Thursday, 23 August 2012

Evolutionary Development by Rob Urquhart


By Rob Urquhart
Evolution is the change in the gene pool of a population over time . A population may evolve when individuals differ in one or more heritable traits that are responsible for differences in the ability to survive and reproduce. The individuals with traits that enable them to out compete their competition are more likely to survive and pass their genes onto the next generation these traits are called adaptations.
 An adaptation is any genetically controlled feature or ability which increases an organism’s chance of survival and therefore its ability to pass on its genes. However an adaptation is only adaptive in present time and location.
Moving from water to land took generations and generations of slight adaptations. The competition for area, food and mates are believed to of driven the advance of the evolution from water to land.
If I was to ask you which evolved from what; the dog to the whale or the whale to the dog, I'd suggest the vast majority would get it wrong. About 300 million years after fish first made it to land, the land dwellers moved back. A discovery made shows that a bone in the hip from a wolf is the same type as a bone found in a whale. At first everyone thought it was from whale to wolf but the first aquatic animals all had vertical tail fins and did not have this bone.
The evolution of the Equus or commonly known as the horse took about 55million years. Through fossils we can essentially see the evolution taking place. The main characteristic change is the loss of the number of digits. The original 'dawn horse' had four digits which it ran on, however over time three digits slowly receded until they became nonexistent. This loss of the digits enabled the horse to move quicker with less energy.
Mutations are the variation of the alleles of a specific gene. These may spread (assuming the gene still works efficiently) throughout the population and thus cause a variation in the gene pool. If this mutation aids in the survival of the individuals (an adaptation) then it can in a number of generations cause the population to evolve.
Mutated alleles may be recessive or dominant, recessive means that the gene is only expressed in the absence of the dominant. But these mutated alleles may not necessarily be an adaptation for example polydactyl. Polydactyl was a mutation in the founders of the Amish community. It commonly occurs due to inbreeding. When inbreeding occurs the offspring will not have a wide enough gene pool so mutations like polydactyl can occur as the offspring may get two recessive alleles for the trait.
British Royal Family known for interbreeding as to keep their blood 'pure'. This allowed the disease haemophilia to be passed through the offspring.



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