Ch. 22.2 The Origin of Species

Question 1

Allopatric (“other country”) Speciation

Answer 1

Gene flow is interrupted when a population is divided into geographically isolated subpopulations.

Reproductive isolation between two populations generally increases as the geographic distance between them increases, a finding consistent with allopatric speciation.

Regions that are isolated or highly subdivided by barriers typically have more species than do otherwise similar regions that lack such features.

Question 2

Sympatric (“same country”) Speciation

Answer 2

Occurs in populations that live in the same geographic area. Can occur by such factors as polyploidy, habitat differentiation, and sexual selection (can also promote allopatric speciation).

Question 3

Polyploidy

Answer 3

Common in plants, may originate form an accident during cell division that results in extra sets of chromosomes.

Question 4

Autopolyploid

Answer 4

A type of polyploidy wherein and individual that has more than two chromosome sets that are all derived from a single species. Can produce fertile tetraploid offspring by self pollinating or by mating with other tetraploids.

Question 5

Allopolyploid

Answer 5

Occurs when two different species interbreed and produce hybrid offspring. Most such hybrids are sterile because the set of chromosomes from one species cannot pair during meiosis with the set of chromosomes from the other species. However, and infertile hybrid may be able to propagate itself asexually. In subsequent generations, various mechanisms can change a sterile hybrid into a fertile polyploid.

Question 6

Habitat Differentiation

Answer 6

Sympatric speciation that occurs when a subpopulation exploits a habitat or resource not used by the parent population. (apple maggot flies example on page 449)

Question 7

Sexual Selection

Answer 7

A type of sympatric speciation. For example, females select males based on their appearance.