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Dispersion and Survivorship Curves
Content Objectives
• SWBAT determine the form of dispersion of different species based on their relative abundance across an area.
• SWBAT describe the survivorship curves of different species based on their life histories and reproduction strategies.
Dispersion• How organisms are spread out across an area.
• Generally they fall into three categories;
• Uniform
• Clumped
• Random
3
UNIFORM
4
CLUMPED
4
RANDOM
2
Which type of Dispersion is this?
2
Which type of Dispersion is this? Clumped
1
Which type of Dispersion is this?
1
Which type of Dispersion is this? Uniform, when viewed in the context of the river.
Human Dispersion Patterns
• Is it clumped, uniform, or random?
World Population Densities
• 59.2% in Asia, 14.2% in Africa, 13.2% in the Americas, and 10.2% in Europe
Where the People Live• 20% of the world’s population lives in eastern China
• 22% lives in India, Pakistan, and Bangladesh
• Only 4.4% in United States
• Only 8.5% in Europe
Where the People Live• China is the same size as the United States, but 90% of its
population lives in the eastern 1/3rd of the country.
• 1.4 billion people (4x the United States) in an area 1/3rd the size. That means a density nearly 12x higher.
Why is the World Clumped?
• Give three reasons to explain this pattern with your partner…
Population Density of Egypt
85 million people, the largest of any Arab country
U.S. Population Density by County
Give Two Reasons for this Pattern
Survivorship Curves
Examples of Survivorship Curves
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Elephant herds protect their young, so the survivorship is quite high early on. They can live for more 70 years. Predation and other risks of death are low since they are so large and strong and stay in herds. But, once they reach “old age” they die off quickly.
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
They produce thousands of eggs, but most of the larva are eaten before they land on a rock. Once settled, few things eat them because of their stinging cells and mucous secretions.
Sea anemones can live for more than 200 years.
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Since song birds take care of their young, their juvenile survivorship is relatively high.
But, young and adults are under constant threat of predation, so their chance of death remains constant.
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Frogs produce egg masses of dozens to hundreds of eggs. Most of the tadpoles will die (eaten, water dries up, etc) before they metamorphose into adults. Once an adult, they can live for 5-15 years depending on the species. But, they are still at risk for predation.
A combination of Type II and III
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Age
% s
urv
ivin
g
Graph the survival curve of each animal and determine which Type it is
Combination of Type I and III
Agave produce hundreds of seeds. Each seed has a small chance of survival in the dry summer heat. But, once established, they will live for decades, because few things feed on them.
When the day comes where they flower and produce seeds, they die.
Content Objectives
• SWBAT determine the form of dispersion of different species based on their relative abundance across an area.
• SWBAT describe the survivorship curves of different species based on their life histories and reproduction strategies.
