Download Biology Chapter 15 Evolution Unit

Biology
Chapter 15
Evolution Unit:
Darwin’s Theory
of Evolution
15-1 The Puzzle of Life’s Diversity
I. Background: Evolution
and Its Core Principles
A. Evolution is a
Central theme in biology
T. Zobzhansky: “Nothing in
biology makes sense
except in the light of
evolution.”
B. Core principles of evolution:
1. All life is linked through a
Common
ancestor
___________________
2. Populations of living things
Change
over time (evolve).
___________________
Environment influences
3. The _______________________
this change (natural selection) so
that advantageous traits are selected over
less advantageous traits.
traits become more
4. The advantageous
_________________________________
common in the population
____________________________________
(descent with modification).
II. Voyage of the Beagle
A. A sea voyage helped
Darwin
frame his theory of evolution.
____________________
1. Darwin was born in
England on February 12,
1809.
2. Set sail on the HMS
Beagle from England in
5 year voyage
1831 for a ____________
around the world.
Darwin’s Journey
Tortoise
Marine Iguana
3. Darwin’s Observations:
Patterns of Diversity plants and
a. ___________________:
animals seemed remarkably well suited
to whatever environment they inhabited.
Living Organisms and Fossils
b. ____________________________:
Many of the fossils that Darwin discovered
resembled living organisms but were not
identical to them.
For example, glyptodon, an extinct animal,
is an ancient relative of the armadillo of
South America. (page 370)
c. The Galapagos Islands:
1.) Located 1000 km west of South America.
2.) Islands were close together but had
_________________
different climates
sparse vegetation
3.) Hood Island had __________________.
long necks
Tortoises on this island had _____________
and a curved shell allowing them to reach the
sparse vegetation.
rich vegetation
4.) Isabel Island had _________________.
Tortoises on this island had
shorter necks and a dome-shaped shell.
_____________
Giant Tortoises of the Galápagos
Islands
Section 15-1
Pinta
Pinta Island
Tower
Marchena
Intermediate shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Hood Island
Floreana
Isabela Island
Dome-shaped shell
Hood
Saddle-backed shell
5.) Galapagos Finches: striking correlation between
form of finches and the environment they inhabit;
similarities and differences with mainland species
Beak Adaptations
Large Ground Finch
Small Tree Finch
Woodpecker
Finch
15-2 Ideas That Shaped Darwin’s Thinking
I. Evolutionary Thinking before Darwin
A. Aristotle
________ believed that species were
fixed and did not evolve.
B. All species were created in a single act
of creation about 6,000 years ago.
C. Buffon (mid-1700’s) suggested that
Earth was much older and raised
_______________________
the possibility that different species
arose from common ancestors.
______________________________
II. An Ancient Changing Earth
A. Hutton (1785)
1. ________________
Geological processes
operate
extremely
________________
slowly.
________________
2. Earth is much older
than a few thousand
years.
B. Lyell (1833)
1. Wrote Principles of
Geology.
2. Promoted the idea of
continual, gradual,
consistent geological
changes.
C. Lamarck (1809) was the
first to support the idea of evolution.
1. Believed organisms
acquired or lost certain
traits during their lifetime.
Example: giraffe
2. Traits could be passed to offspring
therefore, this led to a
change in a species.
Example: Giraffe
D. Malthus (1798)
1. If human populations
increase too fast it
_______________,
would lead to
competition for scarce
resources, and
only some individuals
would survive.
2. Limits to population growth.
E. Wallace (1858)
1. Conceived of
essentially the same
theory as Darwin.
2. Speculates on
evolution by natural selection.
15-3 Darwin Presents His Case
I. Publication of
On the Origin of Species
A. Wallace’s letter outlining
basic principles of natural
selection spurs Darwin
into taking his ideas
public.
B. After much fierce debate,
Darwin publishes his theory in 1859.
1. Contains a well-constructed
argument for natural selection.
2. Backed by considerable evidence.
3. He used the phrase “descent with
modification.”
4. The book is “sold out” in one day.
C. Advances in
genetics in the
twentieth century
yield the
mechanism
through which
natural selection
operates,
vindicating
Darwin’s ideas.
DNA Fingerprinting
II. Inherited Variation and
Artificial Selection
A. Nature provided the variation, and humans
selected those variations that they found useful.
B. Variation existed both in nature and in farms.
This variation was inherited.
produced the most milk
1. Cows that __________________________
were selected by breeders.
the largest and most
2. Plants that produced
__________________________
flavorful fruit were selected.
Artificial Selection: Dogs
Artificial Selection: Plants
III. Evolution by Natural Selection
A. The Struggle for Existence
1. High birth rates and a shortage of
life’s basic needs would force organisms
to compete.
2. Result:
Those prey that are better camouflaged,
or better protected, such as a porcupine
can avoid being caught. Those predators
that are faster or have a better mechanism
to catch prey survive.
B. Survival of the Fittest
1. Fitness – ability of an organism to
survive and reproduce.
2. Darwin proposed that fitness is a result
of adaptation.
inherited
3. Adaptation – any _________________
characteristic that increases an
organism’s chance of survival.
Examples of Adaptations
a. Waxy coating on the
surface of leaves
prevents against
water loss
b. Ability to climb trees
- spider monkey
- Tree boa
c. Coloration
- Octopus
Look closely: It’s an Insect!
4. Those individuals
best suited to their
environment
survive and
reproduce most
successfully.
Darwin called this
process “survival of
the fittest” or natural
selection.
Mantids exhibit camouflage.
C. Descent with Modification
1. All living organisms are related to
one another.
2. Common descent: all species –
living and extinct
__________________–
were derived from
common ancestors.
3. A single “tree of life” links all living
things.
The “Tree of Life”
IV. Evidence of Evolution
Evidence
1. Fossil Record
Example
Fossils – the bones, shells,
teeth, and other remains of
organisms.
Fossils of simpler organisms
are found in older rocks.
Newer strata contain more
complex organisms.
Strata of sedimentary rock at the Grand Canyon.
Figure 17-2 Formation of a Fossil
Section 17-1
Water carries small rock
particles to lakes and seas.
Go to
Section:
Dead organisms are buried
by layers of sediment, which
forms new rock.
The preserved remains
may later be discovered
and studied.
Formation of sedimentary rock and deposition
of fossils from different time periods.
Leaf Fossil
Ammonites
Insect in Amber
Dinosaur Fossil
IV. Evidence of Evolution
Evidence
2. Geographic
Distribution of
Animals
Example
1. All 13 species of Galapagos
finches descended with
modification from a common
mainland ancestor.
2. Similar ecological
conditions cause different
animals to end up evolving
striking features in common.
Darwin’s Finches
The continent of Australia is home to unique animals,
such as these marsupials, that evolved in isolation.
IV. Evidence of Evolution
Evidence
Example
Experimental evidence can
demonstrate natural selection
3. Current Evolution at work.
Example: Peppered moths,
antibiotic resistance of
bacteria.
Overuse of Antibiotics
has lead to Antibiotic
Resistance in bacteria.
Evolution of Pesticide Resistance in insect populations.
IV. Evidence of Evolution
Evidence
Example
Humans select from among
the naturally occurring genetic
4. Artificial Selection variations in species.
Example: Wheat, corn, cows,
race horses, domestic
breeding of dogs – poodles.
Evidence
5. Comparative
Anatomy
Example
Similarities in form and structure
between otherwise differentappearing structures.
Homologous structures: Same
structure but different function.
(organization of bones in fins of
whales, wings of bat, paws of cat
and gorilla point to their common
evolutionary origin)
Vestigial Structures: Useless
structures. (in humans – appendix,
wisdom teeth, muscles that move
the ears and nose.)
Evolution Evidence: Comparative
Anatomy
• Homologous
structures
(homology)
• Descent from a
common ancestor
• Vestigial organs
Ex: whale/snake
hindlimbs; wings
on flightless birds
Comparative Anatomy: Whale hind limb
Fossilized leg bones of Basilosaurus, an ancient whale.
A transitional fossil linking past and present.
Whales are mammals that evolved from land dwellers.
Evidence
Example
Early embryo development in all
animals goes through similar
6. Comparative stages, to the extent of producing
structures
not
seen
in
adults.
Embryology
Example: The fish, bird, rabbit,
and human embryos are similar
in appearance and all have a
two-chambered heart,
pharyngeal slits, and a tail with
muscles to move it.
Evolution Evidence: Comparative Embryology
Evolution Evidence: Comparative Embryology
• Pharyngeal
pouches, ‘tails’
as embryos
IV. Evidence of Evolution
Evidence
7. Comparative
Biochemistry
Example
Similarity in genes that control
cellular function in very
different organisms.
Example: Same set of genes
controls many early events
in the development of the
fruit fly and mouse.
*All living things contain DNA.
Evolution Evidence: Molecular Biology
• Similarities in
DNA, proteins,
genes, and gene
products
• Common genetic
code
V. Summary of Darwin’s Theory
A. Individual organisms differ from one another
in a population.
B. More organisms are produced than can survive.
C. Individual organisms must compete
for limited resources.
A few of the color variations
in a population of Asian lady
beetles.
Overproduction of offspring.
D. Individuals best suited to their environment
survive and reproduce most successfully.
These “best fit” individuals pass their
heritable traits to their offspring.
E. Natural selection, the environment selecting
the best traits (phenotype) under the current
conditions, causes species to change over
time.
Final words…...
• “Absence of evidence
is not evidence of
absence.”
THE END!