Ecads and ecotypes are key concepts in plant ecology and population genetics, distinguishing phenotypic variations based on genetic and environmental factors. The correct answer to the query is option (3): Statement I is true but Statement II is false.

Statement Analysis

Statement I: Ecads of same species are genetically similar and interfertile.
Ecads (or ecophenes) arise from phenotypic plasticity due to environmental influences, without genetic changes. They remain genetically identical to the parent population and can interbreed freely, producing viable offspring.​

Statement II: Ecotypes are genetically different and are not interfertile.
Ecotypes result from genetic divergence via natural selection in distinct habitats, making them genotypically different. However, they stay interfertile as variants of the same species, unlike subspecies.

Option Breakdown

• (1) Both true: Incorrect, as Statement II wrongly claims ecotypes lack interfertility.​

• (2) Both false: Incorrect, since Statement I holds true for ecads.​

• (3) I true, II false: Correct, matching definitions where ecotypes differ genetically but interbreed.

• (4) I false, II true: Incorrect, as ecads are genetically similar and interfertile.​

Ecads of same species are genetically similar and interfertile due to environmental plasticity, while ecotypes represent genetic adaptations yet remain interfertile. This distinction is crucial for exams like GATE Life Sciences.

What Are Ecads?

Ecads, or ecophenes, show morphological changes (e.g., prostrate vs. erect forms in Euphorbia hirta) from habitat stress but share identical genotypes. They interbreed seamlessly with the original population.​

Defining Ecotypes

Ecotypes, like red (calcicole) and green (calcifuge) forms in Primula veris, evolve genetic differences through selection (e.g., dominant vs. recessive alleles). Despite this, they are interfertile within the species.

Key Differences Table