4. Phylogenies - Bio 1 PDF

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Name Evolutionary Relationships & Phylogenies Worksheet (10 pts) Today, we will explore how to evaluate characteristics that organisms share—or don’t share—to create phylogenies, which are hypotheses about organisms’ evolutionary relationships. The characteristics we will consider are both morphological and molecular. Based on differences and similarities between organisms, we will build phylogenies reflecting the most likely relationships between the organisms. PART I: Building a phylogeny as a class Table 1 (below) contains a list of five animal taxa, and five characteristics that have evolved in some, but not all, of these taxa. A “1” in the table indicates that a characteristic is present in a given taxon, and a “0” indicates that it is absent. Four limbs Trout Lizard Duck Toad Rabbit

0 1 1 1 1

Amnion1 0 1 1 0 1

Pre-orbital fenestra2 0 1 1 0 0

Hair

Feathers

0 0 0 0 1

0 0 1 0 0

Use the information in the character table above to label the phylogenetic tree below. Each letter below (near a “tick mark”) denotes a newly evolved character that is shared by species after that point, and each number on the far right side represents a taxon. 1. –––––––––––– 2. –––––––––––– 3. –––––––––––– C. ––––––––––––––

A. ––––––––––––––

4. ––––––––––––

B. ––––––––––––––

5. –––––––––––– D. –––––––––––––– E. ––––––––––––––

1. What is an “outgroup,” and why do we use an outgroup when we construct a phylogenetic tree?

2. Which taxon in Figure 1 would represent an outgroup for all of the other taxa?

3. What is a “shared derived character”?

4. Provide an example of a shared derived character for taxa 3, 4 and 5 in Figure 1.

1 2

The amnion is a fluid-filled membrane around the embryo. Pre-orbital fenestra are holes in the skull located in front of the eyes.

PART II: Building a phylogeny on your own Use the information in the character table below to label the phylogenetic tree below.

species

characters long forelimbs for climbing 0 0 0 1 0 1

A B C D E F

flat face 0 0 0 1 0 0

feathers 0 0 1 0 1 0

talons 0 0 0 0 1 0

hooves 1 0 0 0 0 0

endothermic 1 0 1 1 1 1

fur 1 0 0 1 0 1 1.

2. D. 3.

C. A.

4. E. 5. B. G. F.

6.

PART III: Comparing molecular data For this portion of the worksheet, you will compare amino acid sequences between species to evaluate how closely related they are. Compare the sequences pair-wise and record the number of letter differences in the matrix below. You will not build a phylogeny from these data, but answer the questions that follow. Your instructor will provide you with cutouts of the below sequences to faciliate comparison.

1. Which two species are the most closely related, and how do you know this?

2. Which two species are the most distantly related, and how do you know this? (there may be be more than one pair of species possible for this answer):...