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Ch. 25
1. Aristotle created a great chain of being, called ‘Scala Naturae’. Describe what the
great chain of being is and how it works.
Species were organized into a fixed sequence or increasing size and
complexity. This is a linear scale starting with inanimate matter and ending
with humans at the top. More complexity is equivalent to being higher up.
2. What was Darwin’s theory, and why was it revolutionary
Descent with modification-change over time produced modern, modified
species from ancestral species.
Not a linear patter, but rather a progressive pattern based on variation and
time.
It can be observed and tested!
3. What is a vestigial trait, and what hypothesis does it refute?
A reduced or incompletely developed structure in an organism that has no
(or reduced function)
Plato-species are created perfect. Vestigial traits are evidence that the
characteristics of species have changed over time.
4. Homology is a similarity that exists in species descended from a common
ancestor.
a. Give an example of a genetic homology:
A similarity in the DNA/RNA/amino acid sequences.
b. Developmental homology:
A similarity in the embryo. Phylum chordate-pharyngeal slits.
c. Structural homology:
Similarity in adult morphology. Limb bones.
Bonus question: why are whales the coolest?
Closely related to hippos by DNA comparisons
Vestigial hip and limb bones found in some
Water  land  water?
Biggest organism by volume and weight
Theorists:
Plato, Aristotle, Lamarck, Darwin