Question

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.

Short answer

(A) The statement “choose the tree that assumes all evolutionary changes are equally probable” is false.

(B) The statement “choose the tree in which the branch points are based on as many shared derived characters as possible” is false.

(C) The statement “choose the tree that represents the fewest evolutionary changes, in either DNA sequences or morphology” is true.

(D) The statement “choose the tree with the fewest branch points” is false.

Step-by-step solution

Phylogenetic tree

The term phylogenetic tree is used for describing the diagrammatic representation of evolutionary trends observed in a biological taxon. It helps in estimating the pattern in which organisms evolved, and it also displays the traits which link the evolved groups with an ancestral group.

Explanation of option ‘(A)’

There are several different types of phylogenetic trees, and each is constructed following a distinct theory. The phylogenetic tree in which all the evolutionary changes are considered to have equal probability refers to the Bayesian type of phylogenetic tree.

Thus, a phylogenetic tree with equal probability to each evolutionary change relates to the Bayesian tree.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The construction of a phylogenetic tree based upon the maximum likelihood principle would have branch points with the highest possible number of shared characters among the descendant groups or organisms.

Thus, this type of phylogenetic tree does not relate to the Parsimony theory of phylogeny.

Therefore, the given statement is false.

Explanation of option ‘(C)’

By the Parsimony theory, the most accurate data is the one with the least amount of changes among the groups. A phylogenetic tree with this principle would have the least possible evolutionary changes in terms of morphological character or genomic sequence.

Thus, the description of the phylogenetic tree in this statement is by the Parsimony concept.

Therefore, the given statement is true.

Explanation of option ‘(D)’

A phylogenetic tree in which the number of branch points is minimum does not reflect the least amount of evolutionary change, so it does not relate with the principle of Parsimony.

Thus, least branching in the phylogenetic tree does not relate with Parsimony.

Therefore, the given statement is false.