utilizes the
resources of its environment.
Part of this role may be played as
the predator and part may be played
as the prey.
16.
Niche
Example: Snakes eat mice and other
birds and rodents but snakes are
also eaten by birds of prey and mice
eat grasshoppers and other insects.
17.
Niche
A niche may be described in terms of
space utilization, food consumption,
temperature range and mating
requirements.
An organism’s niche would also take
into account its behavior. You can
think of an organism’s niche as its
job/role in the environment.
18.
Niche
A beaver is an ecosystem engineer. It
cuts down trees and dams up a river
which will flood the forest with a pond.
Eventually the trees will dies, new species
of plants and wildlife will arrive to take
advantage of the new conditions.
Eventually, this forest will become a
meadow. The beaver’s NICHE is the role
it plays in shaping the environment. But…
it is also a main prey species for
predators.
19.
Habitat
Niche is not synonymous with habitat.
Habitat is a place, niche is a pattern of
living. Habitat is the address and niche is
the job or occupation.
If two organisms have the same habitat
and similar niches, they will compete with
each other over the available resources.
(food- water -shelter)
20.
Habitat
Competition is the struggle between two
organisms within their habitat.
If a species can avoid competing they may
co-exist. But if they compete, one will
eventually drive the other out of the
habitat, unless they have slightly different
niches.
Example: times of activity
21.
Different Niches to avoid
competiton:
Nocturnal – active at night
Diurnal - active during the day
Crepuscular – active at dawn and
dusk
22.
Competitive Exclusion
If two different species compete for
the same food source or reproductive
sites, one species may be eliminated.
This establishes one species per
niche in a community.
23.
Different Niches to avoid
competiton: cont…
Migration– moving from one area to
another to use resources
Hibernation – reducing activity
severely for a period of time.
24.
Ecological Succession
Ecological succession is the observed
process of change in the species
structure of an ecological community
over time.
Two different types of succession—
primary and secondary—have been
distinguished.
25.
Primary Succession
Primary succession occurs in
essentially lifeless areas—regions in
which the soil is incapable of
sustaining life as a result of such
factors as lava flows, newly formed
sand dunes, or rocks left from a
retreating glacier.
26.
Secondary Succession
Secondary succession occurs in areas
where a community that previously
existed has been removed; it is
typified by smaller-scale
disturbances that do not eliminate all
life and nutrients from the
environment.
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