Download 5-1 How Populations Grow

5-1 How Populations Grow
o 3 important characteristics of a population
1. _______________________________________________
2. _______________________________________________
3. _______________________________________________
Geographic distribution
 ____________________________________________________________
 ____________________________________________________________
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A few cm for bacteria living on a rotting apple
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Millions of kilometers for a population of whales.
Population Density
 _______________________________________________________________________________
3 factors that affect population size
1. _________________________________
2. _________________________________
3. _________________________________
 A pop will increase or decrease in size depending on how many individuals are added or removed
from it.
Population Growth
 Birth rate > death rate = _________________________
 Birth rate < death rate = _________________________
 Birth rate = death rate = _________________________
 Immigration- __________________________________
 Emigration- the movement of individuals out of a population.
Exponential Growth
 Occurs when the individuals in a pop reproduce at a constant rate.
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___________________________________________________________
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___________________________________________________________
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Under ideal conditions with unlimited resources, a pop will grow exponentially.
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Look at your graph from the deer population activity. At which point did the deer, lion, and
resource populations grow exponentially? _________________________________________
___________________________________________________________________________
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Logistic Growth
(S shaped curve)
 Occurs when a pop’s growth slows (or stops growing exponentially)
-As resources become less available, the growth of population slows or stops.
- Look at your graph from the deer population activity. At which point did the deer, lion, and resource
populations show logistic growth? _________________________________________
___________________________________________________________________________
Carrying Capacity
 _______________________________________________________________________________
 This is where the growth levels off
 _______________________________________________________________________________
Look at your graph from the deer population activity. At which point did the deer, lion, and resource
populations reach carrying capacity? _________________________________________
___________________________________________________________________________
Biotic Factors
What are biotic factors? _________________________________________________________________
 These are living influences.
List some examples of biotic factors. _______________________________________________________
Density-dependent factors
 _______________________________________________________________________________
 Density of the population matters
*Reminder* What is population density? ___________________________________________________
 ______________________________________________________________________________
 Examples include ________________________________________________________________
Abiotic Factors
 _______________________________________________________________________________
 Ex. Climate (temperature, precipitation), sunlight, wind, limiting nutrients, etc.
Density-independent factors
 _______________________________________________________________________________
_______________________________________________________________________________
 Usually abiotic factors
 Examples: ______________________________________________________________________
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A Habitat
 _______________________________________________________________________________
 A habitat includes both the biotic and abiotic factors.
 Together biotic and abiotic factors determine the survival of both an organism and the productivity
of the organism’s ecosystem.
Community Interactions
1. Competition
a. Mutualism
2. Predation
b. Commensalism
3. Symbiosis
c. Parasitism
Competition
 Competition occurs when two organism (of the same or diff species) attempt to use a resource in
the same space at the same time.
 A resource is any life necessity.
List some basic resources. _______________________________________________________________
Competitive Expulsion Principle (CEP)
 Direct competition in nature usually results in a winner and a loser. The loser usually fails to
survive.
 CEP states that __________________________________________________________________
_____________________________________________________________________________________
Predation
 Predation is _____________________________________________________________________
 The organism that does the killing is called the ______________________________
 The organism that gets killed is called the _____________________
Symbiosis
 Symbiosis is any relationship in which 2 species live closely together.
 There are 3 main types of symbiosis.
1. __________________________- both species benefit from the relationship.
2. __________________________- One organism is helped by the relationship, the other, is neither
helped nor harmed.
3. __________________________- One organism lives on or inside another organism, and harms it.
o The parasite receives all or part of its nutrition from the host organism.
o The host is weakened, but not usually killed. Ex. tapeworm
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