A poultry breeder recorded two phenotypic traits in a flock of domestic chickens: comb shape (single, pea, rose, or walnut) and body weight at maturity. Which of the following statements correctly categorizes these two traits based on their pattern of variation and underlying genetic control?
- Comb shape exhibits discontinuous variation controlled by major discrete genes, whereas body weight exhibits continuous variation influenced by polygenes and environmental factors.Answer
- BBoth comb shape and body weight exhibit continuous variation because both traits are influenced by environmental factors such as feed quality.
- CComb shape demonstrates continuous variation due to multiple allele interactions, whereas body weight exhibits discontinuous variation due to single-gene inheritance.
- DBoth comb shape and body weight demonstrate discontinuous variation because both traits fall into distinct phenotypic categories without intermediate forms.
Answer
Comb shape exhibits discontinuous variation controlled by major discrete genes, whereas body weight exhibits continuous variation influenced by polygenes and environmental factors.
The option stating that comb shape exhibits discontinuous variation controlled by major discrete genes while body weight exhibits continuous variation influenced by polygenes and environmental factors is correct. Comb shape is a qualitative trait displaying clear-cut, non-overlapping phenotypes (discontinuous variation) under the control of specific gene loci. In contrast, body weight is a quantitative trait exhibiting a smooth gradient of intermediate phenotypes (continuous variation) governed by multiple additive genes (polygenes) interacting with nutrition and environment.
Step-by-Step Solution
Key Concept
Continuous vs Discontinuous Variation and Genetic Control