chapter 23

Question 1

phylogeny

Answer 1

the history of descent with modification and the accumulation of change over time

Question 2

taxonomy

Answer 2

the branch of science concerned with classification, especially of organisms

Question 3

node

Answer 3

in phylogenetic trees, the point where a branch splits, representing the common ancestor from which the descendant species diverged

Question 4

phylogenetic tree

Answer 4

a diagrammed hypothesis about the evolutionary history, or phylogeny, of a species

Question 5

sister groups

Answer 5

groups that are more closely related to each other than either of them is to any other group

Question 6

taxon

Answer 6

all the species in a taxonomic entity such as family or genus

Question 7

monophyletic

Answer 7

describes groupings in which all members share a single common ancestor not shared with any other species or group of species

Question 8

genus

Answer 8

a group of closely related species

Question 9

family

Answer 9

a group of closely related genera

Question 10

order

Answer 10

a group of closely related families

Question 11

class

Answer 11

in the Linnaean system of classification, a group of closely related orders

Question 12

phylum

Answer 12

a group of closely related classes, defined by having one of a number of distinctive body plans

Question 13

kingdom

Answer 13

a group of closely related phyla

Question 14

domain

Answer 14

one of the three largest limbs of the tree of life; Eukarya, Bacteria, or Archaea

Question 15

character

Answer 15

in the discipline systematics, an anatomical, physiological, or molecular feature of an organism that varies among closely related species

Question 16

character state

Answer 16

the observed condition of a character, such as presence or absence of lungs or arrangement of petals

Question 17

homology (homologous)

Answer 17

describes characters that are similar in different species because of descent from a common ancestor

Question 18

analogy (analogous)

Answer 18

describes similar characters that evolved independently in different organisms as a result of adaptation to similar environments

Question 19

synapomorphy

Answer 19

a shared derived character

Question 20

parsimony

Answer 20

choosing the simplest hypothesis to account for a given set of observations

Question 21

ingroup

Answer 21

a social group to which a person psychologically identifies as being a member

Question 22

outgroup

Answer 22

a social group with which an individual does not identify

Question 23

trace fossils

Answer 23

a track or trail, such as a dinosaur track or the feeding trails of snails and trilobites, left by animals as it moves about or burrows into sediments

Question 24

molecular fossils

Answer 24

sterols, bacterial lipids, and some pigment molecules, which are relatively resistant to decomposition, that accumulate in sedimentary rocks and documents organisms that rarely form conventional fossils

Question 25

Burgess Shale

Answer 25

a sedimentary rock formation in British Columbia, Canada, that preserves a remarkable sampling of marine life during the initial diversification of animals

Question 26

geologic timescale

Answer 26

the series of time divisions that mark Earth’s long history

Question 27

mass extinction

Answer 27

a catastrophic drop in recorded diversity, which has occurred five or more times in the past 541 million years