Bio Chap 26 Set 3

What does phylogeny describe?

The evolutionary history of a species or group of related species

What is the main goal of systematics?

To classify organisms and determine their evolutionary relationships

What does binomial nomenclature provide?

A two-part scientific name for each species

Why is the first part of a scientific name capitalized?

Because it represents the genus

How should the full species name be formatted?

Italicized

What hierarchical classification system did Linnaeus develop?

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

What is the term for any group at a given level in the hierarchy?

Taxon

Why aren't broader taxa comparable across lineages?

Different lineages show different levels of diversity

What diagram represents evolutionary relationships?

A phylogenetic tree

What does a branch point in a phylogenetic tree represent?

A divergence of two evolutionary lineages from a common ancestor

What is a sister taxon?

Two groups that share an immediate common ancestor

What does a rooted tree include?

A branch representing the most recent common ancestor of all taxa

What is a basal taxon?

A lineage that diverges early in the history of a group

Do phylogenetic trees show when species evolved?

No

Do phylogenetic trees show how much change occurred?

No

What is an example of a practical application of phylogenies?

Determining if whale meat was from a legally harvested species

What types of data are used to infer phylogenies?

Morphological, genetic, and biochemical data

What is homology?

Similarity due to shared ancestry

What is analogy?

Similarity due to convergent evolution

What is convergent evolution?

Independent evolution of similar traits in different lineages

What is an example of convergent evolution?

Similarities between the Australian mole and the African golden mole

How can complex structures help determine homology?

The more similarity in complex structures, the more likely they evolved from a common ancestor

What is the first step after sequencing DNA?

Aligning comparable sequences from different species

How do closely related species' DNA sequences compare?

They differ at only a few sites

How do distantly related species' DNA sequences compare?

They differ at many sites and may vary in length

What are insertions and deletions?

Mutations that shift the reading frame of a DNA sequence

How do computer programs assist in DNA sequence comparison?

They align sequences and account for insertions and deletions

What is the goal of cladistics?

To group organisms based on common ancestry

What is a clade?

A group of species including an ancestor and all its descendants

What is a monophyletic group?

A clade consisting of an ancestor and all its descendants

What is a paraphyletic group?

An ancestral species and some, but not all, of its descendants

What is a polyphyletic group?

A group including distantly related species but not their most recent common ancestor

What is a shared ancestral character?

A character that originated in an ancestor of the taxon

What is a shared derived character?

An evolutionary novelty unique to a particular clade

What is an outgroup?

A species or group closely related to but not part of the group being studied

What is an ingroup?

The group of species being studied

What is the principle of maximum parsimony?

The simplest tree with the least number of evolutionary changes is most likely

What is the principle of maximum likelihood?

The most likely tree is the one consistent with known DNA change probabilities

What is phylogenetic bracketing used for?

Predicting shared traits in common ancestors

What feature shared by birds and crocodiles suggests that dinosaurs also had it?

Nest building and brooding

What type of DNA evolves slowly and is useful for detecting ancient relationships?

Ribosomal RNA (rRNA)

What type of DNA evolves quickly and is useful for studying recent evolutionary events?

Mitochondrial DNA

What does gene duplication provide?

New genes for evolutionary change

What are gene families?

Groups of related genes within a genome from repeated duplications

What are orthologous genes?

Genes in different species resulting from a speciation event

What are paralogous genes?

Genes within a species resulting from duplication

Why are orthologous genes useful for studying speciation?

They reflect the history of speciation events

Example of orthologous genes?

Cytochrome c in humans and dogs

What is a molecular clock?

A method for estimating the time of evolutionary change

What is the assumption of a molecular clock?

The number of genetic changes is proportional to time since divergence

Why do some genes evolve at different rates?

Different selective pressures and mutation rates

What are selectively neutral mutations?

Mutations that have no effect on fitness

Why do selectively neutral mutations make molecular clocks more regular?

They accumulate at a constant rate

Why do critical genes evolve slowly?

Harmful mutations are selected against

Why do less critical genes evolve faster?

Neutral mutations are more common

What virus was dated using a molecular clock?

HIV

What is the most widespread strain of HIV in humans?

HIV-1 M

When did HIV-1 M likely spread to humans?

Around 1910–1930

How many domains are recognized in the tree of life?

Three (Bacteria, Archaea, Eukarya)

What mechanism transfers genes between organisms?

Horizontal gene transfer

What are mechanisms of horizontal gene transfer?

Plasmids, transposable elements, viral infection

How does horizontal gene transfer affect the tree of life?

It creates a network rather than a branching tree