Section 2 – How Species Interact with Each Other
An Organism’s Niche
What is a niche?
- The
unique role of a species within an ecosystem
What does a niche include?
- Species
physical home, the environmental factors necessary for the species’
survival, and all of the species’
interactions with other organisms
What is a habitat?
- An
organism’s location
How is a niche related to habitat?
- Niche
is a pattern of use of an organism’s habitat
What niche of large grazing herbivore is similar in which
two species?
- American
bison and kangaroo – large grazing herbivore
Ways in Which Species Interact
How are interactions between species categorized?
- At the
level where one population interacts with another
What are the 5 major types of interactions?
- Competition,
predation, parasitism, mutualism, commensalism
What are the categories of interactions based on?
- Whether
each species causes benefit or harm to the other species
Competition
What is competition and what is its result?
- Relationship
in which different individuals or populations attempt to use the same
limited resource – each individual has less access to resources and so is
harmed by the competition
How can competition occur?
- Within
and between species
How do members of the same species compete?
- Require
same resources – same niche
What is called when two species compete?
- overlap
Indirect Competition
Explain how species can compete even if they never come into
direct contact with each other?
- If two
species use the same resource, but at different times of the day
Adaptations to Competition
What is one of the ways competition can be reduced between
species?
- Dividing
up the niche in time or space
What is niche restriction and when is it observed?
- When
each species uses less of the niche than they are capable of using, in
closely related species that use the same resources within a habitat
Explain how the barnacles use niche restriction?
- Two
species of barnacles divide space.
One (C. stellus) is found in upper level of intertidal zone and
other in deeper (S. balanoides).
When deeper one is not present the upper level one (C. stellus)
will occupy all levels
Predation
What is a predator?
- An
organism that feeds on another organism
What is prey?
- The
organism that is fed upon
In complex food webs what may happen to predators?
- They may
become prey
What have most organisms evolved against predators?
- Mechanisms
to avoid or defend against predators
Explain how the Canadian lynx and the snowshoe hare are
linked?
- Lynx
feeds mainly on hares and so its population shows linked patterns – as one
goes up so goes the other and vice versa
Case Study – Predator Prey Adaptations
Since most organisms are vulnerable to predation, what is
there pressure for?
- Adaptations
that serve as defenses against predators
What is camouflage?
- Disguise
so that organisms are hard to see even when they are in view
What were the examples of camouflage?
- Black
stripes across the eyes, dark bands of color
What animals wait for their prey and how are they
camouflaged?
- Praying
mantises and frogs – so prey does not notice them waiting to attack
What often contain toxic chemicals?
- plants
What do animals with toxic defenses usually have?
- Striking
coloration
Which predators does warning coloration work well against?
- Ones
that can learn and that have good vision
What is mimicry and its advantage?
- When
one species resembles another – the more individual organisms that have
the same pattern, the less chance of any one organism being killed. Predator also learn to avoid all animals
with similar warning patterns
What is a simple defense against predators and give
examples?
- Protective
covering, quills of porcupine, spines of cactus, shell of turtle
Parasitism
What is a parasite?
- An
organism that lives in or on another organism and feeds on the other
organism
What is a host?
- The
organism the parasite takes its nourishment from
What is parasitism?
- The
relationship between the parasite and its host
What are examples of parasites?
- Ticks,
fleas, tapeworms, heartworms, bloodsucking leeches, and mistletoe
Why do parasites usually not kill its host?
- Have
an evolutionary advantage if they do not
What may happen to the host because of the parasite?
- Weakened
or exposed to disease
Mutualism
What is mutualism?
- A
close relationship between two species in which each species provides a
benefit to the other
What do mutualistic bacteria in you intestine do for you?
- Help
break down food you could not digest, produce vitamins your body could not
What do you do for them?
- Warm,
food-rich habitat
How are the acacia trees and the ants mutualistic?
- Trees
provide ants shelter and food , ants defend the trees against herbivores
and other threats
Commensalism
What is commensalism?
- Relationship
in which one species benefits and the other species is neither harmed nor
helped
How are remoras and sharks commensalistic?
- Remoras
attach to sharks and feed on scraps or food left over from shark’s meals
How are birds nest in trees commensalistic and how could it
possibly not be?
- If
birds do not cause harm to trees – might cause damage to tree
Symbiosis and Coevolution
What is symbiosis?
- A
relationship in which two organisms live in close association
Why do organisms coevolve?
- To
reduce the harm or improve the benefit of the relationship
