"Genetic erosion caused by human activities is a threat to agriculture" — Comment.

What is Genetic Erosion?

Genetic erosion refers to the reduction in the genetic variability within a species. This loss can occur within a wild species or within a cultivated crop. It’s a gradual process, but its consequences can be abrupt and devastating for food security and ecosystem stability.

Causes of Genetic Erosion - Human Activities

• Modern Agriculture Practices: The widespread adoption of high-yielding varieties (HYVs) has led to the replacement of traditional, locally adapted varieties. This reduces the gene pool available for future breeding and adaptation.
• Habitat Loss and Fragmentation: Conversion of natural habitats for agriculture reduces the areas where wild relatives of crops can persist, leading to loss of valuable genetic resources.
• Over-Exploitation of Wild Relatives: Unsustainable harvesting practices can deplete populations of wild relatives, which serve as a crucial source of genetic material.
• Climate Change: Shifting climate patterns can render some varieties unsuitable for cultivation, leading to their abandonment and loss.
• Globalization & Monoculture: The increasing trend of monoculture farming – cultivating a single crop over a large area – reduces genetic diversity and increases vulnerability to pests and diseases.

Consequences of Genetic Erosion

The consequences of genetic erosion are far-reaching:

• Reduced Food Security: A narrow genetic base makes crops more susceptible to pests, diseases, and climate change, threatening food production.
• Loss of Traditional Knowledge: The disappearance of traditional varieties often means the loss of associated indigenous knowledge about their cultivation and uses.
• Decreased Resilience: Less genetic diversity reduces the ability of crops to adapt to changing environmental conditions.
• Impact on Biodiversity: Loss of crop wild relatives diminishes overall biodiversity and ecosystem services.

Mitigation Strategies

Addressing genetic erosion requires a multi-pronged approach:

• Conservation of Traditional Varieties: Supporting farmers who cultivate traditional varieties and establishing gene banks to preserve seeds. India’s National Gene Bank at IARI, New Delhi is crucial.
• Promoting Crop Diversification: Encouraging farmers to grow a wider range of crops to enhance genetic diversity and reduce vulnerability.
• On-Farm Conservation: Integrating conservation efforts into farming practices, such as maintaining refugia of traditional varieties.
• Strengthening ex situ Conservation: Maintaining seed banks and botanical gardens to preserve genetic resources.
• Supporting Indigenous Knowledge: Recognizing and valuing the knowledge of traditional farmers about crop varieties and their adaptation.

Case Study: The Rice Diversity of Assam

Assam, India, is a biodiversity hotspot for rice. However, the introduction of high-yielding varieties has led to the decline of many traditional rice landraces, each possessing unique traits like disease resistance and drought tolerance. Initiatives like the "Rice Diversity Block" in community fields are attempting to conserve these varieties and revive traditional farming practices. The outcome is a localized resurgence of biodiversity and increased resilience against climate change.

Aspect	Pre-Green Revolution	Post-Green Revolution
Genetic Diversity	High	Low
Crop Yield	Lower	Higher
Vulnerability to Pests/Diseases	Lower	Higher