Interactions of Life
Interaction
There are three main types of
interaction between organisms:
• Competition
• Predation
• Symbiosis
Competition
• Different species can share the same
habitat.
• Different species can share the same food
requirement.
• If two species share the same niche, the
result is competition and one will usually
squeeze the other out. Gause’s principle.
Competition
Who will be victorious?
Predation
• An interaction between
species in which one kills
and eats the other is called
predation
• Predators have adaptations
to help them catch prey
• Prey have adaptations to
help them avoid being
caught
Predation: Predator-Prey Relationships
• Exploitative Competition
• Predator: animals that feed on other animals (can
also be applied to herbivores feeding on plants)
• How is this Harmful to prey?
• How does this Benefit prey species?
• What is the Potential Benefit to Biotic
Community?
Predation
Predation
Predation: Linkage of predator and prey
population sizes
•
•
•
•
Decreased predator --> increased prey
Increased predator --> decreased prey
Decreased predator --> increased prey
Increased predator --> decreased prey
Interactions of Predator and Prey
Hydra Preys on Daphnia
Symbiosis
• A close relationship
between two species
that benefits at least
one of them.
• 3 types of symbiotic
relationships
– Mutualism
– Commensalism
– Parasitism
Mutualism:
• Symbiotic relationship where both species benefit
Mutualism
Mutualism: a relationship between two species where both benefit.
•
Butterflyweed provides food for
butterflies like pipevine
swallowtails.
•
Butterflies like pipevine swallowtails
pollinate butterflyweed.
Example of Mutualism
• Oxpeckers
tickbirds):
(aka
Example of Mutualism
• Acacias and Ants
Example of Mutualism
• Ants and Aphids
• www.insects.about.com/od
/coolandunusualinsects/f/a
ntsandaphids.htm
Mutualism
•
The acacia provides benefits to ants
– shelter (hollow thorns)
– nectar nectar (secreted near base of
leaves)
•
A mutualism between certain
ants and a small tree, the acacia.
The ant
– attacks and removes herbivorous insects
– removes vines that might overgrow the
acacia
– kills the growing shoots of nearby plants
that might become competitors.
– clears away leaf litter from near the plant
protecting the tree from fire damage as
well
Examples of Mutualism
• Termites and
Protozoans:
• Clownfish and Sea
Anemone:
Mutualism
•
Lichens grow in the leftover spots of the
natural world that are too harsh or limited
for most other organisms.
•
They are pioneers on bare rock, desert
sand, cleared soil, dead wood, animal
bones, rusty metal, and living bark.
"Lichens are fungi that have
discovered agriculture"-lichenologist Trevor Goward.
Mutualism
•
Lichens are composite, symbiotic
organisms made up from members of
as many as three kingdoms.
•
The dominant partner is a fungus.
Fungi are incapable of making their
own food. They usually provide for
themselves as parasites or
decomposers.
•
The lichen fungi (kingdom Fungi)
cultivate partners that manufacture
food by photosynthesis. Sometimes the
partners are algae (kingdom Protista),
other times cyanobacteria (kingdom
Monera), formerly called blue-green
algae. Some enterprising fungi exploit
both at once.
Commensalism
• Symbiotic relationship where one species
benefits and the other is neither helped nor
harmed
Commensalism
• Commensalism is a
relationship between two
species in which one species
obtains benefit from the other,
without harming or benefiting
it.
• The Antarctic scallop may have
a bush sponge attached near
the shell's peripheral margin.
The sponge is seeking the
water flow over the scallop
shell in order to facilitate its
own filter feeding.
Example of Commensalism
• Epiphytes:
Example of Commensalism
• Remora
Example of Commensalism
Barnacles on Whale
Symbiotic Interactions
• Symbiosis: close relationship between two
species
• Parasitism: symbiotic relationship where one
species benefits and the other is harmed
Parasitism
• The tomato hornworm
feeds on the foliage of the
tomato plant
Tomato hornworm
• The braconid wasp lays eggs
in a tomato hornworm.
• The eggs hatch into a wasp
larva that feeds on the
internal organs of the
hornworm.
• Pupa of the wasp form on
the skin of the hornworm
Braconid
wasps lay
eggs under
the skin of
the hornworm
Tomato
hornworm
with Braconid
wasp parasite
s (pupae).
Parasitism
•Mistletoe is a parasitic plant that grows
on trees, particularly hardwood trees like
oak and apple.
•As mistletoe grows on a tree, it sends
out its roots right into the tree's bark and
takes nutrients from the tree.
Mistletoe has solved the
problem of water by
growing as a parasite on
this tree. (photo R.K.
McConeghy)
This red
mistletoe is
growing from
the trunk of a
tree.
•Sometimes, mistletoe can harm a tree
and cause deformities in a tree's
branches, but usually it doesn't kill its
host. If the host dies, the mistletoe dies.
Mistletoe is a
parasitic plant
that grows on
trees.
Examples of Parasitism
• Sea Lampreys:
Examples of Parasitism
• Poison Ivy:
Human Parasites