Exam 26: Phylogeny and the Tree of Life

The question refers to the following table, which compares the percent sequence homology of four different parts (two introns and two exons) of a gene that is found in five different eukaryotic species. Each part is numbered to indicate its distance from the promoter (for example, Intron I is the one closest to the promoter). The data reported for species A were obtained by comparing DNA from one member of species A to another member of species A. % Sequence Homology Species Intron I Exon I Intron VI Exon V A 100\% 100\% 100\% 100\% B 98\% 99\% 82\% 96\% C 98\% 99\% 89\% 96\% D 99\% 99\% 92\% 97\% E 98\% 99\% 80\% 94\% -Based on the tabular data, and assuming that time advances vertically, which phylogenetic tree is the most likely depiction of the evolutionary relationships among these five species?

Humans, chimpanzees, gorillas, and orangutans are members of a clade called the "great apes", which shared a common ancestor about 15 million years ago. Gibbons and siamangs comprise a clade called the "lesser apes". Tree-branch lengths indicate elapsed time. Assuming chimps and gorillas are humans' closest relatives, removing humans from the great ape clade and placing them in a different clade has the effect of making the phylogenetic tree of the great apes ________.

Imagine that you discovered the following information: Feature Bacteria Archaea Eukaryotes RNA polymerase small, simple complex complex Introns absent present present Antibiotic sensitivity sensitive insensitive insensitive Membrane Lipids C chains unbranched C chains branched C chains branched These data would support which of the following conclusions?

Concerning growth in genome size over evolutionary time, which of these is least associated with the others?

If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent discrepancy would be ________.

Which of the following would be most useful in creating a phylogenetic tree of a taxon?

The phylogenetic tree shown ________.

The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are best described as ________.

Based on the tree below, which statement is not correct?

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

-Which tree depicts the microsporidians as a sister group of the ascomycetes?

Which of the following items is most likely to form a simple linear relationship with the number of gene-duplication events, when placed as the label on the vertical axis of the following graph?

Your professor wants you to construct a phylogenetic tree of orchids. She gives you tissue from seven orchid species and one lily. What is the most likely reason she gave you the lily?

There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then hair is a shared ________.

Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis) that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics. In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species. (T. Monis, et al. 1999. Molecular systematics of the parasitic protozoan Giardia intestinalis. Mol. Biol. Evol. 16[9]:1135-44.) - According to the phylogenetic tree in the figure above, G. intestinalis constitutes a ________ group.

- If the figure is an accurate depiction of relatedness, then which of the following should be an accurate statement?

In a comparison of birds and mammals, the condition of having four limbs is

Eukaryotes that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their ________.

Applying the principle of parsimony to the trait "ability to fly", which of the two phylogenetic trees is better?

A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most valid for discerning the evolutionary relatedness of ________.