Slide 21 Flashcards
(20 cards)
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
