1. Modern Classification Objectives:- Know what a species is Understand the binomial naming system Compare and contrast the five-kingdom and three-domain classification system.

2. What is a species?

3. Species the smallest basic taxonomic unit used to define living organisms a group of individuals – with similar key features but show variation – they are usually able to interbreed and produce fertile offspring BUT: this definition does not take into account simple organisms that reproduce asexually

4. Same species? 64 6263 Equus ferus Canis lupus Equus ferus Equus africanus

5. Ligers?! Hobbs (male) from Sierra Safari Zoo Hobbs, with a mane like a lion, the long body of a tiger, and more mass than either, is a striking animal. He exhibits traits of both parents, his mother was a Bengal tigress and his father an African lion. He roars like a lion and swims like a tiger. http://www.sierrasafarizoo.com/animals/liger.htm

6. Breeding a male donkey to a female horse results in a mule Breeding a male horse to a female donkey produces a hinny. http://www.imh.org/imh/bw/mule.html

7. Binomial naming Animals are referred to by their genus and species. For example: Hippopotamus Hippopotamus amphibius Giraffe Giraffa camelopardalis Lion Panthera leo

8. Family Felidae Genus Panthera Genus Leopardus Species leo Species tigris Species pardalis Binomial System Nearest common ancestor of the lion and the tiger Nearest common ancestor of the Ocelot, the lion and the tiger

9. Binomial nomenclature Conventions in writing scientific names – Made up of genus and species name – Genus name starts with a capital letter – Species name all in small letters – If writing by hand: underline – If typing: use italics

10. Binomial nomenclature of wild flowers Common nameScientific name Red cloverTrifolium pratense Herb robertGeranium robertianum Cut-leaved cranesbillGeranium dissectum Meadow thistleCirsium dissectum 1.In addition to writing the name in italics, what other convention is used for scientific names? 2.What genus does red clover belong to? 3.What is the species name of meadow thistle? 4.Which two plants are most closely related: a)Meadow thistle and cut-leaved cranesbill b)Herb robert and cut-leaved cranesbill?

11. Advances in Classifying Organisms

12. Recall: Five Kingdom System PlantaeFungiAnimalia Protoctista Prokaryotae Eukaryotic cells Multicellular Eukaryotic cells Unicellular Prokaryotes

13. However some animals are unrelated but have evolved similar adaptations to their environment due to convergent evolution So would it be more accurate to DNA type them?

14. Organisms and the DNA percentage they have in common with humans! Cat: 90% Cow: 80% Mouse: 75% Fruit Fly: 60% Banana: 50%90%80%75% 60%50%

15. The table shows the percentage difference between the coding DNA of humans, chimpanzees, gorillas and orangutans 1.Which two animals appear to be most closely related? 2.Which two are most distantly related? 3.Explain why these data cannot provide us with firm guidelines about whether humans and chimpanzees should be placed in the same genus. % difference in DNA Humans and chimpanzees 0.87 Humans and gorillas 1.04 Humans and orangutans 2.18 Chimpanzees and gorillas 0.99 Chimpanzees and orangutans 2.14 Gorillas and orangutans 2.25

16. Answers 1.Humans and chimpanzees 2.Gorillas and orangutans

17. Answer to Q3 There is no clear definition of what a genus is and what criteria should be used for placing different species in the same genus. If we use DNA sequences in this way, there is no agreement about whether it is more valid to look at every part of the DNA in a species or whether we should concentrate on particular areas, such as the coding We can also question whether sheer numbers of differences in DNA bases can justifiably be used to determine classification, or whether we should take into account their effects as well.

18. Prokaryotes Protoctists FungiPlantsAnimals BacteriaArchaeaEukaryotae Evidence from molecular studies of RNA has now led to another reassessment of the classification system, with Woese proposing the 3 Domain System in 1990. 5 Kingdom System 3 Domain System

19. The Three Domain system All prokaryotes look the same but they have different metabolic and biochemical pathways Taxonomists decided to split the kingdoms creating 3 domains: Bacteria Archaea Eukaryotes

21. The domains are larger than the kingdoms

22. The 3 domain system of classification groups organisms mainly based on differences in rRNA structure organisms classified into 3 domains and 6 kingdoms The domains are Archaea, Bacteria, and Eukarya. The kingdoms are Archaebacteria (ancient bacteria), Eubacteria (true bacteria), Protoctista, Fungi, Plantae, and Animalia. The Archaea and Bacteria domains contain prokaryotic organisms that do not have a membrane bound nucleus.ArchaeaBacteriaprokaryotic organismsnucleus Eubacteria are classified under the Bacteria domain and archaebacteria are classified as Archaeans. The Eukarya domain includes eukaryotes (organisms with membrane bound nucleus). This domain is further subdivided into the kingdoms Protoctista, Fungi, Plantae, and Animalia.

25. Why was reclassification necessary? EubacteriaArchaeaEukaryotae Different cell membrane structure Similar cell membrane structure Different flagella structure Similar flagella structure Different form of RNA polymerase Same form of RNA polymerase No proteins bound to genetic materials Proteins bound to genetic material Different mechanism for DNA replication and Building RNA. Similar mechanisms for DNA replication and building RNA

27. Discuss whether the five-kingdom and the three-domain classifications are completely different from one another, or if they could possibly be used together.

28. Answer The three domains are the highest taxa. It is possible to have the domain Eukarya, with the kingdoms Protoctista, Fungi, Plantae and Animalia as subdivisions of it. However, we cannot keep the kingdom Prokaryota, as that is now split at a higher level.

29. Other points for classifying organisms together

30. Cytochrome C This is a protein used in respiration in all living organisms (except chemosynthetic organisms). It is made from a sequence of amino acids. which varies slightly from species to species. If the sequence is very similar between two species, we can infer that they are quite closely related. We could also compare DNA or RNA sequences between organisms as opposed to amino acid sequences.