INTRODUCTION TO ECOLOGY

Qus: Do you know how organisms live with each other in

physical environments?

Qus: How do organisms interact with the living and nonliving

factors around them?

Qus: What do organisms need to survive and thrive in their

current environments?

Ans: Study ecology

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 INTRODUCTION TO ECOLOGY
 In 1859, French Zoologist Isodore Geoffroy proposed the term
‘Ethology’

 The term Ecology – coined by combining two Greek words Oikos

means ‘house’ and logos means ‘the study of’

 Ecology - Scientific study of interactions between living things and

the environment

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 INTRODUCTION TO ECOLOGY

 Environment – everything that affects and surround any organism

during its life

 Biotic factors - living components like flora (plants) and fauna

(animals)
 Abiotic factors – non-loving components (physical and chemical
conditions) like temperature, rainfall, moisture etc.

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 SCOPE OF ECOLOGY
 Study of ecology includes – biology or plant science, physics, chemistry, geology, social science etc.
 Ecology play important role in human welfare and many other areas
 agriculture
 Management of grassland
 Forestry
 Biological surveys
 Pest control
 Fisheries
 Conservation of soil
 wildlife etc
Even ecological assistance needed for the international problem of pollution

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 TYPES OF ECOLOGY
Types of Ecology

Autoecology Syncoecology

Study of single species Study of community

Like lion Like lion, deer

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 LEVEL OF ORGANIZATION IN ECOLOGY

 Six levels of organization in ecology:

1. Individual
2. Population
3. community
4. Ecosystem
5. Biome
6. Biosphere

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 Level of Organization in Ecology
1) Individual
 ability to act or function independently
 Eg. Tiger, plant, animal, bacterium, fungi, etc.

 Ecophene/ECAD –
 When a species is transported to a new environment, it will develop the
ability to survive in new environment
 Temporary variations
 Ecotype –
 Ecophene transferred to new environment for long time, it will develop
the ability to survive in new environment
 Permanent changes

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 LEVEL OF ORGANIZATION IN ECOLOGY

2) Population
 group of interbreeding organisms usually of the same species,
occupying a defined area during a specific time
 Eg group of tigers

3) Community
 populations of different kinds of organisms living together and
sharing the same habitat
 Eg tiger, zebra, rabbit etc.
 Also known as Biocenosis

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 LEVEL OF ORGANIZATION IN ECOLOGY

 Types of Community
 Major Community - large-sized and relatively independent eg. autotrophs like
plants
 Minor Communities - dependent on neighboring communities and are often called
societies eg. heterotrophs like Human being
4) Ecosystem
 An ecosystem is defined as a structural and functional unit of biosphere consisting
of a community of living beings and the physical environment, both interacting and
exchanging materials between them
Ecosystem can be big or small
 Study of ecosystem is ecology

Earth Drop
(microbes can interact with each other) 9
 LEVEL OF ORGANIZATION IN ECOLOGY
Classification of Ecosystems

 Natural ecosystems:
 Totally dependent on solar radiation e.g. forests, grasslands, oceans, lakes, rivers and deserts
 Provide food, fuel, fodder, and medicines

 Man-made ecosystems:
 Dependent on solar energy. e.g. agricultural fields and aquaculture ponds
 Dependent on fossil fuel e.g. urban and industrial ecosystems

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 LEVEL OF ORGANIZATION IN ECOLOGY
Classification of Natural Ecosystem

 Terrestrial
 Forest
 Grasslands
 Deserts
 Aquatic
 Fresh Waters
 Running water ecosystem - River (Lotic system)
 Standing water ecosystem - Pond (Lentic system)

 Marine Waters

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 LEVEL OF ORGANIZATION IN ECOLOGY

 Ecological Niche
 Niche means the sum of all the activities and relationships of a species by which it
uses the resources in its habitat for its survival and reproduction
 Niche is all about a single species as a part of a habitat with all its biological
activities as influenced by biotic and abiotic factors
 No two species in a habitat can have the same niche
 If two species occupy the same niche they will compete with one another until one is
displaced

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 LEVEL OF ORGANIZATION IN ECOLOGY

5) Biomes

 Terrestrial part of the biosphere

 Divided into different regions on the basis of various factors:
 climate, vegetation, animal life, and general Soil type

 Types of Biomes – 11 types

1) Tropical Rain Forest 2) Desert
3) Grassland 4) Tundra
5) Boreal Forest 6) Temperate Forest
7) Tropical Deciduous Forest and Savannah
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 LEVEL OF ORGANIZATION IN ECOLOGY

6) Biosphere

 Biological component of the earth

 Includes Lithosphere, hydrosphere, atmosphere

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 INTRODUCTION TO ECOLOGY
Terms to remember

 Ecotone

 Zone of junction or transition area between two biomes

1) Eg mangrove forest - land and water
2) Estuary - River and sea
3) Grassland - forest and desert

 Ecotone also known as Zone of Tension

 Species of both the ecosystems are present

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 INTRODUCTION TO ECOLOGY
Terms to remember

 Edge effect

 Number of species and population density of some of the species is much greater in
this area than the community
 Edge species

 Species or organisms that are found most abundantly in the zone or ecotone

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 INTRODUCTION TO ECOLOGY
Terms to remember

 Eurythermal Organisms – can tolerate and thrive wide range of temperature

 Eg. humans

 Stenothermal Organisms - restricted to a narrow range of temperature

 Eg. Pengwins

 Euryhaline Organisms – can tolerate wide range of salinity like green crab
 Stenohaline Organisms – can survive in narrow range of salinity like Goldfish

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 INTRODUCTION TO ECOLOGY

Terms to remember

 Edaphic Factors – related to structure and composition of soil like

physical and chemical properties of soil such as soil type, soil profile,
minerals, organic matter, soil water, soil organisms

 Inorganic Substances – water carbon, sulfur, nitrogen phosphorus

etc

 Organic Substances – lipid, proteins, carbohydrates etc

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 COMPONENTS OF ECOSYSTEM

 Two basic components of ecosystem

1. Biotic – living component like plats, animals
2. Abiotic – non-living component like climate, temperature, soil, sunlight

 Relationship between biotic and abiotic components – Holocoenosis

 Abiotic component also known as limiting factors

1. Determine and restrict population growth, population number and
diversity of biotic factor
2. Eg Sunlight
3. Deep into the see – no sun light – less amount of living organism will be
present there
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 COMPONENTS OF ECOSYSTEM

 PAR - Photosynthetically Active Radiation

 400-700 nm – Spectral Range in which photosynthesis is possible
 50% of solar radiation – count into PAR
 Out of this 2-10% is captured by plants

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 COMPONENTS OF THE ECOSYSTEM

 solar energy is the basic requirement for any ecosystem to function

and sustain
 The components of the ecosystem are seen to function as a unit
when you consider the following aspects
 (i) Productivity; (ii) Decomposition; (iii) Energy flow; and (iv) Nutrient
cycling

1) Productivity
 Rate of biomass production
 Primary Production – Amount of biomass produced per unit area over a
time period by plants during photosynthesis

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 COMPONENTS OF THE ECOSYSTEM

 Primary Productivity - divided into two parts

1) gross primary productivity (GPP)
2) net primary productivity (NPP).
GPP -Rate of production of organic matter during photosynthesis
NPP - GPP minus respiration losses (R)
GPP – R = NPP
NPP - available biomass for the consumption to heterotrophs (herbivores and
decomposers)
 Secondary productivity - rate of formation of new organic matter by
consumers
Annual NPP of the whole biosphere - approximately 170 billion tons (dry
weight) of organic matter
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 COMPONENTS OF THE ECOSYSTEM
2) Decomposition
 Decomposers break down complex organic matter into inorganic substances like
carbon dioxide, water and nutrients with the use of enzymes like bacteria, fungi
 Important steps in the process of decomposition are fragmentation, leaching,
catabolism, humification and mineralisation
 Detritus
 Consists of dead plant remains like leaves, bark, flowers and dead remains of
animals, including fecal matter
 raw material for decomposition
 Fragmentation
 Process by which detritivores (e.g., earthworm) break down detritus into smaller
particles
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 COMPONENTS OF THE ECOSYSTEM
 Leaching

 Process by which water soluble inorganic nutrients go down into the soil horizon and get
precipitated as unavailable salts

 Catabolism

 Process through which bacterial and fungal enzymes degrade detritus into simpler
inorganic substances

 Humification

 Accumulation of a dark colored amorphous substance called humus

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 COMPONENTS OF THE ECOSYSTEM
 Humus
 Highly resistant to microbial action and undergoes decomposition at an extremely slow rate
 Colloidal in nature
 Reservoir of nutrients

 Mineralisation
 Process by which humus is further degraded by some microbes and release of inorganic nutrients

 Saprotrophs
 meet their energy and nutrient requirements by degrading dead organic matter or
detritus
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 COMPONENTS OF THE ECOSYSTEM

3) Energy Flow

 Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy
for all ecosystems on Earth

 Unidirectional flow of energy from the sun to producers and then to consumers

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 COMPONENTS OF THE ECOSYSTEM
 Consumer

 primary consumers - feed on the producers, the plants,

 they are called primary consumers (herbivores)

 secondary consumers - if the animals eat other animals which in

turn eat the plants

 tertiary consumers-------

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 COMPONENTS OF THE ECOSYSTEM
Carnivores - consumers that feed on these herbivores
 Primary carnivores (though secondary consumers)
 Secondary carnivores - that depend on the primary carnivores for food

Grazing food chain (GFC)

Grass ------------------Goat ------------------ Lion/Man ----------------
(Producer) (Primary Consumer) (Secondary consumer)
Detritus food chain (DFC)
 begins with dead organic matter
 heterotrophic organisms, mainly fungi and bacteria
 They meet their energy and nutrient requirements by degrading dead
organic matter or detritus 28
 COMPONENTS OF THE ECOSYSTEM

 Some of the organisms of DFC are prey to the GFC animals

 These natural interconnection of food chains make it a food web

 Based on the source of their nutrition or food, organisms occupy

a specific place in the food chain that is known as their trophic
level

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 DIAGRAMMATIC REPRESENTATION OF TROPHIC LEVELS
IN AN ECOSYSTEM

Trophic levels of
Ecosystem

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 COMPONENTS OF THE ECOSYSTEM
 Amount of energy decreases at successive trophic levels
 Detritus or dead biomass serves as an energy source for decomposers
 Organisms at each trophic level depend on those at the lower trophic level
for their energy demands

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 COMPONENTS OF THE ECOSYSTEM

Pyramid of a grassland ecosystem

The base of each pyramid represents the producers or the first trophic level while
the apex represents tertiary or top level consumer

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 COMPONENTS OF THE ECOSYSTEM
4. Nutrient Cycling
Nutrient – important as needed to grow, reproduce and regulate various body
functions
 Amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, etc.,
present in the soil at any given time - standing state
 Varies in different kinds of ecosystems and also on a seasonal basis

Nutrient Cycling
 Movement of nutrient elements through the various components of an
ecosystem
 Also called biogeochemical cycles
 Different types of nutrient cycle like Carbon cycle, Nitogen cycle, Phsphorus
cycle etc 33
 COMPONENTS OF THE ECOSYSTEM

Two types of Nutrient Cycle

1) Gaseous Cycle
 Transportation of nutrients from atmosphere
 Eg. Carbon cycle, Nitrogen cycle, water cycle, oxygen cycle

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 COMPONENTS OF THE ECOSYSTEM

2) Sedimentary Cycle
 Transportation of nutrition through earth’s crust
 Eg. Sulphur cycle, Phosphorus cycle

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 RESPONSE TO ENVIRONMENTAL FACTORS
 Responses to abiotic factors
Ways in which organisms respond to abiotic factors

1) Regulate
 Mechanism used by organisms to maintain a constant condition in the
body
 Eg. Humans
 Homeostasis – process of maintaining constant environment

2) Conform (conformers)
 Most of the organisms do not have ability to regulate their body
condition
 Have a fluctuating bodily condition as per the environment
 Eg. amphibians, reptiles
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 RESPONSE TO ENVIRONMENTAL FACTORS

 3) Migrate
 Some organisms travel to far off places during a particular weather condition
and return when the weather condition is restored
 Eg. Birds from Siberia migrate to south during winter to avoid the cold weather

 4) Suspend
 Some organisms have different mechanisms to escape harsh environment
 Eg. Bear going to hibernation during winter

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 RESPONSE TO ENVIRONMENTAL FACTORS

ECOLOGICAL SUCCESSION
Community response to environment over time

 Gradual and fairly predictable change in the species composition - Ecological succession

 Composition and structure of community change in response to the changing environmental conditions

 Change is parallel with the changes in the physical environment

 This is achieved by a community called the climax community

 Ecological succession aims at reaching the equilibrium in the ecological system

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 POND AS ECOSYSTEM

Pond
 fairly a self-sustainable unit
 shallow water body in which all the four basic components of an ecosystem are well
exhibited [(i)Productivity; (ii) Decomposition; (iii) Energy flow (iv) Nutrient
cycling]
 Rate of function of the entire pond depends on:
 The solar input
 the cycle of temperature
 day-length
 other climatic conditions
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 POND AS ECOSYSTEM
Pond comprises of:
Autotrophic components include
phytoplankton,
some algae,
floating, submerged and marginal plants found at the edges

consumers
zooplankton,
free swimming and bottom dwelling forms

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 POND AS ECOSYSTEM

Decomposers
 Fungi, bacteria and flagellates
 Abundant in the bottom of the pond

 This system performs all the functions of any ecosystem and of the
biosphere as a whole

 Unidirectional movement of energy towards the higher trophic levels

and loss as heat to the environment

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Thank you
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