BIOL 191A: Ch.21 Pre-lecture

What does a branch point in a cladogram represent?

A character difference between two species

What is a taxon?

A group of related organisms at any hierarchical level

What is a phylogenetic tree?

A hypothesis depicting evolutionary relationships among species

When comparing the DNA sequences of several species to chimpanzees, researchers discover a range of differences. Which of the following species diverged most recently from a common ancestor shared with chimpanzees?

A species with 1% difference in sequences compared to chimpanzees

What is a monophyletic group?

A taxon that is a clade

From the cladogram, which of the following characteristic is shared derived character of the salmon, lizard, and rabbit?

Hinged jaw

What has to occur for horizontal gene transfer to elicit evolutionary change in multicellular Eukarya?

The genetic material must be retained by the gametes or gamete-producing cells.

Three living species X, Y, and Z share a common ancestor T. Species X has 1% difference in DNA sequences compared to T, species Y has 2% difference in DNA sequences compared to T, and species Z has 3% difference in DNA sequences compared to T. Based on these results, which of these three species diverged most recently from their common ancestor T?

X

A(n) ______ structure is one that evolved independently in two evolutionary lineages and was not found in their most recent common ancestor.

analogous

Convergent evolution can result in:

analogous structures

An analogous structure found in two species is a structure that:

arose independently in the evolutionary lineages of the two species

Which of the following species in this phylogenetic tree are extant?

at the very very top J F

A(n) ______ in a cladogram represents a difference in a character between two related species.

branch point

Molecular clocks and the fossil record

can be used to determine the timing of evolutionary change.

In this phylogenetic tree, species B and E represent a (next to eachother)

clade

The circled species in this phylogenetic tree represent a monophyletic group, or

clade

In which of the following taxonomic levels would the number of traits shared by all members of the taxon be the fewest?

class (higher up than the others)

______________ relationships are used to construct taxonomic groups.

evolutionary

Phylogenetic trees are diagrams used to represent hypotheses about the

evolutionary relationships among organisms

The circled species in this phylogenetic tree are (B and E) at the tips

extinct

homology

refers to similarities among various species that occur because the species are derived from a common ancestor.

Considering the character of a hinged jaw, the species that make up the ingroup in this phylogenetic tree are

salmon, lizard, rabbit

The two factors that researchers think are barriers to horizontal gene transfer in eukaryotes are:

sexual reproduction multicellularity

The groups of the taxonomic hierarchy are called _______.

taxa

Due to horizontal gene transfer, some bacteria have acquired:

the ability to metabolize an organic molecule in the environment antibiotic resistance

A cladogram with __________ is the most likely.

the fewest number of character changes

Among a set of proposed cladograms the preferred is that one that has

the fewest number of character changes.

The scientific name of every organism consists of two components:

the genus name, which is listed first, and the specific epithet, which is listed second

Divergence of humans and chimpanzees from a common ancestor is an example of _______ evolution.

vertical

What term describes the evolutionary history of a species or a group of species?

Phylogeny

For any given organism, which of its taxonomic groups contains the most members? (higher up)

Phylum

Place the taxonomic levels listed below in order of decreasing numbers of species that they contain. Start with the taxon having the most species on top, and end with the taxon that contains the fewest species at the bottom.

Phylum Class Order Family Genus Species

With respect to vertebrae, what species in this phylogenetic tree belong to the ingroup?

Salmon Lizard Rabbit Lamprey

How are character states used in cladistics?

Similarities and differences in character states are useful for studying evolutionary relationships.

How did the field of taxonomy change due to the birth of systematics?

Taxonomic groups began to be based on evolutionary relationships.

How do analogous traits relate to convergent evolution?

Traits that arose from convergent evolution are analogous.

True or false: Analysis of genetic sequences can be used to infer the timing of evolutionary change.

True

Organisms can receive genetic material from other organisms that are not their parents via a process called

horizontal gene transfer.

Phylogenetic tree

is a hypothesis depicting evolutionary relationships based on morphologic and genetic homology.

Taxonomy

is the science of describing, naming, and classifying organisms

Systematics

is the study of biological diversity and the evolutionary relationships among organisms.

In this phylogenetic tree for chordates, the most recently diverged species that can be used as an outgroup is the

lancelet

With respect to vertebrae, which species in this phylogenetic tree is the outgroup?

lancelet

A _______ group is a taxon that is a clade.

monophyletic

The shared ancestral character of the lamprey, salmon, lizard, and rabbit in the cladogram is

notochord

Biologists can construct a _____________ to represent the evolutionary history of a species or a group of species.

phylogeny

Consider the following cladogram. What is a shared derived trait for salmon, lizard, and rabbit?

Hinged jaw

The eukaryotic domain is divided by taxonomists into

7 supergroups

What is the minimum number of character states that allows a trait to be used to establish evolutionary relationships

2

What is the most recent common ancestor of plants D and E?

B

What are the three domains of life?

Bacteria Archaea Eukarya

All forms of life are grouped into three domains:

Bacteria, Archaea, Eukarya

Which of the following is an example of vertical evolution?

Divergence of humans and chimpanzees from a common ancestor

Which domain of life is subdivided into seven groups called supergroups?

Eukarya

What do phylogenetic trees portray?

Evolutionary relationships

What is used to classify organisms into a hierarchy in modern taxonomy?

Evolutionary relationships

True or false: The transfer of genes from ancestors to their descendants is the only relevant evolutionary mechanism.

False

How can a researcher determine the timing of evolutionary changes?

Fossil record

Which of the following groups would contain the most shared traits?

Genus

What two taxonomic designations make up a species name?

Genus and species

What two plants are most distantly related?

H and G (farthest away)

Which of the following is a benefit of using the SSU rRNA gene for evolutionary comparisons?

It has been sequenced in thousands of species.

The SSU rRNA gene has been commonly used in evolutionary studies. What are the reasons why?

It is found in all living organisms. It is a large gene and has a large amount of sequence information. It can be used to study distant evolutionary relationships.

Which of the following is an example of horizontal gene transfer?

The transfer of a gene conferring resistance to an antibiotic from one bacterial species to another

Which of the following statements is true for all of the species that come after a branch point in a cladogram?

They will share at least one shared derived character.

After a branch on the cladogram, each species will share a set of ______ characters that are not found in species below the branch point.

derived

Based on this cladogram, having two front flippers is a shared ________ character for species D and E.

derived

In order to time past evolutionary events, researchers can analyze ____________ sequences to establish an evolutionary "clock."

genetic

Structures that are derived from the same body part in a common ancestor are called

homologous features

Examples of ______ include the arm of a human, the wing of a bat, and the flipper of a whale.

homologous structures

Similarities between species that occur because the species are derived from a common ancestor are referred to as ______.

homologous traits

In addition to descent from a common ancestor, __________ gene transfer, which involves the transfer of genes between different species, has played an important role in evolution.

horizontal

The process in which an organism incorporates genetic material from another organism without being the offspring of that organism is called

horizontal gene transfer