Download Populations: Survivorship Curves

Populations:
Survivorship Curves
“The Ghost of Populations Past”
Objectives:
Students will:
• Investigate survivorship
• Develop survivorship curves from data
collected in the field
• Analyze a human survivorship curve
developed from the collected data
• Describe the various types of survivorship
curves as they relate to ecological life history
strategies
Objectives:
What will you need
What will you be
to know?
able to do?
• Collect human
• Survivorship
survivorship data
• Ecological life history • Develop survivorship
strategies
curves using a
computer spreadsheet
• Survivorship curves
• Analyze survivorship
(Types I – III)
curves of humans and
other organisms
Introduction
• Populations grow, shrink, succeed, or fail
• Survivorship refers to a way that populations
shrink
• Genetics and the environment play a role in
how species survive
• How different species live or die can be
described by means of a Survivorship curve.
Introduction
• Survivorship Curves:
Mathematical models
Show how many
members of a species
are likely to survive
Follows a group of
individuals from birth
to ultimate death of all
members
Protocol/Procedure
• Part 1 Details: A Trip to a Cemetery
Choose a 25-year birth year range.
Ex. 1800-1824, 1825-1849, 1850-1874, etc…
Choose a cemetery, record the location
on the data sheet (be sure to record all
information requested on the data sheet).
In the cemetery, locate 75 males and 75
females who were born in the year range you chose,
record year of birth and year of death on the data
sheets
Protocol/Procedure
No dates on headstone?
Birth date within range?
Can’t use!
Birth date MUST be in
the range you select!
Introduction
Introduction
Protocol/Procedure
• Part 2 Details – Data Analysis and Questions
For all 150 individuals, calculate “Age at
Death” by subtracting the birth year from the
death year (record on the same data sheets)
Using 5 year increments and the second set
of data tables, tally how many males died
every 5 years. Repeat using the females.
(See example next slide.)
Introduction
Protocol/Procedure
Introduction
• Part 2 Calculation Example: Male
Gender
Birth year
Death year
Age at death
male
1876
1900
24
male
1899
1901
2
male
1879
1904
25
male
1881
1981
100
male
1887
1986
99
Age at death
# total from population
0-5
1
21-25
2
96-100
2
Bring your data to school on
the first day of class!
The Standards
• Explain how variations in structure, behavior or physiology allow some
organisms to enhance their reproductive success and survival in a
particular environment.
• Explain that the variation of organisms within a species increases the
likelihood that at least some members of a species will survive under
gradually changing environmental conditions.
• Relate how distribution and abundance of organisms and populations in
ecosystems are limited by the ability of the ecosystem to recycle materials
and the availability of matter, space and energy.
• Relate how birth rates, fertility rates and death rates are affected by
various environmental factors
• Examine the contributing factors of human population growth that impact
natural systems such as levels of education, children in the labor force,
education and employment of women, infant mortality rates, costs of
raising children, birth control methods, and cultural norms.