Classification of Living Things

1. Classification of Living Things Chapter 18

2. Classification • Classification – process of arranging organisms/information into groups based on similarities • Allows scientists to organize a lot of information in an easy way. • Taxonomy – the branch of science that deals with grouping organisms. • Taxonomist – scientist who studies classification. • Taxis = Greek = means arrangement • Taxon (taxa) – group of organisms that share specific traits • Compare traits – the more traits alike the more closely related the organisms are

3. Classification cont. • Determined by: • Phylogeny – evolutionary relationships – compare evolution of species • Physical evidence/structural similarities • Internal and external • Ex. Color, size, weight, bones • Fossils • Genetic evidence – compare DNA sequences • More alike the DNA; more closely related • Ex. American vulture and stork are more closely related than American vulture and African vulture • Geographical distribution – where they live

4. Aristotle • Aristotle – came up with the first system of classification • He divided everything into 2 groups • Plants and animals • Grouped animals based on size and where they lived or spent most of their time • Problem – everything in the air or everything in the water was grouped together • Ex. Birds, bats, flying insects

5. Linnaeus • Linnaeus – came up with the system we use today to group and name organisms • Binomial nomenclature – 2 word naming system • 1st word is the genus name – capitalized • 2nd word describes a characteristic – lowercase • Ex. Homo sapien – Homo = genus name ; sapien = wise • Ex. Ursusmaritimus • Together (underlined)= species name

6. Linnaeus cont. • All scientific names are in Latin • 2 reasons why • Dead language – it does not change • Common names can be misleading • Organisms may have different names in different areas • Ex. Cougar, mountain lion = same; skunk, pole cat/ferret, pole cat = same

7. 7 levels of classification • Ex. humans • Kingdom (largest) Animalia • Phylum Chordata • Class Mammalia • Order Primates • Family Hominidae • Genus homo • Species Homo sapiens • Species – only organisms that can mate and produce fertile offspring.

8. Keys • Dichotomous Key – helps identify species • Asks questions about traits to limit possibilities. • Each question has only 2 choices.

9. Keys cont. • Cladistic analysis – identifies and considers only characteristics of organisms that are evolutionary innovations (new) • Derived characters – appear in recent lineage but not in older • Used to make a cladogram– diagram that shows evolutionary relationships • Divisions of diagram occur because of derived traits

10. Domains • Recently added because of newer technology • Largest groups • Based on cell types • 3 groups • Bacteria – prokaryotes – normal environment • Archaea– prokaryotes – extreme environment • Eukarya– eukaryotes

11. Kingdoms • Began with 2 kingdoms – animalia and plantae • Changed to 5 kingdoms – animalia, plantae, fungi, protista, and monera • Monera was split into 2 groups because there were distinct divisions within the group

12. Today’s kingdoms (6) • Bacteria (Eubacteria) • Unicellular • Autotrophic/heterotrophic • We come into contact with them daily. • Archaea(Archaebacteria) • Unicellular • Autotrophic/heterotrophic • Live in oxygen free environments, areas with high salt content, around sulfur springs.

13. Today’s kingdoms cont. • Protista – may be split into more groups in the near future • Most diverse group • Unicellular/multicellular • Autotrophic/heterotrophic • Ex. Amoebas, paramecium, algae, plasmodium (lives in mosquitoes – causes malaria) • Fungi • Most are multicellular – yeast is unicellular • Heterotrophic – decomposers • Cell wall of chitin

14. Today’s kingdoms cont. • Plantae • Multicellular • Autotrophic • Cell wall of cellulose • Do not move • Animalia • Multicellular • Heterotrophic • No cell walls • All move at some point during life