Question

Explain parsimony as it applies to phylogenetic analysis. What are its assumptions? What are some potential issues with this approach?

Answer 1

Parisomy is nothing but minimizing evolutionary changes. The principle of parsimony is common and basic to all science and tells us to select the simplest scientific explanation that exactly matches with the proof or evidences. In terms of tree-building, that means that, all other things being equal, the best hypothesis is the one that requires the fewest evolutionary changes. It involve two hypothesis about veretebrates using this principle.

1) It require totally six evolutionary changes.

2) It require 7 evolutionary cahnges, a bony skeleton evolving independently, twice. Although both fit the available data, the parsimony principle says that Hypothesis 1 is always better — since it does not hypothesize unnecessarily complicated changes.

Issues:

- It is not relevant to phylogenetic inference because "evolution is not parsimonious.

- The analysis uses the number of character changes on trees to choose the best tree, but it does not require that exactly that many changes, and no more, produced the tree.

-Parsimony can be inconsistent under certain conditions.

2)