Question

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.

Short answer

Question: Calculate the realized heritability for olfactory learning in Drosophila if the mean of the original population is 8.5 trials, the mean of the selected parents is 6.0 trials, and the mean of the offspring is 7.5 trials. Answer: The realized heritability for olfactory learning in Drosophila is 0.4 or 40%.

Step-by-step solution

Calculate the Response to Selection

To calculate the response to selection, subtract the mean of the offspring from the mean of the original population: Response to Selection = Mean of Offspring - Mean of Original Population Response to Selection = $7.5 - 8.5 \\ Response to Selection = -1$

Calculate the Selection Differential

To calculate the selection differential, subtract the mean of the selected parents from the mean of the original population: Selection Differential = Mean of Selected Parents - Mean of Original Population Selection Differential = $6.0 - 8.5 \\ Selection Differential = -2.5$

Calculate the Realized Heritability

Now, we can calculate the realized heritability using the formula: Realized Heritability (h^2) = (Response to selection) / (Selection differential) Plug in the values obtained in Steps 1 and 2 into the formula: Realized Heritability (h^2) = \((-1) / (-2.5)\) \\ Realized Heritability (h^2) = \(0.4\)

Interpret the Result

The realized heritability for olfactory learning in Drosophila is 0.4. This means that 40% of the variance in olfactory learning is due to genetic factors, while the remaining 60% is due to environmental factors or random chance.

Key concepts

Drosophila Learning

Drosophila, commonly known as fruit flies, are popular subjects for genetic research due to their simple genetic makeup and short reproduction cycles. In studies of Drosophila learning, scientists often assess how quickly these flies can learn to respond to different environmental cues, such as specific odors. The learning ability of Drosophila can be measured by the number of trials required for them to avoid certain olfactory cues.
In the context of the given exercise, the original population of Drosophila required a mean of 8.5 trials to learn this task. Scientists then selected a subgroup that learned more quickly, with a mean of 6.0 trials. By studying how the offspring of these selected fast learners performed, researchers are able to investigate the genetic basis behind learning abilities in Drosophila.

Selection Differential

The selection differential helps us understand the genetic differences between the original population and the subgroup chosen for breeding. It's a measure of how much the selected parents' performance differs from the overall population mean.
The selection differential is calculated as the difference between the mean of the selected subgroup and the mean of the original population. In the given exercise, it is -2.5. This negative value indicates that the selected group learned significantly faster than the average flies in the original population. Understanding selection differentials is key in evolutionary genetics, as it highlights the traits that are being preferentially propagated in future generations.

Response to Selection

The response to selection reflects how much the mean trait value in the offspring generation differs from the mean trait value in the original population. It shows the extent to which a particular trait, such as the ability to learn, has been passed down to the next generation.
In this case, the response is calculated as -1. This means the offspring of the selected fast learners showed an improved learning ability compared to the original population but were not as quick as their selected parents. This measure helps researchers understand the effectiveness of selection and the presence of genetic influences on the trait.

Genetic Variance

Genetic variance is a crucial concept when considering traits like learning ability in Drosophila. It encompasses the different genetic factors that contribute to the variation in a particular trait within a population. A high genetic variance indicates that there is a considerable potential for the trait to respond to selection.
In this exercise, the realized heritability of 0.4 indicates that 40% of the variation in olfactory learning can be attributed to genetics. This suggests a moderate genetic influence, meaning that there are significant genetic differences affecting the ability to learn, which can potentially be enhanced through selective breeding.