Download parasites and predators

QOTD
•What is a predator?
PREDATION and
PARASITISM
Mr.Dunnum
CONSUMPTION
• The consuming of one living thing by
another.
• A basic eating relationship between
populations of different species.
• Must be evaluated on the basis of its
effects on populations, not on
individuals.
MAJOR TYPES OF
CONSUMPTION
• Herbivory --- Eating of plants by animals. May not
result in death of individual plant.
• Parasitoidism --- Larvae of parasitoids consume hosts.
• Cannibalism --- The eater and eaten belong to the
same species (intraspecific predation).
• Parasitism --- Host provides nutrition to one or many
individual parasites. Host may or may not die.
• Predation --- Predator kills prey and consumes all or
part.
PARASITOIDISM
• Insects, usually flies and small wasps,
that lay their eggs on living hosts. The
larvae then feed within the body of
the host, eventually causing death.
• Recent experimental evidence
suggests that parasitoids locate their
hosts by responding to airborne
chemical signals from plants damaged
by the host.
PARASITOIDS
• A tachinid fly lays eggs
on a hornworm (moth
larva). The fly larvae
develop by consuming
the hornworm.
• Many species of
ichneumon wasps are
parasitoids.
CANNIBALISM
• An individual consumes another individual of the
same species.
• A form of intraspecific predation.
• Relatively common among insects when density
is high. Usually involves adults consuming eggs
and larvae.
• Demonstrated to be density-dependent factor
regulating experimental insect populations.
PARASITISM
• Occurs when a member of one
species (parasite) consumes tissues or
nutrients of another species (host).
• Parasites live on or in their hosts;
often for long periods of time.
• Parasites are most often much smaller
than their hosts.
• It is not necessarily fatal to the host.
A VERTEBRATE PARASITE
• The sea lamprey was
introduced into the Great
Lakes in 1921 through the
Welland Canal.
• Contributed greatly to the
decline of whitefish and
lake trout (shown).
• Chemical control
programs started in 1956
have reduced lamprey
populations.
INVERTEBRATE PARASITES
• Tapeworm is an
intestinal parasite in
many species of
vertebrates, including
humans.
• The deer tick (small
one) and wood tick
are common external
parasites on
mammals.
VIRAL PARASITES
• The common influenza
virus (top) has inhabited
every host in this room! It
has caused more deaths
than any other pathogen.
• The bird flu virus (bottom)
is a potential threat to
humans.
PREDATION
• The most conspicuous interaction is when an
individual of one species (predator) eats all or
most of an individual of another species (prey).
• The most thoroughly studied consumptive
relationship between species.
• Of high ecological and evolutionary significance.
• An everyday occurrence in nature.
Possible Outcomes of
Predation
Predator population has little effect
on abundance of prey population.
• 2. Predator population eradicates
prey population; this may contribute
to extinction of predator population
due to lack of food.
• 3. Predator and prey populations
coexist in dynamic equilibrium.
• 1.
Description of Dynamic
Equilibrium
• When predator numbers are low, prey numbers increase
rapidly.
• As prey numbers increase, predators begin to increase.
• When predators numbers are high, prey numbers decrease
rapidly.
• As prey numbers decrease, predator numbers fall.
The Hare & Lynx Predator/Prey
Relationship
• Snowshoe hare and
Canadian lynx show
classic population cycles
with a 10-11 year
periodicity.
• Hare are herbivores and
feed on twigs under the
snow in winter; lynx feed
primarily on snowshoe
hare.
Moose and Wolf of Isle Royale
• The world’s longest running
predator/prey research project.
The 47th year of wolf and
moose monitoring was
completed in the winter of
2006.
• Winter provides the best
opportunities for aerial
surveying of the wolf and
moose populations, with leaves
off the trees and snow on the
ground.
Predators as Agents of
Biocontrol
• Predators have been
used in attempts to
control a variety of
plant and animal
pests. Often called:
biocontrol.
• Ladybird beetles and
ant lions (lacewing
larvae) have been
used.
Parasites as Agents of
Biocontrol
• European rabbits were introduced
into Australia in 1859 and became a
major pest.
• In late 1950, the myxoma virus,
spread by mosquitoes, began killing
rabbits in large numbers. By 1953,
rabbit immunity was detected. Today,
the virus may kill only 50 % of the
rabbit population during an
epidemic.
• Another virus (calicivirus), native to
China, was found and testing as a
potential biocontrol agent began in
1995 and continues to the present.