Transcript No Slide Title

EVOLUTION
H.E.KRON-WHRHS-SCI DEPT
EVOLUTION
-CHANGE IN THE
GENE POOL OF A
POPULATION
OVER TIME
SUGGESTS THAT
EXISTING SPECIES
ARE DERIVED FROM
PREVIOUS ONES BY
DESCENTORGANISMS NOW ON
EARTH SHARE A
COMMON ANCESTRY
IS A UNIFYING THEME IN
BIOLOGY & PROVIDES A
FRAMEWORK FOR THE
ORGANIZATION OF
DIVERSE SPECIES INTO A
LINKED PATTERN. A
SLOW PROCESS! (AS A RULE
IT OCCURRENCE CANNOT BE
DEMONSTRATED DIRECTLY.)
LAMARCK-INHERITANCE OF
ACQUIRED CHARACTERISTICSORGANISMS ADAPT TO THEIR
ENVIRONMENT AND PASS
THESE CHANGES TO THEIR
OFFSPRING
USE/DISUSE: SALAMANDER-ON
LAND, LEGS COULDN’T TRAMPLE
THRU TALL GRASS, BEGAN USING
THEIR BELLIES & LEG MUSCLES
WASTED AWAY FROM DISUSE
LEGLESS SALAMANDERS
EVOLVED
WHAT’S WRONG WITH THIS IDEA?
DARWIN’S THEORY OF
NATURAL SELECTION: FROM
HIS BOOK - ORIGIN OF SPECIES.
NEW SPECIES CAME ABOUT BY
NATURAL SELECTION:
OVERPRODUCTION
STRUGGLE FOR EXISTENCE
VARIATION
SURVIVAL OF FITTEST
4 COMPONENTS:
VARIATION
COMPETITION
FITNESS
ADAPTION
VARIATION:
INDIVIDUAL MEMBERS OF A
POP. WITHIN A SPECIES HAVE
HERITABLE DIFFERENCES
THESE TRAITS PASSED ON TO
NEW GENERATIONS
THESE VARIATIONS ARE
RANDOM
COMPETITION:
RESOURCES ARE FIXED:
EXP-FOOD & SHELTER
POP. GROWS TO LIMIT
REPRODUCTION EXCEEDS
SURVIVAL
INDIVIDUALS MUST
COMPETE
FITNESS:
SOME INDIVIDUALS HAVE
TRAITS THAT MAKE THEM
BETTER AT SURVIVAL
THE FITTEST SURVIVE TO
PRODUCE & CARE FOR THEIR
OFFSPRING
FITNESS IS LINKED TO THE
ENVIRONMENT
ADAPTION:
POP. WITH BEST TRAITS OVERPOPULATE & REPLACE LESS FIT
RESULTS IN A NEW POP WITH THE
BEST TRAITS
ADAPTION IS THE END RESULT OF
N. SELECTION: EXP- COAT COLOR,
RUNNING SPEEDS, BODY COVERINGS.
CONCERNS PHENOTYPE OCCURS
WHEN GENES ARE INHERITED
MICROEVOLUTION
VS
MACROEVOLUTION
DIVERSITY
VS
COMPLEXITY
MICROEVOLUTION:
ANIMALS & PLANTS ADAPT TO
CHANGING ENVIRONMENTS
INVOLVES SMALL CHANGES
DOES NOT CREATE NEW
SPECIES
CREATES “DIVERSITY” NOT
COMPLEXITY
EXP: MICROEV-SUPPOSE A
WHITE BIRD IS BORN
AMONG A POP OF BROWNS.
NS FAVORS WHITE IN
WINTER & BROWN IN
SUMMER. Why? An inherited
variation increases an organism’s
chance of survival in a particular
environment.
THE WHITE BIRD IS NO
MORE COMPLEX THAN THE
BROWN!
BEFORE INDUSTRIAL REVOLUTION
THERE WERE PEPPERED MOTHS.
AFTER, % OF BLACK MOTHS
INCREASED DRAMATICALLY. WHY?
Environment changes & moths adapted-black
is no more complex than peppered!
MACROEVOLUTION: evol.
that creates a new species.
CHANGES ARE SMALL & LARGE
Difference between a wolf &
dog=small
Difference between a starfish &
alligator=large
EXP: THAT CREATES “COMPLEXITY”
Descendants of a lizard evolved into
birds with wings & feathers. Birds are
more complex than reptiles.
EXP: THAT CREATES “DIVERSITY”
Descendants of the wolf evolved
into dogs; Huskies, Labs etc. A Lab
is no more complex than a wolf.
NATURAL SELECTION DOES
NOT GUIDE EVOLUTIONARY
TRANSITIONS WHICH
RESULT IN GREATER
COMPLEXITY-THEY DEPEND
ON “CHANCE”
SINCE OBSERVABLE PROCESSES
ONLY CREATE “DIVERSITY” THEY
SHOULD NOT BE EXTENDED TO
EXPLAIN THE ORIGIN OF
“COMPLEXITY"
Modified Sci Method is based more on
speculation than science-c/o-inability of
science to test “Macroevolution”
THE EVOLUTION OF
COMPLEXITY REQUIRES NEW
GENES:
GENES ARE CHEMICALS
GENES DETERMINE TRAITS OF
PLANTS & ANIMALS
NEW GENES ARE REQUIRED
FOR THE EVOLUTION OF NEW
ORGANS & STRUCTURES
NEO-DARWINISM
SYNTHETIC THEORY
MODERN DISCOVERIES HAVE BEEN
INCORPORATED INTO DARWIN’S
NATURAL SELECTION
THE CELL IS
THE SMALLEST
UNIT OF LIFEALL LIFE IS
COMPOSED OF
CELLS
LIFE BEGINS WITH THE INFORMATION
FOUND IN DNA TO MAKE PROTEINS
PROTEINS THAT GENES ENCODE
ULTIMATELY DETERMINE THE
TRAITS OF AN ORGANISM
REPRODUCTION IN HIGHER LIFE
REQUIRES MEIOSIS-OFFSPRING
INHERIT GENES FROM BOTH PARENTS
While NS selects existing variations
already in a pop. It does not create new
varieties. The ultimate source of new
variations would be:
Recombinations of existing genes
Mutations-altered genes/chr
Both of these produce genetic
combinations found in earlier
generations
Recombination/crossing-over:
homologous chrs break & reattach onto
different chrs. The next generation
inherits chrs with new sequences.
Sperm & ova can add even greater
diversity to a pop’s gene pool!
HOW DO NEW SPECIES EVOLVE
Today scientists realize that
variations arise c/o random changesMutations in existing genes.
Point mutation
str. Modified
irreg. #
MUTATION FACTS:
Freq. in human sex cells=1/100,000
Humans may have as many as
100,00 genes
Most sex cells contain mutations &
are common occurrences in
healthy people
Causes: radiation, chemicals,
viruses etc.
For mutation to be subject to
NS-it must be expressed in the
individual’s phenotype.
Selection favors mutations that
result in adaptive phenotypes
and eliminates non- adaptive
ones. Even recessive alleles can
show up in future generations
ENVIRONMENT SELECTS
INDIVIDUALS WITH BEST
SUITED “GENOTYPES” TO
SURVIVE TO ADULTHOOD &
TO REPRODUCE. FOR NS TO
CAUSE EVOLUTION, IT MUST
SELECT FOR OR AGAINST ONE
OF THE FOLLOWING 5
COMBINATIONS:
5 GENOTYPE COMBINATIONS
EITHER: AA OR aa (BUT NOT BOTH)
BOTH: AA OR aa
EITHER: AA & Aa OR aa & Aa
HETEROZYGOTE: Aa
ALL ALLELES: AA, Aa & aa
SELECTION AGAINST ONE OF
THE HOMOZYGOTES:
IF aa IS COMPLETELY SELECTED
AGAINST WHILE AA & Aa ARE
SELECTED FOR- THE
FREQUENCY OF aa CHILDREN
WILL DROP DRAMATICALLY.
THERE WILL BE A PROGRESSIVE
DECREASE IN “a”!
EXAMPLES AGAINST “aa”:
ALBINISM-homozygous recessive
individuals are at a slight selective
disadvantage. Can live to adulthood &
reproduce.
DIABETES-inherited recessive, the
selection is more severe. Prior to this
century those who inherited usually died
in childhood. Since insulin in 1921 it is
no longer a killer of children
SELECTION AGAINST BOTH
HOMOZYGOTES: only Aa would
be able to mate!
NATURE SELECTING AGAINST
BOTH HOMOZYGOTES: Malaria
found in Africa c/o plasmodiaparasites that feed on RBC. People
who produce norm RBC are good
hosts & easily get the disease & death
In African malarial zones there is an
inherited condition of the sickle-cell
trait. “aa” have a resistance to malaria
c/o deflated RBC’s are poor hosts.
However these kids die in childhood
from sickle cell anemia.
People who are Aa for sickle-cell trait
have good resistance to malaria c/o sickle
shaped cells and rarely develop the life
threatening anemia.
Those who are AA produce normal
RBC’s which make excellent hosts for
malaria. So in malarial environments nature selects for Aa sicklers.
It selects against “aa” sicklers & people
who produce normal RBC’s.
EVOLUTION IS THE PROCESS
BY WHICH GENE POOLS OF A
SPECIES WITH TIME. ALL OF
THE SPECIES MAKE UP THEIR
GENE POOL. EVOLUTION
CHANGES GENE POOLS AND
CREATES NEW ONES.
THEREFORE NS ONLY
PRESERVES GENES THAT
OFFER A SELECTIVE
ADVANTAGE
NS only preserves genes that offer a
selective advantage-sometimes called
“competitive” advantage. These genes
are responsible for beneficial variations.
EVOLUTION creates diversity by
altering the gene pool. Mutations
creates alleles. Alleles are not new
genes, but alternate forms of the
same gene. Exp: Hb-a protein for
transporting O2. If mutations change
the DNA encoding process, these
changes may alter aa sequence. If the
altered genes still encode for Hb-then
they are called “alleles”.
NATURAL SELECTION:
PRESERVES THE BEST ALLELES
OPTIMIZES EXISTING GENES
BY SELECTING BEST ALLELES
MicroEVOL. CONCERNS
ORGANISMS ADAPTING TO
CHANGING ENVIRONMENTS & NS
PRESERVES ALLELES MORE FIT.
ENVIRONMENTAL SELECTION:
NO
EXP: LINGULA
Lamp shells found in rock
strata 500 mya. Over all this
time still looks the same today!
Gryphaea-coiled shell
similar to oyster 180mya
Sea bed changed from rocky to
mud. Flat shells only could survive
in rocky areas. Curved shells could
lift upper valve clear of sea bottom
ADAPTIVE LANDSCAPESVISUALIZE FITNESS OF ALLELES
Fitness= series of valleys and hills
Alleles on hill more fit
NS preserves ones on the hill
NS optimizes existing genes by sel. most favorable
ADAPTIVE LANDSCAPE-APPLIES
TO STR & ORGANS:
Consider a reptile evolving into a
bird. Front legs are preserved by
NS. Thus NS fights this transition.
If the transition takes place despite
NS-then only chance can guide it.
Mutations away from optimized
legs lower the fitness of a reptile.
NS is not driving such a process.
GENETIC DRIFT(CHANCE)DETERMINES WHICH GENES
SURVIVE. ALLELES FREQUENCY
OF A GENE POOL DUE TO CHANCE
OR RANDOM EVENTS.
CAUSES GENE POOLS OF 2
ISOLATED POP’S TO BECOME
DISSIMILAR AS SOME ALLELES
ARE LOST & OTHERS FIXED.
The net effect of Genetic Drift on a
small pop’s gene pool can be rapid.
Note the red trait increases
dramatically from generation to
generation
FOUNDER EFFECT-case of gen.
drift in which rare alleles occur in
higher frequency in a pop “isolated”
from general pop. Exp: Darwin’s finches
When a pop is started by one or a
few who randomly separate from a
larger pop-chance may dictate that
allele freq. in new pop. may be
different from original pop.
Island species vary from mainland species
BOTTLENECK EFFECT-genetic
drift in which a severe reduction in pop.
Size results from natural disasters,
predation or habitat reduction. Results
in severe reduction of the total genetic
diversity of the original gene pool.
Exp: Cheetah pop. Was probably
reduced in the great Ice Age 10,000 ya.
Separation causes infertility c/o intense
inbreeding=very little gen. Variation.
WHEN ARE TWO POP’S NEW
SPECIES? - WHEN POP’S NO
LONGER INTERBREED THEY
ARE THOUGHT TO BE
SEPARATE SPECIES.
GENETIC DIVERGENCE
RESULTS WHEN ADAPTION,
DRIFT AND MUTATION ACT ON
POPULATIONS.
Barriers to gene flow isolate pop’s & lead
to formation of a new species.
ADAPTIVE RADIATION-the
diversification of a species into two or
more species as groups adapt to different
environments
Over time, the pop’s genetically diverge
enough so that they can no longer reproduce
with each other
Models of speciation
relate to geographic
subdivisions:
Allopatric-barrier
Parapatric-adj.
Pop’s
Sympatric-coexist
Founder Effectsmall isolated pop
on edge
VARIATION & SPECIATION
VARIATION CAN BE MEASURED
IN DIFF WAYS-HUMANS CAN BE
TALL/SHORT, SKINNY/FAT ETC.
(VARIATION IS A DISTRIBUTION OF AVG
& EXTREMES)
NATURAL SELECTION IS A
PROCESS OF SURVIVAL AND
REDRODUCTION THAT
LEADS TO IN ALLELE FREQ.
OVER TIME AS THOSE
INDIVIDUALS MOST “FIT”
SURVIVE AND LEAVE MORE
OFFSPRING
THREE PATTERNS
STABILIZING SELECTION-favors
the intermediate phenotype. Extremes
in variation are selected against. Infants
weighing less that 5 lbs have higher
rates of infant mortality.
DIRECTIONAL SELECTIONfavors one or the other of the extremes.
Insecticide resistance with DDT after yrs
of use lost its effectiveness on insects.
Resistence to DDT is a gen. Trait only
those resistant survived & reproduced.
DISRUPTIVE SELECTIONfavors individuals at both extremessel. against middle of the curve
causing 2 or more distinct
phenotypes. African butterflies have
2 distinct phenotypes both resemble
brightly colored but distasteful
butterflies of other species. Each one
gains protection from predation
although they are quite edible.
DISRUPTIVE-favors both extremes
HARDY-WEINBERG THEOREM:
IDEA DEVELOPED TO
DETERMINE IF A POP. WAS
EVOLVING. AUTHORS SET UP A
SERIES OF PARAMETERS
WHICH DO NOT EXIST IN
NATURE TO BE FOLLOWED
WHEN DETERMINING THE
ALLELE FREQUENCIES OF ANY
POP.
EVOLUTION WILL NOT OCCUR IF:
NO NATURAL SELECTION
NO MUTATIONS
POP. MUST BE A LARGE SIZE
RANDOM MATINGS
POP. MUST BE ISOLATED-NO
GENE FLOW
SINCE IT IS HIGHLY UNLIKELY THAT ANY
OF THESE CONDITIONS WILL OCCUR IN
THE REAL WORLD, EVOLUTION IS THE
INEVITABLE RESULT
F
O
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S
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L
S
F
O
S
S
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S
FOSSIL EVIDENCE
Remains of living things
that existed long ago
F
O
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S
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S
PETRIFICATION
IMPRINTS
CASTS
FREEZING
TAR PITS
AMBER
BUT THERE ARE MISSING LINKS BETWEEN
EVERY MAJOR GROUP OF PLANTS AND
ANIMALS
STUDY OF FOSSIL RECORDS HELPS
BUILD A HISTORICAL SEQUENCE
OF BIO EVOLUTION OF COMPLEX
ORGANISMS FROM SIMPLE ONES.
Sequence of snail shells oldest on
left & youngest on the right dated
from 10 mya to 3 mya
Horse evolved from 5-toed browser to 1-toed grazer
F
O
S
S
I
L
S
DARWIN BELIEVED THAT OVER
TIME THAT SPECIES EVOLVED C/O
GRADUAL IN FREQ. OF TRAITS.
THEORY OF PUNCT. EQUILIBRIUM
HAS BEEN DEVELOPED TO
EXPLAIN RATES OF THAT OCCUR
AT AN UNEVEN TEMPO.
PE IN NATURE OCCURS C/O
ABRUPT IN THE WORLD’S
CLIMATE & ENVIRONMENTS.
SPECIATION OCCURS RAPIDLY
FOLLOWED BY LITTLE OR NO
FACTS:
Darwin recognized that the fossil record
is not continuous
Most transitional forms have yet to be
found
Missing links undermine the entire
theory of evolution
With PE idea, the fossil record can no
longer be used to disprove evolution
B
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E
O
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R
A
P
H
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DISTRIBUTION OF ORGANISMS
Animals & plants are most closely
related to those in nearby regions
B
I
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E
O
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R
A
P
H
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C
A
L
TWO HYPOTHESES:
RELATED FORMS EVOLVE
IN ONE PLACE & SPREAD
OUT TO OTHER REGIONS
SAME TYPE OF ADAPTION
IN GEOGRAPHICAL
REGIONS SEPARATES
ORGANISMS
GRADUAL ISOLATION
BY NEW LAND FORMS,
WATER, HIGHWAYS,
VOLCANO, EQ, RIVERS.
Ice Age-one body of water
& one species of fish. Dries
up in diff. areas. Fish pop
isolated. Fish diverged &
could no longer interbreed
even if brought together.
REPROD. ISOLATION
Inability of formerly interbreeding to reproduce
offspring. Early and late frog
breeding times have been
selected against c/o predators
CONVERGENT EVOLUTION
Unrelated species become similar in
appearance as they adapt to same kind
of environment.
MANY
DIVERSE
ORGANISMS
SHOW
C
ANATOMICAL
SIMILARITIES
O
M
P
Bat wing
A
N
A
T
O
M
Y
Bird wing
Pterodactly wing
Human arm
HOMOLOGY-SIMILAR STRS IN DIFFERENT
SPECIES OFTEN DESPITE DIFF FUNCTIONS
C
FORM FOLLOWS FUNCTION
O IF 2 SPECIESHAD A COMMON
M ANCESTOR THEYSHOULD
P
HAVE MAINTAINED “BUT
A MODIFIED” THE SAME
N COMPONENT PARTS, BONES,
A MUSCLES ETC.
T
O HOMOLOGOUS STR’S =
M PHYSIOLOGICAL STR’S THAT
Y HAS BEEN ADAPTED FOR A
NEW FUNCTION.
C VESTIGAL STR’S - REMAINS
O OF STR’S THAT WERE
M
FUNCTIONAL IN SOME
P
ANCESTOR. ARE OFTEN
A HOMOLOGOUS TO ORGANS
N THAT ARE USEFUL IN OTHER
A SPECIES.
T
O
M
Y
Human tail bone
is homologous to
functional tails
of other
primates
C
O
M
P
A
N
A
T
O
M
Y
ANALOGY-SIMILAR
FUNCTION BUT
DIFFERENT
STRUCTURES
EXP: BIRD WINGS &
INSECT WINGS=FLIGHT
BUT DIFFERENT STR’S &
VARIATIONS.
NEARLY
ALL
ORGANISMS
USE
THE
B
SAME
BIOCHEMICAL
MOLECULESI
DNA,
ATP
&
ENZYMES
O
C
H
E
M
I
C
A
L
COMPARISON OF BASES BETWEEN
CHIMP AND HUMAN= 99.125%
SIMILARITY
E EARLY STAGES OF
M DEVELOPMENT OF EMBRYOS
B SHOW PECULIAR SIMILARITY
R
Y
O
L
O
G
Y
SUGGESTS COMMON ORIGIN
PURPLE-SULFUR BACTERIA
P
R
E
C
A
M
B
R
I
A
N
T
I
M
E
STROMATOLITES-BACT
COMMUNITIES
CS
P
A
L
E
O
Z
O
I
C
E
R
A
CAMBRIAN EXPLOSION SHOWS NUMEROUS
FAMILIES OF PALEOZOIC FAUNA
BRACHIOPODS
TRILOBITE
SMALL MARINE INVERTEBRATES PLUS CORALS
ECHINODERMATASPINY-SKINNED &
RADIAL SYMMETRY
AGRIOCRINUSFOSSIL SOFT
BODIED &
UNMINERALIZED
PARTS
OUR OWN PHYLUM WAS
C REPRESENTED BY A SMALL
A SLIVER-LIKE THING THE M PIKAIA - FOUNDER OF
B
PHYLUM
CHORDATA?
R
I
A
N
CAMBRIAN
S
I
L
U
R
I
A
N
Plants evolved from algae c/o
chlorophyl & starch storage- moss
first land plants but still need H2O
First vascular land plant- cooksonia-no
leaves, flowers or seeds but probably
S root hairs and sporangia(420mya)
i
l
u
r
i
a
n
D FIRST LAND ANIMALSE Myriapods, centepedes, millipedes
V
O
N
I
A
N
P
E
R
Worms with appendages
TETRAPOD EVOL. FROM FISH
D
OUT OF H2O. FISH HAD SERIES
E
OF
BONES
ARRANGED
LIKE
V
O ARMS/LEGS.
N
I
A
N
P
E
R
TETRAPOD
ANTHRACOSAUR
TETRAPOD AMPHIBIAN-TRANSITION
FORM BETWEEN FISHES & AMPH.
WITH NOTOCHORD SPINE & RIBCAGE
ICHTHOSTEGAAMPH. BELIEVED
TO BE FIRST LAND
VERT. DERIVED
FROM LOBE
FINNED FISH
DEVONIAN DROUGHTS MAY HAVE BEEN CAUSE
FOR NS TO FAVOR THOSE FISHES WHO VENTURED
OUT TO PARCHED EARTH
COELACANTH-LOBE FINNED
RHIPIDISTIANS
LUNGFISH-EXTINCT
AMPHIBIANS
VERT. ADULTS
USE LUNGS
LARVAE-LONG
TAILS USED GILLS
COLD-BLOODED &
EGGS LAID IN H2O
HAVE EXISTED
350MYA
OLDEST GROUP OF
TERRESTRIAL
VERTEBRATES
PTERPLAX
ANDRIAS
C
A
R
B
O
N
I
F
E
R
O
U
S
FERN-ALLOPTERIS (307MYA)
FERNS
GYMNOSPERMS
P
E
R
M
I
A
N
REPTILES
REPTILE-DIMENTRODON
REPTILE-HYLONOMUS
FERN-LYGINOPTERIS
307MYA
FERN-GLOSSPTERIS
FERN-CALAMITESSPORE-BEARING
CLUB MOSSLEPIDODENDRON-LEAF
SCARS ON TRUNK-100FT
ACROSS & 3FT DIA.
CARBONIFEROUS LAND PLANTS
AND INSECTS
POST PERMIAN EXTINCTION-GYMNOSPERMS
BECAME ABUNDANT. HAVE SEEDS FROM
P
SEEDLESS ANCESTORS - HELPED TO DISPERSE
O
& ENCASED SPERM
PONDEROSA
S
T
P
E
R
M
I
A
N
2455 YRA
ARISTATA CONES
2455 YRA
LEBACHIA-OLDEST
RELATIVE OF CONIFERS
BRISTLECONE GHOST
4776 YRA
EUPARKERIA-BELIEVED TO BE
RELATIVES OF ARCHOSAURS
THE CROCODILES, DINOSAURS,
AND BIRDS. SEEM TO BE BIPEDAL
FOR SHORT DISTANCES
TRIASSIC-245-208mya-middle
M
animals-reptile
like
mammals
&
E
S dinosaurs
O
Z
O
I
C
JURASSIC-208-146mya-more
dinosaurs and first mammals appear
CRETACEOUS-146-65mya-first
flowering
plants.
Extinction
of
E
R dinosaurs & modern birds
A appear=life as it now exists on earth.
M TRIASSIC
E Pangaea
S Hot & dry
O
Z Seasonality
O strong
I Small dino’s
C ferns, cycads
E
R
A
Gymnosperms
JURASSIC CRETACEOUS
breaks apart
almost like today
warm/moist
warm, high sea level
no polar ice later sea levels down
flooded plains greater extremes
archaeopteryx dino’s flourish
flying pterosaur angiosperms
large dino’s
ants & butterflies
Major extinction at end of this era
DINOSAURS EVOLVED FROM
ARCHOSAUR REPTILES-THEIR
CLOSEST RELATIVES ARE
CROCODILES
Dinos evolved upright stance & warm
blooded which allowed for continuous
locomotion. Cladistically birds are
dinosaurs.
Transitional fossil-mix of reptilian & avian
C
R
E
T
A
C
E
O
U
S
T
O
T
E
R
T
I
A
R
Y
Angiosperms evolved from
gymnosperms. Closest relatives are
the Gnetophytes=outcrops of the
flowering plants.
ANGIOSPERMS ARE THE DOMINATE
FLORA OF THE WORLD(3/4 OF ALL LIVING
PLANTS ARE ANGIOSPERMS)DEVELOPED
FRUITS & FLOWERS FOR POLLEN AND
SEED DISPERSAL
EXTINCTION-DECREASE IN
BIOLOGICAL DIVERSITY.
99.9% OF ALL SPECIES THAT
EVER EXISTED ARE NOW
EXTINCT!
WHY?
ENVIRONMENTAL CHANGE:
LIVING: competition, new
parasites, new predators, new
prey defenses.
NON-LIVING: climate, soil,
pH, salinity.
Extinction occurs after a species has been
reduced to a very limited distribution or has
become specialized in its food, habitat or
behavior patterns
EXAMPLES:
Everglades kite feeds on a certain snail
who’s pop was reduced by swamp
draining.
Ivory-billed woodpecker was eliminated
by destruction of southern forests
Sea cows swim slowly along shorelines
and were easy targets for whalers in
Pacific NW-went extinct.
Will our species become extinct?
Nuclear winter-cooling effects of a large
number of explosions results in dust or
particles in the air blocking sunlight.
Global nuclear war could produce
temperatures of less than -40 C in 80
days-most crops and some humans
would not survive.
Comets and asteroids-impacts would
throw up large clouds of particulate.
Impact on other species due to:
Habitat destruction by man
Introduction of competing &
predatory species & parasites by
man
Overexploited resources by
humans.
ACKNOWLEDGEMENTS
www.axel-and-alice.com/ghbc
//bioweb.cs.earlham.edu/9-12/evolution
www.talkorigins.org
www.fieldmuseum.org/exhibits
www.xs4all.nl/~steurh
www.time-travel.com/cenozoic
//fp.bio.utk.edu/darwin
www.infoplease.com
//teamwork.icdavis.edu
//bioserve.latrobe.edu.au/vcebiol
//depts.washington.edu/vert
//ald.zen.uni-breman.de
www.gpc.peachnet.edu/~pgore
//library.thinkquest.org/19926
//geology.wr.usgs.gov
//biocrs.biomed.brown.edu.Books
www.ucmp.berkeley.edu/vertebrates
//darwinsmistake.com
www.life.umd.edu/classroom/bsci124
www.sprl.umich.edu/glc
//daphne.palomar.edu/wayne/ww060/
//fig.cox.miami.edu/faculty/Tom/bil160
www.zoomdinosaurs.com
www.sc2000.net/~czarembra
www.kean.edu/~biology
www.truman.edu/academics/ss