25. Phylogeny

The analytical approach to understanding the diversity and relatedness of both extant and extinct organisms is called __________.

What is the focus of the branch of biology called taxonomy?

The binomial system assigns to each organism a unique name that describes its __________.

The two-part format of the scientific name, referred to as binomial, ensures that __________.

Which of the following is the correct taxonomic name for the African forest elephant?

A taxon __________.

Rabbits and guinea pigs both belong to class Mammalia. This means they must also both belong to __________.

Species A and species B are in the same phylum. Species A and species C, but not species B, are in the same order. From this information you can conclude that __________.

Universal phylogenetic trees built from different genes sometimes give inconsistent results. What basic assumption on which phylogenetic trees are based has probably been violated during the history of life?

By applying a molecular clock, researchers have proposed that the first HIV-1 M invasion into humans occurred in the __________.

What does a branch point in a phylogenetic tree represent?

Which of the following methods to establish phylogenetic relationships among organisms has been developed most recently?

Researchers can use molecular homologies to __________.

Which of the following would be the least useful in determining the relationships among various species?

The idea of using molecules as clocks to time evolutionary events is very attractive, but there are many problems in actually applying the technique. What seems to be the best way to get reliable results?

A phylogenetic tree of bird families constructed by cladistic analysis would be a hypothesis about which of the following?

What is the evolutionary significance of orthologous genes?

What is the evolutionary significance of paralogous genes?

Many researchers who study the kingdom Protista argue that all of these organisms should not be placed in the same kingdom because these organisms could not have evolved from a common ancestor. In other words, they argue that the kingdom Protista is __________.

Using cladistic analysis, a taxonomist wishes to construct a phylogenetic tree showing the relationships among various species of mammals. Which of the following would be the least useful for this purpose?

Which statement below is true about an outgroup?

Unlike a regular phylogenetic tree, phylogenetic trees with branch lengths proportional to time can be used to __________.

Paralogous genes __________.

Which statement below is true of parsimonious trees?

Birds and mammals have a four-chambered heart, but most reptiles have a three-chambered heart. How does this fact affect the construction of phylogenetic trees for these groups?

If you wanted to determine the lineage of plants that have evolved on a relatively young archipelago—approximately 15,000 years old—what type of nucleic acid should you compare?

Fill in this concept map about systematics a. b. c. d. e. f. g

How are hypotheses about the evolutionary relationships among living organisms tested?

If you were using cladistics to build a phylogenetic tree of cats, which would be the best choice for an outgroup? a. kangaroo b. leopard c. domestic cat d. iguana

Which of the following could provide the best data for determining the phylogeny of very closely related species? a. the fossil record b. their morphological differences and similarities c. a comparison of nucleotide sequences in homologous genes and mitochondrial DNA d. a comparison of their ribosomal DNA sequences

Phylogenies are created based on the principle that all species descending from a recent common ancestor                   . a. should be identical; b. should share characteristics that evolved in that ancestor; c. should be found as fossils; d. should have identical DNA sequences; e. should be no more similar than species that are less closely related

The traditional tree of life (shown above) presents the three domains as distinct, monophyletic lineages. However, other hypotheses propose different views on the relationships among the Archaea, Bacteria, and Eukarya. In particular, the two-domain hypothesis—or eocyte hypothesis—is emerging as a well-supported alternative to the three-domain hypothesis. The eocyte hypothesis, illustrated below, suggests that eukaryotes evolved from eocytes (also known as the Crenarchaeota—a major lineage of the Archaea). Resolving the relationships among these ancient lineages is difficult, but it has profound implications on our understanding of the origin of eukaryotic cells. Why are Archaea considered a monophyletic group according to the three-domain hypothesis? a. Because this group includes all organisms except eukaryotes. b. Because this group includes an ancestral population and all of its descendants. c. Because all members of this group lack membrane-bound organelles. d. Because this group evolved after the origin of bacteria.

Which are more likely to be closely related: two species with similar appearance but divergent gene sequences or two species with different appearances but nearly identical genes? Explain.

Explain why changes in the regulation of developmental genes may have played such a large role in the evolution of new forms.

What types of molecular comparisons are used to determine the very early branching of the tree of life? Explain.

A paleontologist compares fossils from three dinosaurs and Archaeopteryx, the earliest-known bird. The following table shows the distribution of characters for each species, where 1 means that the character is present and 0 means it is not. The outgroup (not shown in the table) had none of the characters. Arrange these species on the phylogenetic tree below and indicate the derived character that defines each branch point.