Genetic Diversity
மரபணு பன்முகத்தன்மை
Genetic diversity is not just variety; it is the biological insurance policy of a species. If a population lacks allelic variation, a single pathogen can wipe out the entire gene pool. Do not confuse this with species diversity.
The idea
Genetic diversity refers to the variation of genes within a single species across its distributional range. For example, the medicinal plant Rauwolfia vomitoria exhibits variations in the potency and concentration of the active chemical reserpine. India demonstrates this on a massive scale with over 50,000 genetically distinct strains of rice and 1,000 varieties of mango.
Why it matters
Genetic variation allows a species to adapt to changing environments and ensures the survival of the population against diseases or environmental stress.
NEET lens
NEET examiners frequently swap 'Genetic Diversity' with 'Species Diversity' in MCQs. Memorize the specific examples: Rauwolfia vomitoria (reserpine), 50,000 rice strains, and 1,000 mango varieties. Expect a 'Match the Following' or a 'Statement-based' question on these exact figures.
Clinical significance
Low genetic diversity leads to inbreeding depression, increasing the expression of deleterious recessive alleles. In humans, this manifests as an increased incidence of congenital disorders and reduced immune competence. Ecosystems with low genetic diversity lack the adaptive capacity to survive environmental stressors.
Introduction
Genetic diversity is the diversity within a species — a single species might show high diversity at the genetic level over its distributional range.
Core concept
Examples (NCERT): the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges shows genetic variation in terms of the potency and concentration of the active chemical (reserpine) it produces. India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango. Genetic diversity allows populations to adapt to changing environments and is the basis for crop improvement.
Go deeper
Loss of genetic diversity (e.g. when only a few high-yielding varieties are grown everywhere) makes crops vulnerable to new diseases.
From Class 10
All mangoes are one species, yet there are hundreds of kinds — Alphonso, Banganapalli, Neelam. That variety within one species is genetic diversity.