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The Biology of Ecosystems
"When we try to pick out anything
by itself, we find it hitched to
everything else in the universe."
John Muir
What would happen if all the lions on an
African savanna were killed or removed?
Flora and Fauna?
Ecosystem -- all the different organisms
that live in a certain area (the biotic),
along with the abiotic factors.
Often times these systems do
not have clear boundaries.
Organisms and Species -- An organism is an
individual living thing. A species is a group of
organisms that are able to produce fertile
offspring and share common genes. For
Example: Mr. Black-Organism, Homo SapiensSpecies; Fido-Organism, Canine DomesticusSpecies.
Population - is a group of individuals of the
same species living in a particular place.
(Humans living in New Castle)
Community- a group of interacting populations
of different species.
Examples: pond community, desert community,
forest community, etc.
Niche - an organism’s way of life. All of its
relationships with its environment.
Environment consists of what?
•All living things (biotic)
•All nonliving things (abiotic)
A Habitat - the actual place that an
animal lives.
What is the difference between a Habitat
and a Niche?
What is the job of a lion?
•Control the population of prey
What is the job of a gazelle?
•Food source for predators
•Control the plant growth on
the savanna
Does a lion serve a purpose for its prey?
Refining gene traits.
•Faster prey will survive
•Those with better camouflage will
avoid becoming prey
•Those who don’t need to move
around much more often
Ecological Interactions
How Species Interact With Each
other
I. Predation - when one organism kills
and eats another organism
Predator does the eating. Prey is
eaten.
Natural Selection- only animals that are
the fastest, strongest and healthiest are
able to live on and reproduce. Thereby
increasing desirable gene traits in their
offspring
II. Competition - occurs when two or
more organisms of the same or different
species attempt to use the same limited
resources.
List examples:
sunlight, scavengers, exotic species,
vines (kudzu), Pandas.
Can happen even if they never come into
contact:
(Pollinators and nocturnal and daytime
feeders.)
III. Parasitism - the relationship when
organisms live in or on another organism
without immediately killing the organism.
(Gee-- I wonder Why?)
A Host - the organism that the parasite
gets its nourishment from.
Most organisms are negatively affected
by parasites. They may be weakened by
parasitic relationships hence making them
more vulnerable to predators.
List Examples:
IV.
Mutualism - is a cooperative
partnership between two species in
which both benefit.
List Examples:
Our intestines have millions of bacterium
living inside. They help us digest food
and produce Vitamin K that aids in blood
clotting.
We provide living arrangements and food
.......they help us digest food.
V. Commensalism - is a relationship in
which one species benefits and the other
is neither helped nor harmed.
Remoras are fish that attach themselves
to sharks and eat the scraps food that
float around a shark when it is eating.
The Remora benefits and the shark is
neither harmed of helped.
Why is it advantageous for a parasite to
not kill its host?
How could you show a suspected case of
mutualism is not commenselism?
Adapting to the Environment
Adapting to the environment occurs
in three ways
•
I. Evolution through Natural
Selection
•
II. Co-evolution
•
III. Extinction
I. Evolution by Natural Selection:
1. All organisms have the ability to
produce more offspring than can
possibly survive. Ex.: Fish and frogs
lay millions of eggs. Most do not survive
or there would be millions of fish and frog
offspring from one individual.
2. The environment contains things
that kill organisms. The environment is
often hostile: hot/cold dry/flooded.
Predators are common - competition
limits resources. Darwin called this a
“struggle for existence”
3. Individuals vary in their traits. They
may differ in size color, speed, resistance
to disease and many other traits. This
may be an inherited factor to influence
natural selection.
4. Some inherited traits may give
individuals an advantage in coping
with environmental challenges. This
allows them to survive longer and
produce more offspring. They are
naturally selected for survival
5. More species with advantageous
traits have more offspring; each new
generation has more offspring with the
advantageous traits than the previous
generation. Gradually, over many
generations, that species evolves by
natural selection…
This is a form of adaptation - an inherited
trait that increases an organism’s chance
of survival.
II. Co-evolution
When two species evolve in response to
each other. Predator/ Prey relationships
often spur this type of co-evolution.
Why?
Plants and herbivores - plants
cannot move hence they
develop toxic responses. Over
time the herbivore develops a
resistance to the toxicity.
Crabs and snails: The stronger the claws
get on a crab, the harder the shell gets on
the snail.
Why?
III. Extinction
The species simply ceases to exist.
Evolution is the change over time and
adaptation is the trait that is changed