The Ecosystem: The Ecosystem: Interrelationships Interrelationships

between organisms and between organisms and the environmentthe environment

1. 1. Should we care about the survival Should we care about the survival of organisms other than human of organisms other than human beings?beings?2. Can we humans live alone and 2. Can we humans live alone and survive on the planet?survive on the planet?3. Does the way nature operates offer 3. Does the way nature operates offer solutions to our environmental solutions to our environmental problems? problems?

Definition of Terms …1Definition of Terms …1 Ecology:Ecology: A study of the interrelationships A study of the interrelationships

between living organisms and the non-living between living organisms and the non-living components and processes that make up the components and processes that make up the global environment.global environment.

Biosphere:Biosphere: The worldwide system within which The worldwide system within which all life functions. It includes the atmosphere all life functions. It includes the atmosphere (air), hydrosphere (water) and the lithosphere (air), hydrosphere (water) and the lithosphere (soils, rocks)(soils, rocks)

Biome:Biome: A major ecological region within which A major ecological region within which plant and animal species are similar in general plant and animal species are similar in general characteristics and in their relationships to the characteristics and in their relationships to the physical environment. E.g.. Tundra, Deserts, physical environment. E.g.. Tundra, Deserts, Forests Grasslands etc.Forests Grasslands etc.

Definition of terms…2Definition of terms…2 Ecosystem:Ecosystem: A collection of living organisms in A collection of living organisms in

a geographic area, together with the non-a geographic area, together with the non-living things with which they interact. living things with which they interact. • Aquatic EcosystemsAquatic Ecosystems (water-based systems) (water-based systems)• Terrestrial EcosystemsTerrestrial Ecosystems (land-based systems). (land-based systems).

Population:Population: A group of organisms of the A group of organisms of the same kind living in a given area.same kind living in a given area.

Natural CommunityNatural Community:: Populations of different Populations of different species living together and interacting in a species living together and interacting in a given area.given area.

Habitat:Habitat: The environment in which a The environment in which a particular organism lives in the communityparticular organism lives in the community

Definitions…3Definitions…3

Ecological NicheEcological Niche:: An organism’s role An organism’s role within a community.within a community.

Environment:Environment: ComprisesComprises a all the ll the surrounding things that affect an surrounding things that affect an organism or a community of organism or a community of organisms in a given area.organisms in a given area.

The Structure of Ecosystems…1The Structure of Ecosystems…1

Components of an Ecosystem:Components of an Ecosystem:

Biota or Biotic componentBiota or Biotic component:: the the living organisms comprising all living organisms comprising all plants & animalsplants & animals

Abiotic componentAbiotic component:: the non-living the non-living physical and chemical components physical and chemical components consisting of wind, temperature, consisting of wind, temperature, water, soil, precipitation which the water, soil, precipitation which the biotic elements need to survive.biotic elements need to survive.

Structure of an Structure of an Ecosystem…2Ecosystem…2

A A single single abioticabiotic factor factor most lacking most lacking in a particular environment is termed, in a particular environment is termed, a a Limiting FactorLimiting Factor. E.g. water-desert, . E.g. water-desert, temperature-tundratemperature-tundra

The variation in physical factors that The variation in physical factors that an organism can withstand and an organism can withstand and continue to thrive in an environment continue to thrive in an environment is termed - is termed - Range of ToleranceRange of Tolerance

Producers in an EcosystemProducers in an Ecosystem Categories of Organism in an Categories of Organism in an

ecosystemecosystem AutotrophsAutotrophs – – self-nourished species self-nourished species

(e.g. plants)(e.g. plants) HeterotrophsHeterotrophs – – other-nourished other-nourished

species (humans and animals)species (humans and animals)

1. 1. Producers:Producers: Green Plants responsible Green Plants responsible for photosynthesis and the release of for photosynthesis and the release of energy into an ecosystem.energy into an ecosystem.

Consumers and Consumers and DecomposersDecomposers

2. 2. ConsumersConsumers a) Primary Consumers - a) Primary Consumers - HerbivoresHerbivores

b) Secondary Consumers – b) Secondary Consumers – CarnivoresCarnivores

c) Tertiary Consumers - c) Tertiary Consumers - CarnivoresCarnivores

d) Multiple-level Consumers - d) Multiple-level Consumers - OmnivoresOmnivores

3. a3. a)) DetritivoresDetritivores –e.g –e.g. crab, vulture, . crab, vulture, termitestermites

b)b) DecomposersDecomposers – e.g. fungi and – e.g. fungi and bacteriabacteria

The Food ChainThe Food Chain A A food chain or food chain or food webfood web is represented by a is represented by a

sequence of organisms through which energy sequence of organisms through which energy and nutrients flow from one organism to and nutrients flow from one organism to another.another.

A major step in the transfer of energy through A major step in the transfer of energy through the food chain is termed as a the food chain is termed as a Trophic levelTrophic level• Primary consumers – Primary consumers – First trophic levelFirst trophic level• Secondary consumersSecondary consumers - - Second trophic levelSecond trophic level• Tertiary ConsumersTertiary Consumers - - Third trophic levelThird trophic level

The amount of usable energy in the food chain The amount of usable energy in the food chain decreases as we move down the trophic leveldecreases as we move down the trophic level

An example of a marine food An example of a marine food chainchain

Phytoplankton is the Phytoplankton is the first level of marine food first level of marine food chain Zooplanktons are chain Zooplanktons are eaten by krill and other eaten by krill and other Small fish which are all Small fish which are all eaten in turn by Big fish, eaten in turn by Big fish, including penguins, including penguins, seals and whales. The seals and whales. The marine food chain marine food chain continues when these continues when these big fishes are eaten by big fishes are eaten by Mammals like polar Mammals like polar bearsbears

A marine food chainA marine food chain

A marine A marine food chainfood chain

Polar bear - 5Polar bear - 5 Seal - 4Seal - 4 Cod - 3Cod - 3 Krill - 2Krill - 2 Algae - 1Algae - 1

A terrestrial-based food A terrestrial-based food chainchain

A Terrestrial A Terrestrial food chainfood chain

Hawk …Hawk … Snake eaten by Snake eaten by

hawkhawk Frog eaten by Frog eaten by

snakesnake Grasshopper Grasshopper

eaten by frogeaten by frog

Impact of pesticides (i.e., Impact of pesticides (i.e., DDT) on the species of an DDT) on the species of an

ecosystemecosystem

Interactions among species in Interactions among species in an Ecosysteman Ecosystem

PlantsPlants compete amongst themselves for: compete amongst themselves for:1. water, 2. nutrients 3. sunlight and 4. space1. water, 2. nutrients 3. sunlight and 4. space

AnimalsAnimals compete over compete over1. food, 2. water, 3. mating and 4. territory1. food, 2. water, 3. mating and 4. territory

2 main types of relationships 2 main types of relationships • PredationPredation – one species (the predator) – one species (the predator)

feeds on the other (prey) e.g. cat and mousefeeds on the other (prey) e.g. cat and mouse• SymbiosisSymbiosis – species live in an intimate – species live in an intimate

association with each otherassociation with each other

Types of symbiotic Types of symbiotic relationsrelations

Parasitism Parasitism - one species feeds on - one species feeds on another (the host) and may kill it.another (the host) and may kill it.

MutualismMutualism – both parties benefit – both parties benefit equally from the relationship (flowers equally from the relationship (flowers and butterflies)and butterflies)

CommensalismCommensalism – the relationship – the relationship benefits one species but neither helps benefits one species but neither helps nor harms the othernor harms the other

Principles of Principles of EcologyEcology

First Law of EnergyFirst Law of Energy:: “energy can be “energy can be converted from one form to another but converted from one form to another but cannot be created or destroyed”cannot be created or destroyed”

Second Law of Energy:Second Law of Energy: “whenever energy “whenever energy is converted from one form to another, a is converted from one form to another, a certain amount is lost in the form of heat”.certain amount is lost in the form of heat”.

The Law of Conservation of MatterThe Law of Conservation of Matter ““Although matter can be changed from one Although matter can be changed from one

form to another it can neither be created nor form to another it can neither be created nor destroyed by ordinary physical and chemical destroyed by ordinary physical and chemical changes”. changes”.

Biogeochemical Biogeochemical CyclesCycles

Comprise processes through which Comprise processes through which elements that sustain life (water, carbon, elements that sustain life (water, carbon, phosphorus and nitrogen) are phosphorus and nitrogen) are continuously made available to living continuously made available to living organisms. organisms.

Nitrogen cycleNitrogen cycle Hydrological cycleHydrological cycle Carbon cycleCarbon cycle Phosphorus cyclePhosphorus cycle

The Hydrological The Hydrological CycleCycle

The Carbon CycleThe Carbon Cycle

Interruptions in an EcosystemInterruptions in an Ecosystem

Causes:Causes:a) Natural causes – volcanic eruptionsa) Natural causes – volcanic eruptionsb) Human causes – e.g. construction, b) Human causes – e.g. construction,

agriculture, mining, etc.agriculture, mining, etc.

List some of the consequences that List some of the consequences that can result from an abrupt can result from an abrupt interruption in the smooth interruption in the smooth functioning of an ecosystem?functioning of an ecosystem?

What lessons can we learn What lessons can we learn from the way a natural from the way a natural ecosystem operates?ecosystem operates?

Natural ecosystems gain resources, use it and Natural ecosystems gain resources, use it and dispose of wastes through dispose of wastes through recyclingrecycling..

Ecosystems sustain themselves by running on Ecosystems sustain themselves by running on Solar EnergySolar Energy which is exceedingly abundant, which is exceedingly abundant, nonpolluting, constant and long lasting.nonpolluting, constant and long lasting.

Far less of Carnivores can be supported by each Far less of Carnivores can be supported by each ecosystem. Many would soon face ecosystem. Many would soon face extinctionextinction

Every species in a community play an Every species in a community play an important role in the important role in the sustenancesustenance of the of the ecosystemecosystem