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)

DetritivoresDetritivores

Heterotrophic 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 A group of organisms that can breed to produce fully fertile offspringproduce fully 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 FactorsDensity-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 environmentenvironment

NicheNiche 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 PRINCIPLE

G.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 Alien

The 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 replacing the red squirrelsquirrel

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