In the lecture videos, which of the following traits was highlighted to demonstrate polygenic traits and the resulting spectrum of variation that occurs?

Question

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In this question, we’re asked to identify which trait was highlighted in the lecture videos to illustrate polygenic traits and the continuous variation seen across individuals.
Option 1: human weight, a trait that is impacted by a wide variety of gene interactions related to metabolism, fat storage, appetite, and hormones. This option aligns with the concept of polygenic traits because body weight is influenced by many genes that affect metabolism, energy balance, and appetite, producing a broad spectrum of variation. This matches the idea of multiple genetic contributions leading to continuous variation.
Option 2: eye color, where multiple genes on the same chromosome contribute to final eye color, causing a blending effect. While eye color is polygenic and involves several genes, the description of a blending effect on a single chromosome is an oversimplification and may imply simple blending rather than the complex polygenic gradation discussed in lectures. It is not the classic or primary example highlighted for broad polygenic variation.
Option 3: skin color, which is the result of different amounts of melanin, resulting in a spectrum of color from light to dark in the human species. This option directly exemplifies a classic polygenic trait with a continuous range of phenotypes due to the additive effects of many genes controlling melanin production and distribution. It is a textbook demonstration of polygenic inheritance and continuous variation.
Option 4: human height, which is influenced by a combination of genetic and environmental factors (like childhood nutrition and diseases) that determine whether a person meets their maximum height potential or not. Height is indeed polygenic and shows substantial continuous variation, and environmental factors modulate its expression. However, the question specifies the trait that was highlighted in the lecture to demonstrate polygenic traits and a spectrum of variation; while height fits, the phrasing suggests a more canonical example used in introductory discussion, such as skin color, which is often highlighted for its clear, continuous gradient.
Option 5: sickle cell anemia, a disorder that results in the abnormal production of hemoglobin. This is not polygenic in the same sense; it is a Mendelian disorder with a relatively simple genetic basis (single gene with a common mutation). It does not demonstrate a smooth spectrum of variation across individuals.
Option 6: intelligence, which is a complex interplay of genetic and environmental factors, influencing brain structure and function, leading to continuous variation in human populations. While intelligence involves many factors and exhibits a broad spectrum, it is also more controversial and multifactorial than the straightforward demonstration of polygenic inheritance typically presented in lecture clips, which usually relies on more concrete traits like skin color to illustrate additive gene effects.

Summary: Option 3 stands out as the most direct and widely used example in introductory discussions of polygenic traits and continuous variation due to multiple genes affecting melanin production, yielding a smooth spectrum of skin tones across humans. Other options describe polygenic influence or related concepts, but they either include environmental modulation, oversimplifications, or focus on traits less commonly used as the primary demonstration in lectures.

In the lecture videos, which of the following traits was highlighted to demonstrate polygenic traits and the resulting spectrum of variation that occurs?单项选择题

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