EcologyEcology
ENVIRONMENTENVIRONMENT – living and non-living components
ABIOTIC – non-living component or ABIOTIC – non-living component or physical factors as soil, rainfall, physical factors as soil, rainfall, sunlight, temperaturessunlight, temperaturesBIOTIC – living component are other BIOTIC – living component are other organismsorganisms.
The study of the interactions that take The study of the interactions that take place among organisms and their place among organisms and their
environmentenvironment
Biosphere Biosphere
The part of Earth that supports The part of Earth that supports lifelife Top portion of Earth's crustTop portion of Earth's crust All the waters that cover Earth's All the waters that cover Earth's
surfacesurface Atmosphere that surrounds Earth.Atmosphere that surrounds Earth.
EcosystemEcosystem
All the organisms living in an All the organisms living in an area and the nonliving features area and the nonliving features of their environmentof their environment
Energy and organismsEnergy and organismsAutotrophs Autotrophs
Organisms which can synthesise their own complex, energy rich, organic molecules from simple inorganic molecules (e.g. green plants synthesis sugars from CO2 and H2O)HeterotrophsHeterotrophs
Organisms who must obtain complex, Organisms who must obtain complex, energy rich, organic compounds form the energy rich, organic compounds form the bodies of other organisms (dead or alive)bodies of other organisms (dead or alive)
DetritivoresDetritivoresHeterotrophic organisms who ingest dead Heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, organic matter. (e.g. earthworms, woodlice, millipedes)millipedes)
Earth worm(Lumbricus terrestris)
SaprotrophsSaprotrophsHeterotrophic organisms who secrete digestive Heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria)the digested material. (e.g. fungi, bacteria)
Chanterelle(Cantherellus
cibarius)
SpeciesSpecies A group of organisms that can breed to produce A group of organisms that can breed to produce fully fertile offspringfully fertile offspring
PopulationPopulation All the organisms in All the organisms in
an ecosystem that an ecosystem that belong to the same belong to the same
speciesspecies
Populations have size and geographical Populations have size and geographical boundaries.boundaries. The The densitydensity of a population is measured as the of a population is measured as the
number of individuals per unit area.number of individuals per unit area. The The dispersiondispersion of a population is the pattern of of a population is the pattern of
spacing among individuals within the geographic spacing among individuals within the geographic boundaries.boundaries.
The characteristics of populations are The characteristics of populations are shaped by the interactions between shaped by the interactions between individuals and their environmentindividuals and their environment
Population DynamicsPopulation Dynamics
•Characteristics of Dynamics•Size•Density•Dispersal•Immigration•Emigration•Births•Deaths•Survivorship
Parameters that effect size or density of a population:
The size of a population is determined by a balance between births, immigration, deaths and emigration
Birth Death
Emigration
Immigration
Population (N)
Why do all populations eventually stop Why do all populations eventually stop growing?growing?
What environmental factors stop a population What environmental factors stop a population from growing?from growing?
The first step to answering these questions is The first step to answering these questions is to examine the effects of increased to examine the effects of increased population density.population density.
IntroductionIntroduction
Density-Dependent FactorsDensity-Dependent Factors
limiting resources (e.g., food & shelter)limiting resources (e.g., food & shelter) production of toxic wastesproduction of toxic wastes infectious diseasesinfectious diseases predationpredation stressstress emigrationemigration
Density-Independent FactorsDensity-Independent Factors
severe storms and floodingsevere storms and flooding sudden unpredictable severe cold spellssudden unpredictable severe cold spells earthquakes and volcanoesearthquakes and volcanoes catastrophic meteorite impactscatastrophic meteorite impacts
Density-dependentDensity-dependent factors factors increase their affect on a increase their affect on a population as population population as population density increases.density increases. This is a type of This is a type of negativenegative
feedbackfeedback..
Density-independentDensity-independent factorsfactorsare unrelated to populationare unrelated to populationdensity, and there is nodensity, and there is nofeedback to slow populationfeedback to slow populationgrowth.growth.
INTERACTIONS AMONG INTERACTIONS AMONG SPECIESSPECIES InteractionsInteractions Interspecific competitionInterspecific competition PredationPredation ExploitationExploitation SymbiosisSymbiosis
Types of Species Types of Species Interactions Interactions Neutral – two species do not interact Neutral – two species do not interact Mutualism – both benefit Mutualism – both benefit Commensalism – one benefits, other Commensalism – one benefits, other
neutral neutral Parasitism – one benefits, one harmedParasitism – one benefits, one harmed
but not killed but not killed Predation – one benefits, other killedPredation – one benefits, other killed
CommunityCommunity
All the populations in an All the populations in an ecosystemecosystem
Limiting FactorsLimiting Factors Any abiotic or biotic factor that restricts the Any abiotic or biotic factor that restricts the
numbers, reproduction, or distribution of numbers, reproduction, or distribution of organisms.organisms.
CommunitiesCommunities Range of ToleranceRange of Tolerance
The limits within which an organism can The limits within which an organism can exist. exist.
BiodiversityBiodiversity What is Biodiversity?What is Biodiversity?
The variety of life in an area that is The variety of life in an area that is determined by the number of different determined by the number of different species in that area.species in that area.
There are 2 main types:There are 2 main types:
Genetic Diversity Species Diversity
Habitat Habitat The place in The place in
which an which an organism lives organism lives provides the kinds provides the kinds
of food and of food and shelter, the shelter, the temperature, and temperature, and the amount of the amount of moisture the moisture the organism needs to organism needs to survivesurvive
The place of an organism in its The place of an organism in its environmentenvironmentNicheNiche
An organism’s habitat + role + tolerance An organism’s habitat + role + tolerance limits to all limiting factorslimits to all limiting factors
THE COMPETITIVE EXCLUSION PRINCIPLETHE COMPETITIVE EXCLUSION PRINCIPLEG.F. Gause (1934) G.F. Gause (1934) If two species, with the same niche, coexist If two species, with the same niche, coexist in the same ecosystem, then one will be in the same ecosystem, then one will be excluded from the community due to excluded from the community due to intense competitionintense competition
NicheNiche
The niche of a species consists of: The niche of a species consists of: Its role in the ecosystem (herbivore, Its role in the ecosystem (herbivore,
carnivore, producer etc)carnivore, producer etc) Its tolerance limits (e.g. soil pH, humidityIts tolerance limits (e.g. soil pH, humidity) ) Its requirements for shelter, nesting sites Its requirements for shelter, nesting sites
etc, all varying through timeetc, all varying through time
Separate nichesSeparate niches
No overlap of niches. So coexistence is possible
Species A Species B
Overlapping nichesOverlapping niches
Interspecific competition occurs where the niches overlap
Species CSpecies B
Species C
Specialisation avoids Specialisation avoids competitioncompetition
Evolution by natural selection towards separate niches
Species B’ Species C’
Specialisation into two separate niches
Species B
This niche is not big enough This niche is not big enough for the both of us!for the both of us!
Species A Species D
Very heavy competition leads to competitive exclusionOne species must go
Example: Squirrels in BritainExample: Squirrels in BritainThe Red SquirrelThe Red Squirrel
((Sciurus vulgarisSciurus vulgaris) is ) is native to Britain native to Britain
Its population has Its population has declined due to: declined due to:
Competitive exclusion Competitive exclusion DiseaseDisease Disappearance of hazel Disappearance of hazel
coppices and mature coppices and mature conifer forests in conifer forests in lowland Britainlowland Britain
Isle of Wight Tourist Guide
The AlienThe AlienThe Grey SquirrelThe Grey Squirrel ((Sciurus carolinensisSciurus carolinensis))is an alien speciesis an alien speciesIntroduced to Britain in Introduced to Britain in about 30 sites between about 30 sites between 1876 and 1929 1876 and 1929
It has easily adapted to It has easily adapted to parks and gardens parks and gardens replacing the red squirrelreplacing the red squirrel Bananas in the Falklands
CompetitionCompetition
Competition caused by Competition caused by population growth affects many population growth affects many organisms, including humans organisms, including humans
Limits population sizeLimits population size
Intraspecific competitionIntraspecific competition for food can for food can also cause density-dependent behavior of also cause density-dependent behavior of populations.populations. Territoriality.Territoriality. Predation.Predation.
Feeding relationshipsFeeding relationships
Predators & preyPredators & prey HerbivoryHerbivory Parasite & hostParasite & host MutualismMutualism CompetitionCompetition
Large blue butterfly
(Maculinea arion)
Food Chain Food Chain
rose plant rose plant aphids aphids beetle beetle chameleon chameleon hawk hawk
ProducerProducer 11stst order Consumer or Herbivore order Consumer or Herbivore 22ndnd order Consumer or 1 order Consumer or 1stst order Carnivore order Carnivore 33rdrd order Consumer or 2 order Consumer or 2ndnd order Carnivore order Carnivore 44thth order Consumer or 3 order Consumer or 3rdrd order Carnivore order Carnivore Decomposers – consume dead and decaying Decomposers – consume dead and decaying
matter matter
Trophic levelsTrophic levels Each step in a food Each step in a food
chain or a food web is chain or a food web is called a trophic level.called a trophic level. Producers are the first Producers are the first
trophic leveltrophic level Consumers are the Consumers are the
second, third, or higher second, third, or higher trophic leveltrophic level
Each trophic level Each trophic level depends on the one depends on the one below for energybelow for energy
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