Chapter 24- Origin of Species

Question 1

Microevolution

Answer 1

Consists of changes in allele frequency in a population over time

Question 2

Macroevolution

Answer 2

Refers to broad patterns of evolutionary change above the species level

Question 3

Biological Species concept

Answer 3

species is a group of populations who can interbreed and produce fertile offspring but cannot breed successfully with other populations

Question 4

Prezygotic barriers block fertilization from occurring by

Answer 4

1. impeding different species from attempting to mate
2. preventing the successful completion of mating
3. Hindering fertilization if mating is successful

Question 5

Habitat isolation (prezygotic barrier)

Answer 5

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

Question 6

Temporal isolation (prezygotic barrier)

Answer 6

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes.

Question 7

Behavioral isolation (prezygotic barrier)

Answer 7

Courtship rituals and other behaviors unique to a species are effective barriers

Question 8

Mechanical isolation (prezygotic barrier)

Answer 8

Morphological differences can prevent successful mating

Question 9

Gametic isolation (prezygotic barrier)

Answer 9

Sperm of one species may not be able to fertilize eggs of another species

Question 10

Postzygotic barriers

Answer 10

prevent the hybrid zygote from developing into a viable, fertile adult: barriers to reproduction are intrinsic

Question 11

Sympatric speciation (Same Country)

Answer 11

speciation takes place in geographically overlapping populations

Question 12

Polyploidy

Answer 12

the presence of extra sets of chromosomes due to accidents during cell division

it is more common in plants than in animals

Question 13

An autopolyploid

Answer 13

an individual with more than two chromosome sets, derived from single species

Question 14

An allopolyploid

Answer 14

a species with multiple sets of chromosomes derived from different species

Question 15

Habitat Speciation

Answer 15

Sympatric speciation can also result from the appearance of new ecological niches

ex. maggot fly can live in native tree or newly introduced tree

Question 16

Sexual selection

Answer 16

can drive sympatric speciation

Question 17

Sympatric speciation can result from

Answer 17

1. polyploidy
2. natural selection
3. sexual selection

Question 18

Hybrid zone

Answer 18

A region in which members of different species mate and produce hybrids

Question 19

Hybrids

Answer 19

are the result of mating between species with incomplete reproductive barriers

Question 20

when closely related species meet in a hybrid zone what are the three possible outcomes

Answer 20

1. Reinforcement
2. Fusion
3. Stability

Question 21

Reinforcement

Answer 21

The strengthening of reproductive barriers

Question 22

reinforcement of barriers occurs when

Answer 22

hybrids are less fit than the parent species and over time the rate of hybridization decreases

ie. when reinforcement occurs reproductive barriers should be stronger for sympatric than allopatric species

Question 23

Fusion

Answer 23

weakening reproductive barriers

Question 24

Fusion occurs if

Answer 24

hybrids are fit as parents, then there is substantial gen flow between species if gene flow is enough, the parent species can fuse into a single species

Question 25

Stability

Answer 25

Continued formation of Hybrid individuals

Question 26

Stability occurs if

Answer 26

extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone

Question 27

Eldredge and Gould coined the term

Answer 27

Punctuated Equilibrium, which describes periods of apparent stasis punctuated by sudden change

Question 28

the punctuated pattern in the fossil record and evidence from lab studies suggest

Answer 28

that speciation can be rapid

Question 29

depending on the species, speciation might require the change of only

Answer 29

a single or multiple alleles

Question 30

In other species speciation can be influenced by

Answer 30

larger number of genes and gene interactions

Question 31

Macroevolution is the cumulative effect of

Answer 31

many speciation and extinction events

Question 32

Reduced hybrid viability

Answer 32

Genes of different parent species may interact and impair the hybrid’s development or survival

Question 33

Reduced hybrid fertility

Answer 33

Even if hybrids are vigorous, they may be sterile or not very fertile

Question 34

Hybrid breakdown

Answer 34

Some first-generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile

Question 35

1st Limitation of biological species concept

Answer 35

The biological species concept cannot be applied to fossils or asexual organisms (including all proks)

Question 36

2nd Limitation of biological species concept

Answer 36

the concept emphasizes absence of gene flow, but gene flow can occur between distinct species

Question 37

Morphological species concept

Answer 37

defines species by structural features, and applies to sexual and asexual species. Relies on subjective criteria

Question 38

Ecological species concept

Answer 38

views a species in terms of its ecological niche (function). It applies to sexual and asexual species and emphasizes the role of disruptive selection

Question 39

Phylogenetic species concept

Answer 39

defines species as the smallest group of individuals on a phylogenetic tree. It applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species

Question 40

Speciation can occur in two ways

Answer 40

1. Allopatric speciation

2. Sympatric speciation

Question 41

Allopatric speciation

Answer 41

gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations

Question 42

Allopatric speciation can cause

Answer 42

separate populations to evolve independently through mutation, natural selection, and genetic drift. Reproductive isolation may arise as a result of genetic divergence