Transcript Biotic Factors - hrsbstaff.ednet.ns.ca

Biotic Factors
Science 10
Biotic factors

1.
2.
3.
4.
5.
Are factors that affect the living environment
and include all other organisms that interact
with the individual (either the same species
and/or other species).
There are 5 biotic factors:
Detritus: decomposing animals and plants
Disease
Predator/prey interactions
Competition
Symbiotic relationships (symbiosis).
1. Detritus
 Refers to non-living
organic material such as
decomposing dead
organisms as well as
their wastes.
Example:
Sea Foam is caused by
decaying organic
material in the ocean,
such as the dissolved
waste of algal blooms.
Organic pollution from
run off water can also
increase foam
production.
Detritivores or Saprobes
 Obtain nutrients by consuming
detritus (decomposing organic
matter).
Examples:
millipedes, woodlice, terrestrial
worms, burying beetles
 Micro-organisms such as
bacteria, fungi, and protists are
important to an ecosystem
because they recycle materials
by “breaking” them down into
their “elements” and returning
them to the soil (so plants can
use these nutrients).
2. Disease
 is the result of an
infection by fungi,
bacteria, virus, and other
pathogens.
Pathogen:
an infectious agent, or
more commonly “germ”,
is a biological agent that
causes disease or illness
to its host.
 Disease is an important
biotic factor because
disease tends to reduce
the number of organisms
within the community.
3. Predator-Prey Interaction
(Predation)
 is another important biotic factor which helps to limit
the size of populations within an ecosystem.
 Predation occurs when one animal (the predator) eats
another living animal (the prey) to utilize (or use) the
energy and nutrients from the body of the prey for its
own growth, maintenance, or reproduction.
Example of Predation
Jaguar and Tapir (Belize)
 When a jaguar kills a
tapir for food, the jaguar
helps to prevent the
overpopulation of the
tapir.
 If the number of tapir
declines too much the
jaguar will starve.
  there is a balance
between the numbers of
predator and prey in any
ecosystem.
4. Competition
 Is a struggle for survival that occurs (or
happens) between organisms either of
the same or different species.
 Competition tends to limit the size of the
population keeping it in balance with the
available resources.
2 Types of Competition
1. Inter-Specific Competition: competition
between different species.
Example: Lion and hyena or bear and wolf
competing for food
2. Intra-Specific Competition: competition
between species.
Example: Tigers competing for mates or
birds competing for nesting space.
5. Symbiotic Relationships


1.
2.
3.
4.
5.
Are biotic relationships in which different
organisms live in close association with each
other to the benefit of at least one.
There are 5 types of symbiotic relationships
including:
Mutualism
Commensalism
Parasitism
Parisitoidism
Predation.
Mutualism
 resulting in mutual benefit
to both of the organisms in
the relationship.
 An example of this would
be the relationship
between the algae and
fungus of lichens.
 The fungi penetrate the
roots of the plants and
makes soil nitrogen
available to the plant,
receiving carbohydrates in
return. This allows them to
live in an environment in
which neither could survive
alone.
 An example is a
polyp found in the
deep water off the
coast of
Newfoundland
 It attaches itself to
the shell of a certain
species of the hermit
crab, and by
budding, covers the
entire shell with a
colony that dissolves
the original shell.
 Because the colony
grows at the same rate
as the crab, it provides
continuous protection,
and the crab does not
shed its shell at periodic
(varying) intervals as it
normally would.
 The polyp in turn
benefits by moving
around with the crab
(mobile) thus obtaining a
greater food supply then
it would obtain if
attached to a stationary
object (immobile).
Commensalism
 relationship in which one organism
benefits from the relationship but the
other organism seems to neither be
harmed nor benefits.
 An example of
commensalism is
the relationship
between trees and
nesting birds.
 The tree provides a
nesting space for the
bird but the bird may
neither harm nor
benefit the tree.
 On the other hand, if the bird eats insects
that normally cause harm to the tree or if
the bird produces wastes that are
absorbed by the tree, one might argue
that the tree and the bird both benefit.
 In this case the example would be
considered mutualism.
 It is often difficult to determine the
complete nature of any relationship and
as a result it is often difficult to distinguish
between mutualism and commensalism.
 The anemonefish lives
among the forest of
tentacles of an
anemone and is
protected from
potential predators not
immune to the sting of
the anemone.
 The anemonefish is
protected from the
sting of the anomone
tentacles by a
substance contained in
the mucous on its skin.
 The anemone treats
the fish as part of itself
and does not sting it.
Parasitism
 is a symbiotic relationship in which one
organism benefits and the other is harmed.
 The organism that benefits is called the
parasite, the organism that is harmed is called
the host.
 Some parasites only cause slight damage to
their host, while others kill them.
 An example would be the tapeworm. They live
in the digestive tracts of various organisms,
while there they are provided with nutrients and
an environment in which to grow and
reproduce.
 However, the host is harmed by the presence
of the tapeworm.
Parisitoidism
 similar to parasitism. One organism
benefits but the other is eventually killed
- a sort of slow death.
 An example is when
a female wasp stings
a spider causing
paralysis but not
death.
 The wasp then lays a
single egg on the
spider.
 When the egg
hatches into a larva,
it slowly eats the
body of the spider
eventually killing it but slowly.
Predation
 is where the interaction is beneficial to
one species and detrimental to the other.
 This is not always considered a symbiotic
relationship, although it is quite similar to
parasitism, except for the degree of harm
to the host or prey.
 With predation, the prey is killed.
 An example
of predation
is when a lion
kills an
antelope and
eats it as its
source of
food.