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Explain How Darwin's Theory Of Natural Selection Can Be Used To Explain How Evolution Has Occurred In Non-Human Animals

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Introduction

Explain How Darwin's Theory Of Natural Selection Can Be Used To Explain How Evolution Has Occurred In Non-Human Animals Darwin's theory of natural selection has provided us with the explanations of the processes involved in the changes of species over long periods of time. His theory was based on five major assumptions: VARIATION: When Individuals within a species differ from one another in physical characteristics and in their behaviour. HERITABILITY: Some of the variations amongst the members of species is inherited, meaning that the offspring tend to resemble their parents more than the other members of the species. COMPETITION: Members of most species produce far more offspring than can survive. If there weren't problems with survival Darwin figured out that a pair of elephants could have about 19 million descendents alive 750 years after birth! However there are those who don't win competitions for best food and best place to live are the ones who are less likely to reproduce. ...read more.

Middle

this he thought: "Natural selection tends only to make each organic being as perfect as, or slightly more perfect than, the other inhabitants of the same country with which it comes into competition...natural selection will not produce absolute perfection." Darwin presumed that evolutionary change would on the whole happen relatively slowly over periods of hundreds or thousands of years. However there are reasons to why some aspects of behaviour seem to change more than others during evolution (Grier +Burke). Any behaviour that allows the most effective way to use the available resources around them (eg. Bigger jaws for eating whole animals)giving the individual a quick advantage increasing reproductive success. A behaviour which will give an individual a competitive edge will likely lead them to a rapid evolution (eg. A strong male who wins all his competitions will have the right to impregnate the female allowing his genes to be perpetuated). ...read more.

Conclusion

Darwin thought that these trains must have some purpose, so he thought of sexual selection as a variation of natural selection: the peahens find the peacock's long train attractive, so those with the long trains have more reproductive success than those with short ones, turning this characteristic into an advantage and an adaptive trait. The peppered moth is a good example regarding Darwin's theory of natural selection this was done by Kettlewell who studied two variants of peppered moth, one which was light and the other one was dark the difference of colour inherited. The moths are eaten by birds who rely on their sight to find them, he observed them on light and dark coloured lichen trees (trees were in polluted area) and found that the light coloured moths survived best on the light lichen trees and the dark ones on the dark lichen trees. According to Darwin's theory, the number of darker moths should increase if the proportion of dark tress also increase. ...read more.

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