Your descendants have fortunately inherited your fascination with rodent genetics
Fifty
thousand years after the original volcanic eruption (a vicariance, or vicariant event), your
descendants return to the island and repeat the same sampling and DNA sequencing
strategy.
DNA SEQUENCE TABLE
* * * * * * * * * * * *
AACGT TCGAT GCCTT AGCCC TGACT ATGGT CAGTA CGTAC TTCGC
Above is a sequence of the mtDNA region analyzed. The 12 stars mark the 12 nucleotide
sites that vary among the individuals sequenced. Note that most of the nucleotide sites are
the same across all individuals sampled. In presenting the sequences of five randomly
selected individuals below, we show only the base pairs at each of the 12 variable sites.
Initial population, before the volcanic eruption
Population A T=0
1. AATGCCGGACGT
2. AAAGGCGGACGT
3. AATGGCGGACGT
4. AATGCCGGTCGT
5. AAAGCCGGACGT
T=0 after vicariant event
Population A1 Population A2
1. AATGCCGGACGT 1. AATGCCGGACGT
2. AAAGGCGGACGT 2. AAAGGCGGACGT
3. AATGGCGGACGT 3. AATGGCGGACGT
4. AATGCCGGTCGT 4. AATGCCGGTCGT
5. AAAGCCGGACGT 5. AAAGCCGGACGT
T = 50,000 years after the vicariant event
Two fixed differences between A1 and A2
1. AATGCCGGACGA 1. AATGCCGGCCGT
2. AAAGGCGGACGA 2. AAAGGCGGCCGT
3. AATGGCGGACGA 3. AATGGCGGCCGT
4. AATGCCGGTCGA 4. AATGCCGGCCGT
5. AAAGCCGGACGA 5. AAAGCCGGCCGT
T = 100,000 years after the vicariant event
Four fixed differences between A1 and A2
1. AATGCCGGACGA 1. AATGGCGGTCGT
2. AAAGCCGGACGA 2. AAAGGCGGTCGT
3. AATGCCGGACGA 3. AATGGCGGTCGT
4. AATGCCGGACGA 4. AATGGCGGTCGT
5. AAAGCCGGACGA 5. AAAGGCGGTCGT
***If you have population sequence data from an actual gene this could also be used to talk
about specific mutation patterns in that specific gene. Alternatively you could also supply
SNP data over time to help students better understand different types of markers used with
many genomic level studies. This decision is up to the instructor. Many don't discuss SNP
data in their course, so the example could be used as is.
Their data indicate there is no reproductive isolation between members of A1 and A2.
Compare the DNA sequences presented above and give the amount of variation expected:
...between two randomly chosen individuals of A2.
A. relatively low variation
B. moderate variation
C. relatively high variation
A
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