Theories surrounding evolution have sparked controversy among scientists and researchers, because of conflicting results in specific plants and animals. Some of the evolutionary theories include; natural selection, genetic drift, mutation and gene. Scientific research on the desert plant known as Linanthus parryae has sparked controversy and debates for almost six decades because of contradicting theories on the plant`s evolutionary process. In this paper, I will discuss scientific evidence and evolutionary research on L.parrynae indicated that natural selection, genetic drift , mutation and gene flow theories influenced the plant`s flower color change and which evolutionary mechanism caused spatial differentiation in the flowering plant.
The linanthus parrynea, which is a winter annual plant of the Mojave Desert in California, has been the subject of scientific and evolutionary research because of its flower color dimorphism. Scientific analysis indicated that the genetic drift theory could explain the spatial distribution of color morphs in the flower. A few years later, Wright adopted the in breeding coefficients in order to estimate the exact size of L.parryae populations. Genetic drift was supported by the isolation by distance model which proved that spatial distribution was responsible for flower color change (Schemske & Bierzychudek. 2001). Isolation by distance model proved that blue colored flowers would change to white within a short distance. The genetic drift theory was responsible for population differentiation based on the size of the local population and the average rate of migration within an area. This theory supports spatial differences in flower morphs, if there is a barrier to gene flow within the plant. Schemske and Bierzychudek (2006) noted that local differences in flower colors in L.parryae were caused by the effects of genetic drift. Evidence proved that allozymes provided in- depth insight on the patterns, causes, and effects of spatial differentiation. In depth research indicated that the genetic drift mechanism was solely responsible for spatial differentiation in the flowering plant based on genetic markers used to establish the distribution of flower colors within the spatial scale.
The natural selection theory has been attributed to the flower color change in L.parryae. Research proved that the nature surrounding the plant significantly impacted the color change of the flower. Researchers noted that on the west side of shallow ravine areas in the Mojave Desert supported the growth of blue flowered plants and the east had white flowered plants. Natural selection theory proved that L.parryae plants grew in large numbers in land with quality soil properties like organic matter concentration and mineral content. This theory was also supported by the ecological factor based on the abundance of the plant species in the research area. Soil composition influenced the degree of flower color morphs because researchers noted that it was associated with spatial patterns (Irwin& Strauss. 2005). Thus, evolutionary research proved that local differences were caused and maintained by natural selection based on different flower color morph in different locations.
The L.parryae plant produced either white or blue flower and the flower`s color was controlled by a single gene where the blue color was dominant to white. However, gene flow reorganized the genetic makeup of the plant resulting to genetic differentiation within plant populations in a specific ecological environment (Schemske & Bierzychudek 2001). Ecological systems influenced the flower`s gene flow because of the natural resources within the area. The mutation theory suggested that the plant`s gene mutated in order to adapt to new regions as the plant`s population traversed through different ecological surroundings. The mutation theory was based on different locations, whereby the flowering plant would change its flower population based on ecological factors like soil quality.
In conclusion, the natural selection theory influenced the flower color based on location and soil composition while genetic drift theory influenced flower color change based on spatial differentiation in the plant (Linhart & Grant 1996). However, evidence pointed out that natural selection was the most compelling theory in determining the flower color change in L. parryae.
Irwin, R. E., and S. Y. Strauss. 2005. Flower color microevolution in wild radish: evolutionary response to pollinator-mediated selection. Am. Nat, 165:225–237. Print.
Jain, S. K., and A. D. Bradshaw. 1966. Evolutionary divergence among adjacent plant populations. Evidence and its theoretical analysis. Heredity, 21:407–441. Print.
Linhart, Y. B., and M. C. Grant. 1996. Evolutionary significance of local genetic differentiation in plants. Annual Revolution Ecological Systems, 27:237–277. Print.
Schemske, D.W., and P. Bierzychudek. 2001. Evolution of flower color in the desert annual Linanthus parryae: Wright revisited. Evolution, 55:1269– 1282. Print.
Schemske, D.W., and P. Bierzychudek. Spatial Differentiation for Flower Color in the Desert Annual Linanthus Parryae: Was Wright Right? Michigan State University, Michigan. 2006. Print.
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