Recently Josh was doing a study on the genetic distribution of the trait for foo
ID: 34048 • Letter: R
Question
Recently Josh was doing a study on the genetic distribution of the trait for foot color in Boobies on the Galapagos Island. The pattern includes Blue (B) and yellow (R) alleles which are co-dominant, giving a stripped heterozygous condition. Pink (P) feet is recessive to both blue and yellow alleles.
Josh wanted to know if there had been selection occurring on Santiago Island verses Santa Cruz Island.
On Santa Cruz Island 3.5% of the population has pink feet and the frequency of yellow alleles is .28
On the island of Santiago the following data was collected
Blue Footed Boobies 236
Yellow Foote Boobies 89
Pink Footed Boobies 135
Striped Boobies 156
Is selection occurring on Santiago Island as compared to Santa Cruz Island?
If it is explain what the selection is.
Explanation / Answer
On santa cruz Island Data: 3.5 % or 0.35 is the frequency of recessive allele
.28 is for yellow allele.
On the island of Santiago the following data was collected
Blue Footed Boobies 236 Frequency = 236/ 616 = .38
Yellow Foote Boobies 89
Pink Footed Boobies 135
Striped Boobies 156
The frequency of blue allele (B) is maximum on the island of Santiago , When some component of a trait is heritable, selection will alter the frequencies of the different alleles, or variants of the gene that produces the variants of the trait. Directional selection occurs when a certain allele has a greater fitness than others, resulting in an increase of its frequency. This process can continue until the allele is fixed and the entire population shares the fitter phenotype.
In population genetics, directional selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under directional selection, the advantageous allele increases as a consequence of differences in survival and reproduction among different phenotypes. The increases are independent of the dominance of the allele, and even if the allele is recessive, it will eventually become fixed.
It is easily recognizable by its distinctive bright blue feet, which is a sexually selected trait. Males display their feet in an elaborate mating ritual by lifting their feet up and down while strutting before the female. The female is slightly larger than the male and can measure up to 90 cm (36 in) long with a wingspan of up to 1.5 m (4.9 ft).
Thus blue footed boobies are directionally and sexually selected allele .
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