Question

EXERCISE 3A A TAKE-HOME EXAMPLE Complete the following exercise in building a phylogenetic tree at home before the lab period in which you'll explore Exercise 3b. Tou have the following information about four plant species. Plant X is the outgroup. Code the characters as ances tral or derived and then build a phylogeny. There may be more than one possible tree. If you have a character that occurs multiple times (in separate lincages) in the tree, indicate it with an asterisk (*). PLANT REPRODUCTIVE BODY RHIZOMES PLANT HEIGHT absent short seeds seeds TYPE OF LEAVES compound compound compound simple simple TYPE OF STEM smooth smooth hairy hairy hairy present tall seeds present all seeds present short spores present short PLANT CODED CHARACTERS B C # number of character states

Answer 1

To construct a phylogenetic tree for the given plants, code the characters as ancestral or derived, then group the plants based on shared derived traits using maximum parsimony, while noting the outgroup serves as a reference for ancestral states.

Step-by-step explanation:

In order to construct a phylogenetic tree or cladogram for the given plant species, you would need to first code the characters as ancestral or derived. Plant X, being the outgroup, shares the ancestral state for each character with the group. By comparing the reproductive bodies, types of leaves, presence of rhizomes, and plant height, you can determine shared derived characteristics. A cladogram is then built by grouping plants based on shared derived traits, with each branching point, or node, representing a common ancestor with a new derived character.

For example, if rhizomes are a derived trait and only some plants have it, those plants would form a closer group. Height could be another derived character if most plants are short and only one is tall. The presence of seeds versus spores is also a significant derived character to separate angiosperms from non-flowering plants. The tree should be the simplest explanation of evolutionary history with the fewest evolutionary steps, an approach known as maximum parsimony. Note: Without the specific character state data, we cannot draw an accurate tree.