Traits in Dolphins: Curvy-Tipped Flippers vs. Pointy-Tipped Flippers
Tips for Hardy-Weinberg
The key to getting these questions right is to know your genetic vocabulary and to know your math…
The following examples will be based on a dolphin population in which the trait being studied is curvy-tipped flippers versus pointy-tipped flippers. In each individual, the trait is coded for by TWO alleles. In the population, one of the alleles is dominant and one is recessive. Individuals with two dominant alleles (homozygous dominant) have curvy-tipped flippers and individuals with two recessive alleles (homozygous recessive) have pointy-tipped flippers. Heterozygotes have curvy-tipped flippers.
Let’s say the question asks you about the dominant allele… it could say, “the frequency of the dominant allele in the population is”… or it could say, “p is”... This is asking about the individual GENES in the population, not about the individuals.
If the question gives you information about the homozygous dominant individuals, then it could say, “p2 is…” or “the percent of the population that is homozygous for the dominant allele…” (genotype) or the “percent of the population that is homozygous for curvy-tipped flippers” (subset of one phenotype). This is asking about individuals in the population, NOT about the individual GENES.
If you are talking about recessive genes or individuals, the above is all true as well…
Recessive allele in population = q; frequency of the recessive allele
Homozygous recessive individuals = q2 = percent of the population homozygous for the recessive allele = percent of the population with pointy-tipped flippers. NOTE: in this case I don’t have to specifically say that the pointy-tipped flipper dolphins are homozygous… the only way you can have a phenotype for a recessive trait is if you have two recessive alleles.
The only other scenario is that the question could ask at the end for you to tell me the percent or frequency of individuals in the population who are heterozygotes, or the individuals who have the
The key to getting these questions right is to know your genetic vocabulary and to know your math…
The following examples will be based on a dolphin population in which the trait being studied is curvy-tipped flippers versus pointy-tipped flippers. In each individual, the trait is coded for by TWO alleles. In the population, one of the alleles is dominant and one is recessive. Individuals with two dominant alleles (homozygous dominant) have curvy-tipped flippers and individuals with two recessive alleles (homozygous recessive) have pointy-tipped flippers. Heterozygotes have curvy-tipped flippers.
Let’s say the question asks you about the dominant allele… it could say, “the frequency of the dominant allele in the population is”… or it could say, “p is”... This is asking about the individual GENES in the population, not about the individuals.
If the question gives you information about the homozygous dominant individuals, then it could say, “p2 is…” or “the percent of the population that is homozygous for the dominant allele…” (genotype) or the “percent of the population that is homozygous for curvy-tipped flippers” (subset of one phenotype). This is asking about individuals in the population, NOT about the individual GENES.
If you are talking about recessive genes or individuals, the above is all true as well…
Recessive allele in population = q; frequency of the recessive allele
Homozygous recessive individuals = q2 = percent of the population homozygous for the recessive allele = percent of the population with pointy-tipped flippers. NOTE: in this case I don’t have to specifically say that the pointy-tipped flipper dolphins are homozygous… the only way you can have a phenotype for a recessive trait is if you have two recessive alleles.
The only other scenario is that the question could ask at the end for you to tell me the percent or frequency of individuals in the population who are heterozygotes, or the individuals who have the