POPULATION DYNAMICSCharacteristics of Populations

Factors Limiting Populations

Human Populations

http://filipinofreethinkers.org/wp-content/uploads/2011/12/Philippine-Lugaw-Line.jpg, http://www.pensoft.net/J_FILES/1/articles/2447/export.php_files/ZooKeys-200-001-g007.jpg, http://

farm6.staticflickr.com/5191/7238292574_47bdff313f.jpg

http://phycology.mlml.calstate.edu/images/Canopy.jpg, http://bioweb.uwlax.edu/bio203/s2008/bluske_brit/yawning.jpg

Characteristics of Populations1. Geographic

distribution or range

• Area inhabited by a population

“The Philippine tarsier (Tarsius syrichta) is endemic to the southern Philippine islands of Bohol, Samar, Leyte and Mindanao, where it thrives mostly in secondary forests and dense patches or thickets of bush, tall grass and bamboo.”

Characteristic # 1

http://www.tarsierfoundation.org/content/the-philippine-tarsier

Characteristic # 2

http://www.unisdr.org/, http://www.nscb.gov.ph/factsheet/pdf08/FS-200806-SS1-01.asp

3. Population dispersion• Patterns of spacing in relation to other members of the population• Clumped, uniform, random

Characteristic # 3

Concepts and Connections 2002 by Campbell

4. Growth rate, r• change in the number of

individuals in a population per unit time

• Factors affecting population size:

1. # of births

2. # of deaths

3. # of individuals leaving/entering

• Immigration = into

• Emigration = exit

# of individuals added to/taken from the population

Characteristic # 4

If r = pop’n growth rate

b = birth rate/natality

d = death rate/mortality

i = rate of immigration

e = rate of emigration

Express r in terms of b, d, i, and e.

r = (b+i) – (d+e)

b vs. d growth rate

i vs. e

? + ?

? - ?

? 0 ?

http://mysite.verizon.net/res15tbbv/sitebuildercontent/sitebuilderpictures/animal-migration.jpg

, http://pull.imgfave.netdna-cdn.com/image_cache/1288987440350429.jpeg

4. Growth rate, r• Exponential

growth• Individuals in a

population reproduce at a constant rate

• ex. bacterial reproduction: binary fission

Time (hrs) # of cells

0 1

1/3 2

2/3 4

1 8

2 ?

3 ?

: :

24 ?!

Time (hrs) # of cells

0 1

1/3 2

2/3 4

1 8

2 ?

3 ?

: :

24 4.720 x 1021!!!

Characteristic # 4 (con’t)

http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookmito.html

4. Growth rate, r• Exponential growth

• Individuals in a population reproduce at a constant rate

• Logistic growth• Population’s growth

slows/stops following a period of exponential growth

Time (hrs) # of cells

0 1

1/3 2

2/3 4

1 8

2 ?

3 ?

: :

24 4.720 x 1021

J-curve S-curve

Characteristic # 4 (con’t)

lag

log

steady-state

4. Growth rate, r• Logistic growth

• Biotic potential, rmax

• Max rate at w/c a population could increase under ideal conditions

• Environmental resistance• Unfavorable conditions that

prevent a population from reaching its rmax

• Carrying capacity, K• Max # of individuals a given

environment could support with its limited resources

Characteristic # 4 (con’t)

http://www.sustainabilitylabs.org/page/sustainability-five-core-principles

Survivorship Curves

http://www.kv.k12.in.us/moodle/file.php/26/population_curve.jpg

Factors Limiting Populations

• Limiting factor - factor that causes population growth to decrease

• Density-dependent factors• Becomes limiting only when

population reaches a certain level; mostly biotic factors

• Density-independent factors• Affects all populations in

similar ways, regardless of population size; mostly abiotic factors

http://www.cpsu.org.au/multiattachments/17146/Image/slow-down-sign.jpg

Factors Limiting Populations

• Competition• Crowding and stress • Human disturbances• Natural catastrophes• Parasitism and disease• Predation

http://thumbs.imagekind.com/member/3f58d983-4020-4101-a3fb-1e3d67c818ac/uploadedartwork/650X650/d6b32ac0-cede-4422-882d-1723572d56f7.jpg, http://reachthetribes.com/200909/big/kaingin.JPG, http://

static.guim.co.uk/sys-images/Technology/Pix/pictures/2009/10/21/1256124500714/Mount-Pinatubo-eruption-i-001.jpg, http://s3.hubimg.com/u/593274_f260.jpg

Human Population Growth

Which model of pop’n growth (exp’l vs. logistic) does the human pop’n follow?

Human pop’n size has increased through timeWhat factors have controlled human pop’n growth

through the centuries? Centralized agriculture Infectious disease Industrial, technological revolutions Modern medicine

http://www.bbc.co.uk/schools/gcsebitesize/science/images/bihumanpop.gif

Populations in developing vs. industrialized countries

What does this graph tell us about birth rates in different countries?

What about death rates?

DemographicsAge structure and Sex-ratio

What do these graphs tell us about birth rates in different countries? What about death rates? What can age structure diagrams tell us about the population?

http://www.bio.miami.edu/dana/pix/agestructure.gif

What are the effects of human population growth?

What are the effects of different lifestyles?

http://kuro-kuro.org/wp-content/uploads/2010/10/population.jpg

Ecological Footprintshttp://

www.myfootprint.org/en/