Investigating diversity

Ways in which genetic diversity of a species can be measured

‣ Comparing differences in the base sequence of DNA.

‣ Comparing differences in the base sequence of mRNA.

‣ Comparing amino acid sequences of the same protein.

‣ Comparing observable characteristics.

Why is comparing the DNA sequence more useful than comparing the amino acid sequence?

‣ Triplet code is degenerate, so just because two species have the same/similar amino acid sequence → doesn’t mean that their DNA sequences are the same.

‣DNA sequence provides information on non-coding sequences e.g. introns.

What is a disadvantage

of inferring DNA

differences from

observable

characteristics?

‣ Characteristics are often polygenic (coded for by more than one gene).

‣ Characteristics can be modified by environmental factors e.g. diet, climate.

Standard deviation

‣ A measure of the spread of values about the mean.

‣ Large standard deviation means that the values in the sample varied a lot.

‣ If standard deviations overlap, this is an indication that there is NO significant difference between those means (although a statistical test would be needed to confirm).

‣ Standard deviation is a better measure of spread than the range because standard deviation is less affected by extreme values.