Tectonic Events and Evolution

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There was only one species of squirrels that originally inhabited the Ponderosa pine forest, and this is around the rim of the Grand Canyon. However, when then Grand Canyon was formed, a great barrier was created, separating the squirrels living in the area (Kaiser, 2020). Over the decades, the divided squirrel populations evolved to become two different species, that include the Kaibab and Abert squirrels. Currently, the Kaibab squirrels live in the northern rim of the Grand Canyon and have a small range. On the other hand, the Abert squirrels live in the south rim and live in a much larger range. Despite being different, members of the two species are similar in that they are of the same shape and size, and they have a similar diet. However, they have slight color differences, but they are no longer in contact with each other. As a result, they have evolved to become different during their separation, which has made them separate species.

The geographical separation had a massive impact on the development of the squirrels. Natural selection and mutations often add new alleles in a population, and with time spreads to the entire population. However, because the squirrel species were separated, they underwent different changes in their alleles. The separation caused by the barrier of the Colorado River was responsible for stopping the gene flow from one species of the squirrels to the other. As a result of this, the two species evolved to become two different species, and due to this, their genetic code has become more incompatible. It, therefore, implies that a male from one population and a female from the other population cannot be able to reproduce successfully (Roman et al., 2016). Thus, even the Colorado River was removed to rejoin the two species; they would not be able to reproduce together.

Different theories explain how the Grand Canyon developed. One of the theories that stand out is that it formed as a result of erosion primarily by water and ice. The Grand Canyon is located in a desert, and this explains why erosion by water has a great impact. The soil in the Grand Canyon is baked by the sun, and thus it becomes very hard and cannot absorb water when the rains come. However, when the rains come, water comes down in heavy rain that adds to the problem (Douglass et al., 2020). The plants growing around the Grand Canyon have a shallow root system to help them grab as much water as possible on the time of rain. However, the roots are not strong enough to stop erosion by holding the soil in place. With the water having a lot of force, it even uproots trees on its way to Colorado River. Continuous erosion continues to expand the river and cut down deeper the rock layers. The expansion makes it hard for the squirrels to cross from one side to the other.

If the geological change was reversed, there could be only one species of squirrels in the region. The natural selection and mutation would add new alleles to the squirrels in a uniform manner, and this means that there could be no variation with the species. Besides, the squirrels could mate and produce viable offspring since they belong to the same genus and species. Little gene mutations could arise, but it could be evenly distributed with in the populations. As a result, the squirrel populations would have no variations.

ReferencesDouglass, J. C., Gootee, B. F., Dallegge, T., Jeong, A., Seong, Y. B., & Yu, B. Y. (2020). Evidence for the overflow origin of the Grand Canyon. Geomorphology, 107361.

Kaiser, J. (2020). Grand Canyon: The Complete Guide: Grand Canyon National Park. James Kaiser.

Roman, D., Jones, F., Basaraba, D., & Hironaka, S. (2016). Helping students bridge inferences in science texts using graphic organizers. Journal of Adolescent & Adult Literacy, 60(2), 121-130.