Evolution__3rd_Edition

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Study and review questions
1 Match the kinds of taxonomic groups to the schools
that allow them:
Groups: polyphyletic, monophyletic, paraphyletic.
Schools: evolutionary, cladistic, phenetic.
2 Give (i) a phenetic, (ii) an evolutionary, and (iii) a
cladistic classification of the cow, the lungfish, and the
salmon.
3 Here are measurements of two characters in three
species:
Species 1 Species 2 Species 3
Character a 2 5 2
Character b 2 2 6
Calculate the differences for each character and then
calculate (i) the Euclidean distance, and (ii) the mean
character distance, for the three species pairs. Write the
distances in the following matrix above the diagonal for
calculation (i) and below it for calculation (ii).
Species 1
Species 2
Species 3
4 Here are the pairwise distances (either mean character
distance or Euclidean) among five species:
CHAPTER 16 / Classification and Evolution 491
The subject has been the topic of some interesting historic and philosophical work.
Ritvo (1997) is a general, mainly historic book about classification. Hull (1988) gives an
excellent history of the phenetic and cladistic movements to illustrate his evolutionary
philosophy of science. Beatty (1994) uses the controversy among schools of systematics
to discuss a broader philosophical question: why does evolution have so many controversies
about relative frequencies, or relative significance, in contrast with the
Newtonian paradigm of physics, and some other areas of biology, in which questions
are asked that have a single answer. Sober (1994) contains some other philosophical
chapters.
Species 1 Species 2 Species 3
Species 2 3 4 5
1 1 2.31 4.28 5.27
2 2.31 4.28 5.27
3 2 3
4 1
(a) What is the average distance from species 3 to species
1 and 2? (b) What is the average distance from species 3
to species 4 and 5? (c) Which species is the nearest
neighbor of species 3? (d) What is the phenetic
classification of the five species? (e) What do the
answers to (a–d) suggest about the objectivity of
numerical phenetic taxonomic classification?
5 Supporters of phenetic classification have sometimes
replied to the criticism that it can be ambiguous by saying
that if enough extra characters are measured, the
ambiguity will be resolved. (Thus in Figure 16.4, if further
characters were measured in the species, the average
neighbor and nearest neighbor statistics would come
to agree.) Is this a good reply?
6 (a) Why are biological species classified hierarchically
whereas chemical elements are classified nonhierarchically
in the periodic table? (b) Why does
evolution usually have a divergent branching pattern,
in the form of a tree, rather than some other pattern
(in the form, perhaps, of a row of telegraph poles,
or of erratic zigzags)?