Lesson Overview Lesson Overview Genes and Variation Genetic Drift Small populations Definition Genetic bottleneck Founder effect

You are wandering in the tropical rainforest and a giant bright yellow spider hangs dangling in its web in front of you. How would you determine if you had discovered a new species of spider? If it was a new species of spider, what would you name it?

Why do we classify organisms? Communication –Problems with common names Show evolutionary relationship Systematics –Taxonomy

Scientific Names 18 th century –Latin or Greek Binomial nomenclature –Linnaeus –2 word name –Latin –Writing Italics First word – Genus Second word – species Felis catus

Linnaean Classification Hierarch ranking system Taxa (taxon) Kingdom, phylum, class, order, family, genus, species

Problems with Linnaean Classification Species are specifically defined Other groups are subjective New organisms hard to classify Eugenics –Classification of humans –Used to justify discrimination

The following is the Linnaean classification of a moose. Match each with the appropriate category name. Hint: they are in order. alces Alces Cervidae Artiodactyla Mammalia Chordata Animalia

Evolutionary Classification Darwin’s tree of life Phylogeny Group by common ancestors Clades –Definition –Advantage

Cladograms Root Branch –Speciation event Distances Patterns based on –Hypotheses –Molecular data –Embryological development –Fossil record

Creating Cladograms Traits inherited –From common ancestor –Shared by many –Examples Derived characters –Related to speciation event –Show closeness of common ancestor

Reading Cladograms Node Derived characteristics Last clade

Clades and Linnaeus Many overlapping groups –Mammalia Birds very different Both systems are used

DNA and Classification Used sequenced genomes More genes in common –More derived characters in common –More recent common ancestor Shows relationships that can’t be seen –Examples