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ch 14 population dynamics - Coggle Diagram
ch 14 population dynamics
population size fluxuates naturaly over time
becasue of food,nesting, compatiotion ect...
high surface area to volume= more enviromental affect
fluctuations in age structure
large abount at a certan age= large birth quantity
fluxuations of trees after a fire may cut structures (exmp)
overshoots and die offs
overshoot=growing beyond compacity from enviromental change (less rain the next year causing die off)
die off= substantial dropp in population that drops well below compacity
visual in pray and preditor direct relationships
can be a normal behavor eats lots in the summer then die off in winter with hopes that all survive
density dependence with time delaus can cause populations to have cyclic flux
population cycles=ocilation of population size over long periods
like a pendulim of population
in responce to die offs there will be population boom
delayed density dependence
occors based on population density some time in past
long gestation from high food fall to low food sping children de off
or of predeating off pop boom of pray then having children
dN/dt=rN(1-Nt-~t)/K)
dN/dt is tate of change of pop, r is intrensic growth rate, N is pop size at time t, K is carrying cap, ~t is magniture of time delay
r~t<0.37 pop reach compacity without oscilation
(.37<r~t<1.57 initaly oscilates but osications decline
r~t>1.57 large oscilations(also called stable limit cycle
smaller pop most likely to extinct
large pop=density depend factors cause slow growth
small pop dence depend factor cause fast growth
extinction due to variation in pop growth rate
stocastic model=model that incorps random variation in pop rates
demographic stochastiticy=variation in birth rates and death rates due to random differences btn indaviduals
enviromental stochasticity = variation in birth rate n death rate dir to random enviroment conditon
meta pop are composed of subpops that experence indapend pop dynamics
subpop=small groups of conspecifics that live in siolated paches
in sutable habatats surounded by non sutable habatat
subpopulations that live isolated with dispersial are called metapops
fragmented nature of habatats
wetlands (fish stuck in ponds) and gators moving between them
habatat fragmentation=the breakup of a larger habatat into smaller
dispersial allows smaller populations to create new subpopulations
modles of spattial structure
basic
patches of sutable habatat within a matrix of unsutable habatat(all patches are of ewual quality
source-sink
basic + different patches may not be of equal quality
source subpop=high quality patches serve as source of dispersers
sink subpop= poor patches rely on high to continue pop
landscape
source-sink+quality of sourounding matrix
basic model of meta pop dynamics
p*=1-e/c (phat is poportion of occupited patches at equlibrium, e for extint patches, and c for colonised patches)
metapop dynamics in nature
rescure effect= when dispercers enter a declineing pop saving it from extinction