Darwins Theory of Evolution by Natural Selection Essay Example for Free

Darwins Theory of organic evolution by Natural Selection EssayThe mechanisms for individuals in a population to survive heterogeneous habitats have been a sinewy debate within the scientific community. The native European Littorina obtusata are a great model organism to study Darwins Theory of Evolution by Natural Selection. This is because of their vast phe nonypic characteristics, particularly their evolving pillory thickness throughout history due to predatory pressures of the new arrival of Carcinus maenas.Here we psychometric test whether L obtusata three most critical tenants of Darwins theory of evolution by natural selection variation within a population, heritability, and selection. By observant the shell thickness of East edge of N. America L. obtusata where predatory C. maenas are common versus the West Coast of N. America where C. maenas are not found, it will besides provide evidence whether these shell thickness differences are due to natural selection predat ory or phenotypic plasticity occurring. This was tested by placing band crabs in both East and West populations of L. btusata and observing how their shell thickness decreased, make headway proving that L. obtusata cannot sense or smell the presence of C. maenas. These findings provide further evidence for Seeleys research that the accelerating morphological changes of L. obtusata shell thickness was in response to strong selection by C. maenas and not because speciation occurring.Some believe that Darwins theory of evolution by natural selection is operating the morphological breaks found in fossil records within a population. Darwins book On the Origin of Species listed four basic postulates to natural selection there must be variations among individuals in a population, variations must be heritable, survival and reproduction must be variable and non-random (Darwin, 1859). As a result, every generation there will be slight changes in the population.One scientist in particular, R obin Seeley, assay understanding Darwins theory of Natural Selection by studying the thickness of shells of flat periwinkles, Littorina obtusata, of Appledore Island and the new arrival of predatory green crabs, Carcinus maenas. Seeley historied acceleration in natural selection that normally is not observed within the L. obtusata population in response to strong selection by C. maenas. This is because shell thickness affects the survivability and reproduction of L. obtusata when C. maenas claws break them to meal (Trussel, 1996).The observation confirmed that when C. maenas were introduced in the East Coast of N. America, L. obtusata range of shell thickness increased compared to the West Coast of N. America L. obtusata populations where predatory C. maenas were not found (Seeley, 1986). These vast morphological differences in their shell thicknesses was thought to occur because of the C. maenas selection for the thinner-shelled L. obtusata. Seeleys research further showed that sp eciation was not occurring within the intertidal snails as many previous scientists claimed.