Transcript Theory of Evolution - Council Rock School District

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15.1
History of Evolutionary
Thought
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Dinosaur Adaptations
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What is Evolution?
A
scientific theory
 Debated
still today
 Enormous
scientific support
 Religious
conflict
 Keystone
of biological science
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Evolution and Some History
 Evolution: is
the development of new organisms
from pre-existing organisms over long periods of
time
 Evolution: is
a heritable change in the
characteristics of a population from one generation
to the next
 In
the 1700’s, many held the belief that organisms
did NOT change over time and that the Earth was
6000 years old, not the 4.6 billion years old we
support today
 However, some
ideas
scientists did not support these
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Who Thought What
 The
church was a strong influence regarding
species remaining unchanged – biblical view
 God
created an infinite and continuous series of
life forms, each one grading into the next, from
simplest to most complex, and that all organisms,
including humans, were created in their present
form relatively recently and that they have
remained unchanged since then
 Because
these beliefs were strong, no one
attempted to figure out how different species came
to be
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Biological Evolution
 At
this time, however, there were some
scientists who felt that the Earth was much
older and that organisms did change over
long periods of time
 Charles
Darwin, the famous naturalist with
whom we associate biological evolution,
was very much influenced by these
scientists
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Charles Darwin
1809-1882
 Darwin
was a naturalist (biologist) who was
fortunate enough to have taken a voyage around
the world over 5 years
 During
this time, he made many observations and
collected thousands of living and dead specimens
 He
used this information, along with several other
scientists’ to present his theory of evolution
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Theories Influencing Darwin
 Erasmus
Darwin = grandfather who believed that
evolution occurred in all living things and must
have occurred over millions of years
 The
geologists
***Cuvier 1769-1832 – French, observed that
fossils found in deeper strata looked different than
those in more shallow layers; changes were
sudden, organisms became extinct and replaced
by others, so Earth must have developed
catastrophically - catastrophism
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Theories Influencing Darwin, cont.
 Lyell
1797-1875 - British, geologic processes that
formed the Earth are still at work today and that
these changes are slow and progressive – did not
agree with Cuvier – uniformitarianism (developed
earlier by James Hutton, a Scottish geologist); key to
understanding the present is to look at the past!!!
 Bottom
theory
line, both theories contribute to evolutionary
 PS
– Cuvier and Lyell strongly disagreed with one
another about how the Earth changed over time, but
neither accepted the Church’s view either. Cuvier
did not live long enough, but Lyell in time came to
support Darwin’s work on biological evolution. They
remained friends up until Darwin’s death
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Theories Influencing Darwin, cont.
 Lamarck
1744-1829 – French biologist who
believed in evolution and sought to explain
why
 Theory
of the inheritance of acquired
characteristics – use and disuse
 Spontaneous
generation and need
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Wait, there’s more…epigenetics!!!

http://www.teachersdomain.org/asset/biot09_vid_epigeneti
cs/
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Darwin’s Ideas
Number one: Descent with Modification
- organisms change through time
- organisms are descended from pre-existing species
- Galapagos island (South America) observations and
finches = common ancestor!!!
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Darwin’s Ideas, cont.
Number two: Natural Selection – the mechanism for
descent
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Overproduction – Malthus 1766-1834 (British
economist)
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Genetic variation
Struggle to survive
- Differential reproduction – organisms
with the best adaptations survive, reproduce
and pass along those characteristics to their
offspring
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Fitness and Adaptation
 Fitness
= hereditary success for next
generation
 Adaptation
vs. acclimatization = is a tool
which makes an organisms successful in a
particular environment; acclimatization is a
short term “fix” that will not be passed
down through the generations
 Example: a
plant resists extreme drought
over the course of one summer vs. cactus
spines
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Darwin’s Publication
 In
the 1850’s, another naturalist, Alfred
Russel Wallace formed a new theory about
the process of evolution
 In
1858, both scientists’ ideas were
presented at a conference and in 1859,
Darwin published his work in a book
entitled, “On the Origin of Species by
Means of Natural Selection”
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Try This!
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http://www.techapps.net/interactives/pepperMoths.swf
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http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.
html
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Theory of Evolution
15.2 Evidence of Evolution
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How???
Fossils give us evidence for evolution.
Problem: HOW DO LIVING ORGANISMS
PROVIDE EVIDENCE FOR EVOLUTION?
Solution: morphology (similarities in shape
and structure), embryology (development),
DNA, RNA and protein sequences.
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Geologic Time Scale
Evidence #1
Think of the GTS
as a journal that
goes back 4.5
bya – developed
by scientists in
the 1700’s and
1800s
Fossils
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 Remains
of organisms that died long ago
 Can
form under different conditions and in
differing time periods
 Very
powerful evidence even today
 Steno
= superposition
 Superposition
says that undisturbed areas of the
earth form in layers from bottom to top, oldest to
newest
 These
 The
layers contain fossils
Geologic Time scale was developed to
summarize these findings
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Fossils, cont.
 Relative
age of fossils can be determined by
comparing fossils found in these layers
 Absolute
age of fossils can be determined by
radiometric dating – still an indirect method
 An
incomplete history – there are gaps which leave
questions about evolution and how it occurred
 1.7
bya – rocks with fossils of 1st multicellular
organisms
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Fossils, cont.
 Strata
tell us that different organisms lived at
different times, and have definitely changed over
time
 Organisms
from the past in some cases were very
much NOT like organisms today
 Fossils
in adjacent layers are more like one another
than those farther away
 Fossils
provide clues as to an organism’s
environment
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Common Ancestor??? WOW
Paleontologists
have discovered a
fossil of a dinosaur sitting on a nest of
eggs. This finding of brooding
behavior, characteristic of birds,
supports the hypothesis that birds
share a common ancestor with
dinosaurs.
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Fossils, cont: Transitional Species
 These
are species that help us fill in gaps in the
time scale
 They
allow us to make inferences between what we
think existed at particular time periods and what
later descendants looked like
 Whales
evolved from land mammals??? NO
linearity!
+Biogeography
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Evidence #2
Studies where organisms live around the world
 Darwin
and Wallace both noticed two things:
***closely related animals living in different
environments –divergence
@@@unrelated animals living in similar
environments -convergence
***Descent with modification at work
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Anatomy and Embryology
Evidence #3

Structure and development

Ancestor vs. relative – descending from ape OR descending
from a common ancestor
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Descent from your cousin, or from your grandparent
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Common structure, common ancestor, different environment,
different adaptations
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Homologous structures: related structures with different
functions due to different adaptations - different patterns of
evolution forced selective environmental pressures amongst
related organisms
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Analogous structures: related structures have similar
functions but no common ancestor – bird, bat, moth wing –
different patterns of evolution forced selective environmental
pressures
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Homologous Structures
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Analogous Structures
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Embryology
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“Ontogeny Recapitulates Phylogeny”
 Ernst
Haeckel – zoologist 1834-1919
 An
organism's biological development, or ONTOGENY
parallels and summarizes its species' entire
evolutionary development, or PHYLOGENY
 Not
true – these stages of development are not
representative of an adult ancestor, but are similar to
the embryonic stages of the organism’s ancestor.
 Patterns
are repeated, not the actual form of the
organism.
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Biological Molecules
 Organisms
that share traits have a more recent
ancestor
 Still
developing
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Phylogeny, revisited
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Tree Template
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15.3 Evolution in Action: Speciation

Evolution can produce new species of organisms, especially
if there are new habitats to invade
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When many related species evolve from a single ancestral
species, this is called adaptive radiation
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Divergent evolution is the process of two or more related
species becoming more and more dissimilar. Adaptive
radiation is a type of divergent evolution (homologous
structures).
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Example: Galapagos finches, Hawaiian honeycreepers, anole
lizards
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Evolution in Action, cont.

On the other hand, it is possible for unrelated species to
become more and more similar in appearance as they adapt
to the same kind of environment. This is called convergent
evolution (analogous structures).
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Examples include this cactus and spurge (euphorbia):
Notice the resemblance of the cactus (upper left), which
grows in the American desert, to the euphorbia, which grows
in the African deserts. Both have fleshy stems armed with
spines. These adaptations help the plants store water and
ward off predators.
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Artificial Selection
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Where humans choose what their offspring will look like by
selecting the parents for certain traits
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All domesticated dogs today arose a common wolf ancestor
from Eastern Asia about 15,000 years ago
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Coevolution
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When two or more species evolve together because they
influence each other
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Examples: bees and flowering plants, predator – prey,
humans and antibiotics
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Closure
Identify each type of evidence (puzzle pieces) for evolution in
the following examples:
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Mammalian embryos have gill slits
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Human blood proteins are very similar to chimps
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Domestic chickens are descended from jungle fowl of SE
Asia
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All clams have two shells, right and left