Phylogenetic diversity
Species richness of a clade. So are looking for a way to measure taxonomic uniqueness as well as just numbers. Two basic approaches:
- Measure divergence in terms of characters. Faith, 1992. Idea that uniqueness is correlated with the possession of many characters. Are looking to maximize diversity for number of characters or branch lengths. These include methods of looking at genetic or morphological distances between taxa. Such branch length estimates are often interpreted in terms of relative lengths of time. EXAMPLE:
- Measure divergence in terms of hierarchy--based on branching patterns rather than branch lengths. Do this by comparisons of cladistic divergence between species, counting the nodes.