Transcript year 12 ecology powerpoint

Ecology
Patterns in the Environment
• Where an organism
lives is called it’s
Habitat.
• It is shaped by the
organisms interaction
with abiotic and biotic
factors.
habitats
Niche
• An organisms niche is
its functional position in
the environment. It
includes a description
of how the organism
interacts with the
abiotic and biotic
elements of the
environment.
Niche
Law of Tolerance- abiotic factors
The law of tolerance states that “For each abiotic factor, an
organism has a range of tolerances within which it can survive.”
Tolerance range
Number of organisms
Optimum range
Unavailable
niche
Marginal
niche
Examples of
abiotic factors
that influence
size of the
realized niche:
Preferred
niche
Marginal
niche
Unavailable
niche
Biotic factors -Competition and Niche Size
Competition affects the
size of a competitor’s
realized niche.
The effect is dependent
on the intensity and
type of the competition.
Niches are narrower with moderate
interspecific competition (Fig. 1).
Realized niche of species
Fig. 1
Narrower niche
Fig. 2
Intense interspecific competition results
in a very narrow realized niche as species
specialize to exploit a narrower range of
resources (Fig. 2).
Intense intraspecific competition results
in a broader realized niche as individuals
are forced to occupy suboptimal
conditions (Fig. 3).
Broader niche
Fig. 3
Possible tolerance range
Gause’s Principle
Gause’s competitive exclusion principle states:
“two or more resource-limited species, having
identical patterns of resource use, cannot coexist in
a stable environment:
one species will be better adapted and will outcompete or otherwise eliminate the other(s)”.
Amount eaten
If two species compete for some of the same resources (e.g. food items of a particular size),
their resource use curves will overlap. In the zone of overlap, interspecific competition is the
most intense.
Zone of overlap
Species
A
Species
B
Resource use as measured by food item size
Competing species cannot occupy the
same niche
Barnacles
• Chthamalus and
Balanus compete for
space.
• Note that Chthamalus
realised niche is much
smaller than its
fundamental niche as it
is out competed by
Balanus.
Niche Differentiation
Interspecific competition is usually less intense than intraspecific
competition because niche overlap between species is not complete.
Species with similar ecological requirements may reduce competition by
exploiting different microhabitats within the ecosystem.
Example: Ecologically similar damsel fish at Heron Island, Queensland, Australia exploit different resources or regions over the
coral reef.
Pw Pomacentrus wardi
Pf Pomacentrus flavicauda
Pb Pomacentrus bankanensis
Sa Stegastes apicalis
Pl Plectroglyphidodon
lacrymatus
Ef Eupomacentrus fasciolatus
Eg Eupomacentrus gascoynei
Gb Glyphidodontops biocellatus
Reef crest
Sea level
Zonation in a lake
Zonation- changing environments are
often divided into zones
Stratification in a forest is a type of
vertical zonation
Different
organisms
will occupy
different
niches
within the
different
zones
Succession
• Communities change
over time.
• Early communities alter
the environment
allowing other
organisms to colonise.
• Eventually a climax
community will form
Secondary succession occurs after a
catastrophe or something that disrupts
the environment
Succession and stratification
• http://www.bbc.co.uk/
nature/habitats/Tropica
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• http://www.bbc.co.uk/
nature/habitats/Tropica
l_and_subtropical_conif
erous_forests#p00ffnqd
• https://www.youtube.c
om/watch?v=k03vxRYsJ
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• https://www.youtube.c
om/watch?v=CQ2Xl6Zq
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• https://www.youtube.c
om/watch?v=Ax6zlSzyNM