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Flashcards in Life tables Deck (63)
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1

populations have a spacial structure which includes:

1. their range
2. spatial arrangement of individuals within and among the range
- density
- patterns of movement among individuals

2

Populations also have genetic variation
among individuals throughout the population
... or represented in

subpopulations

3

Another component of populations is
associated with age structure

and the
rates at which births and deaths occur
within a population

4

who invented life tables and why

the Insurance and Health Care Industry to monitor mortality and survivorship in human populations

5

When was the first life table developed

in 1921 by Pearl and Parker

6

In order to construct a life table in the first place,
one must have some knowledge of the

age structure within a population

7

the first column of the life table is

x

8

x usually represents

age (could be in days, weeks, years, hours, etc.)

9

individuals that make up x are referred to as a

cohort

10

two inherent weaknesses in life tables

1. only age is considered when allocating individuals to classes (not size, social status, and genotype)
2. life tables almost always include only females for species having distinct males and females. This is because one of the key parameters in a life table is the rate of production

11

the male's contribution to sexual reproduction

difficult to measure in terms of the numbers of young produced

12

how is birth accounted for in life tables

by counting the number of female offspring produced per breeding season or age interval per female in the population (fecundity)

13

Life tables

tables that contain class-specific survival and fecundity data

14

x

age class

15

nx

the number of individuals in each age class immediately after the population has produced offspring

16

sx

the survival rate from one age class to the next age class

17

bx

the fecundity of each age class

18

what is the fecundity of each age class denoted by

bx (b for birth)

19

what does the column bx indicate

new offspring cannot reproduce, but 1-year-olds can each produce one offspring, 2-year-olds can each produce three offspring, and 3-year-olds can each produce two offspring

20

Number surviving to next age class

(nx) x (sx)

21

Number of new offspring produced

(nx) x (sx) x (bx)

22

if we do these calculations for every age class...

we can find the number of individuals that we will have after one time interval

23

the number of individuals in a population after one time interval divided by the initial number of individuals provides...

lambda

24

A POPULATION WITH A FIXED LIFE TABLE
ASSUMES A STABLE AGE DISTRIBUTION AND
GROWS

at a constant rate

25

When age-specific birth bx and survival, sx, rates remain
unchanged for a sufficient length of time, a population
will assume

a stable age distribution

26

Under such conditions, each age class in the population
grows or declines at the same rate; and so, therefore,
does the

total size of the population

27

lambda

the growth rate of the population

28

Under stable age distribution conditions, each
age class grows at the

same rate from year to year

29

Stable age distribution

when the age structure of a population doesn't change over time

30

when does a stable age distribution occur

when survival and fecundity of each age class stays constant over time