BIOL 117 Lecture Notes - Lecture 27: Phylogenetic Tree, Polytomy, Thumb
Document Summary
Phylogeny: pattern component of evolutionary bio, dynamic and updated as new info becomes available. Branches can be rotated at the nodes, so looking off by just the ordering of the labels is not the correct way to approach a phylogenetic tree. Best to look at nodes and branch points. Only derived traits are informative about relatedness: unique traits are helpful for differentiating species, not relating them. Sometimes individual species may seem very similar to other species, but keep in mind about convergent evolution, leading species that are not really that closely related, to have similar characteristics. Ancestral traits = unmodi ed form the ancestor. Derived traits = modi ed from the ancestral state of the characteristics. Advanced vs. primitive is a nono, because suggests progressive evolution! All organisms are mosaics of ancestral traits and derived traits: ex. humans. Derived = opposable thumbs, speech ability, larger brains.
