There is a population of speckled rattlesnakes living in the desert of Arizona.

Question

There is a population of speckled rattlesnakes living in the desert of Arizona. Individuals in this population can range from a dark brown coloration to a speckled white coloration. There are also two types of rock formations in this area: one with high quartz content (white) and table mesa sedimentary rocks (brown). Because of these two types of prominent rock outcroppings, only rattlesnakes at either end of the coloration spectrum are able to sufficiently camouflage themselves to avoid predation. Because of these, individuals with intermediate coloration are unlikely to survive and reproduce. This is an example of:

-Disruptive Selection

-No Natural selection

-Directional selection

-stabilizing selection

Explanation / Answer

Disruptive selection:In this type ove selection the population genetics gets altered in such a way that the extrem phenotpes (here dark white and speckle white) are preferred/selected over the intermediate colured rattlesnakes. Therefore it is also termed as diversifying selection.

Not "no natural selection" = because conditions in the natural habitat are resulting in a change in alleleic as well as genotypic frequences of the trait(here, coloration) that too in a specific pattern. So, some type of selection is playing a role for sure.

not "directional selection" = because in directional selection any one of the 2 extreme phenotypes are preferred over the other.

not "stabilizing selection' = because a stabilizing selection would select the intermediate phenotype over the 2 extreme ones. In the case expained above, the exact opposite is occuring.

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