Chapter 18

Question 1

adaptive radiation

Answer 1

the rapid evolution of many species from a single species that has been introduced to a new environment

Question 2

allopatric speciation

Answer 2

speciation that involves the geographic separation of populations. Most speciation involves geographic separation, followed by the development of intrinsic isolating mechanisms in the separated populations

Question 3

analogy

Answer 3

a structure found in different organisms that is similar in function and appearance but is not the result of shared ancestry. Analogies must be distinguished from homologies to get a true picture of evolutionary relationships

Question 4

ancestral character

Answer 4

a character that existed in the common ancestor of a group of organisms. Cladistics distinguishes ancestral from derived characters and uses these characters to determine evolutionary relationships

Question 5

binomial nomenclature

Answer 5

the system of naming species that uses two names (genus and species) for each species. This system helps identify groupings among living things

Question 6

biological species concept

Answer 6

A definition of species that relies on the breeding behavior of populations in nature. It defines species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups

Question 7

cladistics

Answer 7

the branch of systematics that uses shared derived characters to determine the order of branching events in speciation and therefore which species are most closely related. Cladistics is concerned only with evolutionary relationships, not classification

Question 8

cladogram

Answer 8

the evolutionary tree constructed using the cladistic system

Question 9

convergent evolution

Answer 9

evolution that occurs when similar environmental influences shape two separate evolutionary lines in similar ways

Question 10

derived character

Answer 10

a character unique to groupings of organisms (taxa) descended from a common ancestor

Question 11

extrinsic isolating mechanism

Answer 11

a barrier to interbreeding of populations that is not an inherent characteristic of the organisms in the populations. Geographic barriers such as rivers are extrinsic isolating mechanisms

Question 12

homology

Answer 12

a structure that is shared in different organisms owing to inheritance from a common ancestor. Homologies are used to help decipher evolutionary relationships

Question 13

what are homologies used for?

Answer 13

to help decipher evolutionary relationships

Question 14

intrinsic isolating mechanism

Answer 14

a difference in anatomy, physiology, or behavior that prevents interbreeding between individuals of the same species or of closely related species. One or more intrinsic isolating mechanisms must develop for two populations of the same species to evolve into separate species

Question 15

phylogeny

Answer 15

a hypothesis about the evolutionary relationships of a group of organisms

Question 16

polyploidy

Answer 16

a form of sympatric speciation in which one or more sets of chromosomes are added to the genome of an organism. Human beings cannot survive in a polyploid state, but many plants flourish in it. Polyploidy is a means by which speciation can occur (most often in plants) in a single generation

Question 17

reproductive isolating mechanisms

Answer 17

any factor that, in nature, prevents interbreeding between individuals of the same or closely related species

Question 18

speciation

Answer 18

the development of new species through evolution

Question 19

sympatric speciation

Answer 19

a type of speciation that occurs in the absence of the geographic separation of populations. Polyploidy is a special form of sympatric speciation

Question 20

systematics

Answer 20

the field of biology dealing with the diversity and relatedness of organisms. Systematists study the evolutionary history of groups of organisms

Question 21

taxon

Answer 21

any of the taxonomic categories used in the classification of the Earth’s organisms, both living and extinct. In order of increasing inclusiveness, these categories are species, genus, family, order, class, phylum, kingdom, and domain

Question 22

Name the taxonomic categories

Answer 22

species, genus, family, order, class, phylum, kingdom, and domain