Help with Biology lab..? PLEASE PLEASE PLEASE PLEASE!! HELP?

Question

I did a lab in bio. The purpose was to stimulate natural selectin by using beans of 2 different colors, and to demonstrate how natural selection can affect allelic frequencies over time.

We had to answer the problem question which was:

How does natural selection affect allelic frequency?

Can I get some help with the question?
[Please be descriptive and if you can give a source.]

Thanks to those who answer

Answer 1

Think about this. Natural selection is a natural force that basically kills those individuals that aren't quite as well adapted as others. If one allele (say an allele that is mutated, making you an albino) makes you less adapted to the environment you are in, then it is more likely that the individual carrying that allele will die before breeding and passing it along.

What do you suppose will happen to the frequency (percentage) of that allele over a long period of time?

I hope this helps.

Answer 2

Natural Selection favours the genotype which expresses the phenotype that is more favourable to the selection pressure. Therefore if the phenotype of red flower (RR or Rr) vs. white flower (rr) are taken as an example, and red flowers are favoured than the allelic frequency of the Gene R (found n RR and Rr) increases. This happens since plants having white flower would for example attract less insects and therefore wouldn't be able to reproduce lowering the chances of finding r alleles in the next generation. On the other hand, the plants with the R allele present would reproduce

Hope you will find it helpful :)

Answer 3

Each allele has a frequency (proportion) in the population. For example, imagine a population of 500 wildflower plants with two alleles, C R and C W , at a locus that codes for flower pigment. Plants homozygous for the C R allele ( C R C R ) produce red pigment and have red flowers; plants homozygous for the C W allele ( C W C W ) produce no red pigment and have white flowers; and heterozygotes ( C R C W ) produce some red pigment and have pink flowers. In our population there are 320 plants with red flowers, 160 with pink flowers, and 20 with white flowers. These alleles show incomplete dominance (see Chapter 14). Because these are diploid organisms, there are a total of 1,000 copies of genes for flower color in the population of 500 individuals. The C R allele accounts for 800 of these genes (320 × 2 = 640 for C R C R plants, plus 160 × 1 = 160 for C R C W plants).

When there are two alleles at a particular locus, the convention is to use p to represent the frequency of one allele and q to represent the frequency of the other allele. Thus, p , the frequency of the C R allele in the gene pool of this population, is 800/1,000 = 0.8 = 80%. And because there are only two allelic forms of this gene, then the frequency of the C W allele, represented by q , must be 0.2, or 20%. At loci that have more than two alleles, the sum of all allele frequencies must still equal 1 (100%).

We can easily measure genetic variability at this flower–color locus because each genotype has a distinct phenotype. Although many loci in gene pools have more than one allele, this variability is usually less easy to quantify than in our flower example, because one allele may be completely dominant or the alleles may not have obvious effects on phenotypes.

Camobell and Reece

Answer 4

Look up peppered moth in wikipedia.
The moth comes in black and speckled brown (peppered) colours.
If a black moth rests on very dark bark, then it is more likely to not be seen by a hungry bird than a light coloured bird resting on the same bark. Vice versa for light coloured bark.
During the industrial age in London, more black forms existed, that is, the "black" allele survived more often, and had more offspring, because heavy coal pollution made tree bark darker. When pollution decreased due to more efficient engines etc, the tree bark became lighter, and the "speckled" allele increased in frequency.