Summary Matric IEB environmental studies

fluctuations inthe
mayofinteractions oforganismswiththeirphysical biologicalenvironments
ANDhowthesedeterminethedistributionandmakeup ofpopulationswithinan
sizeof a population ecosystem
andthephysicaland
socialfactorswhich
regulatethesefluctuations


DEFINITIONS
differentspeciesoforganismsthatinteractwitheachotherandwith
Ecosystem
heapsof
pgdguu.ph

couldbeaslargeasa rainforestorassmallas adropletofwaterinafishpond
species agroupoforganismswithsimilarcharacteristics whichproducefertileoffspring
Eglionzebragiraffespecies
individual a singleorganismthatformsapartofthesamespeciesandiscapableof independentexistence
Population agroupoforganismsof thesamespeciesthatarefound in aparticularareaandcan
crossbreedfreely

EgthepopulationofgiraffeintheKrugerNationalPark
community agroup of differentspeciesthatinhabitandinteractin a particulararea
Eglionzebra giraffepopulationsintheKrugerNational Park
Factorsaffectingpopulation size
populationsize ᵗ
in
gain ie9sePafcreapePaetiime
because of achangein
natality birthrate of a population nooflivebirthsperthousandindividualsper
year
mortality deathrateof apopulation no of
deaths per i
thousand ndividuals
peryear
Immigration onewaymovementoforganismsINTOanareawheretheybecomeestablished
Emigration onewaymovementoforganismsOUTofanarea wheretheybecomeestablished

Populationtrends
whennatality mortality immigrationandemigrationinteract generaltrendsoccur
Natality immigration Increaseinpopulationsize
morebabiesbornintopopulation morepeopleenteringpopulation
Mortality emigration Decreasein populationsize
morepeoplearedyingmorepeopleareleavingthepopulation

,Regulation of populationgrowth
Afewindividualsenteranunoccupiedarea
Thereisnoshortageoffoodorotherresources theywillreproduce populationincreasesexponentially
Nopredators moredemandsaremadeonavailable
resources

Eventuallyabalanceisreached causesENVIRONMENTAL RESISTANCE
Thepopulationstabilisesat a thetotalnooffactorsthatpreventapopulation
fromreproducing atitsmaximumrate
particularsizetheecosystem's
carryingcapacity organisms natality immigrationrate
that immunentient slipup mortality emigrationrate


Limitingfactors
thathelpregulatethegrowthof apopulation buildupenvironmentalresistance
Factors


Densityindependentfactors Densitydependent factors
Factorsthat
regulate limit
thepopulationgrowth thatincreasetake
factors arrectwhen numbers
population increase

asaresultofNATURALfactors notbecauseofthe population refectorractors

sizedensityofthepopulation populationresultsin
eg physicalfactors catastrophic
events for
demand food water for
competition resources




ii
im living rate
space stress reproduction
EEgyture EE
a naineruptions
diseases parasitesspread organismsclose
together
ashelter exposedtoweather predators




Populationincrease
epmyiggmgu.is aggtgaEincreases increaseinmortality
decreasein
natality

populationgrowthdecreases


POPULATION SIZE

STABLE UNSTABLE
wherethenoofindividuals
population populationwherenoofindividualsin
inpopulationfluctuatesaroundthe populationfarexceedthecarryingcapacity
capacity
carrying

increase
uhaelaigingeagaug.ly
willmostlikelybedamaged
habitat
deteriorate
quickly

IEets pap
itan'Size
carryingcapacitydecreases
9nmennetips.ca'ferableto
Yetaking.ly 9Ey
ecrease
I
denvironmentalresistance inpopulation
decrease size
iincreaseinpopulationsize even
may extinct
become

, fluctuationdepending on availableresources


seasonal fluctuation Annualfluctuation
sizeofpopulationfluctuatesfromoneseasontoanother sizeofpopulationfluctuatesoverdifferenttimesofyear
egEuropeanbarnswallow egBluewildebeest
winter mytosouth
cold Africa migration fromitsoriginal
better
summer
temps usePaddlingme
pientialfooda
resultsinbreedinga
theirmigrationisbasedontheavailabilityof
landforgrazing whichisdependentonrainfall
wetseason grassyplains
Dryseason woodlands
youngborn betweenJan March when
landforgrazingisplentiful




IMPORTANCE tosee if apopulationischangingovertime



Directmethods Indirectmethods
involvestotalcountofallindividualsinapopulation
onlypartofthepopulation
involvescounting
AKA acensus thiscountisusedas asample todetermine
eg thetotalpopulationsizebystatisticalcalculation

eg


Mark recapturemethod
Method
1 aspecificareaisdemarcated
2 anumberofindividualsarecaughtcountedandmarkedtheyareknownasthefirstsample
3Themarkedindividualsarereleasedintotheenvironment
mustbeallowedforthemarkedindividualstomixwiththerestofthepopulation
4 sufficienttime
5 Asecondgroupofindividualsiscaughtandcountedtheyareknownasthesecondsample
6Themarkedindividualspresentinthesecondsamplearecounted
7Thedatagatheredisusedtodeterminetheestimatedsizeofthepopulation



IE
totalno ofcaughtanimalsinsample2

G estimatedpopulation
size