1. Population Studies

2. Population Studies
Population- a group of individuals of a single species inhabiting a specific area
Why study populations?
Population too high or low = unstable ecosystem
Low species diversity = unstable ecosystem
Examples:
Endangered Species = low population due to human impact
Invasive Species = species introduced to a new ecosystem with no predators or competition allowing the population to increase rapidly

3. Examples of Invasive Species
European Gypsy Moth
Introduced from Europe in 1869
They were imported for silk production
They defoliate sections of forest
Brown Marmorated Stink Bug
Native to Eastern Asia
1st found in Allentown, PA in 1998
Possibly arrived in shipping crates from Asia
They feed on a variety of plants, including fruit trees, ornamental trees and shrubs, and some crops
Currently found in the northeast, mid-Atlantic region and the Pacific northwest

4. What keeps populations from growing out of control?
Limiting factors- A biotic or abiotic factor that a population needs as a resource.
Can be either:
Density Dependent or Density Independent
Carrying capacity- the number of individuals an ecosystem can support.
Amount of Food
Disease
Temperature
Natural Disaster

5. Population Growth = When the birth rate exceeds the death rate, due to an abundance of resources.

6. J-Curve Population Graph
J curve- exponential growth of a population because of no natural predators and an abundance of resources.
(Usually followed by a population crash after exceeding its carrying capacity).

7. S-Curve Population Graph
S curve- population increases to its carrying capacity & levels off due to predators or competition

8. Population Study Example
What kind of relationship does the graph show?
Which population seems to increase first before it drops?
Is the hare and lynx relationship a density dependent or density independent limiting factor?