Classification and phylogeny

1. Classification and phylogeny By:Changting Luo

2. What is Classification • Classification in biology is arranging living organisms into groups.

3. Reasons for classification • Species identification:It is easier to find out to which species an organism belongs with organisms classified rather than forming a disorganized catalogue. • Predictive value:If several members of a group have a characteristic,another species in this group will probably also have this characteristic. • Evolutionary links:Species that are in the same group probably share characteristic because they have evolved from a common ancestor,so the classification of groups can be used to predict how they evolved.

4. Natural classification is base on homologous structures-structures that have a common evolutionary origin,even if their function is different Artificial classification is base on analogous structure-structures with a common function,but a different evolutionary origin. Natural classification VSArtificial classification

5. Natural classification VSArtificial classification

6. Biochemistry and common ancestry • Similarities between living organisms in their biochemistry: • All use Dna as their genetic material • All use the same universal genetic code, with only a few insignificant variations. • All use the same 20 amino acid in their proteins. • All use left and not right handed amino acids • Result:All organisms havd evolved from a ancestor.

7. Phylogeny and biochemistry Tracing evolutionary links and origins is called phylogeny. Phylogenetics using the biochemistry like structure of a protein(dna)to figure out the relationship between the organisms.

8. Example • Nymphalidae phylogeny