This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Certain assumptions are necessary in phylogenetic classifications. A taxon should be monophyletic (all of the members of the taxon should be descendants of a single common ancestor). The characters or features used to identify the taxa must be homologous, which means that they must have a common origin, but not necessarily a common function. For example, all the parts of a flower —petals, sepals, stamens, and carpels—originate in the same way as leaves from primordia in meristems. Although they now have different functions in the flower (they're not photosynthetic), some sepals and petals structurally resemble leaves. Leaves and the parts of the flower are homologous structures. Some features that look alike do not have a common origin and are said to be analogous. An example of analogous structures is the prickles on two groups of succulent desert plants, the cacti...
View Full Document
This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.
- Fall '08