Evolution
Here, we are going to get a lovely lesson someone who had a couple of very productive gap years: Charles Darwin.
Good ol’ Charles was the chap who brought the theory of evolution to the world, which has “evolved” our understanding of Biology and our origins as a species.
Before explaining and understanding evolution, we first must discuss mutations.
Mutations
A mutation is a random change in genetic material. DNA is a line of code, made from bases on nucleotides. This code can change spontaneously. A mutation can be neutral, meaning it poses no positive or negative impact to the cell or organism.
They can be negative, which is a change in genetic code causing a hinderance to the organism’s survival, such as a mouse developing a brightly coloured coat, making it more susceptible to predation. They can also be positive, for example a bacteria having a mutation that resists it from our immune system.
These mutations are spontaneous. They are also the only way that DNA can produce new alleles.
Mutations can be caused by a range of environmental factors, such as radiation and various chemicals. So, organisms close to the Chernobyl nuclear disaster underwent various mutations in their DNA as a result of exposure to radiation. Cigarette smoke leads to mutations in DNA within the lungs and other parts of the body, causing various cancers.
Variation and Natural Selection
Natural selection is the process by which species adapt and change as a result of selection pressures. The organisms that have adapted to be best equipped for the environment around them will carry on to produce offspring and pass on the favourable alleles that are essential for survival.
Specialisation of species occurs when a population is isolated by geographical, behavioural or ecological barriers. Different mutations occur in each sub-population. Due to different selection pressures between groups, different alleles will be favourable, making each sub-population evolve through natural selection until the species are genetically different enough to be classified as separate species.
Key Points!
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Mutations
A mutation is a random change in genetic material. DNA is a line of code, made from bases on nucleotides. This code can change spontaneously. A mutation can be neutral, meaning it poses no positive or negative impact to the cell or organism.
They can be negative, which is a change in genetic code causing a hinderance to the organism’s survival, such as a mouse developing a brightly coloured coat, making it more susceptible to predation. They can also be positive, for example a bacteria having a mutation that resists it from our immune system.
These mutations are spontaneous. They are also the only way that DNA can produce new alleles.
Mutations can be caused by a range of environmental factors, such as radiation, viruses and various chemicals.
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Specialisation and Natural Selection
Natural selection is the process by which species adapt and change as a result of selection pressures. The organisms that have adapted to be best equipped for the environment around them will carry on to produce offspring and pass on the favourable alleles that are essential for survival.
Specialisation of species occurs when a population is isolated by geographical, behavioural or ecological barriers. Different mutations occur in each sub-population. Due to different selection pressures between groups, different alleles will be favourable, making each sub-population evolve through natural selection until the species are genetically different enough to be classified as separate species.