Download CP-Bio Ch. 27 (Populations)

Biology
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Ch. 27 - Populations
Biotic Potential- the highest rate of
reproduction for a population under ideal
conditions
Limiting Factors- prevent a population from
reaching it’s biotic potential
Ex: disease, predation, food supply,
space, seasonal changes
Population Size- All members of the same
species living in the same place at the same
time
• Species- Any group of organisms that are
able to reproduce and produce fertile
offspring
• Birthrate- # of organisms born in a period of
time, usually expressed as the number of
births each year for every 1000 people
Population Growth Curves
• Two Types : (Named after their shape)
“ J” Shape
“S” Shape
* ideal conditions
*limited by limiting factors
* no limiting factors
*prevent organism from
This population is able to reach
reaching biotic potential
It’s biotic potential = highest rate
carrying capacity = greatest
of reproducttion under ideal
# of individuals that an
conditions
environment can support at
a given time.
Carrying Capacity- the greatest # of
individuals in a population supportable by
the environment and local resources
- population size tends to level off at a
certain point due to limiting factors
Population Density- the size of a population
occupying a specific area
Ex: Dense Population- NYC, beehive
Sparse Population- Tolland, meadow
Regulation of Population Size
• Both population density and environmental factors
can limit population size
Density Dependent Factors: limit population size
based on population density/size
ex- space, food supply, predation(predators vs. prey)
Density Independent Factors: do not depend on
population density
ex- seasonal changes, temperature, environmental
factors, natural disasters
Limiting Factors
1) Predation- One organism feeding on another(prey) for
food
- The size of predator and prey populations keep each other in
check
2) Parasitism- a parasite usually harms its host but does
not kill it, why?
3) Disease- disease limits population size by eliminating
susceptible individuals
4) Competition- between different species(interspecific)
or between members of the same species(intraspecific)
Ecology- the study of living things
and their environment
Symbiosis- the interaction of 2 different species of
organism
Mutualism- both organisms benefit from the
relationship
Commensalism- one organism benefits the
other is unharmed
Parasitism- one organism benefits and the other is
harmed
Graphing Growth Curves
Density Dependent
Ex: Yeast Growth
Time
Population Size
0
10
2
29
4
71
6
175
8
351
10
513
12
595
14
641
16
656
18
662
Density Independent
Ex: Moth Population Size
Month
Population Size
Jan
12
Feb
20
Mar
45
Apr
98
May
176
Jun
257
Jul
212
Aug
221
Sept
265
Oct
168
Nov
89
Dec
52