Transcript Community interactionsGrade10

Community Ecology
Studying the interactions between species
• interactions between coexisting population
• Understanding the many spatial and temporal
scales of an ecostystem, including the
distribution, structure, abundance,
demography: habitat and the niche concept
Understanding – and predicting community interactions is difficult
Big questions in Community
ecology
• Why do symbiotic relationships exist? What
would be the motivation?
• Are human behavioural motivations different
from that of other mammals?
• Is it human nature to be co-operative or
adversarial (or co-operversarial?)
What interactions occur within
communities?
All community interactions play an essential role
in survival of both species
Symbiosis
Any ‘long term’ relationship in which two
species live closely together is called
symbiosis.
You should be able to recognise:
1.predation
2.mutualism
3.commensalism
4.parasitism
5.competition
1. Competition
Competition occurs when organisms of the same
or different species attempt to use an ecological
resource in the same place at the same time.
A resource is any necessity of life, such as water,
nutrients, light, food, or space.
Direct competition in nature often results in a
winner and a loser—with the losing organism
failing to survive.
Competition in the plant world
• Japanese knotweed
• David Attenborough tropical conpetition
Competition can even take place between
species from different kingdoms…
• Spider versus plant
2. Predation
Predation
An interaction in which one organism captures
and feeds on another organism is called
predation.
The organism that does the killing and eating is
the predator, and the food organism is the prey.
Monk Seals
3. Parasitism
• yuk.....!
• The parasite of the day Blog...
• One organism lives on or inside
another organism and harms it.
• The parasite benefits in terms of
energy or nutrients, whereas its
host is harmed by the loss of
these reserves
• Parasites often have more
limited metabolism so cannot
survive out of contact with a
host
4. Commensalism/mutualism
Mutualism: both species benefit from an
interdependent relationship.
Commensalism: one member of the
association benefits and the other is
neither helped nor harmed.
Examples: mitochondria and chloroplasts;
nitrifying bacteria and legume root nodules
Symbiotic relationships can take place
between species from different kingdoms!
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Symbiosis
Mutualism, Commensalism and parasitism
Sunfish and seagulls...
Fish Cleaners
Giving Fish a bath
Clownfish and anemones
Community Ecology
Organising ecosystems
Biotic and Abiotic Factors
Ecosystems are influenced by a combination of
biological and physical factors.
Biological factors – these are called Biotic factors
‘The whole cast of characters with which an organism
interacts’ – e.g. plants, trees, predators, competing
organisms’…
Biotic and Abiotic Factors
Physical, or nonliving factors that shape ecosystems
are called Abiotic factors .
Abiotic factors include:
• temperature
• precipitation
• humidity
• wind
• nutrient availability
• soil type
• sunlight
How do biotic and abiotic factors
influence an ecosystem?
Biotic and abiotic factors determine
the types of organisms which can
inhabit any particular ecosystem
How do biotic and abiotic factors
influence an ecosystem?
Any species has a well
Any population of that species
defined habitat
has a well defined niche
•‘its address’
•‘its occupation’
•Where it can live
•The species it interacts with
•What it needs to eat
•The species it depends on
•Breeding grounds
•The species that depend on
it…
•Water requirements
•NICHES CAN GROW AND
SHRINK, DEPENDING ON
•HABITATS ARE DEFINED‘EXTERNAL’ FACTORS
AND CONSTANT
•etc etc
Biotic and Abiotic Factors
The area where an
organism lives is called
its habitat. A habitat
includes both biotic and
abiotic factors.
The Niche
A niche is the full range of physical and
biological conditions in which an organism lives
and the way in which the organism uses those
conditions.
No two species can share the same niche in the
same habitat
‘Nicher’ (French): to Nest
A term describing the way of life of a population
To describe a population’s niche, you need to
describe its ‘specialised habitat’:
– space and territory
– Nutrition and feeding habits
– Interactions with other organisms
– Its reproductive habits
– Its role in the community
The Niche concept: A Working
Analogy
In 1927, Charles
Sutherland Elton, the
British Ecologist, stated:
‘When an ecologist states
‘There goes a badger’, he
should include in his
thoughts a definite idea of
the animal’s role in the
community, just as if he
had said ‘There goes the
vicar’
Defining a Niche : ‘The Boundary
conditions’
• Two species that use
exactly the same
resources cannot
occupy the same
niche
• Only one species or
population can occupy
the same niche for an
extended period
A population has a fundamental AND
a realised niche
Fundamental Niche
A species’ fundamental niche is the full range of
environmental and social conditions under which
it could potentially survive and reproduce
‘potential niche’
•Some species have a broad fundamental niche
•Some species have a narrow fundamental niche
Species with a broad niche
• ‘Generalists’
• Widely distributed
geographically
• Adaptable
Species with a narrow Niche
• ‘Specialists’
• Not adaptable
• Under threat of extinction if the niche changes
Realised Niche
The realised niche is the
specific set of conditions
in which it survives in a
given habitat or
ecosystem, given the
other species or
limitations present.
These are the conditions
to which the population is
best adapted.
‘Realised Niche’ is not a
constant for a species
• In fact, populations of the same species may
occupy different realised niches within different
ecosystems
• It all depends on the other species and
environmental factors involved in ‘sharing of
the resources’
The principle of competitive
exclusion
Aka ‘Gause’s Law’
‘No two species can occupy the
same niche in the same habitat
for a prolonged time’
The Competitive Exclusion Principle
• The best adapted
species will survive
Examples are
abundant
• The loser will struggle
to survive and
reproduce, and will
eventually become
extinct OR migrate (if
its niche is broad
enough)
•Invasive species
•Red versus Grey
Squirrel in Western
Europe
•Gause’s
Paramecium
Competitive Exclusion and Invasive
species…
Invasive Species are those which have been
introduced to a non-native habitat/ecosystem
(usually by human interention). They often outcompete – (and drive towards extinction) – the
native species…
•Grey Squirrels
•Cane toads!
•Zebra Mussels
Competitive
Exclusion:
Squirrels
Competitive Exclusion: Squirrel
Distribution
Competition in the plant world
• Japanese knotweed
• David Attenborough tropical conpetition
Competition can even take place between
species from different kingdoms…
• Spider versus plant
Can species ‘work around’ the
competitive exclusion principle?
Yes they can!: Niche Partitioning
As there is a limited about of space and resources on
Earth, organisms can use niche partitioning
1. Spatial: Two different species use the same resource
by occupying different areas within the range of the
resource
2. Temporal: Two species eliminate direct competition by
using the same resource at different times
Community Interactions
The distribution of these warblers avoids direct
competition, because each species feeds in a
different part of the tree.
Feeding height (m)
18
12
6
0
Cape May Warbler
Bay-Breasted
Warbler
Yellow-Rumped Warbler
Spatial Niche Partitioning
Closely related
bird species
occupy different
foraging locations
on a single tree
species
Temporal Niche Partitioning
Different species of spiny
mouse inhabiting the
same ecosystem may be
either nocturnal OR
diurnal feeders