Download CP Ecology Notes Part 7

Populations
A particular species living in a
particular place at the same time
Population Growth


Biotic Potential: The highest rate of
reproduction a population can reach.
Sentence:
Population Growth


Biotic Potential: The highest rate of
reproduction a population can reach.
Sentence: The biotic potential of fruit
flies is reached when 120 eggs laid by
the female hatch into successful
offspring.
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
432,000
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
432,000
25,920,000
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
432,000
25,920,000
1,555,200,000
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
432,000
25,920,000
1,555,200,000
93,312,000,000
Fruit Fly Population
Growth

Generation
1
2
3
4
5
6
7

# of Offspring
120
7,200
432,000
25,920,000
1,555,200,000
93,312,000,000
5,598,720,000,000
Number of Flies
Fly generations
Number of Flies
Fly generations
The graph looks like the shape of what letter?
Population Growth

We call this type of curve a J – shaped
curve and the population growth it
represents exponential growth
Population Growth (cont.)


Population may be limited by factors
called Limiting Factors.
Examples:
Population Growth (cont.)


Population may be limited by factors
called Limiting Factors.
Examples:
– Water
– Shelter
– Nutrients
– Mates
– Nesting Sites
Population Growth

Carrying Capacity: The maximum
population of a particular species that
a given habitat can support over a
given period of time.
S - shaped Growth Curve
Number of
Individuals in the
population
K = Carrying
Capacity
Time




Growth = Births exceed Deaths
Decline = Deaths exceed Births
Natality: birthrate; the production of new
individuals by birth, hatching, germination,
or cloning.
Mortality: deathrate; the ratio of deaths in
an area to the population of that area.

Immigration: migration into a place

Emigration: migration out of a place
The number of organisms in a
population tends to rise above and fall
below the carrying capacity.
Number of
Individuals in the
population
K = Carrying
Capacity
Time
Limiting Factors

1.
2.
Limiting Factor: an environmental
factor that limits the growth,
abundance, or distribution of a
population of organisms in an
ecosystem (e.g. water, nutrients,
sunlight, prey, etc.).
Density Dependent
Density Independent
Density Dependent

Examples:
Density Dependent

Examples:
– Food
– Water
– Living Space
– Predation
– Disease: High densities makes it easier for
parasites to find hosts and spread the
disease
– Stress: usually has a negative effect on
populations. Stress can make organisms
weak and more prone to disease.
Density Independent

Examples:
Density Independent

Examples:
– Natural Disasters/Weather
(e.g. drought, hurricane, flood, fire)
– Sunlight
– Temperature
– Human Activities
Population Growth Practice:


Bacteria reproduce by splitting (binary fission).
A certain species reproduces every 20
minutes. If we start with one bacterial cell,
how many cells will there be at the end of
3hrs?
Show your work in the form of a population
GRAPH. The independent variable is TIME and
the dependent variable is the
GROWTH/NUMBER of bacteria.
Note: Graph the time in minutes
Data:
Time
(in minutes)
0 min
20 min
40 min
60min (1hr)
80 min
100 min
120 min (2hrs)
140 min
160 min
180 min (3hrs)
Number of
Bacteria
1