Survivorship Curves

Application: The Cemetery Lab

St. James Cemetery, Toronto ON

What is survivorship?

Describes the pattern of mortality and survival in a population

The probability of newborn individuals of a cohort surviving to particular ages

Discuss with a partner

What are the different types of survivorship curves?

Three types of Survivorship Curves - Type I survivorship curves are for species that have a high survival rate of the

young, live out most of their expected life span and die in old age. Humans are a good example of a species with a Type I survivorship curve. Q:

What is the catch?

Type II survivorship curves are for species that have a relatively constant death rate throughout their life span. Death could be due to hunting or diseases.

Examples of species exhibiting a Type II survivorship curve are coral, squirrels, honey bees and many reptiles.

Type III survivorship curves are found in species that have many young, most of which die very early in their life. Plants, oysters and sea urchins are examples of species that have Type III survivorship curves.

Our data from St. James Cemetery

Combine 100 birth and death dates Construct Survivorship Curve as per

instructions in the Tiger Book

Observing Survivorship Data using gravestones (100 min)

Birth date Death date Age at Death

1850 1901

1851 1942

1852 1884

1852 1884

1852 1900

Back at the lab- calculate survivorship (in this example n=22)

Age at death (yrs) No. of original group surviving

Survivorship

5 21 954

10 20 909

27 18 818

27 18 818

Survivorship = No. of original group surviving *1000original number (n)

Graph your data= Survivorship curve

Part 2: Simpson’s diversity index

At the cemetery, collect 100 leaves Sort them based on their species type Count the number of each species Calculate the diversity index for the cemetery

(see handout) Collect 100 leaves at another location and

calculate the index Compare the 2 values. Which location is more

diverse?