YEAR 12 YEAR 12 BIOLOGYBIOLOGYECOLOGYECOLOGY

OverviewOverview OrganismsOrganisms

Components of an ecosystemComponents of an ecosystem HabitatHabitat NicheNiche AdaptationsAdaptations Law of TolerancesLaw of Tolerances

OverviewOverview PopulationsPopulations

FeaturesFeatures Density and distributionDensity and distribution RegulationRegulation GrowthGrowth PatternsPatterns

OverviewOverview

CommunitiesCommunities Food chain and websFood chain and webs Energy flowEnergy flow Nutrient cyclesNutrient cycles Species interactionsSpecies interactions CompetitionCompetition

WhatWhat isis EcologyEcology??

What is Ecology?What is Ecology? Ecology is a branch of science Ecology is a branch of science

concerned with organisms, populations, concerned with organisms, populations, communities and ecosystems.communities and ecosystems.

DefinitionDefinition The study of how organisms interact with The study of how organisms interact with

each other and with their physical each other and with their physical environment.environment.

Species - DefinitionSpecies - Definition Organisms belong to the same species if Organisms belong to the same species if

they normally interbreed and produce they normally interbreed and produce fertile offspring.fertile offspring.

In some cases it is possible to classify In some cases it is possible to classify organisms as belonging to the same organisms as belonging to the same species if they have similar characteristic. species if they have similar characteristic.

Species - SubspeciesSpecies - Subspecies Considerable variety can exist between Considerable variety can exist between

members of a species.members of a species.

In some cases two or more quite distinct In some cases two or more quite distinct varieties exist. These different varieties varieties exist. These different varieties are called are called Subspecies.Subspecies.

SubspeciesSubspecies The Barssica’sThe Barssica’s

GENUSGENUS SPECIESSPECIES SUBSPECIESSUBSPECIES COMMON COMMON NAMENAME

BrassicaBrassica oleraceaoleracea CapitataCapitata CabbageCabbage

BrassicaBrassica oleraceaoleracea CymosaCymosa BroccoliBroccoli

BrassicaBrassica oleraceaoleracea acephalaacephala kalekale

BrassicaBrassica oleraceaoleracea botrytisbotrytis CauliflowerCauliflower

BrassicaBrassica oleraceaoleracea gemmiferagemmifera Brussel Brussel sproutssprouts

Classification KeysClassification Keys Keys are used to identify organisms and Keys are used to identify organisms and

to find the name of individual organisms. to find the name of individual organisms.

TASK:TASK: Using the “Life Science” textbook Using the “Life Science” textbook

complete investigations 3 & 4.complete investigations 3 & 4.

Components of an Components of an EcosystemEcosystem

ENVIRONMENTENVIRONMENT Both physical or non-living (Both physical or non-living (abioticabiotic) and ) and bioticbiotic

(living) factors affect the organisms in a (living) factors affect the organisms in a community. These factors influence their community. These factors influence their distribution, survival, growth and reproduction.distribution, survival, growth and reproduction.

AbioticAbiotic – the physical factors in an – the physical factors in an environment. These are non-living factors.environment. These are non-living factors.

BioticBiotic – the living factors within an – the living factors within an environment.environment.

Environmental FactorsEnvironmental FactorsBiotic FactorsBiotic Factors Abiotic FactorsAbiotic Factors

PredatorsPredatorsParasitesParasitesFood supplyFood supplyHuman Human influenceinfluencecompetitioncompetition

Light intensityLight intensityTemperatureTemperatureHumidityHumidityOO22 and CO and CO22 levelslevelsExposureExposureSalinitySalinity

Water pHWater pHRainfallRainfallDaylengthDaylengthWindWindSoil typeSoil typeWave actionWave actionSoil pHSoil pH

Habitat and NicheHabitat and Niche

Habitat and NicheHabitat and Niche HabitatHabitat – – The place or environment in The place or environment in

which an organism lives is termed its which an organism lives is termed its habitat. It must not just include their habitat. It must not just include their general environment (e.g. forest, ocean) general environment (e.g. forest, ocean) but include some detail about abiotic but include some detail about abiotic conditions in which these organisms conditions in which these organisms must live in to survive.must live in to survive.

Habitat and NicheHabitat and Niche NicheNiche – – You could say that the habitat is an You could say that the habitat is an

organism’s address, and that the ecological niche organism’s address, and that the ecological niche is its profession. The ecological niche is a is its profession. The ecological niche is a description of;description of;

the opportunities provided by the habitat; and the opportunities provided by the habitat; and

The adaptations of the organism that enable it The adaptations of the organism that enable it to take advantage of those opportunities.to take advantage of those opportunities.

Habitat and NicheHabitat and Niche The niche, then, is the role that the species plays in The niche, then, is the role that the species plays in

the community of interacting species. This the community of interacting species. This includes;includes; Where it livesWhere it lives What it eatsWhat it eats How it responds to stress, andHow it responds to stress, and What limits its population growthWhat limits its population growth

Biozone pg67-68Biozone pg67-68

Ecological niche Ecological niche investigationinvestigation

Collect a worksheet from the front of the class.Collect a worksheet from the front of the class. Using your instruction sheet, complete the Using your instruction sheet, complete the

investigation looking at the ecological niche of investigation looking at the ecological niche of the ‘window’ and ‘notch’ caterpillarthe ‘window’ and ‘notch’ caterpillar

Law of ToleranceLaw of ToleranceCopyCopy An organism’s ability to survive variation in An organism’s ability to survive variation in

environmental conditions is called its environmental conditions is called its ToleranceTolerance..

The law of tolerance states that: The law of tolerance states that: For each For each abiotic factor, an organism has a range of abiotic factor, an organism has a range of tolerances within which it can survive. Toward tolerances within which it can survive. Toward the upper and lower extremes of this tolerance the upper and lower extremes of this tolerance range, that abiotic factor tends to limit the range, that abiotic factor tends to limit the organism’s ability to survive.organism’s ability to survive.

Law of ToleranceLaw of Tolerance The wider the tolerance range of a species, the The wider the tolerance range of a species, the

more widely dispersed the organism is likely to more widely dispersed the organism is likely to be. be.

Each species will have an optimum tolerance Each species will have an optimum tolerance range within which the species will be most range within which the species will be most abundant. Outside of this optimum range, abundant. Outside of this optimum range, organism’s may experience physiological organism’s may experience physiological stress.stress.

Biozone pg 65Biozone pg 65

AdaptationsAdaptations These are inherited characteristics which enable These are inherited characteristics which enable

an organism to survive and reproduce in a an organism to survive and reproduce in a particular habitat.particular habitat.

Most organisms are a combination of many Most organisms are a combination of many adaptations that allow them to fit into their adaptations that allow them to fit into their environment easily. Adaptations are grouped environment easily. Adaptations are grouped into three types;into three types; StructuralStructural BehaviouralBehavioural PhysiologicalPhysiological

Structural AdaptationsStructural Adaptations Physical structures of organisms which help Physical structures of organisms which help

ensure success in a habitat.ensure success in a habitat. These include such things as; shape of the These include such things as; shape of the

body, the colour, appendages.body, the colour, appendages.

Example:Example: Wide wings of birds that enable flightWide wings of birds that enable flight Dense plumage of a Kea that provide insulationDense plumage of a Kea that provide insulation Widely spaced eyes of a rabbit to increase field of Widely spaced eyes of a rabbit to increase field of

vision to detect predatorsvision to detect predators

Behavioural AdaptationsBehavioural Adaptations Ways in which members of a species act in Ways in which members of a species act in

order to increase their chance of survival.order to increase their chance of survival. These include such things as; defence These include such things as; defence

behaviour, nocturnal or diurnal, hiding, spitting, behaviour, nocturnal or diurnal, hiding, spitting, stinging.stinging.

Example:Example: Bats roosting in colonies. Provides warmth and Bats roosting in colonies. Provides warmth and

protection.protection.

Physiological AdaptationsPhysiological Adaptations Processes that organisms carry out in order to Processes that organisms carry out in order to

survive.survive. Includes; anything to do with metabolism, the Includes; anything to do with metabolism, the

ability to tolerate high temps or more salty ability to tolerate high temps or more salty waters, secretion of enzymes for digestion, waters, secretion of enzymes for digestion, high reproductive rateshigh reproductive rates

ExampleExample Excellent hearing at high frequencies of bats to Excellent hearing at high frequencies of bats to

locate flying insects ( using echolocation clicks)locate flying insects ( using echolocation clicks) Biozone pg 70,74Biozone pg 70,74

AdaptationsAdaptations

PopulationsPopulations PopulationsPopulations

FeaturesFeatures Density and Density and

distributiondistribution RegulationRegulation GrowthGrowth PatternsPatterns

Features of PopulationsFeatures of Populations A A populationpopulation is a group of organisms which all is a group of organisms which all

belong to the same species and live in the belong to the same species and live in the same location same location

To define a population you need to know the To define a population you need to know the type of individual, the time and the place e.g. type of individual, the time and the place e.g. all the buttercups on the sports field of our all the buttercups on the sports field of our school in February, 2006.school in February, 2006.

Population AttributesPopulation Attributes As an individual you are born, you grow As an individual you are born, you grow

and you die. A population has a birth rate and you die. A population has a birth rate and a death rate. and a death rate.

As there is normally a large number of As there is normally a large number of individuals in a population, you can also individuals in a population, you can also measure population attributes. These measure population attributes. These include density, distribution, age structure, include density, distribution, age structure, survivorship and life expectancy.survivorship and life expectancy.

Biozone pg 76Biozone pg 76

Density & DistributionDensity & Distribution DensityDensity – is the number of individuals of a – is the number of individuals of a

population per unit area of habitat at a population per unit area of habitat at a specific time.specific time.

In low density populations, individuals In low density populations, individuals spaced will apart e.g. Tigers are solitary spaced will apart e.g. Tigers are solitary animals, found at low densities.animals, found at low densities.

In high density populations, individuals are In high density populations, individuals are crowded together e.g. Termites form well crowded together e.g. Termites form well organised, high density colonies.organised, high density colonies.

Density & DistributionDensity & Distribution DistributionDistribution – Populations tend to spread out – Populations tend to spread out

in all directions until they come to a physical in all directions until they come to a physical barrier. Within that barrier, they may be barrier. Within that barrier, they may be randomrandom, , clumpedclumped or or uniformuniform..

Distribution patternsDistribution patterns a) a) random distributionrandom distribution

Spacing between Spacing between individuals is irregular. individuals is irregular.

b) b) uniform distributionuniform distribution Individuals are evenly Individuals are evenly

spaced within an areaspaced within an area c) c) clumped distributionclumped distribution

Individuals are grouped Individuals are grouped in patchesin patches

Biozone pg 77Biozone pg 77 Practical pg 126Practical pg 126

Population RegulationPopulation Regulation Population size is regulated by factors that Population size is regulated by factors that

limit population growth. limit population growth. Density independent factorsDensity independent factors – regardless – regardless

of population density, these factors are the of population density, these factors are the same for all individuals.same for all individuals.

Density dependent factorsDensity dependent factors – the effects – the effects of these factors are influenced by of these factors are influenced by population density.population density.

Biozone pg 78Biozone pg 78

Population GrowthPopulation Growth The number of individuals comprising a The number of individuals comprising a

population may fluctuate considerably over population may fluctuate considerably over time. Populations gain individuals through time. Populations gain individuals through birthsbirths or or immigrationimmigration and lose individuals and lose individuals through through deathsdeaths and and emigrationemigration..

Biozone pg 79Biozone pg 79 A model – collect and complete the A model – collect and complete the

worksheet demonstrating growth of a worksheet demonstrating growth of a sparrow population.sparrow population.

Population Growth CurvesPopulation Growth Curves Populations becoming Populations becoming

established in a new area established in a new area for the first time are often for the first time are often termed Colonising termed Colonising populations. populations.

These show an These show an exponential growth curve.exponential growth curve.

If the resources in the If the resources in the new area were endless new area were endless then the population would then the population would continue to increase at continue to increase at an exponential rate.an exponential rate.

Population Growth CurvesPopulation Growth Curves However, in a natural population, initially However, in a natural population, initially

the growth may be exponential but as the the growth may be exponential but as the population grows, its increases will slow population grows, its increases will slow and it will stabilise at a level that can be and it will stabilise at a level that can be supported by the environment.supported by the environment.

This is called the This is called the CarryingCarrying CapacityCapacity or or KK.. In an established population the population In an established population the population

numbers will fluctuate about K.numbers will fluctuate about K. Biozone page 81Biozone page 81

r and k Selectionr and k Selection There are two parameters that govern There are two parameters that govern

population growthpopulation growth rr and and kk selection selection

rr selection refers to the maximum reproductive selection refers to the maximum reproductive potential of an organism and r-selected species potential of an organism and r-selected species are those with a high intrinsic capacity for are those with a high intrinsic capacity for population increase.population increase.

kk refers to the carrying capacity of the refers to the carrying capacity of the environment and k-selected species exist near environment and k-selected species exist near this point of equilibrium with the environmentthis point of equilibrium with the environment

r and k-selectionr and k-selection R-selected species tend to be opportunists R-selected species tend to be opportunists

because they are poor competitors and must because they are poor competitors and must continually invade new areas in order to gain the continually invade new areas in order to gain the advantage of their high reproductive potential.advantage of their high reproductive potential.

K-selected species are also called competitor K-selected species are also called competitor species because they are challenged in species because they are challenged in competitive environments to use available competitive environments to use available resources more efficiently and thereby resources more efficiently and thereby compensate for their lower reproductive potential.compensate for their lower reproductive potential.

Life Tables and Life Tables and SurvivorshipSurvivorship

Data collected during a population study Data collected during a population study can be presented as a table called a life can be presented as a table called a life table or graphically as a survivorship table or graphically as a survivorship curve.curve.

The shape of a survivorship curve shows The shape of a survivorship curve shows graphically at which life stages the graphically at which life stages the highest mortality occurs.highest mortality occurs.

SurvivorshipSurvivorship There are three types of survivorship curvesThere are three types of survivorship curves

Type IType I Mortality is very low in the infant and juvenile years, and Mortality is very low in the infant and juvenile years, and

throughout most of adult life. Mortality increases rapidly in old throughout most of adult life. Mortality increases rapidly in old age.age.

Type IIType II Mortality is relatively constant through all life stages (no one Mortality is relatively constant through all life stages (no one

age is more susceptible than another)age is more susceptible than another) Type IIIType III

Mortality is very high during early life stages, followed by a Mortality is very high during early life stages, followed by a very low death rate for the few individuals reaching adulthood.very low death rate for the few individuals reaching adulthood.

SurvivorshipSurvivorship

Population Age StructurePopulation Age Structure The age structure of a population refers to The age structure of a population refers to

the relative proportion of individuals in each the relative proportion of individuals in each age group in the population.age group in the population.

The population is usually divided into three The population is usually divided into three groupsgroups Pre-reproductivePre-reproductive ReproductiveReproductive Post-reproductivePost-reproductive

Population Age StructurePopulation Age Structure This is usually shown as a age pyramid. This is usually shown as a age pyramid.

The shape of the pyramid show different The shape of the pyramid show different thingsthings True pyramid – an expanding populationTrue pyramid – an expanding population Bell shaped – a stable populationBell shaped – a stable population Urn shaped – a diminishing populationUrn shaped – a diminishing population

An Expanding PopulationAn Expanding Population

A Stable PopulationA Stable Population

A Diminishing PopulationA Diminishing Population

Patterns in EcologyPatterns in Ecology The three patterns we will be looking at The three patterns we will be looking at

are:are: SuccessionSuccession – the change in species over – the change in species over

timetime StratificationStratification – the vertical layering of – the vertical layering of

organismsorganisms ZonationZonation – the horizontal bands of organisms – the horizontal bands of organisms

which form in relation to a gradient in a major which form in relation to a gradient in a major environmental factor.environmental factor.

Ecological SuccessionEcological Succession After a disaster, new organisms colonise After a disaster, new organisms colonise

the land, and each modifies the the land, and each modifies the environment so that is becomes suitable environment so that is becomes suitable for a new species.for a new species.

This change in species composition over This change in species composition over time is called time is called ecological successionecological succession..

Ecological SuccessionEcological Succession The community passes through a sequence of The community passes through a sequence of

stages (seres) until eventually a stable climax stages (seres) until eventually a stable climax community is formed.community is formed.

Primary SuccessionPrimary Succession Primary succession refers to the Primary succession refers to the

colonisation of regions where there is no colonisation of regions where there is no preexisting community. preexisting community.

Examples includeExamples include New volcanic islandsNew volcanic islands New coral atollsNew coral atolls Islands with communities that have been Islands with communities that have been

extinguished by a volcanic eruption.extinguished by a volcanic eruption.

Primary SuccessionPrimary Succession

Secondary SuccessionSecondary Succession This occurs when an existing community This occurs when an existing community

has been cleared by some disturbance that has been cleared by some disturbance that leaves the soil intact. leaves the soil intact.

In this case the area often eventually In this case the area often eventually returns to its original state.returns to its original state.

Secondary succession can be broken Secondary succession can be broken down into two types: Catastrophe cycle down into two types: Catastrophe cycle and Gap regeneration.and Gap regeneration.

Secondary SuccessionSecondary Succession Gap regenerationGap regeneration

Smaller scale e.g. large tree fallSmaller scale e.g. large tree fall

Catastrophe CycleCatastrophe Cycle Usually large scale e.g. fire, cyclone Usually large scale e.g. fire, cyclone

damage, slipsdamage, slips The degree of destruction variesThe degree of destruction varies

ZonationZonation Bands of organisms may form in relation to a Bands of organisms may form in relation to a

gradient in a major environmental factor. This gradient in a major environmental factor. This is is ZonationZonation..

The plants and animals in the various zones The plants and animals in the various zones have different adaptations that fit the slightly have different adaptations that fit the slightly different environments.different environments.

Some species may overlap onto more than one Some species may overlap onto more than one zone, however, here they often have reached zone, however, here they often have reached their limit of tolerance and cannot compete with their limit of tolerance and cannot compete with the other occupiers of that zone.the other occupiers of that zone.

ZonationZonation Factors that lead to zones on a rocky shore:Factors that lead to zones on a rocky shore:

Exposure to airExposure to air Exposure to extremes in temperatureExposure to extremes in temperature Fluctuations in SalinityFluctuations in Salinity Lack of food while the tide is outLack of food while the tide is out Respiration, gas exchange problemsRespiration, gas exchange problems LightLight Wave actionWave action Toxic wastesToxic wastes PredatorsPredators SpaceSpace

StratificationStratification Stratification – vertical layering, usually of plants.Stratification – vertical layering, usually of plants.

The forest is usually divided into 5 distinct layers, The forest is usually divided into 5 distinct layers, each with its own microclimate.each with its own microclimate. CanopyCanopy SubcanopySubcanopy Tree fern layerTree fern layer Shrub layerShrub layer Ground layerGround layer

StratificationStratification Each successive layer in a forest creates Each successive layer in a forest creates

different microclimates below it. different microclimates below it. Such environmental factors as sunlight, Such environmental factors as sunlight,

wind, temperature and humidity all differ wind, temperature and humidity all differ at each level and determine the types of at each level and determine the types of plants able to survive there.plants able to survive there.

Food ChainsFood Chains

Food WebsFood Webs

Energy Flow in an Energy Flow in an ecosystemecosystem

The two main energy flows in an The two main energy flows in an ecosystem are:ecosystem are: The grazing relationship. Plants are eaten The grazing relationship. Plants are eaten

by herbivores. In turn, herbivores are eaten by herbivores. In turn, herbivores are eaten by carnivores.by carnivores.

The organic detritus relationship. All the The organic detritus relationship. All the dead parts and wastes of organisms are dead parts and wastes of organisms are broken down by bacteria and fungi.broken down by bacteria and fungi.

Energy flow in an Energy flow in an ecosystemecosystem

Both of these systems have food chains, Both of these systems have food chains, or food webs. Each link in the chain or or food webs. Each link in the chain or web is called a trophic level, and at each web is called a trophic level, and at each link energy is lost.link energy is lost.

Only about 10% of the energy is passed Only about 10% of the energy is passed on, which is why most food chains are on, which is why most food chains are only about 4 links long – the energy runs only about 4 links long – the energy runs out.out.

Energy PyramidsEnergy Pyramids Trophic levels of any ecosystem can be Trophic levels of any ecosystem can be

arranged in a pyramid shape. The first arranged in a pyramid shape. The first trophic level is placed at the bottom and trophic level is placed at the bottom and subsequent trophic levels are stacked on subsequent trophic levels are stacked on top in their feeding sequence.top in their feeding sequence.

There are three types of pyramids:There are three types of pyramids: Numbers, Biomass, and Energy.Numbers, Biomass, and Energy.

Nutrient CyclingNutrient CyclingThe Carbon cycleThe Carbon cycle

Life is based on the carbon cycle. It is the key Life is based on the carbon cycle. It is the key compound in carbohydrates, fats and proteins.compound in carbohydrates, fats and proteins.

Key pointsKey points Most carbon is as limestone in the oceans, rocks and Most carbon is as limestone in the oceans, rocks and

the soil. It is not readily available unless there is an the soil. It is not readily available unless there is an upwelling of ocean sediments.upwelling of ocean sediments.

Atmospheric carbon dioxide is only about 0.03% of Atmospheric carbon dioxide is only about 0.03% of air. It is used for photosynthesis for all plants on land.air. It is used for photosynthesis for all plants on land.

Carbon compounds are dissolved in water.Carbon compounds are dissolved in water. Fossil fuels such as coal and oil and natural gas all Fossil fuels such as coal and oil and natural gas all

contain carbon.contain carbon.

How humans affect the How humans affect the cycle.cycle.

We burn down forests. This removes We burn down forests. This removes COCO22 absorptions by photosynthesis and absorptions by photosynthesis and increases COincreases CO22 given out by combustion given out by combustion

We burn fossils fuels such as coal and We burn fossils fuels such as coal and also wood.also wood.

We burn petrol; and diesel and oil We burn petrol; and diesel and oil machines and factories.machines and factories.

The carbon cycleThe carbon cycle

Nutrient cyclingNutrient cyclingThe Nitrogen cycleThe Nitrogen cycle

Key pointsKey points The air is 78% nitrogen ( however, only a few The air is 78% nitrogen ( however, only a few

organisms can use this)organisms can use this) The main entry point into the living world is as a The main entry point into the living world is as a

nitrate ion (NOnitrate ion (NO33--). This gets dissolved in soil water ). This gets dissolved in soil water

and is absorbed by plant rootsand is absorbed by plant roots These are absorped by the plant roots and turned These are absorped by the plant roots and turned

into proteins.into proteins. Animals then eat these proteins and each other.Animals then eat these proteins and each other.

The nitrogen cycle cont..The nitrogen cycle cont.. At each step of the food chain, wastes such as dead At each step of the food chain, wastes such as dead

leaves and bodies, urine and faeces are acted on by leaves and bodies, urine and faeces are acted on by decay fungi and bacteria. Eventually ammonia is formed.decay fungi and bacteria. Eventually ammonia is formed.

The ammonia is turned into Nitrite (NOThe ammonia is turned into Nitrite (NO22--) by nitrifying ) by nitrifying

bacteria. It is called nitrification.bacteria. It is called nitrification. Then the nitrite is turned into nitrate by different nitrifying Then the nitrite is turned into nitrate by different nitrifying

bacteria.bacteria. The nitrate is now available for plants to absorb again.The nitrate is now available for plants to absorb again. Nitrogen in the air can be fixed by lightning or certain Nitrogen in the air can be fixed by lightning or certain

nitrogen-fixing bacteria. This process is called nitrogen nitrogen-fixing bacteria. This process is called nitrogen fixation.fixation.

The Nitrogen cycle cont..The Nitrogen cycle cont.. Some nitrogen is lost to the system. Some nitrogen is lost to the system.

There are denitrifying bacteria which can There are denitrifying bacteria which can break down nitrates to nitrogen which break down nitrates to nitrogen which moves to the reservoir in the air. This is moves to the reservoir in the air. This is known as denitrification.known as denitrification.

The nitrogen cycleThe nitrogen cycle

Species InteractionsSpecies Interactions