Relationships Are Complicated!
Where we live and what we do


Habitat: Where an organism lives and all the
resources (biotic and abiotic) it needs to survive
Niche: The species’ role in its environment
 e.g., type of food, predators, ability to reproduce,
habitat needs
 Competition: When organisms attempt to use the
same resource in the same place and time
 Competitive exclusion principle: No two species
can occupy the same niche in the same habitat
at the same time.
What Is Symbiosis?

Symbiosis: a close ecological relationship
between the individuals of two (or more) different
species (sym = together; bio = life)

Competition: Both organisms are harmed

Mutualism: Both organisms benefit




Commensalism: One organism benefits, other is
unaffected
Parasitism: Parasite benefits, host is harmed (but
not killed)
Predation: Predator benefits, prey is killed
Herbivory: Herbivore benefits, plant is harmed or
killed
Competition
http://elementy.ru/images/eltbook/competitive_exclusion_principle_520.jpg
Two
flowering
plants that
compete
for the
same
space
(both are
harmed
due to
energy
expense).
Competition – introduced species
Eastern Bluebird losing numbers
to the House Sparrow, a nonnative species
http://my.core.com/~paper-images/Eastern_Bluebird022v.jpg
http://photogallery.canberrabirds.org.au/images/Sparrow_House_Dabb.jpg
Competition – introduced species
•
Kudzu was introduced to the
•
•
•
United States in 1876 at the
Centennial Exposition in
Philadelphia, PA.
Kudzu “outcompetes” other
native plants so they don’t
have a place to grow.
&imgrefurl=http://www.yahoolavista.com/kudzu/&h=288&w=432&sz=35&hl=en&start=11&tbnid=tp85kKj4SEtsvM:&tbnh=84&tb
nw=126&prev=/images%3Fq%3Dkudzu%26svnum%3D10%26hl%3Den%26lr%3D
Mutualism - Clownfish and Anemone
The anemone protects the clownfish, and the
clownfish keeps the anemone free from dirt and
debris
Clown Fish
http://www.bigfishhooked.com/clown_fish_and_anenome.jpg
Mutualism - Dove and cactus
Cactus provides fruit for the dove; dove eats the fruit
(including the seed) and transports the seed (along a dose
of fertilizer!) to a new location.
Oxpecker and Ox
Oxpecker feeds on ectoparasites of the cattle (such as
ticks) and warns the animals of approaching predators
Mutualism – Caterpillar and ants
Caterpillar feeds the ants with drops of honeydew,
Ant &
ants protect caterpillar from predators
Catepillar Movie
Commensalism - Cattle Egret and
Cattle
Cattle stir up insects, which the egrets eat
Commensalism - Shark and Remora
Remora (attached by a sucker) gets a ride on the shark,
sometimes also gets food dropped by shark
Commensalism – whale and barnacle
The barnacle larvae swim around, attach to the whale, and
form the adult; whale habitat is good location for finding food
Parasitism – Cuckoo & Small
Nesting Birds
Cuckoo lays egg in host’s nest to be
raised by host (and kills host’s eggs)
YouTube:
Cuckoo Bird & Duck
Parasitism - Leeches and Mammals
Leech feeds on blood of mammal host
Parasitism - Tapeworm and Mammal
http://gecko.gc.maricopa.edu
/~lsola/bio182/labreview/plat
yhelminthes/tapeworm.jpg
Tapeworm feeds off digestive tract of
mammal
Predation – Spider and prey insects
In this Predator-Prey
relationship, the
spider is eating an
insect that it has
trapped.
http://www.flickr.com/photos/flashmaggie/50552812/
Predation – Snake and mouse
• The snake is the only one benefiting in this
relationship!
The Ultimate Predator – a Wildcat!
http://www.birdsasart.com/cheetah-w-prey-_T9J1935-Sambura-WR,-Kenya.jpg
Predator/Prey “Arms Race”

Predators and prey are involved in an everescalating evolutionary “arms race”!



e.g., antelope gets faster, so cheetah gets faster
For many populations predation is the main cause
of death.
BUT the prey determines the predator population


When the prey population increases, predator
population increases
When prey population decreases, predator population
decreases