The following is the life table of a natural population of a small annual succulent where 'x' is its life phase, 'lₓ' is its survivorship till that stage, and 'dₓ' is its age-specific mortality.xlₓdₓSeed produced1.0000.16Seeds Available0.8400.63Germinated0.2100.17Established0.0330.009Rosettes0.0240.010Mature individuals0.0140.014Which of the following options from the above life phases show the lowest age-specific mortality rate?

lₓ

dₓ

Seed produced

1.000

0.16

Seeds Available

0.840

0.63

Germinated

0.210

0.17

Established

0.033

0.009

Rosettes

0.024

0.010

Mature individuals

0.014

Correct option is A

Life Table: Age Specific Mortality

The rate of population growth depends on both the survival and mortality.
To obtain a clear and systematic age-specific information of survivor and mortality within a population, ecologists construct a life table.
There are two basic kinds of life tables.
One type is the cohort (or dynamic or horizontal) life table and the other is static (or time-specific or stationary or vertical) life tables.
A cohort is a group of same-aged individuals.
In cohort life table, the fate of a group of same-aged individuals is followed from birth to death whereas a static life table is made from data collected from all ages at one particular time.
Static life table is based on the assumption that each age class is sampled in proportion to its numbers in the population and the death and birth rates are constant and the population is stable.

A life table contains the following information:

X = Age classes.
nₓ = Number alive at age x.
lₓ = Age-specific survivorship ( $n_{x} / n_{0}$ ).
dₓ = Age-specific mortality, i.e., the number of individuals dying during the age interval x to x + 1 ( $n_{x} - n_{x + 1}$ ).
qₓ = Age-specific mortality rate ( $d_{x} / n_{x}$ ).
Fₓ = Age-specific total reproductive output of the entire population.
mₓ = Age-specific mean number of offspring produced per individual (age-specific birth rates or fertility).