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\% - Regarding these sequence homology data, the principle of maximum parsimony would be applicable in ________.

The following phylogeny shows six living species (a-f) and five ancestral (now extinct) species (#1-5). If the phylogeny had been developed on the basis of similarities in bone structure, which of the following predictions would you make in terms of the structure of a particular enzyme?

Based on this tree, which statement is correct?

Which of the following is (are) problematic when the goal is to construct phylogenies that accurately reflect evolutionary history?

Which of the following trees, if any, depicts the same relationship among species as shown above?

Phylogenetic trees constructed from evidence from molecular systematics are based on similarities in ________.

The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma. These species have apparently undergone speciation from ancestral stock since the last glacial retreat about 10,000 years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?

Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores". The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. A crucial photosynthetic gene of the cyanobacterium that gave rise to the chromatophore is called psaE. This gene is present in the nuclear genome of the cercozoan, but is not in the genome of the chromatophore. This is evidence of ________.

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labelled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted. Cyanobacteria were once called "blue-green algae" because they are photosynthetic. According to the phylogeny shown, the cyanobacteria are more closely related to gram-positive bacteria than to ________.

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.) - Which of the following changes would a modern systematist be most likely to make after learning of the results of the rRNA analyses?

The legless condition that is observed in several groups of extant reptiles is the result of ________.

Which of the following statements best describes the rationale for applying the principle of maximum parsimony in constructing phylogenetic trees?

The term convergent evolution is most applicable to which of the following features?

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Horizontal lines indicate instances of gene or genome transfer. A possible phylogenetic tree for the three domains of life. - Which of these processes can be included among those responsible for the horizontal components of the figure?

Given that phylogenies are based on shared derived characteristics, which of the following traits is useful in generating a phylogeny of species W, X, Y, and Z? Species W Species X Species Y Species Z Trait 1 Trait 2 Trait 3