Chapter 26

Question 1

Species

Answer 1

the fundamental category of taxonomic classification, ranking below a genus or subgenus.

Question 2

Speciation

Answer 2

the formation of new and distinct species in the course of evolution.

Question 3

Genetic Isolation

Answer 3

The lack of interbreeding or little genetic mixing between organisms of the same species

Question 4

Genetic divergence

Answer 4

the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time.

Question 5

Biological species concept

Answer 5

defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance. Although appearance is helpful in identifying species, it does not define species.

Question 6

Reproductive isolation

Answer 6

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

Question 7

Prezygotic isolation

Answer 7

spatial, behavioral, mechanical and temporal isolation. Keeping two organisms from mating

Question 8

Postzygotic isolation

Answer 8

A type of reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce.

Question 9

Temporal isolation

Answer 9

‘isolated in time’, so this is a mechanism that prevents species from mating because they breed at different times. These differences can be time of day, season, or even different years.

Question 10

Habitat isolation

Answer 10

species live in the same area but different habitats. ( Encounter each other rarely, never technically not geographically isolated, Ex. water vs land snakes)

Question 11

Behavioral Isolation

Answer 11

An isolating mechanism in which two allopatric species do not mate because of differences in courtship behavior. Also known as ethological isolation.

Question 12

Gametic barrier

Answer 12

A species is a group of organisms that can interbreed or exchange genes. A hybrid is the result of interspecies mating. Prezygotic barriers prevent fertilization from taking place. Gametic isolation is a type of prezygotic barrier where the gametes (egg and sperm) come into contact, but no fertilization takes place.

Question 13

Mechanical isolation

Answer 13

This evolutionary mechanism is when different species are isolated by their mechanics - the genitalia of the males and females may have different sizes, shapes, or locations. While mating may still be attempted, evolution has led to genitals that are extremely complex and unique to each species, and this can prevent breeding among even closely related species.

Question 14

Hybrid viability

Answer 14

When two organisms of different species breed and their offspring is able to reproduce fertile offspring as well.

Question 15

Hybrid sterility

Answer 15

When two organisms of different species breed and there offspring is not fertile or able to reproduce.

Question 16

Morphospecies

Answer 16

A group of biological organisms that differs in some morphological respect from all other groups.

Question 17

Phylogenetic species concept

Answer 17

the smallest set of organisms that share an ancestor and can be distinguished from other such sets. Under this definition, a ring species is a single species that encompasses a lot of phenotypic variation.

Question 18

Monophyletic group

Answer 18

taxon (group of organisms) which forms a clade, meaning that it consists of an ancestral species and all its descendants. The term is synonymous with the uncommon term holophyly.

Question 19

Clade

Answer 19

a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor.

Question 20

Lineage

Answer 20

term used to describe cells with a common ancestry, that is developing from the same type of identifiable immature cell. The descendants of one individual; his entire lineage has been warriors.

Question 21

synapomorphy

Answer 21

a shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors.(homologous traits)

Question 22

common ancestry

Answer 22

a group of organisms that share common descent and are usually similar genetically

Question 23

phylogeny

Answer 23

the evolutionary history of a group of organisms

Question 24

subspecies

Answer 24

a populations that has distinctive traits and some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species

Question 25

allopatric speciation

Answer 25

the divergence of populations into different species by physical isolation of populations in different geographic areas

Question 26

endangered species act

Answer 26

an act that was put in place to conserve and protect endangered and threatened species and their habitats.

Question 27

allopatry

Answer 27

refers to species being split up by geographic means

Question 28

dispersal

Answer 28

the movement of individuals from their place of origin to a new location

Question 29

vicariance

Answer 29

the physical splitting of a population into smaller isolated populations by a geographic barrier

Question 30

Biogeography

Answer 30

the study of how species populations are distributed geographically

Question 31

colonization

Answer 31

by which a species spreads to new areas. Colonisation often refers to successful immigration where a population becomes integrated into a community, having resisted initial local extinction

Question 32

sympatry

Answer 32

populations or species that live in the same geographic area

Question 33

sympatric speciation

Answer 33

the divergence of populations living within the same geographic barrier into different species as the result of their genetic isolation

Question 34

disruptive selection

Answer 34

the pattern of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Maintains overall genetic variation within a population

Question 35

polyploidy

Answer 35

the state of having more than two full sets of chromosomes

Question 36

nondisjunction

Answer 36

an error that can occur during meiosis or mitosis in which one daughter cell receives two copies of a particular chromosome, and the other daughter cell receives none

Question 37

triploid

Answer 37

a cell that has three full sets of chromosomes

Question 38

tetraploid

Answer 38

cells that contain more than two paired sets of chromosomes, one set coming from each parent

Question 39

autopolyploidy

Answer 39

the state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number

Question 40

allopolyploidy

Answer 40

the state of having more than two full sets of chromosomes due to hybridization between different species

Question 41

self-fertilization

Answer 41

in plants, the fusion of two gametes from the same individual to form a diploid offspring

Question 42

hybrid zone

Answer 42

a geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring

Question 43

secondary contact

Answer 43

the interaction of two diverged species, can often lead to hybridization

Question 44

hybridization

Answer 44

the crossing of two species that results in a hybrid

Question 45

backcrossing

Answer 45

cross (a hybrid) with one of its parents or an organism with the same genetic characteristics as one of the parents.