Classification and The Tree of Life Unit 1: Chap 25-26

Classification/Taxonomy Carolus Linnaeus Swedish botanist and anatomist Taxonomy: ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences. Not based on evolutionary relationships but resemblance

Binomial nomenclature Common names (monkey, fish) refer to more than 1 species. A 2 part scientific name (binomial) was created by Linnaeus 1. Genus: to which the species belongs 2. Specific epithet: unique for each species within the genus Ex: Leopard = Panthera pardus

Hierarchical Classification Species are placed into groups belonging to more comprehensive groups.

Classification+evolutionary history = Phylogeny Phylogenic trees: branching diagram that represents a hypothesis about evolutionary relationships. Constructed from a series of dichotomies, 2 way branch points; divergence of 2 species from a common ancestor. • It is a hypothesis. •

Phylogeny + Shared Characteristics Cladogram: diagram depicting patterns of shared characteristics among species. Clade: within a tree, a group of species that includes an ancestral species and all its descendants Cladistics: analysis of how species are grouped

Cladogram

Cladistics: 1. Monophyletic: single tribe - Ancestral species and ALL descendants 2. Paraphyletic: result of lack of information on clade members - Ancestral species and SOME descendants 3. Polyphyletic: several species that lack a common ancestor

Homologous VS Analogous Structures in different species that are similar because of a common ancestry. Similarity between 2 species due to convergent evolution rather than to descent from a common ancestor with the same trait.

Phylograms Length of a branch reflects the number of changes in a specific DNA sequence in that lineage. Different lengths but all lineages have survived for the same number of years. Indicates that a given gene evolves at slightly different rates in the different lineages.

Ultrametric Trees Same branching as a phylogram but all branches are of equal length. Branches reflect measurements of geological time.

History of Taxonomic Systems 2 Kingdom: plant (fungi, bacteria) and animal (protozoans) 5 Kingdoms: Monera, Protista, Plantae, Fungi, Animalia (Eukaryotes/Prokaryotes) Finally: 3 Domain System: Bacteria, Archaea, Eukarya (Plants, Animals, Fungi) - level higher than Kingdom

3 Domain System