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Ch. 25 - Quantitative Genetics and Multifactorial Traits
Chapter 24, Problem 17

Suppose you want to develop a population of Drosophila that would rapidly learn to avoid certain substances the flies could detect by smell. Based on the heritability estimate you obtained in Problem 16, do you think it would be worth doing this by artificial selection? Why or why not?

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span>Step 1: Understand the concept of heritability. Heritability is a measure of how much of the variation in a trait can be attributed to genetic differences among individuals in a population. It ranges from 0 to 1, where 0 means no genetic contribution and 1 means all variation is genetic.</span
span>Step 2: Recall the heritability estimate from Problem 16. This value will help determine the potential success of artificial selection. A high heritability suggests that the trait is largely influenced by genetics and can be effectively selected for.</span
span>Step 3: Consider the implications of a high heritability estimate. If the heritability is high, it indicates that the trait of learning to avoid certain substances is strongly influenced by genetics, making artificial selection a viable strategy.</span
span>Step 4: Evaluate the potential for rapid change. With a high heritability, the population can be expected to respond quickly to selection, as the genetic basis for the trait is strong.</span
span>Step 5: Make a decision based on heritability. If the heritability is low, it suggests that environmental factors play a larger role, and artificial selection may not be as effective. If high, it would be worth pursuing artificial selection to develop the desired trait.</span

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Heritability

Heritability is a measure of how much of the variation in a trait within a population can be attributed to genetic differences among individuals. It is expressed as a value between 0 and 1, where a higher value indicates a greater genetic contribution to the trait. Understanding heritability is crucial for predicting whether traits can be effectively altered through selective breeding.
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Calculating Heritability

Artificial Selection

Artificial selection is the process by which humans breed plants and animals for specific traits. This method relies on selecting individuals with desirable characteristics to reproduce, thereby increasing the frequency of those traits in future generations. Evaluating the feasibility of using artificial selection in Drosophila requires understanding the heritability of the learning behavior in question.
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Artificial Selection

Learning and Memory in Drosophila

Drosophila, or fruit flies, are widely used in genetic studies due to their relatively simple nervous system and well-understood genetics. They exhibit various forms of learning and memory, particularly in response to olfactory cues. Investigating the genetic basis of these behaviors can inform whether artificial selection could effectively enhance their ability to learn to avoid certain substances.
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Drosophila P Element
Related Practice
Textbook Question

A hypothetical study investigated the vitamin A content and the cholesterol content of eggs from a large population of chickens. The following variances (V) were calculated.

Which trait, if either, is likely to respond to selection? <>

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Textbook Question

In a herd of dairy cows the narrow-sense heritability for milk protein content is 0.76, and for milk butterfat it is 0.82. The correlation coefficient between milk protein content and butterfat is 0.91. If the farmer selects for cows producing more butterfat in their milk, what will be the most likely effect on milk protein content in the next generation?

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Textbook 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.

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Textbook Question

In a population of tomato plants, mean fruit weight is 60 g and h² is 0.3. Predict the mean weight of the progeny if tomato plants whose fruit averaged 80 g were selected from the original population and interbred.

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Textbook Question

In a population of 100 inbred, genotypically identical rice plants, variance for grain yield is 4.67. What is the heritability for yield? Would you advise a rice breeder to improve yield in this strain of rice plants by selection?

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Textbook Question

Many traits of economic or medical significance are determined by quantitative trait loci (QTLs) in which many genes, usually scattered throughout the genome, contribute to expression.

What general procedures are used to identify such loci?

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