Nursing:
Purpose
The aim of the lab was to investigate what happens when a natural physical barrier suddenly splits a species within a given population.
Introduction
A species is a group of organisms within a population that can interbreed under natural conditions to produce fertile and viable offspring (The University of Miami, n.d.). In this context, a species exhibits reproductive isolation, in which physical and behavioral traits allow them to reproduce only with organisms that possess similar traits (Howard & Berlocher, 1998). Speciation describes how new sets of species are created and occurs when a group of organisms within a species separates from the other members and develop unique individual characteristics. There are two primary ways speciation can happen; anagenesis and cladogenesis (Kessen & Zink, 2016). Anagenesis speciation is where a species splits and genetically evolve into separates groups while remaining in the same place due to impediments to gene flow. The obstruction can happen when a mutation present in a segment of a species results in an immediate barrier to reproduction or disruptive mating selection become dominant (Kessen & Zink, 2016). Cladogenesis happens when a species splits into two or more species by natural barriers and is the type this report explicates. The physical separation of a species is of great interest regarding bio-diversification and genetic isolation of the affected organisms. Its principal mechanism is allopatric speciation (Kessen & Zink, 2016).
Allopatric speciation occurs when a species is separated into two or more groups by some physical barrier resulting from events as geological occurrences like earthquakes, climate variability, or significant natural (at times human) changes in the environment. For instance, the formation of a mountain range in a natural environment can divide an ancestral species into isolated groups. The separated groups then accumulate genetic changes that differentiate them from each other due to the different environmental demands of the new habitat resulting to genetic drift (Figure 1) (National Geographic Society, 2016).
Figure 1: Physical barrier to speciation
Image as retrieved from (Audesirk, Audesirk, & Byers, 2008)
Therefore, by a variety of processes, involving either species selection or chance, the two physically separated groups of organisms may accumulate genetic and phenotypic differences between them. This development is the first part of the speciation. The second part involves barriers of gene flow between the separated groups, as individuals from one group cannot cross the barrier to mate with individuals in the other groups. This limitation causes genetic isolation of each group from the others thus permitting the development of genetic differences in the groups. A persistent impediment to gene flow between the isolated groups will cause the units to accumulate significant trait differences over time to become entirely different and separate species. If these groups happen to come back into contact due to factors such as range expansion, reproductive isolation mechanism (a byproduct of diversification) act to preserve the differences (Howard & Berlocher, 1998).
Hypothesis
At the end when a species within a population is split into two by a physical barrier deriving from natural events like an earthquake, they evolve differently.
Methods
Analysis of the animated time progression of speciation and online searches were used to gather the information utilized in the lab.
Results
The study results from the lab investigation show that the separation of a species by a natural barrier will lead to the creation of separate groups of species from the ancestral population.
Discussion
The results obtained from the experiment as discusses previously demonstrates that the hypothesis of the study was correct. When a physical barrier separates a geographically continuous population, the gene flow (the movement of genes across the organisms) is prevented. When the separation persists for long, the isolated populations evolve along different trajectories. While several factors can contribute to this phenomenon, the effects of the environment such as predation, competition, and climate change are perhaps the most dominant forces causing natural selection. Natural selection then favors divergent adaptations in each group.
Conclusion
The sudden separation of a species from a parent population by physical barriers like a mountain range or a canyon can result in the creation of distinct groups of organism. Not only would there be obstacles to gene flow between the separated groups but also the effects of the new living environment will alter both the genetic as well as the phenotypic attributes of the groups. The experiment showed that these impacts over time would allow the separated species to evolve into distinct populations.
References
Audesirk, T., Audesirk, G., & Byers, B. E. (2008). Biology: Life on earth with physiology. Upper Saddle River, NJ: Prentice Hall.
Howard, D. J., & Berlocher, S. H. (1998). Chapter 9: Ecological Causes of Speciation. In Endless forms: Species and speciation. New York: Oxford University Press.
Kessen, A. E., & Zink, R. M. (2016). Speciation. Retrieved April 11, 2016, from http://www.biologyreference.com/Se-T/Speciation.html
National Geographic Society. (2016). Speciation. Retrieved April 11, 2016, from http://education.nationalgeographic.org/encyclopedia/speciation/
