1. Life tables
Were first used to estimate insurance risk in human populations
Divides the population into age specific classes
Estimates the age-specific mortality risk in each class

2. A life table for a town in the East Midlands
age
pop
death
% death
1 death in
<1
2533 20
127
1-4
11130 1
5-9
15519 2
7760
10-14
16409 4
4102
15-19
16133 9
1793
20-24
21482 10
2148
25-29
15997 22
727
30-34
16026 35
458
35-39
19800 34
582
40-44
16076 39
412
45-49
13404 59
227
50-54
13027
108
121
55-59
10051
136 74
60-64
10220
176 58
65-69
9190
320 29
70-74
7427
445 17
75-79
5231
414 13
80-85
2884
355 8
85+
1840
347 5

3. Assembling a life table
Cohort or Dynamic life table
Assembled by following the fate of a cohort from birth to death.
Static life table
Assembled estimating the age specific death risks from the age structure at a given time

4. Dynamic life table Static life table age 1999 2000 2001 2002
survivorship lx
1000
1.00 1
400
0.40 2
100
0.10 3 20
0.02
Static life table
estimated
age
1999
survivorship lx
1000
1.00 1
400
0.40 2
100
0.10 3 20
0.02

5. However a static life table assumes the population is stable which is usually not true
estimated
age
1999
survivorship lx
1000
1.00 1
400
0.40 2
100
0.10 3 20
0.02
Original
estimates
estimated
age
1999
original population
survivorship lx
survivorship
1000
1.00 1
400
1200
0.40
0.33 2
100
1400
0.10
0.07 3 20
1600
0.02
0.13
But what if the population is decreasing?
Decreasing population

6. Population increasing
estimated
age
1999
original population
survivorship lx
survivorship
1000
1.00 1
400
900
0.40
0.44 2
100
800
0.10
0.13 3 20
600
0.02
0.03
Population increasing

7. Phlox drummondii (annual phlox) is native to central and eastern Texas
Phlox drummondii (annual phlox) is native to central and eastern Texas. It is a winter annual and grows abundantly in sandy fields and on roadside verges. It germinates in response to cool rainy weather.

8. qx=lx-lx+1
the proportion of individuals that have died over a time period =
the mortality rate.

9. Mortality analysis time days time days Average mortality rate per day
Log scale
time days

10. Where bx seed=number of seed per plant (Bx/Nx)

11. Fecundity analysis
Number of seed produced per plant
time days

12. Diagrammatic dynamic life table for Phlox drummondii
Rectangles=stages in the life-cycle
Inverted triangles= transition probabilities
Diamond=seed production

13. A more complex diagrammatic life table of the biennial ragwort Senecio jacobea
Dispersal
Seed bank dynamics
germination
immigration
establishment
Biennial lives for 2 years reproducing at the end of the second year

14. Survivorship curves
Type I = Found where there are ample resources e.g. human population in developed countries
Type II = A constant risk of death throughout lifespan e.g. seeds in a buried seedbank
Type III = High early mortality e.g. many plants reproducing by seed

15. Survivorship curve for Phlox drummondii

16. Survivorship curves of Erophila verna at different densities
b=5-10
c=15-20
d=35-50
e=>50
1000s m-2
Survivorship curves for a species depend on a range of conditions

17. In plants stage of development can be a more useful definition of progress than age. Data are for a perennial Ranunculus acris
juveniles
immature
vegetative
generative
dead