Question

1. How might life tables of humans and wildlife be used to inform policy makers? .

2. Describe the advantages and disadvantages of using different age class ranges (e.g. 0–4 years v 0–25 years) when constructing life tables. Would ten year age classes be appropriate for Geococcyx californianus (Greater Roadrunner)? Would ten year age classes be appropriate for Larrea tridentata (Creosote Bush)? (Students must explain their reasoning)

Answer 1

1. Health policy makers estimate the life expectancy of an individual using life tables. These life tables assess the relative age of survival or mortality of an individual based on their age , sex, occupation, country and many other factors.With help of these life tables the policy makers simulate the individual lifespans and calculate the remaining life expectancy,model age at death, life disparity, entropy.Though reliable sometimes can be misleading too.Life insurance companies heavily rely on mortality tables to determine the premiums and to make sure they remain solvent.

2.Life tables are formulated using the demographic data to calculate the mortality experience of a single generation consisting of 100000 births. Different age groups are considered to assess the overcoming consequences in varied age groups or else only assessment can be done in less range of population if a large cohort is not considered and it may not be useful for long term surveys. life tables are known as actuarial tables as they simulate the upcoming years. It is an long term measure if the age group is 0-25 years. moreover comparison of different age groups clearly depicts the chances of mortality or disabilities or incidence and prevalence of diseases. More complex analysis can be done for diseases that involves comparison of two populations or population in two points in time.

Certainly, the age class should be determined by the life span of the creature.In case of Geococcyx califorianus(Greater Roadrunner) their development is quite rapid and even catches their own prey in a short span of 3 weeks, attains sexual maturity by 2-3 years. their lifespan is 6-8 yrs only. As the maximum life expectancy is less than 10 years age class ten years is not appropriate for this group and lesser age class would be appreciable.

On the other hand ten year age classes might not be appropriate for Larrea tridentata(Creosote Bush) as when compared to its minimum life expectancy which is around 100-200 years the age class of ten years is quite small. The largest clone is expected to be 9000 to 11000 years old. Given the remarkable age researchers have concluded that it is difficult to assess the survivorship curve and that there is no senescence in these species.