Chapter 18 Classification

Classifying A great diversity of organisms requires a universal way to name them Taxonomy – allows biologists to name and classify organisms in a logical manner - usually based on similarities and differences in appearance Ex: teachers and mechanics vs. biology teachers and auto mechanics

Scientific Naming Carolus Linnaeus – Swedish botanist brought order and devised a system for naming and categorizing organisms Binomial Nomenclature – two word system of scientific name Genus (capitalized and italized) – depicts species association - Specific epithet (lower case italized) – unique species within genus Ex: Ursus arctos Canis familiaris

Hierarchical Classification System of levels that categorize organisms in increasingly more specific groups - Broad at the top to most specific at the bottom - Organisms grouped at the bottom share more common characteristics compared to organisms near the top

Hierarchical Classification Domain - 3 domains (Eukarya, Bacteria, Archaea) Kingdom – 4 kingdoms within Eukarya Phylum Class Order Family Genus Species

Hierarchical Classification

Classification

Evolutionary Classification Phylogeny- grouping organisms into categories that represent lines of evolutionary descent - Refers to the evolutionary history of a species or group of species - Usually constructed from fossil record to describe origin.

Cladograms Cladistic analysis - identifies characteristics that are new and innovative as lineages of a species evolved over time Derived characters – features that appear in recent parts of lineage but not in older members Cladogram – diagram that shows evolutionary relationship among groups of organisms - depicts patterns of shared characteristics - useful in understanding how one lineage branched from another - resembles a family tree

Cladograms

DNA & RNA Organisms of different anatomies can have common traits – How? All organisms use DNA and RNA to pass on information and to control cell growth and development. Genes can show similarities at the molecular level and can help determine classification and evolutionary relationships

Molecular Clocks Molecular clocks - use DNA comparisons to estimate the length of time that 2 species have been evolving independently - relies on mutations to indicate time - DNA sequences of 2 species can show dissimilarity - any degree on difference indicates how long ago the 2 species may have shared a common ancestor

Domains Bacteria - unicellular and prokaryotic - thick, rigid cell walls Kingdom – Eubacteria - diverse organisms that are both free living and deadly parasites - some are photosynthetic - some require oxygen, other are anaerobic Ex: E. coli, Streptococcus

Domains Archaea - unicellular and prokaryotic - extremophiles- live in extreme habitats 1. thermophiles - volcanic hot springs ( hydorthermal vents) 2. Halophiles - Brine pools (Dead sea) 3. Methanogens – black organic mud (sewage treatment)

Domains Eukarya Eukaryotic – unicellular and multicellular 4 Kingdoms 1. Protista – paramecium, green algae 2. Fungi – yeast, mushrooms 3. Plantae – cell walls, chloroplasts 4. Animalia- you