Transcript Interaction Among Species

Interaction between
Species
A closer look…
First, a review
 What

How big a population can get while still being
supported, having enough resources
 How


is carrying capacity?
can you increase carrying capacity?
Altering ecosystem so more energy,
resources are available
Altering behaviour
Copy this down

Humans have altered the ecosystems that
support us, so the carrying capacity is high

But, modern human societies are still subject to
the ecological principle of carrying capacity

Human growth has rapidly accelerated over the
past 400 years

With a current doubling time of less than 1 human
lifetime
Human Population Growth
Ecological Footprint
 Def:
an estimate of how much land and
water required to support someone’s
lifestyle
 What is your ecological footprint?

Mine is 6
Urban Sprawl

A city’s growth as it’s population increases

More and more development on the ‘outskirts’ of a
city
The Golden Horseshoe
West end of Lake Ontario
Interaction Among Species
 Resources
and abiotic factors are not the
only influences on a population
 Organisms interact with each other too
Ecological Niche
Species focus on

1.
2.
They do not have jobs, but they do
contribute a ‘role’



Surviving
Reproducing
Provide benefits to the ecosystem
Def: the role an organism plays within its
ecosystem (biotic and abiotic factors)
Ecological Niche
 Sample



niches
Regulation of a population (like insects)
Decomposition of dead matter
Cycling of matter
 There
are millions of spots on Earth
 There are millions of niches too
Carnivorous Plants
#1
Predation and Population Size
Predators and prey influence one
another in 2 ways

1.
2.
Bottom-up population regulation
Top-down population regulation
Bottom-up population regulation
 Grasshoppers
eat grass; shrews eat
grasshoppers
 GrassGrasshopperShrew
 If the grasshoppers eat too much grass,
population could decrease due to lack of
food.
 If the population of grasshoppers
decreases, there is not enough food for
shrews  their population decreases
Bottom-up population regulation
 This
is called…
… because there is a
shortage in the plant resource at the base
of the food chain which affects animals in
higher trophic levels
Top-down population regulation

Now consider this…

What if the population of rabbits increases?

With more rabbits to eat, coyote population
increases
 But with more coyotes eating rabbits, the rabbit
population will decrease
 This is top-down regulation because a higher (top)
trophic level organism influences the population of
a lower trophic level

(eventually the # of coyotes would decrease too)
#2

Competition
As the population of a
species increases, so
does the competition
for resources


Can limit population size
The more energy an
organism spends
competing, the less
energy it has for growth
and reproduction
#3
Symbiosis

The interaction
between members
of 2 different species
that live together in
close association

2 types of symbiosis
1.
2.
Mutualism
Parasitism
Mutualism

Def: symbiotic relationship between 2 species
where both benefit

Ex: clownfish and anemones
In symbiotic mutualism, the
clownfish feed on small
invertebrates which otherwise
could potentially harm the sea
anemone, and the fecal matter
from the clownfish provides
nutrients to the sea anemone.
The clownfish is additionally
protected from predators by the
anemone's stinging cells, to which
the clownfish is immune.
Parasitism

Def: symbiotic relationship between 2 species
where 1 organism (parasite) depends on another
larger organism (host)

Frequently the parasite benefits at the host’s expense
These primitive fish attach to the bodies of
native fish and feed on the fish's body fluids.
This often leads to the death of the native
fish. Species at risk in the Great Lakes
include prized commercial and recreational
species such as lake trout, salmon, rainbow
trout (steelhead), whitefish, walleye and
catfish.
Brain Worm

White-tailed deer
aren’t affected


Brain-worm cycle
successful
Other animals are
very vulnerable

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Moose disease
Sheep
Elk
Caribou
1.
2.
3.
4.
5.
Worm lays eggs in brain
Eggs travel to lungs and hatch
Larval worms excreted
Eaten by slugs
Eaten by deer
Human Parasitism
Cutaneous larva migrans (CLM) was
first described as "the creeping
eruption" and diagnosed by a physician
in 1874. Today, it is one of the most
common hookworm infections acquired
from subtropical and tropical regions of
the world.
A 28-year-old medical resident and a
companion returned from hiking in
Central America with pruritic,
erythematous, single-track linear and
serpiginous lesions located
predominantly on their lower extremities.
A physician clinically examined the skin
disorder and diagnosed the two patients
with cutaneous larva migrans after
learning that they had been walking
barefoot on the beach during their
vacation.