Review Sheet Chapter 22 BIOL 1407 Mr. Sanregret
1) The taxonomic system of Linnaeus classified species based on anatomical and structural similarity,
rather than superficial and extrinsic qualities. How did Linnaeus lay the groundwork for the modern
theory of evolution?
2) A fossil is an impression or a relic of a long dead organism. Many fossils are formed in sedimentary
rock. Different layers of sedimentary rock, called strata, can be distinguished from the different
fossils found in each. Where are the most recent fossils found?
3) Cuvier explained the different strata with the catastrophism model. Explain this model.
4) Hutton and Lyell explained the presense of strata with the gradualism and uniformitarian models.
How were these models different from the catastrophism model?
5) The ideas of gradualism and uniformitarianism paved the way for Darwin’s theory of evolution by 1)
establishing that the Earth is very old; and 2) introduced the idea that many small changes can lead to
large changes.
6) Lamarck developed a model of evolution (Lamarckian evolution) where:
a) organisms acquire traits that make them more slightly more adapted to their environment
(e.g.giraffe ancestor stretches to reach high leaves, slightly longer neck results)
b) acquired traits are passed on to offspring
c) a gradual accumulation of inherited traits results in large adaptive changes over a long time period
(e.g. modern giraffe has neck many feet longer than ancestor).
7) Lamarck was on the right track in that he correctly guessed that:
a) evolution explained the stratification of the fossil record
b) evolution is a gradual process
c) evolution adapts organisms to their environment
8) The Theory of Evolution has two main parts a) species descend from ancestor species; and b) species
adapt to their environments because of natural selection.
9) In summary, the Darwinian model of evolution works as follows 1) Populations usually produce
more than enough offspring to replace the individuals that die; 2) however, population size usually
stays the same; 3) therefore, there is a struggle to survive and reproduce; 4) Individuals within a
population vary in heritable traits, and some traits effect the chances that an individual will survive
and reproduce; 5) therefore, those traits that are more fit in the environment will be more likely to be
passed down and will tend to increase in the population.
10) Only populations evolve and adapt, not individuals. Individuals may acclimate, but do not adapt.
11) Only heritable traits are subject to natural selection.
12) Only traits that exist in the gene pool and that are physically possible may be selected. E.g. bacteria
frequently adapt to antibiotics, but not to bleach, intense heat, etc.
13) Fitness and adaptation are relative to the environment. Nearsightedness in humans was more unfit
20,000 years ago than it is now.
14) In empirical science, hypotheses are proposed and tested. Experimental testing can disprove, but not
prove hypotheses. When many attempts to disprove a hypothesis are made, but the hypothesis fails to
be disproven, scientist will say that the hypothesis is supported by the evidence, but not “proven.”
Rejecting a hypothesis is relatively straightforward (e.g. Lamarckian evolution can be rejected based
on our modern knowledge of genetics, with little disagreement from anyone). In contrast, accepting a
hupothesis is gradual and the point at which it becomes accepted theory is not clearly defined (e.g.
Darwinian evolution became accepted theory sometime between 1859 and the 1930’s, depending on
who you ask).
15) Evidence of evolution: Observation of evolution in action in the present. Examples are pesticide
resistance in insects and antibiotic resistance in bacteria.
16) Evidence of evolution: Homologous structures in related groups. E.g. bones and muscles of
vertebrates are all very similar, even when adapted for very different functions. Note that some
homologous parts are vestigial (e.g. snake’s pelvis), and also some homologies are only evident in the
embryonic stage (e.g. pharynx in vertebrates). Homology means that two parts have the same origin.
17) Analogous structures parts have similar functions, but have different origins. E.g. bird wings and
insect wings.
18) Evidence for evolution: Molecular homology. Almost all organisms have the same genetic code.
Taxonomically related species are more genetically similar to each other than to other species, just as
relatives are more genetically similar to each other than to strangers.
19) Evidence of evolution: Biogeography. Species tend to be taxonomically closer to species that are
geographically close, more so than to species that are distant but similar in function. This was what
first suggested to Darwin that neighbor species might be genealogically related.