Date post: | 20-May-2015 |
Category: |
Education |
Upload: | guru-charan-kumar |
View: | 226 times |
Download: | 6 times |
2.6.1-.4, 2.1.7 Population
Dynamics
5/11/2013 Author -Guru IB/ESS 1
Population Dynamics
A look at the factors that tend to increase or
decrease the size of a population.
5/11/2013 Author -Guru IB/ESS 2
The population size of a species in a given space at a given time is determined by the interplay between BIOTIC POTENTIAL and ENVIRONMENTAL RESISTANCE.
Biotic potential = growth rate with unlimited resources.
Environmental resistance = all the factors acting jointly to limit population growth.
5/11/2013 Author -Guru IB/ESS 3
POPULATION SIZE
Growth factors (biotic potential)
Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients)
Abiotic
Biotic High reproductive rate
Generalized niche
Adequate food supply
Suitable habitat
Ability to compete for resources
Ability to hide from or defend against predators
Ability to resist diseases and parasites
Ability to migrate and live in other habitats
Ability to adapt to environmental change
Decrease factors (environmental resistance)
Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients)
Abiotic
Biotic Low reproductive rate
Specialized niche
Inadequate food supply
Unsuitable or destroyed habitat
Too many competitors
Insufficient ability to hide from or defend
against predators
Inability to resist diseases and parasites
Inability to migrate and live in other
habitats
Inability to adapt to environmental
change
5/11/2013 Author -Guru IB/ESS 4
Four variables change population size:
1. NATALITY = birth rate
2. MORTALITY = death rate
3. IMMIGRATION = rate of organisms moving in
4. EMIGRATION = rate of organisms moving out
5/11/2013 Author -Guru IB/ESS 5
Nu
mb
er
of
ind
ivid
uals
Time
Carrying capacity
K species;
experience
K selection
r species;
experience
r selection
K
REPRODUCTIVE STRATEGIES
5/11/2013 Author -Guru IB/ESS 6
Opportunistic or r-Selected Species
cockroach dandelion
Many small offspring
Little or no parental care and protection of offspring
Early reproductive age
Most offspring die before reaching reproductive age
Small adults
Adapted to unstable climate and environmental
conditions
High population growth rate (r)
Population size fluctuates wildly above and below
carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
5/11/2013 Author -Guru IB/ESS 7
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental
conditions
Lower population growth rate (r)
Population size fairly stable and usually close
to carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
elephant saguaro
Competitor or K-Selected Species
5/11/2013 Author -Guru IB/ESS 8
SURVIVORSHIP CURVES
5/11/2013 Author -Guru IB/ESS 9
Population density affects population growth.
5/11/2013 Author -Guru IB/ESS 10
DENSITY INDEPENDENT FACTORS = affect a
populations’ size regardless of its population density.
1. Weather
2. Earthquakes
3. Floods
4. Fires
. . . Natural disasters
R-strategists populations are most affected by these.
5/11/2013 Author -Guru IB/ESS 11
DENSITY DEPENDENT FACTORS = affect a
populations’ size depending on its population density.
1. Predation
2. Disease
3. Availability of food and water
4. Space
Negative Feedback!!
5/11/2013 Author -Guru IB/ESS 12
INTERNAL FACTORS = might include density-dependent fertility or size of breeding territory.
EXTERNAL FACTORS = might include predation and disease.
5/11/2013 Author -Guru IB/ESS 13
Species interactions influence population growth and carrying capacity = SYMBIOSIS
Competition for resources.
High
Low
Rela
tive p
op
ula
tio
n d
en
sit
y
0 2 4 6 8 10 12 14 16 18
Days
Each species grown alone
Paramecium
aurelia
Paramecium
caudatum
High
Low
Re
lati
ve
po
pu
lati
on
de
ns
ity
0 2 4 6 8 10 12 14 16 18
Days
Both species grown together
Paramecium
aurelia
Paramecium
caudatum
5/11/2013 Author -Guru IB/ESS 14
Resource Portioning
5/11/2013 Author -Guru IB/ESS 15
PREDATION
PREY
POPULATION
PREDATOR
POPULATION
5/11/2013 Author -Guru IB/ESS 16
Span worm Bombardier beetle
Viceroy butterfly mimics
monarch butterfly
Foul-tasting monarch
butterfly
Poison dart frog When touched, the
snake caterpillar
changes shape to look
like the head of a snake
Wandering leaf insect
Hind wings of io moth
resemble eyes of a
much larger animal
Avoiding predators
5/11/2013 Author -Guru IB/ESS 17
Parasitism
5/11/2013 Author -Guru IB/ESS 18
Mutualism
Oxpeckers and black rhinoceros Clown fish and sea anemone
5/11/2013 Author -Guru IB/ESS 19
Shark and ramora
5/11/2013 Author -Guru IB/ESS 20
Cleaning station
Sabertooth blenny
Cleaner blenny
5/11/2013 Author -Guru IB/ESS 21
Commensalism
5/11/2013 Author -Guru IB/ESS 22
Herbivory
5/11/2013 Author -Guru IB/ESS 23