Speciation and Hybridization

Question 1

Allopatric speciation

Answer 1

formation of new species in populations that are geographically isolated from one another; geographic separation creates two populations of the same species who are isolated from each other and as a result, no genetic exchange can occur between them; can occur when a population is divided into geographically isolated subpopulations (vicariance) or when individuals colonize a remote area (dispersal)

Question 2

Sympatric speciation

Answer 2

formation of new species in populations that live in the same geographic area; occurs if gene flow is reduced by polyploidy, sexual selection or habitat differentiation

Question 3

Vicariance

Answer 3

the geographical separation of a population, typically by a physical barrier such as a mountain range or river, resulting in a pair of closely related species

Question 4

Autopolyploid

Answer 4

an individual that has more than two chromosome sets that are all derived from a single species

Question 5

Allopolyploid

Answer 5

a fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combining their chromosomes

Question 6

Which of the following could facilitate allopatric speciation?

Mountain range

River

Road

Ocean strait

All of the above

Answer 6

All of the above

Question 7

Polyploidy

Answer 7

accidents during cell division that can cause presence of extra sets of chromosomes; can form a new species within a single generation w/o geographic separation; Ex: oats, cotton, potatoes, tobacco, and wheat are all polyploids

Question 8

Sexual selection

Answer 8

can drive sympatric speciation; Ex: speciation of cichlids in Lake Victoria was likely driven by female mate choice based on male breeding coloration

Question 9

Which type of reproductive barrier prevents the breeding among the seedeater species?

Habitat isolation

Reduced hybrid viability

Behavioral isolation

Temporal isolation

Answer 9

Behavioral isolation

Question 10

Habitat differentiation

Answer 10

sympatric speciation can also result from the exploitation of new habitats or resources; Ex: apple maggot flies evolved in North America after switching hosts from hawthorn to apple

Question 11

Punctuated equilibria

Answer 11

in the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change

Question 12

What is the average time between speciation events?

Answer 12

6.5 million years

Question 13

Hybrids

Answer 13

result of mating between species w/ incomplete reproductive barriers

Question 14

Hybrid zone

Answer 14

a region in which members of different species mate and produce hybrid offspring; typically located wherever habitats of interbreeding species meet

Question 15

What happens when geographically isolated species come back into contact?

Answer 15

Reinforcement, fusion, stability, or hybrid speciation

Question 16

Reinforcement

Answer 16

if hybrids are less fit than the parent species, then there will be strong selection for prezygotic barriers that reduce hybrid production; “reinforces reproductive barriers”; Male pied flycatchers closely resemble male collared flycatchers in allopatric, but no sympatric, populations

Question 17

Fusion

Answer 17

there can be substantial gene flow between species if hybrids are as fit as their parents; reproductive barriers can weaken and the two parent species may fuse into a single species; Ex: pollution in Lake Victoria has reduced the ability of female cichlids to visually distinguish between males of their own and different species

Question 18

Stability

Answer 18

continuous formation of hybrids; extensive gene flow from outside the hybrid zone can be so high that the selection effects are not strong enough to increase reproductive isolation inside the hybrid zone; Ex: members of both parent species of Bombina constantly migrate into the narrow hybrid zone, resulting in ongoing hybridization

Question 19

Hybrid Speciation

Answer 19

hybrid in a hybrid zone may become reproductive isolated from both parental types; Ex: sunflower Helianthus anomalus was formed by hybridization between two other sunflower species followed by rapid speciation

Question 20

There is a hybrid zone of two species of frogs that look similar. After some generations, one species has yellow bellies and green bellies. The color prevents breeding between the two species. What type of outcome is this?

Reinforcement

Fusion

Hybrid speciation

Stability

Answer 20

Reinforcement