Question

Why is it likely that MOST speciation is allopatric?

a. Because disruptive selection between forms of traits in sympatric populations is always very strong.
b. Because gene flow between diverging populations is strong in allopatry.
c. Because related species are always found in allopatry rather than in sympatry.
d. Because vicariance events are common.
e. Because gene flow between populations prevents genetic divergence in sympatry.

Answer 1

Most speciation is likely to be allopatric e. Because gene flow between populations prevents genetic divergence in sympatry.

Step-by-step explanation:

The likely reason why most speciation is allopatric is because of the geographic separation between populations. Allopatric speciation occurs when populations become geographically discontinuous, preventing the free flow of alleles. This separation allows populations to evolve along different trajectories, leading to increased genetic divergence.

Factors such as environmental conditions, climate, resources, predators, and competitors for each population can differ, causing natural selection to favor divergent adaptations. However, two populations that are physically separated from one another are unable to breed, and as a result, there is no gene flow between them, which causes genetic divergence and speciation. Thus, sympatric speciation is less prevalent than allopatric speciation.

Answer 2

e. Because gene flow between populations prevents genetic divergence in sympatry.

Step-by-step explanation:

Speciation requires genetic divergence between populations of a species to isolate them reproductively. however, when present in the same habitat, gene flow between populations of a species does not allow their reproductive isolation and thereby, prevents the formation of new species. These populations need strong episodes of disruptive selection for their reproductive isolation.

On the other hand, two geographically isolated populations can not interbreed and thus, there is no gene flow between them leading to their genetic divergence and speciation. So, allopatric speciation is more common than sympatric one.