lesson overview lesson overview genes and variation genetic drift small populations definition...

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

• 18th 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