For the following situations, describe whether allopatric or sympatric speciatio

Question

For the following situations, describe whether allopatric or sympatric speciation is more

likely to occur, or no speciation at all. Support your answer.

a. In a small grove of chestnut trees near a large river, chipmunks are happily living.

One day a flood reroutes the river through the grove. Some chipmunks get consumed

by the river and float downstream to a new grove of alderwood trees, of the

chipmunks that remain, some live in chestnut trees on one side of the river and some

live on the other.

b. A volcanic eruption partitions the feeding habitat at the base of the volcano where

grizzly bears forage for berries and flowers. Some bears perish but the remaining

bears scour the area in search of food.

c. Along the African Savannah, competition for mates between lions is fierce. Aside

from intrasexual selection, females can choose their preferred male. Some male lions

have manes that are darker in color than others. Some females find this darker mane

more attractive and begin to leave their prides for dark maned males.

d. Competition for wood-boring insects in pine trees is fierce among a population of

woodpeckers. As a result, some of the woodpeckers start to feed on the seeds of the

pine trees instead of the insects. The seed-eating woodpeckers build their nest among

the branches of the tree while the insect eating woodpeckers build their nest in the

trunk of the tree.

Explanation / Answer

Speciation is the process that leads to evolution of two or more novel species from an existing species. This is a slow process. It needs that the population of a species gets segregated due to geographical or biological isolation.

Speciation can be allopatric or sympatric. In allopatric speciation, the population of a species gets separated into parts by physical barriers like mountains, water bodies, etc. These populations then get exposed to different environmental forces of selection and gradually get converted into new species.

In sympatric speciation, there is no separation of members of a species by physical barrier. There is reproductive isolation and the individuals of a species living in the same area are not able to mate. One of the examples is polyploidy where there is a change in the number of sets of chromosomes. This change in chromosome number reproductively isolates the individual from the rest of the population. It is seen usually in plants.

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