In a randomly wind-pollinated population of 1000 redwoods, the G locus affects t

Question

In a randomly wind-pollinated population of 1000 redwoods, the G locus affects the development of seedlings. Gg seedlings have the highest fitness. GG seedlings survive 70% as well as do the Gg seedlings. gg seedlings survive 25% as well as the Gg seedlings. The allele frequency of "g" at the start of a generation is 0.85.

a) What will the allele frequency of "g" be at the start of the next generation?

b) Consider a different redwood population with the same "G" and "g" alleles. The fitnesses are all the same as they were for the population in part (a), but in this population, the allele frequency of "g" at the start of a generation is 0.01. What will the allele frequency of "g" be at the start of the next generation?

c) What do you think will happen to the frequency of "g" in these redwood population over time (e.g. will either become fixed or lost? Will either increase or decrease?). Please explain

Explanation / Answer

Relative fitness of Gg (W Gg) = 1

Relative fitness of GG (W GG) = 70% (0.7) and

Relative fitness of gg (W gg) = 25% (0.25)

The allele frequency of g (q) = 0.85

q 2 = 0.7225

So, the allele frequency of G (p) = 1-q = 1-0.85 = 0.15

p 2 = 0.0225

Average fitness, W = p2WGG + 2pq(WGg) + q2Wgg

= 0.0225(0.7) + 2(0.15)(0.85)(1) + 0.7225(0.25)

= 0.01575 + 0.255 + 0.180625

= 0.451

a) Frequency of "g" at the start of next generation,

= q2Wgg/W + pqWGg/W

= 0.7225(0.25)/0.451 + (0.15)(0.85)(1)/0.451

= 0.4 + 0.28

= 0.68

The frequency of allele,"g" at the start of next generation is 0.68

b) Allele frequency g (q) = 0.01

So,allele frequency G (p) = 0.99

Average fitness

Average fitness, W = p2WGG + 2pq(WGg) + q2Wgg

= 0.98(0.7) + 2(0.99)(0.01)(1) + 0.0001(0.25)

= 0.686 + 0.019 + 0.000025

= 0.705

Frequency of "g" at the start of next generation,

= q2Wgg/W + pqWGg/W

= 0.0001(0.25)/0.705 + (0.99)(0.01)(1)/0.705

= 0.00003 + 0.014

= 0.014

c) The frequency of "g" in redwood population would decrease over time due to difficulty in survival.

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