Populations have a genetic variation among individuals and that is important to the populations ability to survive in different situations that have an affect on the natural selection. There are different factors which can increase or decrease the genetic diversity, and influencing natural selection. These factors can include an environmental factor, one of the major factors, which can cause changes in the genetic variation of a population and influence the natural selection. A famous and important example of the environmental factors affecting natural selection was made during the industrial revolution when many more gray moths made up the moth population. This was so that they could blend in with the soot from factories to avoid predators.
Genotypes of the dog color are:
BB dominant homozygous-brown phenotype
bb recessive homozygous-white phenotype
Bb heterozygous-tan phenotype
Cross between brown and pan dog would be:
P: BB x Bb
F1: BB Bb BB Bb
The ratio would be 1:1 (brown dog:pan dog).
Answer:
The first male was bb Ee, and the second male was bb EE.
Explanation:
In Labradors coat colour is controlled by two genes. Suppose the two genes are B and E. B produces black colour and recessive form bb gives brown colour. Gene E is epistatic over gene B in its recessive form which means that ee will produce yellow colour regardless of the genotype present of B gene.
The first case is possible if the female lab is bbee (yellow) and the male lab is bbEe (brown):
bbee X bbEe
bE be
be bbEe bbee
So half of the offspring will be brown (bbEe) and half of them will be yellow (bbee)
The second case is possible if the same female bbee mates with a brown male of different genotype which can be bbEE:
bbee X bbEE
bE
be bbEe
So all offspring will be brown (bbEe)
Hence, the first male was bbEe and the second male was bbEE.
