Life table / life cycle (Chitra ).pptx

Life table / life cycle

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 Life cycle

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 D

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 S

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 E Life cycle

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 . E Life cycle

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 offspring T=∑ lxMxX ∑ lxm Life cycle

8. Gross Reproductive Rate (GRR) 20.0 Net Reproductive Rate (NRR), R = 11.44 Life cycle

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 . 3. Type Ill or Concave Curve . 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 end of the lifespan, at medium densities; and a type lll curve in the early stages of life at the highest densities Survival curve

11. Reference E- P ODUM BROTANICA ENCYCLOPEDIA SOME ONLINE ARTICLES https://www.youtube.com/ https://www.google.com/ Life cycle

12. Thank you Life cycle