Population Dynamics

1
Chapter 5

• Population Dynamics
• Human Population Growth

2
Chapter 5 Concept Map
Population Density
Density dependent factors
Density independent factors
Population Growth
Exponential growth
Logistic Growth
Carrying capacity
Limiting factors
Parasitism and disease
Predation
Competition
Demography
Immigration
Age structure diagram
Emigration
Demographic transition
3
Population Dynamics

• Populations often change size over time.
• Some increase in size, others decrease.
• We will concentrate on population growth
• How fast?
• For how long will growth continue?
• Population Density of individuals per unit
  area

Population Growth Around the World since 1 A.D.
http//desip.igc.org/mapanim.html
4
Population Dynamics

• Population growth can be linear

Population of lions.
http//www.fotosearch.com/DGV119/029069/
5
Population Dynamics

• Population growth can be exponential

J-Shaped Curve
Population of Seagulls..
http//www.acclaimimages.com/_gallery/_pages/0018-
0312-3010-5037.html
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Population Growth

• Exponential growth when the number of organisms
  grows by a constantly increasing rate.
• Ideal situation with unlimited resources.
• Results in a population

EXPLOSION
7
Population Dynamics

• R-selected organisms that grow out of control,
  exponentially
• Exponential growth can occur for short periods of
  time, but cannot continue forever!
• Why?
• What limits exponential growth?

http//www.sgnhs.org/mouse.html
Mice and weeds are examples of r-selected
organisms
http//montana.plant-life.org/page_weeds.htm
8
Population Dynamics

• Population growth can be logistic

http//animaltrial.com/animals/Elephantpictures/af
ricanelephantherdpict.html
S-Shaped Curve
Population of Elephants.
Logistic Growth a populations growth slows or
stops following a period of exponential growth.
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Population Dynamics

• Carrying Capacity The number of organisms of
  one species that a habitat or environment can
  hold
• Once carrying capacity (k) is reached, the
  population maintains at that size.
• These populations of organisms are called
• k-selected.

http//buten.net/max/My2001/10_monkeys/index_10_mo
nkeys.html
http//www.wildlife-pictures-online.com/image-file
s/xfamily.jpg
Most primates and Elephants are k-selected
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Population Dynamics
http//www.wildlife-pictures-online.com/image-file
s/xelecalf3a.jpg
For logistic growth, population sizes always
level out at the carrying capacity (k)
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Characteristics of K and R selected organisms

• K-selected organisms
• Big
• Usually mammals (parental care)
• Longer life span
• Stable environments
• Humans, bears, elephants
• R-selected organisms
• Small bodied
• Often insects
• Short Life span
• Mature early, lots of offspring
• Mosquitoes, bacteria.

http//www.theglobalroad.com/zoo/polar1/polar0025.
shtml
http//classroomclipart.com/cgi-bin/kids/imageFoli
o.cgi?actionviewlinkAnimals/Insects/Antsimage
P7190888AB.jpgimgtt
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Estimating Populations in Nature

• Random Sampling counting organisms in a few
  small areas and projecting those counts for the
  entire area
• Ex. if 10 squirrels live in a 200 ft2 area, then
  we might predict that 100 squirrels live in a
  2000 ft2 area
• What are some problems with this technique? What
  could affect its accuracy?

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Estimating Populations in Nature

• Mark-Recapture capturing of live organisms,
  marking them, and releasing them back into the
  habitat
• Organisms are recaptured and data is taken in
  regards to how many have already been marked or
  tagged
• A mathematical formula is used to estimate
  population size
• Estimate of Pop. Size captured x marked
• total recaptured with mark

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Estimating Populations in Nature

• A biologist originally marks 40 butterflies.
  Over a month long period, she traps 200
  butterflies. Of the 200, 80 were marked with
  tags. What is the estimate for butterflies?

15

• Limiting Factors Biotic or abiotic factors that
  restrict or prevent the existence, numbers,
  reproduction, or distribution of organisms.
• Ex. A predator such as a lynx is a limiting
  factor for a prey such as a hare.
• Ex. A cold snowy winter is a limiting factor for
  thousands of species that would die under those
  conditions.
• Ex. In brackish water, fish cant pass from salt
  water to fresh water. The salinity of the water
  is a limiting factor.

http//www.yukonman.com/pictures2-8.asp
http//www.fotosearch.com/COR356/110000/
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Population Dynamics

• Limiting Factors can be biotic or abiotic.
• List examples of each!

http//www.facethewind.com
Abiotic
Biotic
http//www.spottycat.com/marlos/emporium/cougar/bi
gcat11.jpg
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Population Dynamics

• Density Dependent Factors Factors that limit the
  size of a population and only exist when
  populations get too big
• Ex. Disease, competition, parasites, and a
  limited amount of food.
• These would not have caused so many problems had
  the population remained small.

http//gbgm-umc.org/umcor/00/eth6.stm
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Population Dynamics

• Predation One animal constantly consuming
  another, limits its population size
• Ex. Owls keeping a mouse population small, or
  hunters keeping deer numbers in check.
• Ex Lynx and Hare
• Predator cant eat all prey or food will be gone
  for good.

http//www.naturia.per.sg/buloh/birds/Ardea_cinere
a.htm
http//www.colostate.edu/Depts/CoopExt/4DMG/Pests/
spiders.htm
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Lynx Chases Hare
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Lynx and Hare Graph
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Population Dynamics

• Competition A density dependent factor.
  Individuals competing for limited food source or
  other resources.
• Crowding and Stress Not completely understood,
  but causes
• fighting
• Infertility
• decreased parental care
• decreased immunity to disease
• death
• Parasitism and Disease parasites limit the
  growth of a population by causing diseases

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Population Dynamics
Floods

• Density Independent Factors Limiting factors
  that would affect all populations regardless of
  size
• Most are abiotic factors.
• Ex. Floods, hurricanes, drought, habitat
  destruction.

http//www.danieldesign.com/otherlinks.htm
Volcanic Eruptions
Fire
http//www.arenal.net/
http//www.worldphotos.com/s/worldphotos/weather.h
tml
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Human Population Growth

• Demography the study of human population growth
  characteristics.
• Scientists called Demographers.
• See Fig. 5.10 on p. 129 for graph of exponential
  human growth.
• Demographic transition a dramatic change in
  birth and death rates

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Human Population Growth

• Birth Rate Usually its the number of babies
  that were born in the past year.
• of births in a sample size of 1000 individuals
• Death Rate Usually its the number of people who
  have died in the past year.
• of deaths in a sample size of 1000 individuals

http//www.ux1.eiu.edu/cfruf/popfac.htm
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Human Population Growth

• Fertility Rate The number of babies each woman
  is having during her fertile years.

Total Fertility rates in the U.S. from 1917
to2000. Note Baby Boom After WWII
http//www.ux1.eiu.edu/cfruf/els_fertility_rates.
htm
26
Human Population Growth

• Age Structure can be used to determine how
  quickly a country or area is growing.
• Are most individuals post-reproductive?
• Are most individuals reproductive?
• Are most individuals pre-reproductive?
• Which of these would most likely be growing the
  fastest?
• The slowest?
• ? ? ?Populations that are not growing have about
  the same numbers of each age group. ? ? ?
• See p. Fig 5.13 pg. 131
• Age Structure Diagram population profiles,
  graphing the number of people in different age
  groups

Age Structure Diagram
http//www.ux1.eiu.edu/cfruf/popagestruc.htm
27
(No Transcript)
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Human Population Growth

• Immigration movement by individuals into a
  country or area.
• Emigration movement by individuals out of a
  country or area.
• Neither change world populations but both change
  populations of the countries involved.

http//www.terragalleria.com/america/alaska/alaska
-misc/picture.alas6416.html
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Important Study Tips!

• J-Shaped Curve/S-Shaped Curve/Linear
• Carrying Capacity
• R-selected/K-selected populations
• Density Dependent/Independent Factors
• Predation/Competition/Overcrowding and Stress
• Demography
• Birth/Death/Fertility Rate
• Age Structure
• Emigration/Immigration

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References Population Growth Around the World
Diagram http//desip.igc.org/mapanim.html Lion
Herd Photo http//www.fotosearch.com/DGV119/02906
9 Seagull Photo http//www.acclaimimages.com/_gal
lery/_pages/0018-0312-3010-5037.html Elephant
Herd Photo http//animaltrial.com/animals/Elephan
tpictures/africanelephantherdpict.html Monkey
Photo http//buten.net/max/My2001/10_monkeys/inde
x_10_monkeys.html Elephant Photo
(K-selected)http//www.wildlife-pictures-online.c
om/image-files/xfamily.jpg Deer Mouse Photo
http//www.sgnhs.org/mouse.html Weed Photo
http//montana.plant-life.org/page_weeds.htm Polar
Bear Photo http//www.theglobalroad.com/zoo/pola
r1/polar0025.shtml Ant Photo http//classroomclip
art.com/cgi-bin/kids/imageFolio.cgi?actionviewli
nkAnimals/Insects/AntsimageP7190888AB.jpgimg
tt Tornado Photo http//www.facethewind.com

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References Mountain Lion and Deer Photo
http//www.spottycat.com/marlos/emporium/cougar/bi
gcat11.jpg Man Photo http//gbgm-umc.org/umcor/00
/eth6.stm Flood Photo http//www.danieldesign.com
/otherlinks.htm Volcanic Eruption Photo
http//www.arenal.net/ Fire Photo
http//www.worldphotos.com/s/worldphotos/weather.h
tml Herron eating Fish Photo http//www.naturia.p
er.sg/buloh/birds/Ardea_cinerea.htm Spider eating
Bee http//www.colostate.edu/Depts/CoopExt/4DMG/P
ests/spiders.htm Stressed Out Monkey
http//www.lifeisajoke.com/pictures292_html.htm Bi
rth/Death Rate Diagram http//www.ux1.eiu.edu/cf
ruf/popfac.htm Fertility Rate Diagram
http//www.ux1.eiu.edu/cfruf/els_fertility_rates.
htm
32
References Age Structure Diagram
http//www.ux1.eiu.edu/cfruf/popagestruc.htm Migr
ating Geese Diagram http//www.terragalleria.com/
america/alaska/alaska-misc/picture.alas6416.html
33
Chapter 6 Review
Density-dependent factors
Density-independent factors
Populations
Growth patterns
Age Structure Diagram
Animal
Human
R
K
Exponential growth
Population explosion
Logistic growth
Carrying capacity (k)
J-Shaped Curve
S-Shaped Curve
Limiting factors
34
Population Dynamics Tree Map
Population Dynamics
Competition Density-dependent factor Compete for
a limited resource(s) and mates
Crowding and Stress Fighting Infertility Decreased
parental care Greater possibility of
disease Death
Parasitism and Disease Limits growth of
population by causing diseases
Predation When one organism preys upon another
organism Keeps population in check
35
R-Selected Vs. K-Selected Double Bubble Map
Carrying Capacity (Include picture)
Many offspring
Growth Patterns
Exponential Growth
Parental Care
K-Selected
R-Selected
J-shaped
Examples
Involves life
S-shaped curve
Mature early
Stable environment
Short Life Span
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Dependent Vs. Independent Double Bubble Map
Examples
Limiting factors
Competition
Not affected by size
Density-Independent Factors
Density-Dependent Factors
Example
Abiotic factors
Based on population size
Controls Population
Affect ALL populations
Limits size
37
Demography Thinking Map
of babies born in the past year
of people who have died in the past year
Birth rate
Into
Death rate
Immigration
Demography
Fertility rate
Emigration
Out
Demographic Transition
Age structure
Dramatic change in birth and death rates
Diagram of how quickly a country is growing