Question

PROBLEM SET 2 Name: Instructor: Date: Section 1. First, separate the OG (outgroup) and Flowers 9, 13, 14, 17, 18, and 20 from the stack of flowers and lay them in a row. Then, set the unused stack of flowers aside. Note: The letters and numbers are the names of the flowers and do not give any indication of the order in which the flowers will be placed on your phylogenetic tree. 2 For the following characters, write the character state designations given to you by your instructor Leaf Margin: Corolla (petal) Fusion: Fruit Type: Leaf Tip Shape: Flower Orientation: e Tuberous Roots: Number of Flowers per Plant: 3. Determine and record in Table 7.2 the character states per character for the five flowers Use the blank rows for additional characters that you might use to later resolve (i.e., abil ity to separate flowers with a synapomorphy or autapomorphy) the tree. flowers. TABLE 7.2 Character and character state designations for five hypothetical herbaceous Character States Character outgroup (OG) 9 13 14 1718 20 Leaf Margin Corolla Fusion Fruit Type Leaf Tip Shape Flower Orientation Tuberous Roots Number of Flowers per Plant BI0112 Ecology and Evolution Lab69

Answer 1

In a phylogenetic tree, the species of interest are shown at the tips of the branches of the tree. The branches are connected to each other in the way in which we think they evolved from a common ancestor through a series of divergence events.

When we build phylogenetic trees, the characteristics that arise during the evolution of a group and that differ from those of the ancestor of the group are called derived characters. An ancestral character is what we think was present in the common ancestor of the species of interest, in our case, the traits of the external group. So, this way we could assume that its features represent the ancestral form of each feature. A derivative character is that which we think arose somewhere in the lineage that descends from that ancestor.

Now, we can start to build our tree by grouping the organisms according to their shared derived characteristics. A good place to start is to see what character is shared by the greatest number of organisms, in our case, the leaf margin: all organisms except the species of the outer group have dentate leaf. Next, we do the same for all others traits.

Character	OG	9	13	14	17	18	20
Leaf margin	Entire	Dentate	Dentate	Dentate	Dentate	Dentate	Dentate
Corolla fusion	No	No	Yes	Yes	Yes	Yes	No
Fruit type	1.1	2.1	2.2	2.2	2.3	2.3	3.1
Leaf type shape	Elliptic	Ovate	Ovate	Ovate	Lanceolate	Lanceolate	Ovate
Flower orientation	Vertical	Vertical	Vertical	Vertical	Diagonal	Diagonal	Vertical
Tuberous root	No	No	Yes	Yes	No	No	No
Number of flowers	One	Two	One	One	One	One	One

The most parsimonious phylogenetic tree that combines all the derived characteristics is the following:

OG 20 13 14 18 17 2 Flòwers etous Diagonal Flower Frut 3.1 Lanceolate leaf Corolla fusion Fruit 2.1 Dentate Leaf