Classification of Living Things

1. Classification of Living Things UNIT 16

2. Learning Objectives • Living things can be classified based on • structural evidence • embryological evidence • evolutionary evidence • molecular (relatedness of DNA sequence) evidence • Carolus Linnaeus developed the system of taxonomy and binomial nomenclature that is still in use today.

3. Classification • Method of organizing plants and animals into categories based on their appearance and the natural relationships between them • DNA composition is most reliable method for identifying the relationships among organisms • Taxonomy • science of classifying organisms • makes sense of the diversity of life in order to study it better

4. Aristotle • Began arranging organisms according to their physical similarities (previously – useful vs. harmful) • animals: red blood (vertebrates) vs. no red blood • plants: size; herbs, shrubs, trees

5. Benefits of Classification • Helps biologists • keep track of living things • study their differences and similarities • learn how living things are related to one another through evolution (the process by which living things change over generations) • save time and effort

6. Benefits of Classification • Today’s system: • natural system since it represents genuine relationships between organisms • the more closely organisms are related to each other, the more features they have in common • hierarchical – categories are grouped according to size in a series of successively larger ranks

7. Carolus Linnaeus • Swedish physician and naturalist (1707-1778) • “Father of taxonomy” • Established 1st orderly system of classifying living things • Introduced binomial nomenclature • His system was able to impose a much-needed order on the study of life 

8. Classification Groups • Taxons (groups) range in order of specificity • General to specific • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species

9. Classification Examples • Animal Diversity Web