Ans 1: Natural Selection may occur in any organism population and affect the individuals. Considering the natural selection of the Beetles, they face a constant struggle to survive and reproduce; however due to the gene called allele that differentiates the color, they overcome this drawback and evolve again. The frequency of the allele changes as the population evolves. Green beetles have a green allele or green and a brown allele, and brown beetles have brown alleles. Suppose the island on which the beetles evolve is affected by drought, and in this dry environment the brown beetles are better disguised than the green beetles. Birds are more likely to see and eat the green beetles. Overtime brown beetles survive and produce more beetles and this is a good example of natural selection. The beetles that survive due to the inheritance factor are better suited to their environment and produce more offspring than other individuals. Here the natural selection causes the frequency of the brown allele to increase through natural selection, and this population is better adapted to its new environment.
Ans 2: Evolution by natural selection is likely to occur in the population of mosquitoes, most of which are initially killed when exposed to chemicals and only a few survive and reproduce. The mosquito’s become resistant to insecticide or pesticide overtime. It is a proven fact that if a mosquito is resistant to the chemical then most of its future generation will be resistant to the chemicals. Though the life span of the mosquitoes is only for a few weeks they can increase their immunity against the chemicals that harm them. The mosquitoes that do not develop immunity will die and the strongest will survive. Using more insecticide on the mosquitoes increases the possibilities of developing immunity in these insects. Mosquitoes reproduce at a rapid rate and many generations are born within months.
Ans 3: A man spends many hours in the gym exercising and is able to increase his body weight, muscle mass, and strength, which makes him more attractive to the opposite sex. This scenario does not result in an evolution as it does not conclude if the man is able to reproduce. Exercise can be done to increase the fitness levels and live a long life; however for evolution it is important for the man to reproduce.
Ans 4: Whatever the specific bio-geographical details, it is clear that the adaptive differences between apple and hawthorn races were derived from a pre-existing geographical cline established in either Parapatry or Allopatry (Jiggins & Bridle, 113). The apple maggot flies are not distinguishable and they have the same reproduction pattern though some use hawthorn berries and some use apples as host for breeding. The inclination of the fruit types is a barrier to the gene flow between the two types of flies and can be considered as a separate species. Genetic transformations have developed in these flies in the past three centuries. As the fruits on which the flies breed are not geographically separated they are not allopatric. The example of apple maggot fly is well suited for sympatric speciation. They are separate species because the male flies mate with the female flies that find the same fruit, for example, apple finding males mate with apple finding females. The apple maggot flies lays more eggs per fruit in comparison with the hawthorn maggot flies. These flies lay their eggs in the respective trees, such as apple maggot flies lays eggs in apple trees and the hawthorn maggot flies lays eggs in hawthorn trees.
Ans 5: When speciation occurs due to complete geographic separation of differing populations it is referred as Allopatric speciation. An example of allopatric speciation is the Abert and the Kaibab squirrels. The Kaibab squirrels have black bellies and white tails compared to the white bellies and dark tails of the Abert squirrels. These squirrels can be noticed in the Grand Canyon area that is covered with ponderosa pine forests on one side and desert on the other side. There existed only one species of squirrel million years ago; however with the development of the canyon over the years, most of the squirrels could not migrate to the other side of the canyon. As the canyon grew, the environmental conditions differed on both sides of the canyon and the squirrels on each side adapted to their existing environment. This was a result of the genetic change and the two populations were unable to mate with each other causing an allopatric speciation between them.
Works Cited
Jiggins. D Chris., Bridle, Jon R. Speciation in the apple maggot fly: a blend of vintages?
TRENDS in Ecology and Evolution, Vol.19 No.3, Retrieved from
www3.nd.edu/~mpfrende/Evolutionary_Biology/PDFs%20for%20Essay/Jiggins.pdf, March 2004.
