Populations change over time Changes in U.S. Bird Populations by habitat Science News 2009.
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Transcript of Populations change over time Changes in U.S. Bird Populations by habitat Science News 2009.
tt RNN 1
Exponential Growth Model
Population size 2005 = 100
Population size 2006 = 200
R100
200100200 R
2R
tt RNN 1
Exponential Growth Model
Assumption: all individuals are equal.
Is this assumption is wrong???
tt RNN 1
Competing models
Population size 2005 = 100
Population size 2006 = 200
2R
Model #1 Model #2
Not all individuals are equalAll individuals are equal
Juvenile survival = 0.45Adult survival = 0.9
0.33 Juveniles become adultsAdults produce 13 offspring each
Population size 2005 = 10090 Juveniles, 10 adults
Population size 2006 = 200
???2R
1 2 30
100
200
300
400
500
600
700Original DataNew Data
Year
Popu
latio
n Si
ze
Year 2 = 200 for both
Year
Popu
latio
n Si
ze
1 2 3 4 5 6 7 8 9 10 110
200000400000600000800000
100000012000001400000160000018000002000000
Original DataNew Data
Huge difference!
Stage and Size predict survival and fecundity
Plants- seed, seedling, adult
Invertebrates- number of molts, larva-pupa-adult
Fish- size predicts sex and number of eggs produced
Amphibians- egg-tadpole-adult
Birds- egg-chick-adult
Mammals- newborn, juvenile, adult
tt RNN 1
Exponential growth model
Nt=30 individuals
Age-structured model
Nt = 2082
newborns
1-year olds
2-year olds
tt RNN 1
Exponential growth model
Nt=30 individuals
Age-structured model
0
0
S0
F1
S1
0
F2
0
00 1 2
F1 F2
S0 S1
tt RNN 1
Exponential growth model
Nt=30 individuals
Age-structured model
Nt+1=0
0
S0
F1
S1
0
F2
0
0
20
8
2
tt RNN 1
What about growth rate?
R = Growth Rate, or λ (lambda)
Luckily, λ is an intrinsic property of the matrix
Nt+1=0
0
S0
F1
S1
0
F2
0
0
20
8
2
Only one solution For Lambda for
each matrix