1. Limiting Factors QQ
How are population sizes limited?

2. QQ#1: Review: Explain the difference between these two graphs in relation to population growth

3. How Can population Growth be slowed?
As a populations carry capacity limits the population’s size based on the amount of resources present.
Population sizes can also be limited by two types of factors called limiting factors

4. QQ#2: what do you think the difference between these two factors are?
Two types of limiting Factors
Density Independent Factors
limiting factors that do not depend upon a population’s size.
Density Dependent Factors
limiting factors that depend upon the population size.
The “density” of a population is determined by how many individuals are living in a set amount of space
QQ#2: what do you think the difference between these two factors are?

5. Density Independent Factors
Density Independent Factors are limiting factors that do not depend upon a population’s density.
Examples include:
Natural Disasters (i.e. earthquakes)
Seasonal Variation (i.e. drought)
Human activities such as deforestation

6. Density Dependent Factors
Unlike density independent factors, these will play are larger or smaller part in limiting growth depending on how dense the population is.
Examples include:
Competition
Predation
Parasitism
Disease

7. Competition
When populations become crowded (more dense) organisms compete
They compete for food, water, space, sunlight, and other essentials.
Competition among members of the same species is a density-dependent limiting factor.
QQ#3: what kinds of things do you think individuals of the same species compete for?

8. Predation Populations in nature are often controlled by predation
The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control

9. QQ#4: explain what trends you notice between the predator and prey relationship below in regards to population sizes

10. Parasitism and Disease
QQ#5: Why do you think Disease is considered a density dependent limiting factor?
A parasite lives in or on another organism (the host) and consequently harms it
Parasites/Diseases can limit the growth of a population by killing their hosts
Parasites/disease are more easily spread in highly dense populations

11. Check for Understanding (you do not need to write these)
A limiting factor that affects all populations in similar ways regardless of their size might be
drought.
disease.
predation.
crowding.

12. Check for Understanding
Within a limited area, if the population of a predator increases, the population of its prey is likely to
increase.
decrease.
remain about the same.
become extinct.

13. Check for Understanding
Which of the following is a density-independent factor affecting populations?
predation
disease
a destructive hurricane
parasites