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Intraspecific Population Regulation 11/17/2015
Intraspecific Population Regulation:
No population is able to grow indefinitely
What are the liitations iposed by ebers fro the sae
species!
The environment functions to limit population growth:
"he e#ponential population growth odel is based on se$eral
assuptions about the en$ironent
o dN/dt =%b d&N
what are these assuptions!
o 'nliited essential resources
o ( constant en$ironent
What happens when resource consuption is greater than
replenishent!
)irth and death rates are N*" constant
"he en$ironent functions to liit population growth
"he line representing change in birthrate as a function in
population
si+e is described by
o ) , b0 - aN
o ( is slope of the line delta)/N
b0 is the a#iu birthrate under ideal conditions. used in the
e#ponential growth odel
b is the actual birthrate =b0 reduced by aN as population
si+e
increases
"he line representing change in death rate as a function of
population si+e is described by
o d=d0 cN
where d0 is the yintercept and c is the slope of the line
%d/N&
d0 is the iniu death rate under ideal conditions. used in
the
e#ponential growth odel
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d is the actual death rate =d0 increased by cN as population
si+e
increases
iit to growth
If d , b. then
dN/dt , 0
The population size at which birthrate is equal to death rate
is
the maximum sustainable size in the current environment
=%b0 d0&/%ac&
is the carrying capacity3 a# sustainable population si+e for
a
pre$ailing en$ironent
"his is the logistic odel of population growth
"his odel has two coponents3
rN - e#ponential growth
%1 N/& slowing of population
Inflection Point
4efinition3 a point of cur$e where
( parabola where it reaches its a#iu /2
6ray 8uirrel population e#aple3
, 200
R , 019 calculated fro life table
"he initial population si+e is :0 indi$iduals
;#ponential $s logistic
lowed down growth so don
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o 'sed for regulation
o eep soething stable
o )ody teperature rises. you sweat. it cools you down and
your body tep drops. etc etc
Positi$e feedbac= loops
o ;#aple3 account balance grows. ore interest earned. ore
growth
o 6lobal waring is an e#aple of positi$e feedbac=
(s population density increase. resource a$ailability decreases.
and
that decrease helps to regulate the population
4ensity dependent population regulation
"wo places to control population3 birth and death
Reduce aount of births you ha$e or death rate increasing
"his is to stabili+e your population
>odel3 birth rates stay the sae but your death rate increases
you
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@opetition results when resources are liited
Why do organiss of the sae species copete! "hey all need the
sae resources3 sae ates. sae food. sae habitat
@opetition only happens when resources are liited
Intraspecific competition: sae species copeting
crable copetition - liited resources and e$erybody
struggles?
water a$ailability in a drought
o 6rowth and reproduction are depressed e8ually aong all
indi$iduals
o @an result in all indi$iduals ha$ing insufficient
resources
o @an lead to e#tinction of a local population
@ontest copetition - soe winners. soe losers? soe
indi$iduals
will do $ery well and others will perish
o *nly the unsuccessful will perish
o *nly negati$ely affects the unsuccessful indi$iduals
crable and contest are usually species specific but at
different
stages of life cycles they can shift
;arly life , scrable? later life , contest in soe insects
Exploitation3 copetition that is indirect
Not all directly fighting. but less for you and less for e?
trees ta=e
up water in the soil and lea$e less water for other trees
Interference:direct copetition ta=ing resource fro another
indi$idual
'se resources and pre$ent other indi$iduals fro accessing
those
resources
o )ird species fighting o$er a nesting area
In agriculture. any studies on density3 plants for a gi$en
area
(s density increased. the weight of each plant decrease
Net photosynthesis decreased
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>ean leaf area decreased
*nly increase3 leaf area ratio? ta=e leaf area di$ided by
total
bioass? so whate$er food the plants can get they
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In soybean populations3 indi$idual seed production is greatly
reduced
at highly densities
6rowing less gets ore beans
o In glasswort. an annual herb. the nuber of seeds produced
per plant declines with increasing density
Aigh density is $ery stressful for indi$iduals (ffects fecundity
and aturity
tress releases horones that affect indi$iduals
4ispersal can be density dependent
When a population becoes too dense. populations will
disperse
;#aple3 oldest feales will disperse in soe s8uirrels
ocial beha$ior3
"wo opposing factors3
o Binding a ate and need for indi$idual space
Bind3 carni$ores need the ost space
"oo little of a population can also hurt your population
pecies don
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all populations
4istance between colonies increased
4ecrease in colony si+e
(lways had to be $igilant
6ained protection while being in a group? when didniniu dynaic
area3 not enough to thin= about Dust nubers. thin=
about how uch area is a$ailable to the
6i$es an estiate of area per indi$idual
Bound3 large carni$ores need uch larger area than large and
sall
herbi$ores
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1000 gri++ly bears need 2 illion =E2
in order to ha$e large carni$ores. we need to create nature
reser$es
for the
>ontana study3 any population less than 50 indi$iduals
becae
locally e#tinct within 50 years %wal=ing dead. Dust a atter of
tie
they will becoe e#tinct& @onser$ation efforts3 create
corridors for populations to o$e
between areas to =eep the ali$e and healthy
Plants holding territory
4up soil so only they can use it
hade other plants with their lea$es
@o$er the ground with lea$es to stop any sprouting fro going
on
@an deplete soil resources in their root +one
