Lecture 21- Speciation

Question 1

What is speciation?

Answer 1

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

Question 2

What is habitat isolation?

Answer 2

Prezygotic isolation mechanism by which habitat preferences lower the probability of mating between individuals associated with differing habitats

Question 3

What is hybrid breakdown?

Answer 3

Postzygotic isolation mechanism in which the offspring produced by first-generation hybrids are feeble and/or sterile

Question 4

How is a species defined according to the ecological species concept?

Answer 4

Species are defined based on their niche (role in environment)

Question 5

What are hybrids?

Answer 5

Offspring resulting from the sexual reproduction of different species

Question 6

What are the five prezygotic isolation mechanisms?

Answer 6

Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, & gametic isolation

Question 7

What is sympatric speciation?

Answer 7

Type of speciation which occurs when two groups of the same species live in the same geographic location, but evolve differently until they can no longer interbreed and are considered different species

Question 8

How is a species defined according to the biological species concept?

Answer 8

A species is a group of populations whose members naturally interbreed and produce viable, fertile offspring

Question 9

What are the limitations of the ecological species concept?

Answer 9

The complex interactions which define the organism(s) of interest undergo must be well understood

Question 10

What is temporal isolation?

Answer 10

Prezygotic reproductive barrier mechanism in which species are prevented from mating with each other because each individual species of interest breeds at different time of day or different season, different year etc

Question 11

How are species differentiated according to the morphological species concept?

Answer 11

Groups of physical traits that are unique to each species

Question 12

What is allopatric speciation?

Answer 12

Type of speciation which occurs when two populations of the same species become isolated from each other due to geographical changes

Question 13

What are the three postzygotic isolation mechanisms?

Answer 13

Reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown

Question 14

What is reproductive isolation?

Answer 14

Collection of evolutionary mechanisms, behaviors, physiological processes which prevent members of different species from producing offspring (or ensure any offspring are sterile)

Question 15

What are the limitations of the biological species concept?

Answer 15

BSC can only be used to define species that are alive and undergo sexual reproduction

Question 16

What is behavioral isolation?

Answer 16

Prezygotic isolation mechanism which occurs when two species are capable of interbreeding but don’t because of differences in their courtship rituals

Question 17

What is reduced hybrid viability?

Answer 17

Postzygotic isolation mechanism by which offspring have a low potential to survive due to parents have no incompatible genetics (mostly because the parents mated despite being different species)

Question 18

What are the limitations of the morphological species concept?

Answer 18

The physical traits by which species are differentiated by must be well defined, logical, and agreed upon

Question 19

Which species concepts can be used to define species that are extinct and/or reproduce asexually?

Answer 19

Morphological species concept and ecological species concept (not biological species concept)

Question 20

What is mechanical isolation?

Answer 20

Prezygotic isolation mechanism by which morphological differences prevent mating

Question 21

What is gametic isolation?

Answer 21

Prezygotic isolation mechanism by which fertilization is inhibited due to differences in gametic cells

Question 22

What is reduced hybrid fertility?

Answer 22

Postzygotic isolation mechanism which occurs when offspring are healthy (survive beyond reduced hybrid viability) but sterile

Question 23

Which phenomena can lead to sympatric speciation?

Answer 23

Disruptive selection, polyploidy, sexual selection, and/or habitat differentiation/host shift