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Concept Check Questions
Chapter 25 – Phylogeny and Systematics
25.1
Phylogenies are based on common ancestries inferred from fossil, morphological, and molecular
evidence
1. Suggest whether each of the following pairs of structures more likely represents an analogy or a
homology, and explain your reasoning: (a) a porcupine’s quills and a cactus’s spines; (b) a cat’s
paw and a human’s hand; (c) an owl’s wing and a hornet’s wing.
2. Which of the following are more likely to be closely related: two species with similar appearance
but very different gene sequences, or two species with very different appearance but nearly
identical genes? Explain.
25.2
Phylogenetic systematics connects classification with evolutionary history
1. Which levels of the classification below do humans share with a leopard?
domain
kingdom
phylum
class
order
family
genus
species
Eukarya
Animalia
Chordata
Mammalia
Carnivora
Felidae
Panthera
pardus
2. What does the phylogenic tree in Figure 25.9 (orange book) or 25.8 (green book) indicate about
the evolutionary relationships of the leopard, striped skunk, and wolf?
25.3
Phylogenetic systematic informs the construction of phylogenetic trees based on shared
characteristics
1. To distinguish a particular clade of mammals within the larger clade that corresponds to class
Mammalia, would hair be a useful character? Why or why not?
2. Why might the most parsimonious tree not necessarily be the most accurate in representing
evolutionary relationships among a particular group of species?
25.4
Much of an organism’s evolutionary history is documented in its genome
1. Explain how comparisons between proteins of two species can yield data bout their evolutionary
relationship.
2. Contrast orthologous genes with paralogous genes.
25.5
Molecular clocks help track evolutionary time
1. What is a molecular clock? What assumption underlies the use of a molecular clock?
2. Explain how numerous base changes could occur in DNA, yet have no effect on an organism’s
fitness.