Anthropology - DNA Molecules, Genes, and Chromosomes - Essay Example

In meiosis, due to the crossing over during the metaphase, a mutation occurs. It can thus be concluded that the traits that are inherited from both parents and genetic mutation that may take place during crossing over in meiosis are accountable for the characteristics found in offspring.

Question 2

Hardy-Weinberg's principle is based on the fact that genetic variation is constant through generation in the absence of other evolutionary forces. For these variations to remain constant some limiting factors should be in place. One of the factors is the existence of random mating. According to him, populations have specific gene frequencies. If random mating does not take place then the proportions that Hardy proposes cannot be achieved. An example of non-random mating could be through inbreeding where homozygosity of genes in the population is achieved. Selection is another factor that leads to rapid changes in allele frequencies where the desirable characteristics are favored. This can be changed through artificial breeding where all the traits are maintained. Mutation has minimal effects on allele order. However, it can cause remarkable changes in the population if it is recurrent. Migration also affects allele frequencies (Ridley, 84). With migration homogeneity of genes within the population is increased since it causes random mating.  Lack of migration would result in a certain population having almost homozygous traits. Genetic drift is another factor. This occurs in small-sized populations and this causes swift changes in gene frequency. This is not applicable to large-sized populations.

Question 3

Natural selection is the process through which the organism that is best adapted to live in a certain environment survives while the organisms which have weak traits die out or migrate. It is nature’s way of retaining organisms with the best trait on the planet while the weaker genes die out. The process of natural selection has been cited as an important stage in evolution. Darwin supported the theory of natural selection using several premises. One is that natural selection comes as a result of the existence of variations in organisms. You will find that a certain trait will be displayed over a range of characteristics within the same species. For instance, there is a wide range of skin completion in men. These differences allow for the creation of new traits in the next generation when parents with different traits mate. This creates a room where the trait that is best suited for a certain environment is favored bringing about natural selection. There are however other traits that do not show variation such as the number of eyes in mammals. Moreover, some traits that organisms have are acquired from the parents while others are obtained from the environment. The traits acquired from the environment are passed to the next generation bringing about differentiation. Another factor that brings about natural selection is high levels of population growth rate. The population of organisms increases when the conditions are favorable for example vegetation population in the forest during the heavy rains. Drought causes the organism to compete over limited resources.  The organisms that survive during such conditions are the ones that have been adopted to survive with less water while the others die out. Some may completely be lost from that habitat if the drought conditions persist. Another factor is differential survival and reproduction. The alpha males and alpha females have a higher possibility of getting mates compared to their counterparts who have lesser attractive traits (Ridley, 32). This allows for reproduction to take place within organisms with the desirable traits and they pass these traits to the next generation. Industrial melanism is an example of natural selection. Due to industrialization and air pollution resulting in the darkening of surfaces, black moths became dominant over white moths as the black ones were harder to spot by predators. The rat snake is another example. These snakes have developed a wide range of colors to avoid being captured by their hunters. Because of the excessive use of insecticides, some insects have developed resistance to insecticides. A thousand years ago, not all male peacocks had feathers with bright colors. However, since the female went for the males with bright colors the ones with darker colors were slowly eradicated.

Question 4

Natural selection can result in the stability of a certain species if the organism exists in an environment that has adequate resources for all organisms over some time. For instance, several years ago before the industrial revolution, the ocean species remained fairly the same over a long period. This is because there were no major changes in the ocean environment. In some species, however, natural selection has resulted in changes within the species. For instance, the wings of penguins were originally structured for flying. However, since the penguins have lived in water for a long time, these wings because adopted for swimming (Ridley, 130).  Natural selection can result in the splitting of species into two descendants depending on the location. An example is the splitting of the ancestral primate lineage where one group became the monkeys and the other group became hominids.