Inferring genetic differences
Genetic diversity refers to the variety of different alleles of genes. It can be investigated indirectly by comparing the frequency of measurable or observable characteristics.
This method does not examine the DNA itself. Differences in characteristics are instead used as evidence from which genetic differences may be inferred.
| Type of characteristic | Examples |
|---|---|
| Measurable | Numbers of legs, seeds in a berry, petals, or indentations on a leaf. |
| Observable | Colour, patterns on fur, scales or feathers, habitat, or the presence of hair, wings or fins. |
Limitations
Comparing characteristics is relatively quick, but it gives less precise evidence of genetic diversity than comparing molecular sequences directly.
- One feature may occur in many different organisms, so a single characteristic may give poor discrimination.
- A characteristic that is distinctive to a particular group can still be useful.
- Measurable features can sometimes distinguish organisms that appear very similar from simple observation.
- Phenotype can be influenced by both genes and environmental conditions, so phenotypic differences do not always indicate DNA differences.
Exam Tip: When evaluating this approach, describe characteristics as indirect evidence of genetic differences. Do not assume that every phenotypic difference must result from a difference in DNA.