1. Alberts, Bray, Hopkins, Johnson Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Professor: Dr. Barjis Room: P313 Phone: (718)2605285 Email: ibarjis@citytech.cuny.edu General Biology Sylvia S Mader Lecture 1: Chapter 20 Classification of Living Things

2. Outline Taxonomy – Binomial System Species Identification Classification Categories Phylogenetic Trees – Tracing Phylogeny Cladistic Systematics Phenetic Systematics Classification Systems

3. Taxonomy (arrange” and “law ) Taxonomy is the branch of biology dealing with the naming, identification, and classification of organisms. Taxonomy uses a binomial system developed by Linnaeus. Taxonomy uses reproductive isolation as the basis of definition of a species. taxonomists use following categories of classification: domain, kingdom, phylum, class, order, family, genus and species

5. Classifying Organisms

6. Binomial System In mid-eighteenth century, Linnaeus developed the binomial system of naming species. – First word is genus. – Second word (specific epithet) refers to one species within genus.  A species is designated by the full binomial name (Genus species).  Genus can be used to refer to group of related species.

7. Species Identification – Character traits are used to distinguish one group from another are:  structural features.  chromosomal.  molecular features. – A primitive character is one that is present in the common ancestor and all members of a group – Early biologists referred to animals as ‘‘simple’’ and ‘‘advanced,’’ but now it is more accurate to use the terms: ‘‘primitive’’ and ‘‘derived,’’

8. Classification Categories Modern taxonomists use the following classification: – Species – Genus – Family – Order – Class – Phylum – Kingdom – Domain

9. Classification Categories The higher the category, the more inclusive. Organisms in the same domain have general characteristics in common.

10. Phylogenetic (tribe” and “producing”) Trees Systematics is the study of the diversity of organisms at all levels of organization. One goal of systematics is to determine phylogeny or evolutionary history of organisms by gathering – Fossil Record - – Homology – – Molecular Data  Protein comparison  RNA and DNA comparison  DNA hybridization  Molecular Clock

11. Phylogenetic (tribe” and “producing”) Trees Phylogenetic tree is a diagram that: – Indicates common ancestors and lines of descent. – Explain similarities and differences among modern living groups. – Reflect patterns of shared and unique sections of DNA among groups of animals.

12. Classification and Phylogeny

13. Tracing Phylogeny Fossil Record – Fossil record is incomplete; thus, it is often hard to tell to which group a fossil is related. Homology is character similarity stemming from a common ancestor. – Convergent evolution is similarities in structure in distantly related groups due to adaptation to the environment – Parallel evolution similarities in structure in related group that cannot be traced to a common ancestor.

14. Tracing Phylogeny Molecular data – Protein comparison- distinction between two organisms are determined by sequencing of amino acids – DNA and RNA comparison, – DNA hybridization, – Molecular clock

15. Systematics Today There are three main schools of systematics today – Cladistic – Phenetics – Traditional

16. Cladistic Systematics Uses shared derived characters to classify organisms and arrange taxa (like phylogenetic tree) called cladogram.

17. Phenetic Systematics In phenetic systematics, species are classified according to the number of their similarities. – Ignores the possibility that some of the shared characteristics are probably the result of convergence or parallelism.

18. Traditional Systematics Traditional systematics mainly use anatomical data to classify organisms and construct phylogenetic trees based on evolutionary principles. – Stress both common ancestry and degree of structural difference among divergent groups.  Not strict in making sure all taxa are monophyletic.

19. Five-Kingdom System The evolution of organisms in the five kingdoms is most accurately described as Monera to Protists, from Protists separately to Fungi, Plants, and Animals

20. Three-Domain System Molecular data suggest there are two groups of prokaryotes, the bacteria and archaea, that are so different, they should be assigned to separate domains.

21. Three-Domain System – Archaea live in extreme environments.  Methanogens  Halophiles  Thermocidophiles

22. Three-Domain System Domain Eukarya contains unicellular and multicellular organisms whose cells have a membrane-bound nucleus. – Sexual reproduction common. – Contains 4 kingdoms:  Protista  Animals  Fungi  Plants

23. Review Taxonomy – Binomial System Species Identification Classification Categories Phylogenetic Trees – Tracing Phylogeny Cladistic Systematics Phenetic Systematics Classification Systems