Natural Selection and Extinction.

Natural selection is a process through which the traits that are helpful in the survival of an organism are passed on to the next generation while those that can hinder survival are eliminated. Natural selection then only allows the very well adapted species to reproduce. This is done to ensure survival in the ever-changing environmental conditions. Due to the evolutions that have been taking place, the habitat of organism change and to cope up with these changes, the organisms develop some genetic characteristics that would enhance their survival. However, even with natural selection, studies have shown that some organisms, both plants and animals have become extinct. Dinosaurs became extinct sixty five million years ago. Another example is the thylacine tiger of Australia. Other animals that are already endangered meaning that they are also in the process of becoming extinct. This paper shall therefore seek to explore why some organisms are becoming extinct while natural selection is supposed to prevent such occurrences.

Causes for Extinction
Natural selection only allows those organisms with desirable characteristics to survive and eliminate those that do no have any desirable adaptations. It is then clear that natural selection itself causes extinction. This is the main reason as to why even with natural selection organisms are still becoming extinct. The minority of the organisms in the environment are the ones that become extinct together with those that are unable to survive the changes in the environment. The minority are unable to compete with the majority for survival means. Moreover, when new species are being formed or modified they exert pressure on the existing ones and finally eliminate them. The introduction of new breeds of animals leads to the extinction of the inferior ones.
   
An organism is considered to be extinct after the last individual of that species has died. Factors that cause extinction are inclusive but not limited to human activities, toxic pollution and climatic changes. Human activities may be the major causes of the extinction because they are diverse in nature. Some animals that have become extinct like the thylacine tiger in Australia have been affected by human activities like hunting. Increased and uncontrolled hunting is very dangerous since it occurs within a short duration of time. In the situation where the big mammals and other animals are eliminated by human activities, that can be viewed to be a form of natural selection. They become extinct because they are not well adapted to cope with their enemies.
   
Although Snook (2008) argues only 20 of the extinction that is associated with human activities, it is clear that even the other 80 is still associated with the same only that it is indirect. In cases where toxic pollution lead to extinction, then humans may be the contributing factors. The species that are poisoned by the pollution die, and those that remain are always too weak to reproduce. Therefore, by natural selection, such species are eliminated and they end up becoming extinct since the remaining ones cannot be allowed to reproduce. The same studies reveal that where fossils of extinct animals have been found in North America are the same places where human beings inhabited. This means that these animals were killed for food to support human life until they became extinct. Through natural selection, the well-adapted species are able to kill those that are not well adapted to enhance their survival. Thus, what led to the extinction of those small animals was natural selection.
   
The main reason why extinction still occurs is that natural selection is good at maintaining and even improving species adaptations while on the other hand it eliminates those species that are the minority and those that are not well adapted. It is then clear that natural selection does not only play a role of preventing extinction, it also supports extinction of the species that are not well adapted for survival. This being the case then, extinction is bound to prevail even if natural selection is still there.

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