DEMOGRAPHIC TRANSITION
Way to explain changes in population
composition e.g. high to low birth rate.
FOUR STAGES:
STAGE ONE:
Both death and birth rate high (preindustrial).
Balance in population.
DEMOGRAPHIC TRANSITION
STAGE TWO:
DEVELOPING COUNTRIES
Death rates drop dramatically – better food
and sanitation, less disease. Better
education, healthcare, access to technology,
better farming techniques.
Birth rates continue to be high.
Increase in population occurs, pressure on
economy, health care, education etc.
DEMOGRAPHIC TRANSITION
STAGE THREE:
DEVELOPING TO DEVELOPED
COUNTRIES
Birth rates fall – contraception, higher
wages, urbanisation, decrease in
subsistence agriculture, increase in
education and status of women, children
don’t work, parents invest in children’s
education.
DEMOGRAPHIC TRANSITION
STAGE FOUR:
DEVELOPED COUNTRIES
Low birth rates, low death rates.
Birth rate may drop to below replacement level
(Germany, Italy, Japan). Death rate may increase
due to lifestyle diseases and ageing population.
Threat to industries relying on population growth.
Economic burden on shrinking working population.
Factors that can cause a decrease
in population growth
Kaposi sarcoma, a skin cancer
typical of HIV/AIDS
Diseases such as
HIV/AIDS, bird flu,
H1N1 etc.
Better living
conditions and better
education leading to
better family planning.
Better contraceptives.
Wars.
Natural disasters.
Factors that influence
community structure
Predasie
Kompetisie
Kompeterende
uitsluiting
Hulpbronafbakening
Simbiose
Suksessie
Predation
Competition
Competitive
exclusion
Resource
partitioning
Symbiosis
Succession
PREDATOR-PREY-RELATIONSHIP
PREDASIE
PREDATOR-PREY RELATIONSHIP
Direct link between predator and prey
numbers.
As prey increase, there will be more food
for predators, so will predators increase.
Increase in predator numbers put pressure
on prey numbers. Prey will decrease.
Decrease in prey will mean less food for
predators, numbers will decrease etc.
ROL VAN KOMPETISIE
Kompeteer om
dieselfde, maar
beperkte bronne bv.
Water, lig, voedsel,
gebied, paarmaat.
Intraspesifiek –
dieselfde spesie.
Interspesifiekverskillende spesies.
Hyena and lion
Intraspecific or interspecific?
Explain your choice
Competition
1. Intraspecific competition: the competition
between organisms of the same species
depending on the same resources like food,
space, shelter, water and access to mates.
Competition
2. Interspecific competition: the competition
between organisms of different species depending
on the same resources e.g. light, space, water,
shelter, food
COMPETITIVE EXCLUSION:
The competition in which one of the two
competing species is much more successful that
the other, to such an extent that the successful
species survives and the other species
disappears.
Kompeterende uitsluiting: Een van die spesies
is ‘n baie beter kompeteerder; wanneer hy saam
met ‘n ander spesie in diese3lfde habitat is, sal
hy oorleef en die ander uitsterf.
Competitive
exclusion
Wie is
die beter
kompeteerder?
RESOURCE PARTITIONING:
The kind of competition situation in which
competing species coexist in the same habitat
since they use the resources slightly differently.
HULPBRONAFBAKENING:
Kompeterende spesies kan saam bestaan en
oorleef omdat hulle bronne op verskillende
maniere benut.
Resource partitioning amongst
plants
Resource partitioning: co-existing
shore birds
Wat is simbiose?
Simbiose beteken letterlik “saamleef” –
sym = saam, en bio = lewe.
Die saamleefverhouding is gewoonlik
lewensbelangrik vir ten minste een van die
partye.
Dit is ‘n langtermyn saamleef en nie
toevallig of tydelik nie.
MUTUALISME
Tot voordeel van
beide partye.
Geen party word
benadeel nie.
Voorbeeld: vlinder en
blom – blom word
bestuif, vlinder kry
nektar.
Verpligte
mutualisme
Die saamleefverhouding is
lewensbelangrik vir
albei partye.
Ligene (korsmosse) –
swamme verskaf
blyplek en absorbeer
water; alge fotosinteer
en verskaf voedsel.
Nie-verpligte mutualisme
Die saamleef-verhouding
is steeds belangrik,maar
nie noodwendig tussen
twee spesifieke individue
nie bv. Die vlinder en
blom (reeds genoem).
Die bosluisvoël kry
voedsel en die wildsbok
is vry van parasiete.
KOMMENSALISME
Die een party word
bevoordeel – die
ander party word nie
bevoordeel of
benadeel nie bv.
Beesryer wat hier ‘n
saamry-geleentheid
kry, maar goggas op
grond vreet waar
bees vroetel.
Nog kommensalisme …
Die remora-suigvis
gebruik die haai as ‘n
taxi en vreet van die
afvalstukkies voedsel
wanneer die haai
vreet.
SUIER AAN BO-KANT
VAN REMORA
PARASITISME
Een party word
bevoordeel, die ander
word beslis benadeel.
Parasiete wat op
diere teer (en self
diere is), kan
ektoparasiete of
endoparasiete wees.
Plantparasiete
Semi-parasiete is slegs
vir water en minerale van
die gasheer afhanklik en
kan self fotosinteer bv.
voëlent (Viscum).
Holoparasiete is geheel
en al afhanklik van die
gasheer en bevat geen
chlorofil nie bv. Dodder.
Community change over time:
Ecological succession
TERMINOLOGY IMPORTANT
1. Primary succession:
the sequence of
organisms that occupy a
new habitat.
2. Pioneer plant: a plant
that can colonise bare
soil and that is part of
the community that
forms the first stage in
the process of
succession
3. Secondary succession:
the sequence of organisms
that occupy a disturbed
habitat or when an
established community has
been disturbed in a
catastrophic manner.
4. Climax community: the
final stage in the process
of succession that refers to
a mature community of
plants that will remain
stable with few, if any,
changes over time
The gradual replacement
of one plant community
by another through
natural processes over
time
Succession
PRIMARY SUCCESSION
colonization of new sites by
communities of organisms – takes
place on bare rock
PRIMARY SUCCESSION
New bare rock comes from 2
sources:
PRIMARY SUCCESSION
New bare rock comes from 2
sources:
PIONEER ORGANISMS
the first organisms to
colonize a new site
Simple plants like mosses
and ferns can grow in the
new soil
plantecology.wordpress.com
Wanneer pionierplante bygedra het tot die ontstaan van `n
plantgemeenskap, begin diertjies om hulle daar te vestig.
Primary SuccessionRock
Begins in a place that ALREADY has
soil and was once the home of living
organisms
Occurs faster and has DIFFERENT
pioneer species than primary
succession.
Secondary succession-
Secondary succession-
CLIMAX COMMUNITY