Unit 1d. Systematics & Taxonomy

What is phylogeny?

The evolutionary history of a species or group of species.

What is systematics?

The study of classifying organisms and determining their evolutionary relationships.

What is taxonomy?

The ordered naming and classification of organisms.

Who created binomial nomenclature?

Carolus Linnaeus.

Why is binomial nomenclature important?

It created a uniform naming system.

What are the two parts of a scientific name?

Genus and species epithet.

What does the genus name represent?

A group of closely related species.

What is an epithet?

The unique name for a species within a genus.

Example of a binomial name?

Panthera pardus.

Taxonomic ranks from broad to narrow?

Domain, kingdom, phylum, class, order, family, genus, species.

What is a taxon?

A classification unit at any level.

What is a phylogenetic tree?

A hypothesis of evolutionary relationships.

What does a node represent?

A divergence of two species.

What are sister taxa?

Groups that share an immediate common ancestor.

What is a rooted tree?

A tree showing the most recent common ancestor.

What is a basal taxon?

A lineage that diverged early.

What do phylogenetic trees show?

Patterns of descent.

What do phylogenetic trees NOT show?

Time, amount of change, or phenotypic similarity.

What is homology?

Similarity due to shared ancestry.

What is analogy?

Similarity due to convergent evolution.

What is convergent evolution?

Unrelated species independently evolve similar traits.

How can homology be identified?

Fossils, complexity, and DNA similarity.

What suggests two traits are homologous?

Many shared complex elements or similar DNA sequences.

What is molecular systematics?

Using DNA and molecular data to determine relationships.

Why are computer tools used?

To compare DNA and identify coincidences (homoplasies).

What is cladistics?

Grouping organisms by common descent.

What is a clade?

An ancestor and all its descendants.

What is a monophyletic group?

A valid clade with all descendants.

What is a paraphyletic group?

An ancestor with some, but not all, descendants.

What is a polyphyletic group?

Species with different ancestors.

What is a shared ancestral character?

What is a shared ancestral character?

What is a shared derived character?

A synapomorphy.

What is an outgroup?

A related species that diverged before the ingroup.

What is an ingroup?

The group being studied.

Why compare ingroup to outgroup?

To identify ancestral vs. derived traits.

What can branch length represent?

Genetic change or time.

How is time determined on trees?

Fossil record calibration.

What is maximum parsimony?

The tree with the fewest evolutionary changes.

What is maximum likelihood?

The most likely tree based on DNA change models.

What data supports phylogenetic hypotheses?

Morphological, molecular, and fossil evidence.

What is phylogenetic bracketing?

Inferring ancestor traits from descendants.

What is a molecular clock?

Uses DNA change rates to estimate time.

What are orthologous genes?

Genes separated by speciation.

What are paralogous genes?

Genes separated by duplication.

How are molecular clocks calibrated?

Using fossil-dated branches.

Five-kingdom system?

Monera, Protista, Plantae, Fungi, Animalia.

Current classification system?

Three domains: Bacteria, Archaea, Eukarya.