Biology Unit 7 Notes: Phylogenetics & Cladograms

(1) Phylogenetics The study of the evolutionary relationships between different organisms. Based Off of: Genetics Anatomy and Physiology Dating of Fossil Evidence The study comes from Charles Darwin’s discovery that organisms have changed over time, with slight modifications, from their ancestors.

(2) Cladistic Analysis Identifies characteristics between organisms which were significant in their evolution from their ancestors. Cladogram: The diagram used to display the analysis and compare organisms over time. Derived Characters: Traits seen on cladograms, which show up in recently evolved organisms (but not in their ancestors). Shows that these “newer” organisms had to adapt to their changing environments.

(3) Parts of a Cladogram: Looks like an upside down concept map, or looks like a tree. Very Bottom = Common Ancestor = The organism from which all others evolved. Very Top = Most recently evolved organisms. Moving Upward = More recent evolutions Moving Downward = Going back in time The CLOSER organisms’ branches are  The MORE SIMILAR their derived characters are. The FURTHER away organisms’ branches are  The MORE DIFFERENT their characteristics are.

(4) Constructing a Cladogram: Organism Derived Character BACKBONE LEGS HAIR Earthworm Absent Trout Present Lizard Human Identify the organism in the table that is least closely related to the others. Identify organisms which are more closely related. Draw and Label your cladogram.