Modelling populations 2 Flashcards
what is population growth
an increase in the number of individuals within a population over time
Geometric population growth
growth of population with pulsed reproduction
what do geometric population growth and exponential pop growth have in common
-unlimited environment
-overabundant resources
-density independent
What about the resource abundancy of logistic pop growth
Limited environment
resources can be depleted
DENSITY DEPENDENT
Logistic pop growth is density
Dependent
Geometric and exponential pop growth are density
independent
pulsed reproduction
(generations do not overlap, successive generations differ by constant ratio)
when is R0 equal to lambda in geometric growth?
in species that have DISCRETE generations
Geometric rate of increase to the t power?
lambda to t power
Geometric graph produces a
J shape curve
in a geometric pop, to calculate ending population size Nt, at time t,
multiply lamda tothe power of time by initial pop size N0
when do geometric and exponential growth actually happen
when resources very abundant and it is very short
unrealistic for long term
when does exponential growth happen?(3)
- small pop size at beginning
- favorable environment
- establish new territory
logistic population growth
what shape
when resources become limited, pop growth rate will slow and stop
has S shape
when is K reached
when per capita b+I=d+e
what is the outcome in density dependence if per capita births and immigration equal deaths and emigration?
K
why do carrying capacities exist?
all resources are limited, thus there is only so much space in environment
in the logistic pop growth, where does the growth rate level off?
at K
what is K?
carrying capacity
What is the x axis’s for a population graph
time
what is the y axis for population graph
population size
describe a logistical population graph
- pop starts at small size
- pop grows quickly
- pop levels off
what is the difference between rmax and r?
rmax is the intrinsic rate of increase, the maximum per capita rate of increase, under exponential growth
realized r is less than r max
r is the per capita rate of increase
