To apply parsimony to constructing a phylogenetic tree, a. choose the tree that assumes all evolutionary changes are equally probable. b. choose the tree in which the branch points are based on as many shared derived characters as possible. c. choose the tree that represents the fewest evolutionary changes, in either DNA sequences or morphology. d. choose the tree with the fewest branch points.

Key Concepts

Parsimony in Phylogenetics

Parsimony is a principle used in phylogenetics to select the simplest explanation or tree that requires the least number of evolutionary changes. This approach assumes that the most likely evolutionary pathway is the one that minimizes the total number of changes, whether in DNA sequences or morphological traits. By favoring simpler trees, parsimony helps avoid overfitting the data with unnecessary complexity.

Shared Derived Characters

Shared derived characters, or synapomorphies, are traits that are present in a group of organisms but absent in their distant ancestors. These characters are crucial for constructing phylogenetic trees as they provide evidence of common ancestry and help define evolutionary relationships. The more shared derived characters two species have, the more closely related they are likely to be.

Phylogenetic Tree Construction

Constructing a phylogenetic tree involves organizing species based on their evolutionary relationships, often using data from morphology or genetic sequences. The tree is a visual representation of these relationships, with branch points indicating common ancestors. The goal is to accurately reflect the evolutionary history of the organisms, which can be achieved through methods like parsimony, maximum likelihood, or Bayesian inference.