Mechanisms of Speciation

Question 1

What is the order of events that leads to allopatric speciation?

Answer 1

Geographic separation, then genetic divergence, then reproductive isolation

Question 2

What is the mode of speciation described.

Researchers studied five species of annual sunflowers of the genus Helianthus. Two species, H. annuus and H. petiolaris, grow across central and western US. The other three, H. anomalus, H. deserticola, and H. paradoxus, grow in extreme environments such as the dry, sandy soils of Nevada and Utah, or the salt marshes in west Texas. Genetic studies have shown that these three hardy species, which originated between 60,000 and 200,000 years ago, are hybrids of the first two parental species.

Answer 2

Allopolyploidy

Question 3

In which type of selection does a physical barrier block gene flow?

Answer 3

Allopatric speciation

Question 4

In which type(s) of speciation does gene flow decrease?

Answer 4

All types

Question 5

Disruptive selection is associated with which type of speciation?

Answer 5

Sympatric

Question 6

What type(s) of speciation would be favoured by a small population?

Answer 6

Allopatric

Question 7

True or false?

Allopatric speciation is likely to take place within a population of snails that was just separated by a rising tide.

Answer 7

True. New environment + physical barrier

Question 8

If the haploid number of a population of rats increases from 5 to 10, is there speciation taking place? If so, which type?

Answer 8

No type of speciation can explain this. Autopolyploidy explains the passing from 2n to 4n, but not the doubling of the value of n itself.