BIO153H5 Lecture Notes - Lecture 9: Absolute Time And Space, Mutation Rate, Phylogenetic Tree
Document Summary
Show the relative relatedness of organisms on the tree. We can say which common ancestors or which divergences in the species are more ancient and more recent. Branch lengths mean nothing on cladograms (the shape of the tree usually determines branch length) When we want to put a sort of time-scale on the phylogenetic tree. Time scales are represented by the lengths of the branches on the tree. Can go beyond just knowing the relationships between organisms, we can put approximate times on them. Branches need to be scaled accordingly since the branches represent time. To distinguish it from a cladogram, it must have a legend to represent the amount of time a branch signifies. Fossil layers are preserved by time; older fossils are always lower than newer fossils: we can attach absolute time to certain layers we find fossils in, we can assign certain ages to fossils that are found.
