8/10/2019 Lecture 11 Bio10

1/5

1

Human Population Growth

http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html

Write down the current human population:

2

Population Biology

Population Biology: populations the

!n"ironment

How to do we de#ine a population$$$

% population&s e'tent is o#ten user(

de#ined

Northern fur seals (Callorhinus ursinus) on St. Paul Island,off the coast of Alaska

)*eaths emigrationremo"e indi"iduals #rom

a population.

How many indi"iduals are

there$ + ,

How are the indi"iduals

dispersed in space$ +,.

What #actors in#luence

the number age o#

indi"iduals$ + population

dynamics

Births immigration addindi"iduals to a population.

Births

Immigration

Populationsize

Emigration eaths

*escribing Populations

-

ounted directly

!stimated based on some sign

ar0 recapture

uanti#ying Population *ynamics

adio(tagging 3rac0ing

ommon a"en 4Corvus

corax5

6lympic Peninsula7 W%

ommon a"en 4Corvus corax5

o8a"e *esert7 %

adio(tagging 3rac0ing

%merican rocodile 4Crocodylus acutus5

9ucatan Peninsula7 e'ico

8/10/2019 Lecture 11 Bio10

2/5

*ispersion

How are the indi"iduals distributed in the

landscape$

What #actors in#luence that distribution$

B,. #actors

%,. #actors

lumped *istributions

;

ur"i"orship ur"es

1???

1??

1?

1

@umbero#sur"i"ors4logscale5

? 2 - A 1?

%ge 4years5

ales

Cemales

ale #emale Beldings ground sDuirrels

8/10/2019 Lecture 11 Bio10

3/5

1)

EdealiFed >ur"i"orship ur"es

I

II

III

? 1???1

1?

1??

17???

Percentage o# ma'imum li#e span

@umbero#sur"i"ors4log

scale5

3ype E + , 3ype EE + , 3ype EEE + , 1-

eproducti"e 3ables

pawning salmon

1

1??

?

A?

-?

2?

?

educed brood

siFe

@ormal brood

siFe!nlarged brood

siFe

Parentss

ur"i"ingthe#ollowingwinter

45

ale

Cemale

Parental are Patterns >how 3rade(6##s

3o increase their

#itness7 di##erent

species e"ol"ed

"arious patterns

any o##spring7

no parental care Cew o##spring7 lots

o# parental care

Within the same

species7 tradeo##s

e'ist between the

components o#

#itness 4sur"i"al

reproduction51

En"estment in the @e't Generation

(a) ost weedy plants7 such as this dandelion7 grow Duic0ly

produce a large number o# seeds7 ensuring that at least some willgrow into plants e"entually produce seeds themsel"es.

(!) >ome plants7 such as this coconut palm7 produce a m oderate

number o# "ery large seeds. 3he large endosperm pro"ides nutrients#or the embryo7 an adaptation that helps ensure the success o# a

relati"ely large #raction o# o##spring.

Plants usually

dont show

parental care

Plants do "ary their

in"estment towardindi"idual o##spring

8/10/2019 Lecture 11 Bio10

4/5

1;

What =imits Population >iFe$

>ur"i"al reproduction in#luenced by:

,#actors:

3erritoriality

esource a"ailability

ompetition

,.#actors:

Entrinsic #actors li0e genetic "ariation

limate change7 pollution7 etc.

2?

*ensity *ependence

1?? 1??

1??

?

17???

1?7???

%"eragenumbero#seeds

perreproducing

indi"idual

4logscale5

%"erageclutch

siFe

>eeds planted per m2 *ensity o# #emales

? ?1? 2? )? -? ? A? ?2.

).?

).2

).-

).A

).

-.?

(a) Plantain. 3he number o# seeds

produced by plantain 4Plantago major5decreases as density inc reases.

(!) Song sparro". lutch siFe in the song sparrow

on andarte Esland7 British olumbia7 decreasesas density increases #ood is in short supply.

Why is reproduction reduced by increasing

numbers o# the same species 4conspeci#ics5$

21

3erritoriality

Why do some animals ha"e territories$

How does this beha"ior a##ect their

populations$

22

Esle oyale oose Population

esearchers regularly sur"eyed the population o#

moose on Esle oyale7 ichigan7 #rom 1;A? to 2??). *uring that

time7 the la0e ne"er #roFe o"er7 so the moose population wasisolated #rom the e##ects o# imm igration emigration.

#IE$ S%&'

6"er -) years7 this population e'perienced

two signi#icant increases collapses7 as well as se"eral less se"ere

#luctuations in siFe.

ES&$%S

1;A? 1;? 1;? 1;;? 2???

9ear

/oosepopulationsiFe

?

??

17???

17??

27???

27??

>teady decline probably

caused largely by wol#

predation

*ramatic collapse caused by se"ere

winter weather #ood shortage7

leading to star"ation o# more than o# the population

What #actors

in#luence the

number o# moose$

%re they density(

dependent or

density(

independent$

2)

9ear1? 1 1;?? 1;2

?

-?

?

12?

1A?

?

)

A

;

=yn'populationsiFe

4thousands5

HarepopulationsiFe

4thousands5

$n*

Sno"shoe hare

>nowshoe Hare =yn'

>ome population

cycles are tightly

lin0ed

2-

What *oes !'ponential Growth ean$

3he r. Peanut

hallenge: eat

peanuts e'ponentially

each day

1(day I 1 peanut 2nd day I 2 peanuts

)rd day I - peanuts

-th dayI peanuts

How many peanuts do

you need to eat on the

last day o# the month$

8/10/2019 Lecture 11 Bio10

5/5

2

Human Population Growth

1;?(1;;? doubled #rom 2. billion to billion.

(12 billion be#ore 2?;;

*uring each lecture7 J1?7??? are born7 K) per

secondL 2A

Encrease in Global Human Population

1;? 1; 2??? 2?2 2??

9ear

2??)

Percentincrease

2.2

2

1.A

1.-

1.2

1

?.

?.A

?.-

?.2

?

1.

Good news:

increase is

getting smaller

Bad news: 1

o# billion is

still larger than

2 o# ) billion

3he total

number o#

births/year is

still increasing

2

Human Population Growthhttp://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html

Write down the human population #rom the

beginning:

Write down the current human population:

How many people were born during this

lecture$

an the !arth sustain this rate o# human

population growth$

2

an the !arth >upport ; Billion People$

We can expect at least 9 billion people by 2050

We are degrading the environment faster than it can

replace itself

Many resources are finite on a human time scale

People in ealthy countries use far more resources !

create more pollution

Political ! social challenges contribute to the dise"uilibrium

!cological Cootprint