1933773
Life processes in
the biosphere
-POP DYNAMICS
- Population dynamics
- understanding
factors that
influence pop
change is
important in ...
- In monitoring species survival
- Success of conservation strategies
- Assessing the maximum
sustainable yields of a exploited
species
- In monitoring species survival
- actual size of
pop is
controlled by
num of births,
deaths and
migration
patterns
- pop size=starting
pop+br+immigration-deaths-emigrants
- pop size=starting
pop+br+immigration-deaths-emigrants
- Factors affecting
birth rates
- Number of
births=controlled by
natural
reproductive
potential of the
species (biotic
potential). -Evolved
over long time
to=sufficient
offspring to replace
the individualsthat
die
- Must= surplus of young so
pop survives in bad years
without wasting
time+resources that
threaten the survival of
them all
- Must= surplus of young so
pop survives in bad years
without wasting
time+resources that
threaten the survival of
them all
- species e.g
herring produce
many young as
chances of dying
are high. In
contrast,
elephants
produce few
young as chances
of dying are low.
These species
can be
particularly
vunerable to an
increase in DR
- Number of
births=controlled by
natural
reproductive
potential of the
species (biotic
potential). -Evolved
over long time
to=sufficient
offspring to replace
the individualsthat
die
- Factors
affecting
mortality
rates
- Num of deaths controlled by
enviro factors that prevent
some individuals from surviving
- range of enviro factors affect likelihood
of organism dying. Density independant
factors=draught, flood and volcanic
eruption. Density independant factors=
food supply and disease
- Density independant factors- "A factor that is not
influenced by the population denisty of the species
that may be affected e.g draught"
- Density dependant facotrs-" A factor
whose effect is affected by the density of
the population e.g disease"
- Density dependant facotrs-" A factor
whose effect is affected by the density of
the population e.g disease"
- Density independant factors- "A factor that is not
influenced by the population denisty of the species
that may be affected e.g draught"
- Num of deaths controlled by
enviro factors that prevent
some individuals from surviving
- understanding
factors that
influence pop
change is
important in ...
- Homeostatic regulation of pop size
- Carrying capacity
- "The greatest
population that can be
supported sustainably in
an area"
- if pop rises above cc density
dependant factors become
stronger so mortality
increases+pop decreases
- If pop drops below cc density dependent
factors=weaker so mortality decreases+pop
increases. mortality changes if pop is above
or below cc
- "The greatest
population that can be
supported sustainably in
an area"
- Predator prey pop relationships
- self regulation. found in
habitats where prey species
is main food of a predator
- where there is a few food
species available, a reduction
in availablilty of one food
species+big impact on
predator numbers
- where there is a few food
species available, a reduction
in availablilty of one food
species+big impact on
predator numbers
- self regulation. found in
habitats where prey species
is main food of a predator
- Artificial pop control
- Culling of a pop may be needed
to conserve a species of habitats
where natural control
mechanism no longer exist
- e.g Red deer in scotland
since wolves no longer exisit
- Artifically killed by
disease, predator
introduction,
sterilisation and
destroying nests
- Artifically killed by
disease, predator
introduction,
sterilisation and
destroying nests
- e.g Red deer in scotland
since wolves no longer exisit
- Culling of a pop may be needed
to conserve a species of habitats
where natural control
mechanism no longer exist
- Carrying capacity
- Sigmoidal pop
growth- "The growth
pattern of a pop
where abundant
resources allow rapid
rowth followed by
pop stabilisation as
the carrying capacity
is reached"
- Lag,log,slow growth,
stable phase,death
phase.---- discuss
environmental resistance
- Lag,log,slow growth,
stable phase,death
phase.---- discuss
environmental resistance
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