Transcript Ch.17-1,2BiologComm

Ch. 17 Biological Communities (pg. 361)
How Organisms
Interact in
Communities
Evolution in
Communities
Interaction Among Species
Coevolution – the process in which long-term,
interdependent changes take place in 2 species as a
result of their interactions
Example: flowers and their pollinators
Predators and Prey Coevolve
Predation – an interaction between 2 species in
which one species, the predator, feeds on the other
species, the prey
Parasitism – a relationship between 2 species in
which one, the parasite, benefits from the other
species, the host, and usually harms the host
Plant Defenses Against Herbivores
Primary Defense – thorns,
spines
Secondary compounds –
Defensive compounds in
plants
Ex.
Make the plant taste bad
Toxic compounds
How Herbivores Overcome Plant Defenses
Many herbivores have the ability to breakdown the
secondary compounds – produce enzymes
Ex. Cabbage butterfly larva breakdown mustard oils
that are toxic to most other insects
Monarch butterflies and milkweed
Symbiotic Species
Symbiosis – a relationship in which different
organisms live in close association with each other
3 kinds of symbiotic relationships:
Mutualism
Commensalism
Parasitism
Mutualism – a relationship between 2 species in
which BOTH species benefit
Flower and pollinator
Coral and photosynthetic algae
Ant and “milking” an aphid
© Gregory G. and Mary Beth Dimijian
A remarkable 3-way mutualism appears to have evolved between
an ant, a butterfly caterpillar, and an acacia in the American
southwest. The caterpillars have nectar organs which the ants
drink from, and the acacia tolerates the feeding caterpillars. The
ants appear to provide some protection for both plant and
caterpillar.
Ant and acacia
The ant hollows out the
large thorns of the plant
for nests, feed on sweet
secretions from the base
of each petiole
Ants in return protect
these trees from
invertebrate as well as
vertebrate herbivores.
With any movement of
the branch, the ants
emerge releasing a nasty
odor as well as
physically attacking the
surprised herbivore.
Commensalism – a relationship between 2
organisms in which one benefits and the other is
unaffected
Shark with pilot fish
Whale with barnacles
Clownfish
and sea
anemone
Parasitism– a relationship between 2 species in which
one, the parasite, benefits from the other species, the
host, and usually harms the host
Tapeworm in carp
Tapeworm
Tick feeds on blood of host
How Competition Shapes Communites (pg. 365)
Common Use of Scarce Resources and Competition
Competition – a relationship between species
that attempt to use the same limited resource
Niche – the position (way of life) of a species in an
ecosystem in terms of the physical characteristics
(such as size, location, temperature, pH, etc) of the
area where a species lives AND the function of the
species in the biological community (position in
food web, when it breeds, etc.)
No two species can occupy the exact same
niche at the same time
Fundamental niche – the largest ecological niche
where an organism or species can live without
competition
(Realized niche – the range of resources that a
species uses, the conditions that the species can
tolerate and the functional roles that the species
plays as a result of competition in the species
fundamental niche)