Biology 2 - Natural selection and Artificial selection.

What is VST - artificial selection

Variation, selection, and time.

Variation meaning

Differences that exist among individuals of a population.

Selection meaning

Humans select individuals with a favourable traits to breed, passing on favourable alleles to the next gen.

Time meaning

Over time, the frequency of favourable alleles will have increased within the population.

Example of a VST paragraph - Watermelons.

Variation - In the original watermelon population in the 1600’s, there was a variation in the size of the seeds and amount of flesh in the watermelon.

Selection - Farmers are going to choose the watermelons that produce the smallest seeds, and most flesh and breed these. The offspring with the desirable trait (small seeds/ more flesh) were then bred, and so on, for many generations.

Time - Over time the frequency of small seeds and more flesh alleles increased in the watermelon population.

What is VOSSR - natural selection

Variation, Over production, Selection, Survival of the fittest, Reproduction.

Variation Paragraph - Natural selection - beetles

There is a natural variation between beetles in a population. Some beetles are light coloured and some are dark coloured (different alleles).

Overproduction paragraph - natural selection - beetles

Beetles tend to produce more offspring than can survive to maturity.

Selection paragraph - natural selection - beetles

A factor in the environment acts as the selection pressure. If the soil is a lighter sandy colour, the dark beetles are more obvious or conspicuous, and the birds eat them. The dark beetles are selected against, and the light beetles are selected for.

Survival of the fittest paragraph - natural selection - beetles.

More light beetles survive due to their light alleles and reach the age at which they can reproduce. The light beetle reproduced, passing on its favourable allele to the next generation. The dark coloured beetle is killed before it can reproduce.

Reproduction paragrph - natural selection - beetles.

Over time, the frequency of the light coloured allele increases in the population, and the frequency of the dark coloured allele decreases.