Download Evolution and the History of Life

Earth and Life History
Chapter 8
MLK
Fall 2006
M.Elizabeth
www.marric.us/teaching
• Chapter 8.1 Change Over Time
– Differences Among Organisms
– Do Species Change Over Time
– Evidence of Evolution: The Fossil Record
•
•
•
•
Fossils
Reading the Fossil Record
Gaps in the Fossil Record
Vestigial Structures
– Case Study: Evolution of the Whale
– Evidence of Evolution: Comparing Organisms
• Comparing Skeletal Structures
• Comparing DNA from Different Species
• Comparing Embryonic Structures
Changes Over Time
• Differences between species relate to
adaptations.
• Adaptations – a hereditary characteristic
(attribute) that helps an organism survive
and reproduce in its environment.
•
– Physical adaptations are heredity. Which
means that the organism has no choice about
the characteristics.
– Emotional, cultural, and behavioral
adaptations are choices that humans can
make.
It’s all about Species
• What is a Species?
– A population of organisms that can mate
with one another produces fertile offspring.
• Example: Horses, Donkeys, and Mules
– Breeding a male donkey to a female horse results in a mule;
– Breeding a male horse to a female donkey produces a hinny
+
=
Sterile Mule
Horses and Donkeys are separate species
Do Species Change Over Time
The Earth is very old – 4.6 Billion Years
• The Earth was formed approx. 4.6 bya
– The oldest rock is 3.5 Billion years
• Fossil evidence suggests that species have
changed over time because younger fossils
are different, yet similar to older fossils
giving rise to the idea of common ancestor
for all life on Earth.
Evolution
• Evolution is the process by which
populations of organisms acquire and
pass on unique traits from generation to
generation, affecting the overall makeup
of the population and potentially leading
to new species.
Geologic Time Notations
ya – Years Ago
mya – Million of years ago
bya – Billion years ago
Precambrian
Paleozoic ERA
Mesozoic ERA
Cenozoic ERA
Era word roots
• Geologist use the clues in some of these words.
• For example:
–
–
–
–
zoic refers to animal life
paleo means ancient
meso means middle,
ceno means recent.
• So the relative order of the three youngest
eras, first Paleoozoic, then Mesozoic, then
Cenoozoic, is straightforward.
Check for Understanding (T or F)
True
• _______
Scientists believe that all living
things, including daisies, crocodiles, and
humans, share a common ancestor.
True
• _______
A great number of species have
died out since life first appeared on
Earth.
False
• _________
The first mammals appeared
on Earth at about the same time as the
first terrestrial plants.
Evidence of Evolution: The Fossil
Record
•
•
•
•
Fossils
Reading the Fossil Record
Gaps in the Fossil Record
Vestigial Structures
Fossils
• Are found in the
earth’s crust – the
very uppermost
part of the earth
that is exposed to
the surface or
lying immediately
below the oceans.
The Best Crust for Fossils
• Sedimentary Rocks are the best crust for
fossil formations;
Example: The
Grand Canyon.
Strata = Layers
of sediment so
its called
sedimentary
rock
Rocks contain clues to the Earth’s past.
What are Fossils
• Fossils are the mineralized remains of
animals or plants or other traces such as
footprints.
• All of the fossils and their placement in
rock formations and sedimentary layers
(strata) is known as the fossil record.
• The study of fossils is called paleontology.
What kind of rock is this?
Sedimentary Rock
Reading the Fossil Record
Law of Superposition: Youngest on Top
• An undeformed sedimentary rock layer is
older than the layers above it and younger
than the layers below it
D
C
B
A
Law of Superposition
• In terms of Relative Age
• Rock Layer B must be younger than Rock Layer A
• but
Rock Layer B is older than Rock Layers C and D.
D
C
B
A
• Once the order of formation is known, a
RELATIVE AGE can be determined for
each rock layer
http://pubs.usgs.gov/gip/fossils/
Gaps in the Fossil Record
• Occur because specific conditions are needed for
fossils to form
• Organisms with hard body parts (skeletons) are more
likely to form fossils than organisms with soft body
parts. Basic to this is that organisms cannot be
completely eaten before fossilization
– Why so many are shells and bones
• Fossils form best without oxygen – why peat bogs and
tar pits have great fossils. Burial by sediments reduce
oxygen exposure.
• Freezing also allows fossil formation – Mammoth that
Japanese scientists are trying to clone from DNA
extracted from frozen Mammoth fossil.
• Fossils once formed can be destroyed.
Sea shells embedded in
marine rock near Santa Cruz
Ammonites near
Redding
Human Remains
• Fossils found in the upper layers of the
Earth’s crust are _______than fossils
found in the lower layers. (newer or older)
• There are gaps in the fossil record because
a. the conditions needed for fossils to
form are rare.
b. very few different organisms have lived
on Earth.
c. many fossils have been destroyed.
d. not many people are looking for fossils.
Vestigial Structures
• Mammals are warm blooded vertebrates
• Vertebrates are animals with backbones.
• Vestigial structures are organs that have
no apparent function.
• Examples:
– Human appendix – narrow tube attached to
the large intestines
– Chimpanzee, gorilla, and orangutan appendix
is functional and used to help digest tough
plant material
Appendix
Whale evolution
(terrestrial to aquatic in ~ 8 Myr)
8 million years total
PBS Whale Evolution
One structural remnant (remaining part) of this
evolutionary process are hind limb bones. These
bones are called vestigial structures.
http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html
Evidence of Evolution:
Comparing Organisms
• Comparing Skeletal Structures
• Comparing DNA from Different Species
• Comparing Embryonic Structures
Comparing Skeletal Structures
• Homologous Structures
– Having similar origins and anatomical
patterns (homo - same
– Anatomy: study of the structure of
biological organisms
– Examples – bird wings, human arms, whale
flippers, bat wings, cat legs.
Homologous Structures
Analogous Structures
• Analogous structures
do the same thing –
similar function, but
different anatomy.
– Wings (butterfly
external skeleton,
bat internal skeleton
• Analogous structures:
wing of an insect, bird,
bat and pterosaur
Comparing DNA from Different Species
• DNA is a biological molecule called
deoxyribonucleic acid and is the genetic
material of all living things on earth
• The actual molecular characteristics of DNA
is measured and compared to other
organisms.
• There are four different nucleotides in DNA
(Adenine, Guanine, Cytosine, and Thymine).
• Gene sequencing – sections of DNA are
sequenced for the order of nucleotide bases
(ATCG or ATGC or ACTG, etc).
Looking for Relatedness
Comparing Embryonic Structures
• Ontogeny: Development of the Individual
from conception to maturity.
• Phylogeny: study of evolutionary
relatedness among various groups of
organisms (e.g., species, populations)
• Vertebrate organisms (those having a
backbone) have similar stages of life as
an embryo
Open Court
Publishing
Company
Check for Understanding
• All living organisms have the same type of
genetic material
_______________
• All ____________look very similar when
they are in the embryonic stage. (living
things or vertebrates)
Chapter 8.2 How Does Evolution Occur
• Charles Darwin
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Darwin’s Excellent Adventure
Darwin’s Finches
Darwin Does Some Thinking
Darwin Learned from Farmers and Animal
and Plant Breeders
Darwin Learned from Geologists
Darwin Learned from the Work of Thomas
Malthaus
Natural Selection
More Evidence of Evolution (DNA Mutation)
Darwin
• Darwin’s father wanted Darwin to become
a Doctor, but Darwin earned a degree in
Theology instead. Later, Darwin was the
naturalist on the HMS Beagle.
Darwin’s Excellent Adventure
• HMS Beagle – Galapagos Island Travels
• Galapagos Islands are part of the country
of Ecuador though the islands are about
1,000 kilometers west of the continent of
South America in the Pacific Ocean.
There are 19 volcanic islands with a land
area of 8,000 km2 in an area of the Pacific
Ocean over 60,000 km2
About Darwin
http://www.aboutdarwin.com/timeline/time_01.html
Darwin’s Finches
Diversity
• Darwin saw finches that were very
different from each other as he traveled
to the various islands of the Galapagos.
• Because of their physiological differences
(beak shapes), the finches had very
different diets
Darwin Does Some Thinking
• Darwin wonders how did the finches become so
different. He thought maybe there was a storm
that separated the original population resulting
in geographic isolation (one of the ways that
speciation can occur)
• Darwin’s hypothesis was that the Galápagos
finches were descended from an original
population of finches that was blown from South
America to the Galápagos Islands.
Darwin Learned from Farmers and
Animal and Plant Breeders
• Darwin was very familiar with artificial
selection or better known as selective
breeding.
• Certain traits are determined by the
breeder to be favorable. If only those
organisms with the favorable traits are
bred then the trait will occur more often
in the population. By isolated certain
individuals the differences can grow.
All from an ancestral dog
Darwin Learned from Geologists
• Darwin learned from Charles Lyell that
the Earth was formed over a long period
of time by natural process.
• This idea of geologic time (really really
long time ago) helped Darwin to more
seriously consider natural processes for
changing populations.
Darwin Learned from Thomas Malthus
• Thomas Malthus was an economist.
• Malthus reasoned that humans have the
potential to reproduce beyond the capacity
of their food supply.
• Malthus recognized that there are some
limitations to human population growth:
– War (for animals it is predation-predators)
– Disease
– Starvation
Competition
• Because there are some limitations to
growth, Darwin thought that those
survivors must be better equipped
(adapted) to their environment allowing
them to out-compete other individuals.
• The offspring of the successful
competitors have the same traits so are
also more likely to survive in the same kind
of environment.
Natural Selection
Darwin theorized that evolution occurs through a
process he called natural selection
1. Overproduction – Each species produces more
offspring that will naturally survive.
2. Genetic Variation – individuals will be slightly
different from one another.
3. Survival Struggle – competition for resources
Abiotic and Biotic factors
4. Successful Reproduction – fitness
(Survival of the fittest)
More Evidence of Evolution
• Darwin did not know what the mechanism
was for how parents passed their traits to
their offspring.
• Gregory Mendel (1822-1884) the Catholic
monk studied traits in sweet peas.
• With Mendel's work and biochemistry we
now know that the mechanism is meiosis
involving DNA that is subject to mutation.
Mutation
• Changes to the heredity material- DNA,
deoxyribonucleic acid – result in a changed
genotype.
• Some changes that occur are not observed
because the change did not significantly
affect a function. Changes that affect
function result in a different phenotype
(what things look or function like).
Natural Selection
Darwin theorized that evolution occurs through a
process he called natural selection
Overproduction
1. ______________
– Each species produces
more offspring that will naturally survive.
Genetic Variation – individuals will be
2. ______________
slightly different from one another.
3. ____________
– competition for resources
Survival Struggle
Abiotic and Biotic factors
Successful Reproduction – fitness
4. ___________________
(Survival of the fittest)
Chapter 8.3 Natural Selection in Action
•
•
•
Insecticide Resistance
Adaptation to Pollution
Formation of New Species
•
•
•
Separation
Adaptation
Division
Insecticide Resistance
• Insects that cause economic or health
damage are becoming more difficult to kill
due to insecticide resistances.
• Insecticides are compounds designed to
kill insects (cidal – to kill).
• Insects that are resistant to a particular
insecticide can survive and reproduce
while those that do not have the genotype
that infers resistance will die and will not
reproduce.
Resistance
• The application of the harmful material (by
humans) results in an artificial selection for those
insects that are resistance.
• The same, unfortunately occurs to disease causing
bacteria and virus, creating “super bugs” which
often times results in incurable situations or
death because antibiotics (against life) are no
longer effective.
• This is why it is so important when prescribed an
antibiotic to complete the treatment to avoid
mutation during treatment of a pathogen creating
a resistant pathogen that can survive – generation
times of bacteria and virus is measured in
minutes.
Adaptation to Pollution
• Peppered moths are the classic case.
• Dark moths were low in population because
they did not blend well with the
environment and so where eaten by
predators. The pale moths were high in
population because they were camouflaged.
• Then comes along the Industrial Revolution
with coal burning to fuel factory machines
and heat homes. The results of burning
coal are sooty smoke, acid rain, and
mercury contamination.
• Well, the sooty smoke coated the
vegetation made those pale moths
stand out like a sore thumb and the
dark moths became camouflaged. So
what do you think happened?
• The population of dark moths
increased and the population of pale
moths decreased.
Peppered
Moths
Match each statement about the peppered moth population
(1-4) with the appropriate step in natural selection (a-d).
B
A
D
C
1. Moths that live to
maturity may mate and
produce offspring.
2. A population of peppered
moths contains some
light-colored moths and
some dark-colored moths.
3. Many moths do not
survive because they are
eaten by birds.
4. Peppered moths lay many
eggs.
a. Genetic
variation
b. Successful
reproduction
c. Overproduction
d. Struggle to
survive
Formation of New Species
Steps: Separation, Adaptation, Division
(speciation).
• Separation allows the gene pool to be
come isolated where no mixing of the
populations occur.
• Adaptation are mutations that help the
species to be successful in the new
environment.
• Division occurs over time these mutant
changes result in a separate species that
cannot interbreed, speciation.
Chapter 8 Review
• One species evolves into another through
speciation
the process of _____________________.
• A group of similar organisms that can mate
with one another to produce fertile
species
offspring is known as ________________.
adaptation helps an organism
• A(n) __________
survive better it its environment.
Evolution
• ____________is
the process by which
populations change over time
•
•
•
•
Artificial selection
In ______________________________,
humans select traits that will be passed from
one generation to another.
A change in a gene at the DNA level is called a
Mutation
__________________.
The theory of evolution combines the
Natural selection and
principles of _________________________
genetic inheritance
__________________.
The fact that all organisms have DNA as their
genetic material is evidence that all organisms
desended__________________________.
from a common ancestor.
______
Everything had to start somewhere.