Download Day 10- population

And the Interactions in
Ecosystems
• The resources in the environment will not
be able to support an infinite increase in
the population of a species.
• Eventually the # of births will equal the
number of deaths as resources become
relatively scarce.
• This will mean the
population is at equilibrium.
• When the population hits the maximum number
of individuals an ecosystem can support
without reducing its ability to support future
generations of the same species, it is said to
be at its carrying capacity
• One of the things that determines the
carrying capacity of a population is called a
limiting factor. Usually if the limiting factor is
eliminated the carrying capacity will increase.
• The limiting factor is an
environmental factor
that prevents an
increase in the number
of organisms of a
population or prevents
them from expanding
into new habitats.
• Abiotic limiting factors include sunlight,
water, soil, fires, droughts etc.
• Biotic limiting factors include competition
for resources, predation, disease etc.
• Competition is the interaction between 2 or
more organisms for the same resource in
a given habitat.
• There can be intraspecific competition (2
animals of the same species) as well as
interspecific competition (different species)
• For 2 species to coexist
in an area they must
have slightly different
niches.
• Often competition for
resources will cause
species to specialize on
certain aspects of their
potential niche.
• Predation occurs when
an organism eats
another organism to
obtain food.
• Prey organisms will
adapt to the predators
that hunt them so that
they are faster,
stronger or more aware
of their surroundings.
• Some other animals use mimicry to avoid
being eaten.
• The monarch butterfly and the viceroy
butterfly both taste terrible and they look
very similar. This makes it easy for
predators to recognize and stay away from
them.
• There are a couple snakes in Ontario that
mimic the rattlesnake to avoid predation.
• The fox snake does not look too much like a
rattlesnake but when upset it will shake its tail
back and forth in the dead leaves on the
forest floor which makes a rattling sound.
• Example of how predation affects
populations
• Symbiosis is the close interaction between
species where one species lives in, on or
near members of another species.
• There are 3 types of symbiosis:
1. Mutualism – both species benefit
2. Commensalism
– one species
benefits while
the other is
unaffected.
3. Parasitism – one species benefits at the
expense of another species.
• Answer questions 1-3 pg 42