In an assessment of learning in Drosophila, flies were trained to avoid certain olfactory cues. In one population, a mean of 8.5 trials was required. A subgroup of this parental population that was trained most quickly (mean=6.0) was interbred, and their progeny were examined. These flies demonstrated a mean training value of 7.5. Calculate realized heritability for olfactory learning in Drosophila.

Verified step by step guidance

1. Identify the key variables in the problem: the parental population mean (\( \bar{P} = 8.5 \)), the selected subgroup mean (\( \bar{S} = 6.0 \)), and the progeny mean after selection (\( \bar{O} = 7.5 \)).
2. Calculate the selection differential (\( S \)) using the formula: \[ S = \bar{S} - \bar{P} \] This represents the difference between the mean of the selected parents and the original population mean.
3. Calculate the response to selection (\( R \)) using the formula: \[ R = \bar{O} - \bar{P} \] This represents the difference between the progeny mean and the original population mean.
4. Use the formula for realized heritability (\( h^2 \)) which is the ratio of the response to selection over the selection differential: \[ h^2 = \frac{R}{S} \]
5. Substitute the values of \( R \) and \( S \) into the heritability formula to find the realized heritability for olfactory learning in \emph{Drosophila}.

Key Concepts

Realized Heritability

Realized heritability measures the proportion of phenotypic variation in a trait that is due to additive genetic factors, estimated from selection experiments. It is calculated as the ratio of the response to selection (R) to the selection differential (S), indicating how much of the selected trait is passed to the next generation.

Selection Differential (S)

The selection differential is the difference between the mean phenotype of the selected parents and the mean phenotype of the original population. It quantifies the strength of selection applied and is essential for calculating realized heritability.

Response to Selection (R)

Response to selection is the difference between the mean phenotype of the offspring generation and the mean phenotype of the original population. It reflects the genetic change achieved after selection and is used alongside the selection differential to estimate heritability.