ch.12

monophyletic group

(also, clade) organisms that share a single ancestor

3. What is a phylogeny a description of? a. mutations b. DNA c. evolutionary history d. organisms on Earth

C

6. Which best describes the relationship between chimpanzees and humans? a. chimpanzees evolved from humans b. humans evolved from chimpanzees c. chimpanzees and humans evolved from a common ancestor d. chimpanzees and humans belong to the same species

C

8. Which statement about analogies is correct? a. They occur only as errors. b. They are synonymous with homologous traits. c. They are derived by response to similar environmental pressures. d. They are a form of mutation.

C

12. A monophyletic group is a ________. a. phylogenetic tree b. shared derived trait c. character state d. clade

D

5. Which statement about the taxonomic classification system is correct? a. There are more domains than kingdoms. b. Kingdoms are the top category of classification. c. A phylum may be represented in more than one kingdom. d. Species are the most specific category of classification

D

13. How does a phylogenetic tree indicate major evolutionary events within a lineage?

The phylogenetic tree shows the order in which evolutionary events took place and in what order certain characteristics and organisms evolved in relation to others. It does not generally indicate time durations.

analogous structure

a character found in two taxa that looks similar because of convergent evolution, not because of descent from a common ancestor

shared ancestral character

a character on a phylogenetic branch that is shared by a particular clade

shared derived character

a character on a phylogenetic tree that is shared only by a certain clade of organisms

clade

a group of taxa with the same set of shared derived characters, including an ancestral species and all its descendants

maximum parsimony

applying the simplest, most obvious way with the least number of steps

rooted

describing a phylogenetic tree with a single ancestral lineage to which all organisms represented in the diagram relate

phylogenetic tree

diagram used to reflect the evolutionary relationships between organisms or groups of organisms

phylogeny

evolutionary history and relationship of an organism or group of organisms

species

the most specific category of classification

taxonomy

the science of classifying organisms

systematics

the science of determining the evolutionary relationships of organisms

sister taxa

two lineages that diverged from the same branch point

domain

the highest level category in the classification system and that includes all taxonomic classifications below it; it is the most inclusive taxon

molecular systematics

the methods of using molecular evidence to identify phylogenetic relationships

binomial nomenclature

a system of two-part scientific names for an organism, which includes genus and species names

1. Figure 12.3 In what levels are cats and dogs considered to be part of the same group?

1 Figure 12.3 Cats and dogs are part of the same group at five levels: both are in the domain Eukarya, the kingdom Animalia, the phylum Chordata, the class Mammalia, and the order Carnivora.

9. What kind of trait is important to cladistics? a. shared derived traits b. shared ancestral traits c. analogous traits d. parsimonious traits

A

10. What is true about organisms that are a part of the same clade? a. They all share the same basic characteristics. b. They evolved from a shared ancestor. c. They all are on the same tree. d. They have identical phylogenies.

B

11. Which assumption of cladistics is stated incorrectly? a. Living things are related by descent from a common ancestor. b. Speciation can produce one, two, or three new species. c. Traits change from one state to another. d. The polarity of a character state change can be determined.

B

4. What do scientists in the field of systematics accomplish? a. discover new fossil sites b. organize and classify organisms c. name new species d. communicate between field biologists

B

7. Which best describes a branch point in a phylogenetic tree? a. a hypothesis b. new lineage c. hybridization d. a mating

B

15. Dolphins and fish have similar body shapes. Is this feature more likely a homologous or analogous trait?

Dolphins are mammals and fish are not, which means that their evolutionary paths (phylogenies) are quite separate. Dolphins probably adapted to have a similar body plan after returning to an aquatic lifestyle, and therefore this trait is probably analogous.

2. Figure 12.8 Which animals in this figure belong to a clade that includes animals with hair? Which evolved first: hair or the amniotic egg?

Rabbits and humans belong in the clade that includes animals with hair. The amniotic egg evolved before hair because the Amniota clade is larger than the clade that encompasses animals with hair.

17. How does a biologist determine the polarity of a character change?

The biologist looks at the state of the character in an outgroup, an organism that is outside the clade for which the phylogeny is being developed. The polarity of the character change is from the state of the character in the outgroup to the second state.

16. Describe maximum parsimony

a character-based approach that infers a phylogenetic tree by minimizing the total number of evolutionary steps required to explain a given set of data assigned on the leaves.

cladistics

a method used to organize homologous traits to describe phylogenies using common descendent as the primary criterion used to classify organisms

branch point

a point on a phylogenetic tree where a single lineage splits to distinct new ones

taxon

a single level in the taxonomic classification system

14. List the different levels of the taxonomic classification system.

kingdom, phylum or division, class, order, family, genus, species

order

the category in the taxonomic classification system that falls within class and includes families

kingdom

the category in the taxonomic classification system that falls within domain and includes phyla

genus

the category in the taxonomic classification system that falls within family and includes species; the first part of the scientific name

phylum

the category in the taxonomic classification system that falls within kingdom and includes classes

family

the category in the taxonomic classification system that falls within order and includes genera

class

the category in the taxonomic classification system that falls within phylum and includes orders