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home / study / math / statistics and probability / statistics and probability questions and answers / dr. francis has determined the sequence of a gene from four fish species. below, it is described ... Question: Dr. Francis has determined the sequence of a gene from four fish species. Below, it is described ... Dr. Francis has determined the sequence of a gene from four fish species. Below, it is described a segment of the sequence of this gene for the 4 species (NA-Sp, North Atlantic species; SA-Sp, South Atlantic species; Pc-Sp, Pacific species; Md-Sp,Mediterranean species). The letters below the codons are the amino acids encoded.

Answer 1

I think below image has the complete question that you want to ask.

Answer:

a-1)Between NA-Sp and SA-Sp

I have shown here in the picture how to calculate the differnces in the synonymous and non-synonymous site between two sequence.Please take a look

Similarly, i have calculated the differences below for all the pairs

2) Between NA-Sp and PC-Sp

No. of non-synonymous differences = 2

No. of synonymous difference = 4

3) Between NA-Sp and MD-Sp

No. of non-synonymous differences = 5

No. of synonymous difference = 6

4) Between SA-Sp and PC-Sp

No. of non-synonymous differences = 1

No. of synonymous difference = 4

5) Between SA-Sp and MD-Sp

No. of non-synonymous differences = 4

No. of synonymous difference= 6

6)  Between PC-Sp and MD-Sp

No. of non-synonymous differences = 3

No. of synonymous difference = 6

b) Total number of non-synomynous sites between any two sequence = 24

Total number of synomynous sites between any two sequence =12

*Here, were are going to divide the number of differences (non-synonymous/synonymous) by total number of sites (non-synonymous/synonymous).

1) Between NA-Sp and SA-Sp

Ds (Synonymous) = 1/12 = 0.083 = 8.3%

Da (Non-synonymous) = 1/24 = 0.04 =4%

2)Between NA-Sp and PC-Sp

Ds (Synonymous) = 4/12= 0.3 = 30%

Da (Non-synonymous) =2/24 = 0.08 = 8%

3)Between NA-Sp and MD-Sp

Ds (Synonymous) =6/12 = 0.5 =50%

Da (Non-synonymous) = 5/24 = 0.20 =20%

4)Between SA-Sp and PC-Sp

Ds (Synonymous) = 4/12= 0.3 =30%

Da (Non-synonymous) = 1/24 =0.04 = 4%

5)Between SA-Sp and MD-Sp

Ds (Synonymous) =6/12 = 0.5 = 50%

Da (Non-synonymous) = 4/24 = 0.16 = 16%

6)  Between PC-Sp and MD-Sp

Ds (Synonymous) = 6/12 = 0.5 = 50%

Da (Non-synonymous) = 3/24 =0.125 = 12.5%

c)Between NA-Sp and SA-Sp

Ds (Synonymous) = 1/12 = 0.083 = 8.3%

Da (Non-synonymous) = 1/24 = 0.04 = 4%

we will multiply the non-synonymous sites with 10, because of its non-synonymous changes only , the two species diverge.

Their divergence time = 4*10 = 40 Million year ago

So, the two species have diverged about 40 million years ago.

Hope it helps, Good luck !!!!
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