Population Dispersion

advertisement
Populations and
Limits to Growth
Population Density and Dispersion
• Population Density: a measurement of the number of individuals
living in a defined space
• Example: rural area vs. city
• Population Dispersion: the way individuals in a population are
spread in an area
• Clumped dispersion: live close together
• Uniform dispersion: live at specific distances from each other
• Random dispersion: individuals spread randomly
Population Growth
• Affected by:
•Number of births (increase)
•Number of deaths (decrease)
•Number of individuals that enter (immigrate)
or leave (emigrate) a population
•Immigration: movement of individuals into an
area
•Emigration: movement of individuals out of
an area
Exponential Growth
• Occurs when the
individuals in a population
reproduce at a constant
rate
•Occurs under ideal
conditions with unlimited
resources
Logistic Growth
• Occurs when a population’s growth
slows or stops following a period of
exponential growth
• Most common type of growth
• As resources become less available,
the growth of a population will slow or
stop
• Reaches carrying capacity: largest
number of individuals that a given
environment can support
Limits to Growth
• Limiting factors: factors that cause a populations
growth to decrease
•Competition
•Predation
•Parasitism and disease
•Drought and other climate extremes
•Human disturbances
Density-Dependent Factors
•Limiting factors that depends on
population size
•Affect mostly large populations
•Do not really affect small, scattered
populations
•Include: competition, predation,
parasitism and disease
Density-Independent Factors
• Limiting factors that affect all
populations in similar ways, regardless of
population size
•Unusual weather, natural disasters, seasonal
cycles, human activities
Download
Related flashcards
Bone fractures

40 Cards

Injuries

44 Cards

Epidemiology

43 Cards

Carcinoma

28 Cards

Create flashcards