POPULATION

DYNAMICS Characteristics 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

Kelp Forest

Sea Urchins

Sea Otters

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

Characteristics of Populations

1. 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/sitebuilderpicture

s/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 time

What 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?

Demographics Age 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 Footprints http://www.myfootprint.org/en/