Multiple Choice
Which of the following is an example of a trait that could be present in a newt population as described in studies of genetic variance?
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20. Quantitative Genetics
Traits and Variance
Multiple Choice
In the context of traits and variance, which statement best distinguishes a single-gene (Mendelian) trait from a polygenic trait?
A
Polygenic traits are controlled by one gene with many alleles, whereas single-gene traits are controlled by many genes with two alleles each.
B
Single-gene traits typically show discrete phenotypic categories, whereas polygenic traits usually show continuous variation due to the additive effects of many genes.
C
Single-gene traits always have higher heritability than polygenic traits because environmental effects are negligible for Mendelian traits.
D
Polygenic traits cannot be influenced by the environment, whereas single-gene traits are strongly influenced by environmental variation.
Verified step by step guidance1
Understand the difference between single-gene (Mendelian) traits and polygenic traits: Single-gene traits are controlled by one gene, often resulting in distinct phenotypic categories (e.g., pea color in Mendel's experiments).
Recognize that polygenic traits are influenced by multiple genes, each contributing a small additive effect, which leads to continuous variation in the phenotype (e.g., human height or skin color).
Recall that single-gene traits typically show discrete phenotypic classes because the presence of specific alleles leads to clear-cut outcomes, while polygenic traits show a range of phenotypes due to the combined effect of many genes.
Consider the role of environmental influence: polygenic traits often show variation influenced by both genetics and environment, whereas single-gene traits may be less affected by environment but not necessarily negligible.
Evaluate the given statements by matching these concepts: the correct distinction is that single-gene traits show discrete categories, and polygenic traits show continuous variation due to additive gene effects.
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