A population is a group of the same species that lives in the same area and competes for resources like food, water, and space. Populations are always changing in size due to limiting factors, which are abiotic or biotic factors that control population numbers. Limiting factors include temperature, drought, space, predators, and competition between organisms over resources needed for survival and reproduction.

1. LIMITING FACTORS
8SCIENCE: Mon. Oct. 25

2. Interactions among living organisms
REVIEW:
What is a population?
- A population is a group of the same kind of
species that live in the same area
- They compete for resources like:

3. Populations
• Characteristics:
– Size
• how many organisms
(species!) does this
population have?
– Spacing
• need enough space to live
– Density
• The number of individual
organisms in a certain area
• The size of populations is
always changing
– One way populations
change is through
limiting factors

4. Limiting Factors
• Can populations grow forever?
– No! Why not?
• Limiting factor: Any abiotic or biotic factor
that controls the number of individuals in a
population

5. Limiting Factors
• What limits the growth of a population?
• Abiotic limiting factors:
– Temperature
– Drought and other
weather events
– Space to live
– Others?
• Biotic limiting factors:
– Predators
– Others?

6. Limiting Factors
• Competition
– The struggle among organisms to get the resources
they need to:
• Survive
• Reproduce
– Example: many birds may move to a new tree to live.
They are competing for space to create their nest.
– Example: Students at GI compete with each other to
have a good place in line for pizza at the tienda during
recess