Compare allele frequencies

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or browser document; an ordinary calculator is optional.
• Rule: Allele percentage equals 100 times focal copies divided by twice individual count. Formula: 100*a/(2*b). Variable key: a = focal allele copies, b = diploid individuals
• Distinct worked inputs and result: A distinct diploid model has 10 focal copies among 20 individuals: 100×10/40=25%.
• Assessment case 1: Supplied case 1: focal allele copies=12; diploid individuals=20, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?
• Assessment case 2: Supplied case 2: focal allele copies=18; diploid individuals=30, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?
• Assessment case 3: Supplied case 3: focal allele copies=20; diploid individuals=25, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?
• Assessment case 4: Supplied case 4: focal allele copies=24; diploid individuals=40, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?
• Assessment case 5: Supplied case 5: focal allele copies=30; diploid individuals=50, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?
• Assessment case 6: Supplied case 6: focal allele copies=36; diploid individuals=45, using the explicitly named quantities. Allele percentage equals 100 times focal copies divided by twice individual count. What result follows?

Learn the idea

Allele frequency is allele copies divided by total copies at the locus. The supplied fictional population is diploid, so each individual contributes two copies; the lesson does not assume all species are diploid.

Allele percentage equals 100 times focal copies divided by twice individual count. The formula in the supplied model is 100*a/(2*b). Variable key: a = focal allele copies, b = diploid individuals. Use two allele copies per stated diploid individual. Individuals and allele copies are different counts.

A distinct diploid model has 10 focal copies among 20 individuals: 100×10/40=25%. Frequency change does not by itself identify a mechanism. Track the quantity and unit before calculating. Explain the meaning of a positive, negative or fractional result when relevant. A numerical answer supports the stated model calculation; broader claims require the additional measurements and assumptions described here.

1. Name the measured quantities and their units before substituting values.
2. Write the stated rule and use the variable key to match each symbol to its explicitly named quantity.
3. Calculate each supplied case separately, keeping intermediate arithmetic and the result unit.
4. Explain the result in context and identify the assumption that would invalidate direct use of the rule.

Check your reasoning

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Take it further

Changed-input task: use the same stated model with focal allele copies=13; diploid individuals=20. Expected result: 32.5 %. Explain what changes and keep this assumption: Frequency change does not by itself identify a mechanism.

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