Question

please explain

Use the following information to answer the next two questions. 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.) Giardia intestinalis Subgroups A-D B C Giardia muris D Giardia microti According to the phylogenetic tree in the figure above, the G. intestinalis group, and its common ancestors, constitutes a group. a b) monophyletic polyphyletic paraphyletic c) By examining the phylogenetic tree diagrammed in the figure above, what conclusion can you draw about the species G. microti? It evolved before G. intestinalis. It is more closely related to G. muris than to G. intestinalis. It should not be labeled a species distinct from G. intestinalis. It is part of a monophyletic group that also includes G. intestinalis.

Answer 1

Question 5:
Answer: (C) Paraphyletic
In the above phylogenic tree, falls in to paraphyletic group since it includes most recent common ancestors but not descendants unlike Monophyletic group.
In polyphyletic group common most recent ancestors are not included.

Question 6:
Answer: (D) It is part of monophyletic group that also includes G.intestinalis
G. intestinalis is a species complex and G. microti is a member of this complex.