Question

Key deer are found only on certain islands in the Florida Keys. Populations are typically small enough that genetic drift has caused significant deviation among populations on different islands. For example, the population on No Name Key has allele frequencies of A1 = 0.43 and A2 = 0.57 while the population on Big Pine Key has allele frequencies of A1 =0.21 and A2 = 0.79. Construction of roads has recently increased migration rates between these populations to approximately 0.08 per generation. What will the frequency of A1 be on Big Pine Key after a single generation of migration from No Name Key?

Answer 1

Answer:

The frequency of A1 be on Big Pine Key after a single generation of migration from No Name Keyp is 0.2276

Explanation:

Whenever it occurs migration between two populations, there is genetic flux going on. Genetic flux might be considered as an evolutive strength only if migration > 0 and if the allelic frequency in one generation is different from the allelic frequency in the next generation.  

Genetic flux acts homogenizing the allelic frequencies between the two populations, and it might introduce variability.

By knowing the allelic frequencies in both populations at a certain time and the migration rate, we can calculate the allelic frequencies of populations in the next generation. This is:

pA₂=pA₁(1-m)+pB₁ m

pB₂=pB₁(1-m)+pA₁ m

Being

• A one population and B the other population

• pA₁ and pB₁ the frequencies of the p allele before migration,

• pA₂and pB₂ the frequencies of the p allele after migration,
• m the migration rate

In the exposed example, we know that:

• No Name Key population allelic frequency: A1 = 0.43 and A2 = 0.57

• Big Pine Key population allelic frequency: A1 =0.21 and A2 = 0.79

• Migration rate m=0.08

Let´s say that p represents A1 allele, and q represents A2 allele.

The frequency of A1 allele (p) be on Big Pine Key (Population B) after a single generation of migration from No Name Key (Population A)

pB₂=pB₁(1-m)+pA₁ m

pB₂=0.21 x (1 - 0.08) + 0.43 x 0.08

pB₂= 0.2276

The allelic frequency in a population after one generation is the allelic frequency of individuals of that population that did not migrate (21 x  (1 - 0.08) plus the allelic frequency of the new individuals that came from the other population (0.43 x 0.08).

You can corroborate your result by calculating the q allele frequency in the next generation and summing both of them up. The result should be one.

qB₂= qB₁(1-m)+qA₁ m

qB₂= 0.79 x (1 - 0.08) + 0.57 x 0.08

qB₂= 0.7724

p + q = 1

0.2276 + 0.7724 = 1