BILD 3 Lecture Notes - Lecture 13: Phylogenetic Tree, Polyphyly, Paraphyly
Document Summary
Phylogenetic trees: clade: group of taxa and their most recent common ancestors. Node and everything descended from it: same as monophyletic group, can be defined at any level on the tree, polyphyletic group: contains taxa with different recent ancestors, paraphyletic group: contains common ancestor and some but not all descendants. How to build a phylogenetic tree: example with birds, bats, and monkeys: measure as many characters as possible: morphological, behavioral, genetic, etc. by creating a character matrix. Bird: fur, wings, bony tail, live birth, separated digits, nursing, teeth. What makes characters similar: convergent evolution due to similar environments (selection, analogous, can also get convergent evolution due to random events, common when comparing dna sequences, ancestral dna sequence tgctatt changes to tgctttt. Then revert to tgctatt later, causing it to look more related to ancestor: to resolve the tree, look at more of the sequence (more characters, homologies: similarity due to inheritance of traits from a common ancestor.
