When a trait is highly heritable, ________.
a. It is influenced by genes
b. It is not influenced by the environment
c. The variance of the trait in a population can be explained primarily by variance in genotypes
d. A and C are correct
e. A, B, and C are correct

Verified step by step guidance

1. Understand the concept of heritability: Heritability refers to the proportion of phenotypic variance in a population that is attributable to genetic variance. It does not apply to individuals but rather to populations.
2. Analyze option (a): If a trait is highly heritable, it is influenced by genes. This is correct because heritability measures the genetic contribution to the trait's variation.
3. Analyze option (b): Consider whether the environment influences highly heritable traits. High heritability does not mean the environment has no influence; it means genetic factors explain most of the variation in the population.
4. Analyze option (c): High heritability implies that the variance of the trait in a population can be explained primarily by variance in genotypes. This is correct because heritability quantifies the genetic contribution to phenotypic variance.
5. Combine the correct options: Based on the analysis, options (a) and (c) are correct, but option (b) is not. Therefore, the correct answer is (d), 'A and C are correct.'

Key Concepts

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 influence. Importantly, heritability does not indicate the extent to which a trait is determined by genes in an individual, but rather how much genetic factors contribute to differences in the trait across a population.

Environmental Influence

Environmental influence refers to the impact that external factors, such as nutrition, climate, and social interactions, have on the expression of traits. While heritable traits are influenced by genetics, environmental factors can also play a significant role in shaping phenotypes. Understanding the balance between genetic and environmental contributions is crucial for interpreting heritability estimates.

Genotype-Phenotype Relationship

The genotype-phenotype relationship describes how the genetic makeup (genotype) of an organism interacts with environmental factors to produce observable traits (phenotype). In cases of high heritability, the variation in phenotypes within a population is largely explained by differences in genotypes, suggesting that genetic factors are the primary drivers of trait expression. This concept is essential for understanding the implications of heritability in evolutionary biology and genetics.