Download Ecological Principles

The Environment
HabitatEcology
and Niche
By
KAPMAN LIFE SCIENCE ACADEMY
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Ecology
Scientific study of the relationships between organisms
and their environment.
Environment comprises of physical and chemical components
as well as the biological or living components of an organism’s
surroundings, that is, Biotic and Abiotic Factors
Biotic Factors: Living factors in an organism’s environment
such as plants, animals, microbes.
Abiotic factors: The non-living factors such as air, water,
precipitation.
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Abiotic Factors
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Atmosphere
1.
2.
3.
4.
Troposphere
Stratosphere
Mesosphere
Thermosphere/Ion
osphere
5. Exosphere
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Light
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Water
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Temperature
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Rocks and Soil
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Ecological Levels of Organization
Organism: An individual
Population: Individual organisms of a single
species that share the same geographic
location at the same time
Community:
A group of interacting
populations that occupy the same area at the
same time
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Ecosystem: A biological community and
all of the abiotic factors that affect it
Biome: A large group of ecosystems that
share the same climate and have similar types
of communities
Biosphere: All biomes together make the
Biosphere ; The Earth
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Climate
• Long term pattern of weather in a locality, region, or even over the
entire globe.
• Weather: is the short term properties (temperature, pressure,
moisture) of atmospheric conditions for a specific place and time.
• Climatic zone are Tropical, Subtropical, Temperate and Arctic and
Antarctic
• Microclimate: represents the climatic conditions that prevail at a local
scale, or in areas of limited size, such as the immediate surroundings of
plants and animals.
• For example, in a forest, dense foliage reduces the amount of light
reaching the ground. This also results in a changed air temperature
profile in a forest
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Thermoregulation and Homeostasis
• Homoiothermic or endothermic animals (warm blooded)
• Poikilothermic or ectothermic animals (Cold-blooded)
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Ecological Rule
Allens rule: Warm blooded animals tend to have shorter extremities
(ears, tails) in colder climates than they have in warmer climates
Bergmann's rule: Larger body size in animals living in colder
climates than those of the same group living in warmer
climates
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Ecological Rule
Glogers rule: Warm blooded animals tend to have more
pigmentations in warm, humid areas than in cool, dry area
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Tolerance range
• Environmental conditions exist as gradients. Changes in the
performance of an organism along such a trend are called
environmental gradient
• There are upper and lower threshold values on the gradient
beyond which the species cannot survive known as upper limit of
tolerance and lower limit of tolerance
• The whole range over which a species is able to survive is known
as range of tolerance
• Steno: Narrow tolerance
• Eury: Wide tolerance
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Ecological amplitude
• Different species differ from each other in terms of their
demands from their environment and consequently also in
respect to the extent to which they can tolerate the
fluctuations in their environmental conditions.
• This range of demands and consequent range of tolerance of
a species is known as its ecological amplitude.
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Ecological Species Concept
• Ecotype: An ecotype is a population of individuals of
a species which are genetically different. Different
ecotypes of a particular species may differ in their
edaphic, biotic or microclimate requirements. In
ecotypes, adaptations become irreversible or
genetically fixed
• Ecotypes are genetically adapted local populations
• Ecospecies: is a unit of classifications which contains
one or more ecotypes.
• Ecospecies although interfertile but do not cross or
at least do not produce viable offspring, if crossed
with ecotypes of other species.
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Ecological Species Concept
Ecads: Also known as ecophenes.
• An ecad of a plant species is a population of individuals which
although belong to the same genetic stock (genetically similar)
but differ in vegetative characters such as size, shape, number
of leaves, stem etc.
• They are genetically same but differ morphologically.
• Variations are environmentally induced and thus are
temporary or reversible, one type of ecad may change into
another with a change in its habitat.
• Ecads show phenotypic plasticity, i.e., environmentally
induced phenotypic variation
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• Ecological equivalents: Organisms
that occupy the same or similar
ecological niches in different
geographical regions.
• Species that occupy same equivalent
niches and occur in widely separated
regions are generally taxonomically
much different.
 Ecological equivalents result from
convergent evolution.
• For instance, sharks (fish) and
dolphins (mammals) live in a marine
habitat and superficially resemble
each other.
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Concept of Habitat and Niche
Habitat is a place, niche a pattern of living
• The niche an organism occupies is the sum total of
all the ways it utilizes the resources of its
environment.
• A niche may be described in terms of space
utilization, food consumption, temperature range,
appropriate conditions for mating, requirements
for moisture, and other factors
• Each habitat provides many different niches.
• The ecological niche is defined by first, the
functional role of the species in its community
(trophic position) and second, by its environmental
gradients
• Niche is defined by n variables: Multidimensional
hypervolume
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Fundamental and Realized Niche
Fundamental niche is the
maximum theoretically
inhabited hypervolume where
a species can live,outer limits
of its tolerance.
Realized niche is a smaller
hypervolume which is
occupied by the species under
interference from the
competition of other species.
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Gause and the Principle of
Competitive Exclusion
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Niche Overlap
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Competitive Exclusion
Gause’s principle of competitive exclusion can be restated to say that
no two species can occupy the same niche indefinitely when
resources are limiting.
Certainly species can and do coexist while competing for some of the
same resources.
Nevertheless, Gause’s theory predicts that when two species coexist
on a long-term basis, either resources must not be limited or their
niches will always differ in one or more features; otherwise, one
species will outcompete the other and the extinction of the second
species will inevitably result, a process referred to as competitive
exclusion
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Resource partitioning
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• Resource partitioning is often seen in
similar species that occupy the same
geographical area.
• Such sympatric species often avoid
competition by living in different
portions of the habitat or by utilizing
different food or other resources.
• This is also the example of Divergent
Evolotion
• E.g. Darwin's Finches ,Warbler
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