Transcript Evolution

Evolution
DO N O W ! !
• What is Evolution?
• How does Evolution Occur?
Evolution: A summary
• Evolution - The process of change over time
– Evolution applies to life and responds to the
environment.
• Our Universe is billions of years old (9-12b
years)
– Earth was created approx 4.5b years ago.
• Human existence is only a small fraction of time
since the beginnings of the universe.
The Cosmic Calendar
• If the 12 billion year history of the
universe was a string it would
look like this!!!
• If the 12 billion year history of the
universe was fit into a calendar
year, it would look like this…..
Cosmic Calendar (From The Dragons of Eden - Carl Sagan)
Pre-December Dates
Big Bang
January 1
Origin of Milky Way Galaxy
May 1
Origin of the solar system
September 9
Formation of the Earth
September 14
Origin of life on Earth
~ September 25
Formation of the oldest rocks known on Earth
October 2
Date of oldest fossils (bacteria and blue-green algae)
October 9
Invention of sex (by microorganisms)
~ November 1
Oldest fossil photosynthetic plants
November 12
Eukaryotes (first cells with nuclei) flourish
November 15
Monday
Sunday
Tuesday
Wednesday
Thursday
Friday
Saturday
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Precambrian
ends. Paleozoic
Era and Cambrian
Period begin.
18
19
20
oxygen
atmosphere
develop on
Earth.
First
Worms.
More
Inverts
21
Devonian Period
begins.
First
insects
28
Cretaceous
Period.
First
flowers.
Dinosaurs
extinct.
22
First
amphibian
sFirst
winged
insect
29
Mesozoic Era
ends. Cenozoic
Era and Tertiary
Period begin.
First cetaceans.
First
primates.
23
Carboniferous
Period.
First
trees.
First
reptiles.
30
First evolution of
frontal lobes in
the brains of
primates.
24
Permian Period
begins.
First
dinosaurs
31
End of Pliocene
Period.
Quaternary
(Pleistocene and
Holocene) Period.
First
First
hominids. humans.
vulcanism and
channel
formation on
Mars.
First
oceanic
plankton.
Trilobite
25
Paleozoic Era
ends.
Mesozoic Era
Begins.
Ordovician
Period.
Silurian Period.
First fish,
First Verts
First
vascular
plants
26
Triassic Period.
27
Jurassic Period.
First
mammals
First
birds
DECEMBER
December 31
Origin of ancestors of apes and men
~ 1:30 p.m.
First hominids A. afarensis
~ 10:30 p.m.
Widespread use of stone tools by Homo habilis
11:00 p.m.
Domestication of fire by Homo erectus
11:46 p.m.
Beginning of most recent glacial period. Homo Neanderthalis & Homo sapiens evolve
11:56 p.m.
Seafarers settle Australia
11:58 p.m.
Extensive cave painting in Europe
11:59 p.m.
Invention of agriculture
11:59:20 p.m.
Neolithic civilization; first cities. Colonization of North and South America across Bering straits
11:59:35 p.m.
First dynasties in Sumer, Ebla and Egypt; development of astronomy
11:59:50 p.m.
Invention of the alphabet; Akkadian Empire
11:59:51 p.m.
Hammurabic legal codes in Babylon; Middle Kingdom in Egypt
11:59:52 p.m.
Bronze metallurgy; Mycenaean culture; Trojan War; Olmec culture; invention of the compass
11:59:52 p.m.
Iron metallurgy; First Assyrian Empire; Kingdom of Israel; founding of Carthage by Phoenicia
11:59:53 p.m.
Asokan India; Ch'in Dynasty China; Periclean Athens; birth of Buddha
11:59:54 p.m.
Euclidean geometry; Archimedean physics; Ptolemaic astronomy; Roman Empire; birth of Christ
11:59:55 p.m.
Zero and decimals invented in Indian arithmetic; Rome falls; Moslem conquests
11:59:56 p.m.
Mayan civilization; Sung Dynasty China; Byzantine empire; Mongol invasion; Crusades
11:59:57 p.m.
Renaissance in Europe; voyages of discovery from Europe and from Ming Dynasty China; emergence of the experimental
method in science
11:59:58 p.m.
science and technology; emergence of global culture;; first steps in spacecraft planetary exploration and the search of
extraterrestrial intelligence
11:59:59 p.m.
You were born
11:59:59.999999999
seconds before
new year
Darwin & Natural Selection
•Modern evolutionary thought arose
through the inquiries of Charles
Darwin.
•Darwin was a Naturalist aboard an
exploration ship called the HMS
Beagle.
•Collected and catalogued biological
specimens for return to England.
The Voyage of the Beagle
Pictures of Galapagos Islands
The Galapagos Finches
•Darwin was fascinated by the species
of Finches he observed in the
Galopagos Islands.
•He found that these birds were quite
similar to a species found on mainland
South America. However they differed
significantly in the shapes of their
beaks.
•Darwin reasoned that these species of
finches arose from a common ancestor,
and gradually changed over time to
accommodate their particular diets.
•This led him to develop his theory of
evolution through Natural Selection
Darwin & Evolution
• 2 Theories of Evolution.
• Lamarckian Theory of Inheretance of Acquired Characteristics
– Held that traits acquired throughout life of an organism would be
passed on to offspring.
– Eg. If you lifted weights during your life, your children would be
stronger or, if you did'nt exercise your children would be weaker
– Theory has been replaced by Darwin's theory of natural selection.
• Darwin’s Theory of Natural selection:
– Based on following premises:
• There are not enough resources for all organisms to survive.
• Some organisms are more "fit" to survive.
• Fitness is:
– The ability of an organism to survive in its environment.
– The ability of an organism to survive long enough to
reproduce.
– New genes/traits arise from random mutations.
– Most are either Neutral (no effect), or disadvantageous (decrease an
organism's chance for survival).
Lamarck vs.
Darwin
Natural Selection : The Peppered Moth:
• The peppered moth is a species of moth which uses
camouflage against tree bark to avoid being eaten by
birds. It is normally a light grey color.
• During England's industrial revolution, pollution caused
a darkening of the bark of the trees.
• There was a natural variation in moth coloration with
some being darker than others.
• Those moths of a lighter color, were easier to spot and
eat by birds. And were eaten at a faster rate.
• The survivors tended to be darker, and when they
mated, their offspring tended thus to be darker also.
• Over time, this resulted in the species becoming darker
in color.
Effects of Natural Selection
•
•
Natural selection can have many
different effects on species appearance.
These types of natural selection have
been named as:
1. Directional selection
2. Stabilizing selection
3. Disruptive selection
Directional Selection:
• Eliminates one extreme variation from an array of
possible phenotypes. Results in a shift towards
the other extreme.
Stabilizing Selection:
• Selection acts to eliminate both extremes of an
array of phenotypes. Results in an increase in
individuals exhibiting an intermediate phenotype.
Disruptive Selection
• Selection acts to remove the intermediate
phenotypes favoring the extreme phenotypes:
Convergence
• Convergence occurs when species evolve
into a common phentoypic form due to a
common need. For example the following
diagram shows a shark (fish),
ichthyosaurus (reptile), a penguin
(bird)and a dolphin (mammal). They all
have a torpedo body shape, pectoral,
caudal and dorsal fins. This is based on
their common need to swim rapidly in an
aquatic environment.
Divergence / Adaptive Radiation
•Divergence occurs
when species
evolve in several
directions away
from a common
ancestor. This
happens usually to
fill a vacant
ecological niche.
Also known as
adaptive radiation.
Common
Ancestor
(First
Mammal)
Convergence and Divergence Together
By contrasting North American
placental mammals with
Australian marsupials. One
can see how convergence and
divergence works together.
•In each case an ancestor
mammal evolved into several
ecological niches.
•Since each niche required a
specific phenotype, what
results are 2 groups of
mammals which have NEVER
made contact, evolving into
similar shapes.
Rates of Speciation:
Two models exist to describe the rates of
speciation.
• Gradualism:
– Refers to the model which holds that evolutionary
change occurs in a gradual linear fashion. A species
will change its morphology over time.
• Punctuated equilibrium
– Describes the process in which a species remains
relatively unchanged for relatively long periods of
time. Following which, a period of stress causes
rapid change, followed by another period of relative
stability.
Rates of Speciation:
Evidences of Evolution
Fossils:
•Formed when animal remains are trapped
in sedimentary layers.
•Organic material replaced by minerals
over millions of years.
•Result is a "mineral cast" of the dead
organism.
•Where a fossil is located in the
sedimentary strata can indicate it's age.
•Successive changes in fossil forms of an
organism can help in developing a fossil
record of an organism's evolution.
•Some rare fossils can show "soft tissues"
which give invaluable information on an
organism's physiology
•Example: paleontologists recently
discovered a dinosaur with a fossilized
heart. This indicates that this species
was most likely warm blooded.
Fossilized Trilobite
Fossilized Dinosaur Heart
Radiometric Dating:
• Based on the fact that radioactive materials decay at a fixed
rate.
– Rate is known as a half-life: The amount of time in which only 1/2 of
a radioactive sample remains
– By measuring the amount of radioactive material in a fossil, one can
determine how old it is.
– Example is 14C dating.
• 14C is an isotope of 12C which radioactively decays to 14N.
– It occurs naturally in the environment, and is ingested by organisms
while alive.
– Once an organism dies, 14C intake stops, and the 14C begins to
decay
– One can then measure the amount of 14C remaining in a sample, and
determine its age.
Similarities in Embryological Development
• In early embryo
development, it
appears that embryos
"play out" their
evolutionary history.
• we have not
"forgotten" our
evolutionary history,
only built upon it.
Homologous Structures
• Refers to the fact that
organisms' structures are
formed from similar
anatomy.
• Example the wing of a
bird, arm of a man, wing
of a bat, and flipper of a
whale, all appear to be
formed from a common
set of bones.
• Implies that these
organisms evolved from
some common ancestor.
Amino Acid Differences
Molecular studies of
genetic similarity
support estimates of
evolutionary
relationship from the
fossil record and
anatomical
studies.
Many independent
lines of evidence all
support the
conclusion that all
living things share
common ancestors.
Vestigal Structures:
• Refers to the fact that organisms have
structures which are disused
• These structures, however, a remnants of
structures the organisms used earlier in their
evolutionary history.
• Examples:
• Hip bones in whales
• Tail in humans
• Appendix in humans
• Legs/hips in snakes
Human Vestigial Structures
Analogous and Homologous
Structures
Analogous
StructuresSame function, but
different structure
Homologous
StructuresDifferent Functions,
but the same
structures