Cladistics

Cladistics The process of grouping living organisms Allows us to see evolutionary relationships based on similar features called homologous structures These characteristics show us how organisms have evolved from a common ancestor

Prediction of Characteristics Characteristics that are shared by organisms within a group would be expected to be found in other species that are closely related

Cladograms Evolutionary relationships are shown with branching tree diagrams

Species placed in order that they descended from a common ancestor

DNA as Evidence Since organisms use DNA as their genetic material, similarities and differences in DNA can be used to show common ancestry Example: Species 1 - AAT GGC CCT TCC Species 2 - GAT GCC CCT TCC Species 3 - GAT GCC ACT TCG

Clade: is a group of organisms evolved from a common ancestor including all species alive today, common ancestral species, and extinct species that evolved from that common ancestor

Derived characteristics are traits shared by clade members Determine how species are arranged on a cladogram More closely related species share more derived characteristics

Nodes represent the most recent common ancestor of a clade.

Cladograms video http://www.youtube.com/watch?v=ouZ9zEkxGWg