ap bio chapter 20: Concept 20.1: Phylogenies show evolutionary relationships

What is taxonomy?

The ordered division and naming of organisms.

What do phylogenies show?

Evolutionary relationships between organisms.

How are taxonomy and phylogeny related?

Phylogenies help organize and name organisms in taxonomy.

Who developed the system of taxonomy still used today?

Carolus Linnaeus in the 18th century.

What are the two key features of Linnaeus’s system?

Two-part species names (binomial) and hierarchical classification.

What is binomial nomenclature?

A two-part naming system: genus and species.

What is the correct format for writing a scientific name?

Genus is capitalized, species is lowercase, and both are italicized (e.g., Homo sapiens).

What does the specific epithet refer to?

It is unique for each species within a genus, but it does not name the species alone.

What are the taxonomic ranks from most specific to broadest?

Species, Genus, Family, Order, Class, Phylum, Kingdom, Domain.

What is a taxon?

A taxonomic group at any level of the hierarchy.

Are broader taxa always equally diverse?

No, different groups can have different amounts of genetic diversity.What do systematists use to show evolutionary relationships?

What do systematists use to show evolutionary relationships?

Phylogenetic trees.

What are sister taxa?

Groups that share an immediate common ancestor.

How does Linnaean classification differ from phylogeny?

Linnaean classification is based on appearance; phylogeny is based on evolutionary evidence.

What does each branch point on a phylogenetic tree represent?

The divergence of two taxa from a common ancestor.

What is a rooted tree?

A phylogenetic tree with a branch representing the most recent common ancestor of all taxa.

What is a basal taxon?

The first lineage to diverge early from the common ancestor in a tree.

What is a polytomy?

A branch from which more than two groups emerge; shows uncertainty.

What does the ancestral lineage represent?

The common ancestor of all organisms in the phylogenetic tree.

What do phylogenetic trees show?

Patterns of descent, not physical similarities or timing of evolution.

Can you tell how much change occurred in a lineage based on branch length?

No, branch length does not represent amount of change or time.

Do sister taxa evolve from each other?

No, they share a common ancestor but do not evolve directly from one another.

How can DNA sequences be used in phylogeny?

They can help infer evolutionary relationships and identify species.

Why is DNA evidence important in phylogenies?

Similar DNA means similar genes and traits, showing common ancestry.

What is the main purpose of a phylogenetic tree?

To represent a hypothesis about evolutionary relationships.