Vocabulary:
Fossil Record: fossilized artifacts and their placement in the geological strata.
Ancestor: Preserved remains or imprints of organisms that lived in the past (we
use to learn about the past).”
Convergent Evolution: species that have evolved similar characteristics, but fall
under different lineages.
Divergent Evolution: When organisms have the same characteristics, but then
branch, creating two organisms with at least one different characteristic
Phylogenetic tree: family trees, that group like organisms and place them in
order of their evolution
Natural selection- the process in which biologic traits (genotypic or phenotypic)
become more or less common within in a population
Genetic Drift- the change of frequency of an allele in a population due to random
events
Charles Darwin- ‘Father of Evolution,’all species of life have descended from
common ancestor
Phenotypes- an observable characteristic or trait that is expressed physically
1. After reading the short article on Ardi, one of our more recent common ancestors,
as well as discussing the fossil record in class, how do you think that scientists
were able to determine how old Ardi was and how she is a common ancestor to
humans?
a. Scientists were able to determine the age of Ardi by looking at where the
fossil remains were found among the earth’s strata in the fossil record.
Carbon dating is another way that the age of Ardi may have been
determined. Molecular testing is probably the most likely way that
scientists were able to link Ardi as one of our recent ancestors. Looking at
the structures that the fossils created when put together is another way that
scientists may have linked Ardi as a common ancestor of humans.
2. How are fossils formed?
a. Having a dead organism’s remains being preserved forms fossils. This can
happen in a few ways including the remains being buried in mud and silt,
while the plant or animal remains decompose. This process takes a lot of
time and is rare because most organisms are not well preserved because
they decay before being buried in the appropriate conditions. Another
possible way for fossils to form is by being subjected to high temperatures
and pressures, such as those conditions that follow volcanic eruptions.
3. The diagram below illustrates the change that occurred in the frequency of
phenotypes in an insect population over 10 generations. What would be a
probable explanation for this change??
-genetic drift due to changes in environment
-allele frequencies fluctuate from random event causing change
-possible causes; predation, better camouflage, growth or death of
plants/mosses, etc
4. Why are there gaps in the fossil record?
There are gaps in the fossil record because not all organisms that die fossilize.
Fossilization is a rare event, but important in helping scientists look at the history
of life on Earth.
Essay Questions:
#1: What role does the fossil record play in evolution?
Main points that students should address:
Looking at relatedness of species
Looking at a timeline for fossils, predicting evolution
Looking at the patterns of the environment (conditions, what was living,
etc..)
#2. After reading the short passage about the Peppered moths in England, how is this an
example of natural selection? How does natural selection support the theory of
evolution?
-
Natural selection is the change in gene frequencies within a population
In England, the peppered moth population changed because of an outside cause
Genetic drift was a result
As lichen died, predators were more easily able to see the light moths than the
darker ones.
Thus the dark allele was selected for as a means of protection and better survival
-
Natural selection is a gradual change over time.
Evolution states that changes in species happen over time.
Natural selection is the main idea/supporting law behind evolution
We know that natural selection has happened by looking at the fossil record.