Natural selection in a snail population?
A particular snail species possesses three possible variants in terms of shell phenotype; white, tan and dark. The tan snail is usually found in larger numbers. However a researcher recently discovered a population of these snails on a island which experienced a volcanic eruption. Here, the populations consist of a large number of dark snails close to the area surrounding the base of the volcano and a smaller population of tan snails in the remaining grassy areas. During extensive observation of the two populations it was noticed that they do not mate with one another.
a) Which factor(s) could have been possible selection pressures against the white-shelled snail?
b)What is the type of natural selection which is being demonstrated in the scenario?
c)How does the type of speciation depicted in this scenario differ from allopatric speciation?
A particular snail species possesses three possible variants in terms of shell phenotype; white, tan and dark. The tan snail is usually found in larger numbers. However a researcher recently discovered a population of these snails on a island which experienced a volcanic eruption. Here, the populations consist of a large number of dark snails close to the area surrounding the base of the volcano and a smaller population of tan snails in the remaining grassy areas. During extensive observation of the two populations it was noticed that they do not mate with one another.
a) Which factor(s) could have been possible selection pressures against the white-shelled snail?
b)What is the type of natural selection which is being demonstrated in the scenario?
c)How does the type of speciation depicted in this scenario differ from allopatric speciation?
1 Answer
see below
Explanation:
there are many forms of natural selection which depend on the trait which is favored. an example can be diversifying or disruptive selection when nature favors two extremes.
for example, there is a wide variety of a snail population which exhibits a wide range of bright colors, intermediate colors, and dark banded shells.
if the environment was fairly dark, let's say a rain forest, where sunlight doesn't reach the ground due to high vegetation, dark snails will have the advantage because they aren't seen and will be preyed upon to a lesser extent.
while in another land which is bright and uniform, the dark snails and intermediate colored snails will be spotted more often and preyed upon.
both traits continue to exist and the population begins to diverge resulting in polymorphism because two opposing traits are selected for. this can lead to the divergence of the populations resulting in two new species.
