present day extinctions - San Francisco State Universityonline.sfsu.edu/bholzman/_private/316/present day extinctions.pdfPresent Day Extinctions ... 1 A.D.- 1750 A.D. 750 Million 1750-1900

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Present Day ExtinctionsI. Extinctions in recent time

A) human population increase B) natural selection

II. Who gets it A) r-selected vs. K-selected species B) loss of habitat C) loss of range

III. Human Impacts

Past Mass Extinctions

Climate changes led to other changes

Geography 316.01 SFSU Dr. B. Holzman

For the exclusive use of students enrolled in GEOG 316 Fall 2006 SFSU

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PLEISTOCENE MEGAFAUNA

Global Warming

EXTINCTIONExtinction is a biological reality:It is a process of Evolution.

It is estimated that about one fourth of the species of birds and mammals that have become extinct since 1600 A.D. may have died out naturally.



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1600 A.D: 4226 livingspecies of mammalssince then……120 have become extinct

Mammals

Africa Quagga

Birds

1600 A.D. 8684 livingspecies of birds since

then….

162 have become extinct

Species can become extinct or endangered because of several human impacts:

Excessive exploitation: hunting

Introduced species: invasion

Environmental contaminants: pollution

Habitat Destruction and Change: this is the biggest contributor to current extinctions without replacement



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Mammals 169 315 612 1096 120Birds 168 235 704 1107 162 Reptiles 41 59 153 253 21 Amphibs 18 31 75 124 5Insects 44 116 377 537 73

Other 471 423 1194 2088 343

Total extinct

vulnerablethreatenedendangeredCritically endangered

CLASS

The following listed native fish and wildlife are threatened with extinction in the US.

Mammals:Indiana Bat - Myotis sodalisDelmarva Peninsula Fox Squirrel - Sciurus niger cinereusTimber Wolf - Canis lupus lycaonRed Wolf - Canis nigerSan Joaquin Kit Fox - Vulpes macrotis muticaGrizzly Bear - Ursus horribilisBlack-Footed Ferret - Mustela nigripesFlorida Panther - Felis concolor coryiCaribbean Monk Seal - Monachus tropicalisGuadalupe Fur Seal - Arctocephalus philippi townsendiFlorida Manatee or Florida Sea Cow - Trichechus manatus latirostrisKey Deer - Odocoileus virginianus claviumSonoran Pronghorn - Antilocapra americana sonoriensis

Loss of habitat



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Between 1980 and 1995 Africa lost 10.5 percent of its forest cover, Latin America 9.7 percent, and Asia 6.4 percent. But developed areas managed to increase their forest cover; Europe by around 4 percent.

Loss of range

“A cat is about the worst mammal there is on the bluebird trail,"

Domestic cats are responsible for 33 bird going extinct since the 1600s



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Who gets it?Depends on species strategy

and human perception

Exponential and Logistic Growth

YearYear

Time (t)

Popu

lation

size

(N)

Exponential GrowthTime (t)

Popu

lation

size

(N)K

Logistic Growth

YearYear

Num

ber

of r

eind

eer

Num

ber

of r

eind

eer

2.02.0

1.51.5

1.01.0

.5.5

Num

ber

of s

heep

(millions

)Num

ber

of s

heep

(millions

)

18001800 18251825 18501850 18751875 19001900 19251925

2,0002,000

1,5001,500

19101910 19201920 19301930 19401940 19501950

1,0001,000

500500

K selectedlarger adultsfewer youngparental careslower maturityslow rate of increaselong gestationadapted to limited fluctuation

in environmentgreater survivability thermoregulationimmune systemlonger lifespanstable populations

Examples:



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r- strategysmall adultsmany younglittle - no parental careearly maturitylittle to no immune systemshort gestationshort lifespanvulnerable to environmental changepopulation unstableBoom and Bust cycle

examples:

Characteristics of Species affecting survival

Small sizeGrazer, scavenger, insectivoreWide habitat tolerancesNot a source of natural productsBroad distributionLives largely in one country

Reproduction by solitary pairs or in many small aggregatesShort gestation periodBig litters and quick maturationTolerance of humansPerceived as harmlessAdaptive

Large sizePredator Narrow habitat tolerancesValuable fur, oil, hide,etcRestricted distributionLives largely in international watersMigrates across international boundariesReproduction in one or two vast aggregatesLong gestation periodSmall littersIntolerance of the presence of humansDangerous to humans, livestock, etc

SafeEndangered

1-2 MYA 2-10 Million8000 BC- 1A.D. 200-400 Million1 A.D.- 1750 A.D. 750 Million1750-1900 1.5 Billion1900-1965 3.0 Billion1990 5.3 Billion2000 6.5 Billion2020 7.8 Billion.

Current population: 6.5 billion………

Population



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Human Impact

Human population3.75 MYA East Africa (Australopithecus)

2 MYA (4?) Species of Hominids3 Australopithecus1 Homo habilis

• 1.75 MYAA. boisei, A. robustusHomo erectus

• 1 MYAHomo sapienHomo neanderthal

• RecentHomo sapien sapien H. sapien sapien made it to the New World @ 20 KYA (although there is archeological evidence to suggest that humans were in South America prior to this time)

Human ImpactDomestication of plants and animals:

– Earliest domestication is thought to have been cereals (wheat, barley): Palestine/Syria

@ 11-9KYASimultaneous cultivation may have occurred



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Early Domestication

Origins of some cultivated plants:SW Asia: millet, soybean, radish,tea, peach, apricot, orange, lemon

C. Asia: spinach, onion, garlic, almond, pear, apple

India/S.E. Asia: rice, sugar cane, cotton, banana

Mexico/S. America: maize, cotton, red pepper, agave

S. America: tomato, potato, tobacco, peanut, pineapple



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Human Impact

Agriculture leads to food surplus which leads to increased population

Increased population leads to increaseuse of resources (pollution, sedimentation of waterways, local loss of species)

Industrial Revolution : 1750



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Increased technological innovationincreases life span “quality of life” and use of resources

Low

High

Relative

pop

ulat

ion

size

Birt

h ra

te a

nd d

eath

rat

eBi

rth

rate

and

dea

th r

ate

(num

ber

per

1,00

0 pe

r ye

ar)

(num

ber

per

1,00

0 pe

r ye

ar) 80

70

60

50

40

30

20

10

0Low

growth rateIncreasing Growth

growth rateVery highhigh

growth rategrowth rateDecreasingDecreasinggrowth rategrowth rate

LowLowgrowth rategrowth rate

ZeroZerogrowth rategrowth rate

NegativeNegativegrowth rategrowth rate

Birth rate

Total population

Death rate

TimeTime

Stage 2Transindustrial

Stage 1Preiindustrial

Stage 4Postindustrial

Stage 3Industrial

Green Revolution: 1960sGene Revolution: 2000s

World Population Growth, 1750–2150



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Human Impacts on Ecosystems

Habitat degradation and fragmentationEcosystem simplification Predator eliminationIntroduction of non-native species Over-harvesting renewable resourcesInterference with ecological systems

Easter Island



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In the end we will conserve only what we love, We will love only what we understand and we will understand only what we are taught.

Baba Dioum (Senegal)



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Be safe !

I hope you have the time of your life…..

FINAL EXAMTUESDAY December 19 8:30



Documents

present day extinctions - San Francisco State Universityonline.sfsu.edu/bholzman/_private/316/present day extinctions.pdfPresent Day Extinctions ... 1 A.D.- 1750 A.D. 750 Million 1750-1900