Exam 5: Inferring Phylogeny

If the two sister species on the phylogenetic tree in the figure below differ from the other two species in a single character state (e.g., dark fur, whereas the other taxa have light fur), where would the evolutionary change(s) have occurred? Indicate change(s) by placing an arrow-or arrows-on the tree. Be sure to label the presumed ancestral state, and label the arrow(s) as a "loss" or "gain."

One of the principle ways to understand the large-scale effects of natural selection is to compare traits across groups of species. However, there are many ways researchers can be misled by applying the comparative method without properly accounting for phylogeny-shared evolutionary history. Using the five-species tree shown, list and describe or label all possible independent contrasts.

The figure shown is a phylogeny created with DNA sequence data and has high bootstrap support values. The tree also includes observed phenotypes (in varying shades of gray) for the five taxa. The character states are indicated by "B" or "b," "G" or "g," and "P" or "p." Evaluate the hypothetical phylogenetic tree using a parsimony approach. For which of the following taxa were there the FEWEST state changes if the inferred ancestral state was "bGP"?

Bootstrap resampling

Describe how fossils of Tiktaalik roseae discovered by Ted Daeschler and his colleagues in 2005 help biologists "fill the phylogenetic gap" between fish and tetrapods.

The figure shows six pairwise genetic distances among four species (A, B, C, and D). Which of the following would be grouped as sister taxa on a tree constructed using distance measurements? A B