BIO 182: Chapter 21

_ is the science of describing, naming, and classifying organisms. _ is the study of biological diversity and the evolutionary relationships among organisms.

taxonomy; systematics

Which of the following elements are required in a taxonomic hierarchy?

* Successive levels
* Nested groups

What is a taxon?

A group of related organisms at any hierarchical level

In the current system used for taxonomy, all organisms are placed into three categories of life. Each of these categories is called a(n)

domain

In the current taxonomic system, all forms of life are grouped into _ domains.

three

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

Taxonomic groups began to be based on evolutionary relationships.

What are the three domains of life?

* Bacteria
* Eukarya
* Archaea

What term describes a system of organization that involves successive levels?

Hierarchy

The eukaryotic domain is divided by taxonomists into _ supergroups.

7

The groups of the taxonomic hierarchy are called _______.

taxa

In the taxonomic hierarchy, what is the name of the taxon that falls between domain and kingdom?

Supergroup

What is a domain?

A taxonomic level above kingdom

Which of the five historical kingdoms is not classified in the domain Eukarya?

Monera

Into how many domains of life are living things grouped?

3

Members of the domain _ usually have linear chromosomes.

Eukarya

All forms of life are grouped into three domains: _, _, and _.

bacteria; archaea; eukarya

Compared to members of the domains Archaea and Bacteria, members of the domain Eukarya: 

have intracellular compartmentalization

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

Eukarya

Order these major taxonomic categories into an increasingly inclusive hierarchy.

Species, genus, family, order, class, phylum, kingdom, domain

The taxon that lies between domain and kingdom in the domain Eukarya, but not in Bacteria or Archaea, is known as the

supergroup

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

Genus

The domain Eukarya consists of members of which four historical kingdoms?

Protista, Fungi, Plantae, and Animalia

For any given organism, which of its taxonomic groups contains the most members?

Phylum

Which domain includes organisms that typically have linear chromosomes?

Eukarya

With very few exceptions, cellular compartmentalization occurs only in the domain _.

Eukarya

The scientific name of every organism consists of two components: the _ name, which is listed first, and the _, which is listed second.

genus; specific epithet

Below the domain and the supergroup is the kingdom, which is divided into taxa called _.

phylum

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

Class

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

Phylogeny

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.

1. phylum
2. class
3. order
4. family
5. genus
6. species

What do phylogenetic trees portray?

Evolutionary relationships

 the scientific name of the gray wolf is _.

canis lupus

A(n) _ is a diagram that describes the evolutionary relationships among various species.

phylogenetic tree

What two taxonomic designations make up a species name?

Genus and species

A(n) _ is a hypothesis depicting evolutionary relationships based on morphologic and genetic homology.

phylogenetic tree

The vertical axis of a phylogenetic tree represents _.

time

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

phylogenic tree

The evolutionary process in which a single species evolves into a different species is called _.

anagenesis

Phylogenetic trees are diagrams used to represent hypotheses about the _ relationships among organisms.

evolutionary

The formation of new species occurs in two ways. Which ones?

* Cladogenesis
* Anagenesis

Which of the following provides a description of the evolutionary relationships between different species?

Phylogenetic tree

The divergence of one species into two or more species is called _.

cladogenesis

What is a phylogenetic tree?

A hypothesis depicting evolutionary relationships among species

In a phylogenetic tree, what do the nodes illustrate?

Divergence of one species into two or more species

In a phylogenetic tree, time is represented by a(n):

vertical arrow

What is the purpose of systematics?

To organize groups into clades

What is the process through which a single species evolves into a new species?

Anagenesis

The two processes by which new species can be formed are _ and _.

cladogenesis; anagenesis

What is cladogenesis?

The divergence of one species into two or more species

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

homology

The nodes of a phylogenetic tree represent _______, the divergence of one species into two or more species.

cladogenesis

One of the goals of modern systematics is the creation of taxonomic groups that reflect ______ relationships among species.

evolutionary

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

homologous

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

homologous traits

If genes in two separate organisms are considered homologous:

they must have been derived from the same ancestral gene

Before the advent of molecular sequencing, _______ data was used to establish evolutionary relationships.

morphological

In modern systematics, species are organized into monophyletic groups based on their evolutionary relationships; that is, they are organized into

clades

What information in the fossil record allows researchers to chart the evolutionary relationships of extinct species?

Morphological features

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

homologous structures

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

arose independently in the evolutionary lineages of the two species

Genes in different species are _ if they are derived from the same ancestral gene.

homologous

How do analogous traits relate to convergent evolution?

Traits that arose from convergent evolution are analogous.

What kind of data were used to create the earliest phylogenetic trees?

Morphological data

What is molecular systematics?

The use of genetic data to study genetic homologies and to propose phylogenetic trees

What feature of DNA sequences makes them useful for phylogenetic analysis?

The sequences change over many generations due to mutation.

The fossil record is a source of ______ data that can be used to study the evolutionary lineages of species.

morphological

How do independent mutations arise between species?

After they diverge, each species acquires independent mutations in homologous genes.

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

What term describes the classification of species based on evolutionary relationships?

Cladistics

The analysis of genetic data, such as DNA and amino acid sequences, to identify and study genetic homologies and to propose phylogenetic trees is called _ systematics.

molecular

What is a character state?

One of two or more variations of a character

DNA sequences change over many generations due to the accumulation of _.

mutations

Which of the following would be considered cladistics?

Evaluating possible phylogenetic trees to determine evolutionary relationships

Why do homologous genes differ between species?

They accumulate different independent mutations.

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

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

arose independently in the evolutionary lineages of the two species

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

branch point

A variant of a homologous trait used for cladistic analysis is known as a(n):

character state

How does cladistics evaluate phylogenetic trees?

By looking at characteristics that are shared or not shared among species

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.

What does a branch point in a cladogram represent?

A character difference between two species

In a cladogram, a(n) _ is the group whose evolutionary relationships we wish to understand.

ingroup

In cladistics, a(n) _______ is a species or group of species that is assumed to have diverged before the species whose evolutionary relationships are being studied.

outgroup

A character state shared by the outgroup and the ingroup is:

primitive

The principle of _ states that the preferred hypothesis is the one that is the simplest for all the characters and their states.

parsimony

What is an ingroup?

A group of species whose evolutionary relationships are being studied

Which of the following statements are correct about an outgroup?

* It diverged prior to all of the species in the ingroup.
* It lacks at least one shared derived character found in the ingroup.

Researchers are only interested in the pathways of evolutionary change and not the actual timing of the events.

False

A character that is shared by the outgroup and the ingroup is derived.

False

The preferred hypothesis is the one that is the simplest for all the characters and their states. This is referred to as the 

principle of parsimony.

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

In a cladogram, a(n) _ is the group whose evolutionary relationships we wish to understand.

ingroup

What types of genes are useful for studying distant evolutionary relationships?

Genes that mutate slowly.

What is vertical evolution?

Changes in groups of species due to descent from a common ancestor

Why are systematists interested in molecular clocks?

They are interested in the timing of evolutionary change as well as the likely pathways.

Which of the following is an example of vertical evolution?

Divergence of humans and chimpanzees from a common ancestor

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

What has the traditional view of evolution been since Darwin?

Vertical evolution

The gene that encodes SSU rRNA is an example of a ______ gene that is used to evaluate ______ evolutionary relationships.

slowly changing; distant