CLaSSIFICaTION
Reading: Read Taxonomic Characters and Phylogenetic Reconstruction and Theories of Taxonomy on pages 344-351; stop when you get to Major Divisions of Life.
Before Class: Complete the reading assignment
and answer the questions below. If you would like to see some example problems using
cladistics, this site should help -- http://www.txwesleyan.edu/biology/cladedata.html#3
In Class: Be able to define a
species. Be prepared to use information about the characters of organisms to produce
a cladogram.
Key Words: phylogeny, characters, homology, analogy, outgroup comparison, clads, synapomorphy, nested hierarchy, cladogram, phylogenetic tree, comparative morphology, comparative biochemistry, monophyly, paraphyly, polyphyly, adaptive zone, grade, biological species, evolutionary species, phylogenetic species
Questions:
1. Which of the following would best test the hypothesis that two populations of very similar squirrels, isolated from contact with each other by a canyon, are different species?
a. Examine many individuals to determine whether there are any
morphological differences between the two
populations.
b. Examine DNA from many individuals to assess genetic
differentces
between the two populations.
c. Examine the environments in the two locations to determine
whether the
same selection pressures would be operating.
d. Capture live individuals from bothe populations and determine
whether
they can crossbreed and produce viable, fertile
offspring
e. Look for hybrids between the two populations in the wild.
2. An ensyme was purified gfrom eight organisms; the amino acid sequence was determined from the same region of each enzyme. The region that was studied was 45 amino acids long. The organism labelled Mx162 had a certain amino acid sequence in its enzyme. Each of the other seven organisms was scored for the number of amino acids it had in common with Mx162. For example, if Mx162 has a certain amino acid at position 31, then an organism that has the same amino acid at position 31 is scored one point. Use the data below to indicate similarity of organisms, prepare a cladogram to express the relationships among the organisms.
Number of Amino Acids
Organism in Common with Mx162
Copia
6
EcA
26
EcB
26
Gypsy
12
HIV
15
MtP
14
Typ912
8
