Transcript Theory of Evolution Power Point

What exactly is
evolution?
Evolution is the biological change process by
which descendants come to differ from their
ancestors.
Or, simply: gradual change in organisms over time
Theories of geologic change set the
stage for the evolutionary theory.
 There were three theories of geologic
change.
Hey You! Row 3,
 Catastrophism
 Gradualism
 Uniformitarianism
Seat 3 … Yeah You!
What type of
species isolation is
this?
Catastrophism
 Natural disasters such
as floods and volcanic
eruptions have
happened often during
Earth’s long history
 These events shaped
landforms and caused
species to become
extinct in the process
Gradualism
 Landforms result from slow changes over a
long period of time
 Creation of canyons, laying down of soil
Uniformitarianism is the prevailing
theory of geologic change.
• Geologic processes that shape Earth are uniform
through time
10.5 Evolutionary Biology Today
Pssssssssssssssssttttt..
Hey all of you fine looking Biology
students!! I need a recap of this
evolution stuff! Can you jot one
word, yes just one word that can
explain each of these terms?
• Catastrophism
• Gradualism
• Uniformitarianism
Evidence for evolution came from
several sources.
( Fossils, Geography, Embryology, and Anatomy )
 Fossils provide evidence of evolution.
 Fossils in older layers are more
primitive than those in the upper
layers.
 The study of geography provides evidence
of evolution.
– island species most closely resemble nearest mainland
species
– populations can show variation from one island to
another
Biogeography is the study of the distribution of organisms
around the world
 Embryology provides evidence of evolution.
– identical larvae, different adult body forms
– similar embryos, diverse organisms
Larva
Adult crab
Adult barnacle
 The study of anatomy provides evidence of
evolution.
– Homologous structures are similar in structure but
different in function.
– Homologous structures are evidence of a common
ancestor.
Human hand
Mole foot
Bat wing
• The study of anatomy provides evidence of
evolution.
 Analogous structures have a similar function.
 Analogous structures are not evidence of a
common ancestor.
Bat wing
Fly wing
Row 4, Seat 2
Is this Divergent
or Convergent
Evolution?
Umm Why?
Structural patterns are clues to the
history of a species.
 Vestigial structures are remnants of organs or
structures that had a function in an early ancestor.
 Ostrich wings are examples of vestigial structures.
Ostriches use
their wings for
balance not
flight!
10.5 Evolutionary Biology Today
Umm….Need a little Help!
Lets Talk, Can we??????
How can I remember
these terms on my test?
•Homologous Structures
•Analogous Structures
•Vestigial Structures
10.5 Evolutionary Biology Today
Wisdom teeth are a third set of molars that
usually appear in humans between the ages of
17 and 25, and often need removing because
they crowd our other teeth. Explain why
wisdom teeth are vestigial structures.
Use your own paper to respond and turn in when
you are finished.
Early scientists proposed ideas
about evolution.
– Linnaeus: classification system from kingdom to species
– Buffon: species shared ancestors rather than arising
separately
– E. Darwin: more-complex forms developed from lesscomplex forms
– Lamarck: environmental change leads to use or disuse
of a structure
Then there was Darwin.
 Influenced by Lyell’s views of gradual
geologic change
 1831 - HMS Beagle traveled to South
America. Conducted studies of evolution
on the Galapagos Islands
 Found much evidence to support Lyell’s
views
 Formulated his own opinions
10.5 Evolutionary Biology Today
Galapagos Islands … Let’s
go!!
Pack your
bags!!
Take a NOVA
Galapagos
Island Tour
Darwin observed differences
among island species.
 Variation is a difference in a physical trait.
 Galápagos tortoises that live in areas with tall
plants have long necks and legs.
 Galápagos finches that live in areas with hardshelled nuts have strong beaks.
10.5
Today
DoEvolutionary
you see anyBiology
variation
in this population of
King Penguins? How might this population of
penguins change if Antarctica suddenly got
much warmer?
Species may somehow be able to adapt
to their surroundings…
 An adaptation is a feature
that allow an organism to
better survive in its
environment.
– Species are able to adapt to their
environment.
– Adaptations can lead to genetic
change in a population.
Darwin observed fossil and geologic
evidence supporting an ancient Earth.
 Darwin found fossils of extinct animals that
resemble modern animals.
 Darwin found fossil shells high up in the Andes
mountains.
Shells in the mountains …. No possible
way!! Who can possibly explain that???
Raise your hands 
 He saw land move from underwater to above
sea level due to an earthquake.
 Darwin’s observations supported Lyell’s theory
that daily geologic processes can add up to
great change over a long period of time.
 Darwin extended his observations to the
evolution of organisms.
Darwin proposed natural
selection as a mechanism for
evolution.
Star-nosed mole
Snout’s 22
fingerlike rays can
touch up to 12
objects in just one
second!
Several key insights led to Darwin’s
idea for natural selection.
 Darwin noticed a lot of variation in
domesticated plants and animals.
 Traits that weren’t in their wild relatives
 In order for artificial or natural selection to
occur, the trait must be heritable.
 Heritability is the ability of a trait to be
passed down.
Artificial Vs. Natural Selection
 Natural selection
is a mechanism by which
individuals that have
inherited beneficial
adaptations produce
more offspring on
average than do other
individuals.
 Artificial selection
is the process by
which humans select
traits through
breeding.
neck feathers
crop
tail feathers
Artificially Bred Pigeons
Natural selection explains how
evolution can occur.
 There are four main principles to the
theory of natural selection.
 Variation
 Overproduction
 Adaptation
VARIATION
OVERPRODUCTION
DESCENT
withwith modification
ADAPTATION
Descent
MODIFICATION
10.5 Evolutionary Biology Today
Use your Biology Book (p. 306) to define each
main principle to the theory of natural
selection.
Inherited trait that is selected for over time
because it allows organisms to better survive
1. Variation: in their environment.
Having many offspring raises the chance that
2. Overproduction: some will survive, it increases competition for
resources.
A certain variation allows an individual to survive
3. Adaptation: better than other individuals it competes with.
Species with adaptations suited for
4. Descent with Modification: survival and reproduction; these
adapataions will continue in future
generations.
Survival of the Fittest?
 Fitness is the
measure of survival
ability and ability to
produce more
offspring.
 Jaguars with larger
teeth and jaws have a
higher fitness than
other jaguars in a
population.
 Other jaguars
reproduce less
because they were
less fit.
Natural selection acts on
existing variation.
 Natural selection
can act only on traits
that already exist. five digits
 Structures take on
new functions in
addition to their
original function.
wrist bone
The panda’s wrist bone also functions like a thumb.
New technology is furthering
our understanding of
evolution.
Fossils provide a record of
evolution.
 Paleontology is the study of fossils or
extinct organisms.
 Paleontology provides evidence to
support evolution.
Molecular and genetic evidence
support fossil and anatomical
evidence.
 Two closely-related organisms will have
similar DNA sequences.
Evolution unites all fields of biology.
 Scientist from many fields contribute to the
understanding of evolution.
 The basic principles of evolution are used in
many scientific fields.