Phylogenetic reconstruction know leaves, infer interior nodes similarity: parallel evolution or common ancestor? old: morphology observable similarities new: molecular DNA sequences - nucleotides protein sequences - amino acids [research.amnh.org/programs/genomelab] [gwis2.circ.gwu.edu/~atkins] horse: ...CCTGAACCG... tapir: ...ACTCTACCG... rhino: ...GCTCTACCG... 58