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Ch. 19 - Genetic Analysis of Quantitative Traits
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 19 - Genetic Analysis of Quantitative TraitsProblem 1e
Chapter 19, Problem 1e

Which of the following traits would you expect to be inherited as quantitative traits?
Coat color in dogs

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Understand the concept of quantitative traits: Quantitative traits are traits that are influenced by multiple genes (polygenic inheritance) and often show a continuous range of variation, such as height, weight, or skin color. These traits are also influenced by environmental factors.
Determine if coat color in dogs could be a quantitative trait: Coat color in dogs can be influenced by multiple genes, such as those controlling pigment production, pigment distribution, and patterning. This suggests that coat color may exhibit polygenic inheritance.
Consider the variation in coat color: If coat color in dogs shows a wide range of shades and patterns (e.g., black, brown, white, brindle, merle), this supports the idea that it is a quantitative trait.
Evaluate the role of environmental factors: Quantitative traits are often influenced by the environment. For example, the appearance of coat color might be affected by factors like sunlight exposure or nutrition, further supporting its classification as a quantitative trait.
Conclude based on the evidence: Based on the polygenic inheritance, the continuous variation in coat color, and potential environmental influences, coat color in dogs is likely to be inherited as a quantitative trait.

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Key Concepts

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

Quantitative Traits

Quantitative traits are characteristics that are influenced by multiple genes and can be measured on a continuous scale, such as height, weight, or coat color. Unlike qualitative traits, which are typically determined by a single gene and exhibit distinct categories, quantitative traits show a range of phenotypes due to the additive effects of several alleles.
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Polygenic Inheritance

Polygenic inheritance refers to the phenomenon where multiple genes contribute to a single trait. Each gene may have a small effect on the phenotype, and the cumulative impact of these genes results in the continuous variation observed in traits like coat color in dogs, which can range from light to dark shades.
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Environmental Influence

Environmental factors can significantly affect the expression of quantitative traits. For example, the coat color in dogs may not only be determined by genetic factors but also influenced by environmental conditions such as temperature, nutrition, and exposure to sunlight, leading to variations in the phenotype that are not solely attributable to genetics.
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Related Practice
Textbook Question

For the traits listed in the previous problem, which do you think are likely to be multifactorial traits, with phenotypes that are influenced by genes and environment? Identify two environmental factors that might play a role in phenotypic variation of the traits you identified.

Textbook Question

Which of the following traits would you expect to be inherited as quantitative traits?

Growth rate in sheep

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Textbook Question

Which of the following traits would you expect to be inherited as quantitative traits?

Milk production in cattle

Textbook Question

Compare and contrast broad sense heritability and narrow sense heritability, giving an example of each measurement and identifying how the measurement is used.

Textbook Question

In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams (g) of fruit weight in the F₁ is 2.25 g and the variance among the F₂ is 5.40 g. Determine the genetic and environmental variance (VG and VE) for the trait and the broad sense heritability of the trait.

Textbook Question

Which of the following traits would you expect to be inherited as quantitative traits?

Fruit weight in tomatoes