Slide 21 Flashcards
Define population
Individuals of the same species
living in the same space
at the same time
Define demography
Study of factors that affect population size and structure
4 things population dynamics depend on
+
* birth
* immigration
-
* death
* emigration
What does a population need to do in order to maintain itself through generations
- survive until reproductive age
- make enough offsprings to replace itself
Briefly describe the survivorship curve. Give example of each type
x-axis: age
y-axis: number of survivors
Type 1: humans
Type 2: birds
Type 3: plants
How to calculate survivorship (Ix)?
(# survivors at time t)/(# survivors at time 0)
How to calculate age specific fecundity
If not given, use total # offspring / # of surviving females
How to calculate Ro (net reproductive rate)
Ro = sum(Ix*Mx)
How to interpret Ro?
Ro > 1: population increase in size
Ro = 1: population remains constant in size
Ro < 1: population decrease in size
How do you calculate expected population size after 1 generation?
N1 = No * Ro
Define growth rate
change in number of individuals per unit time = deltaN/deltaT
How do you calculate growth rate if there is no immigration/emigration
DeltaN/DeltaT = N * (#births-#deaths)
how do you calculate r, per capita rate of increase?
birth - # death
How do you predict growth rate in continuous generations
DeltaN/DeltaT = N * r
if r > 0: growth rate is positive
if r = 0: no growth
if r < 0: growth rate is declining
What is rmax
Ideal growth rate for a species
How to calculate population growth if r is positive and constant over time
e^(rt)
t: time in years
What is meant by density-independent growth
r does not change with density (exponential growth)
How to calculate Nt in exponential growth?
Nt = No * e^(rt)
r: per capita rate of increase
t: time in years
What symbol do we use to calculate discrete population growth
Lambda
+: pop growth
0: pop constant
-: pop decline
Formula for r using Ro and g
r = L(n(Ro))/g
g: generation time in years
lambda = e^r
