The document discusses life tables, which present numerical data from population studies, explaining two methods for constructing them: dynamic horizontal and static vertical. It introduces concepts such as gross reproductive rate (GRR), net reproductive rate (NRR), and survivorship curves, categorizing the latter into three types based on mortality patterns. Examples are provided, including a static life table for red deer hinds and the utility of survivorship curves in understanding population dynamics.

1. Life cycle
GOVERNMENT E. RAGHAVENDRA RAO PG SCIENCE COLLEGE,
BILASPUR (C.G.)
Department of zoology
Topic – Life table
Guided by -
Mr. Santosh Agrawal
Submitted by - Chitrakanta pendro
M.Sc. III semester

2. • The numerical data collected
during a population study can be
presented as a table of figures
known as Life Table.
• Life tables usually represent
data from cohort called cohort
life table). Two method of
constructing life table.
1. Dynamic Horizontal
2. Static or stationary vertical
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3. • Dynamic
Horizontal
In this we start with a
known group of individuals
called cohort and observe
bow many die at each age
till all of them die. This
method of constructing life
table is called Dynamic
Horizontal.
Dynamic Horizontal

4. • Static or stationary
vertical
The other method is called
static or stationary vertical. In
this method a cross section of
population at given time is
taken and its age structure
related observation are taken.
Life
cycle

5. Example of Cohort Life Table
Where, Age (years) = x Proportion
of original cohort surviving to the
beginning of age class x = lx .
Proportion of original cohort dying
during age class x = dx Mortality
rate = qx
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6. Example of Static Life Table
Static life Table for red deer hinds
on Rhum island. based on
reconstructed age structure of the
population in 1957 .
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7. Individual fecundity or Age
Specific Birth Rate, m.
• It is the mean number of offspring
produced per individual or it is the
number of offspring that a given
female produces during a particular
age.
Gross Reproductive Rate (GRR)
GRR=∑mx Net Reproductive Rate (NRR)
Ro = ∑Ix.mx
Generation times
• It is the time lapse between birth of
the parent and the birth of the
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8. Gross Reproductive Rate (GRR)
20.0 Net Reproductive Rate
(NRR), R = 11.44
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9. 2. Survivorship Curve
• Cohort life table data are often shown
as a survivorship curve for a particular
particular population
• This is a graph showing the number of
individuals which survives through each
phase of life
• Pearl described 3 types of
survivorship curve
l. Type I or Convex Curve .
2. Type II or Diagonal straight line .
Survival curve

10. • Type I or Convex Curve:
In such population, there is little mortality until some age and then fairly steep mortality is
observed for example modem industrialized man, and many species of large animals.
• Type II or Diagonal straight line:
In such populations, mortality is constant at all age groups for example birds, rabbit and
mice, hydra, animals related to jellyfish etc.
• Type III or Concave curve
Such populations are characterized by high mortality during the young stage but
lower or nearly constant in the adult e.g. Oyster, most trees, many fishes and insects.
This appears to be the most common survivorship curve among animals and plants in
nature These types of survivorship curve are useful generalizations, but in practice,
patterns of survival are usually more complex. Thus, in a population of Erophila
verna, a very short-lived annual plant inhabiting sand dunes, survival can follow a
type I curve when the plants grow at low densities; a type II curve, at least until the
Survival
curve

11. Reference
 E- P ODUM
 BROTANICA ENCYCLOPEDIA
 SOME ONLINE ARTICLES
https://www.youtube.com
/
 https://www.google.
com/
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12. Thank
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