Understanding Genetic Erosion
Genetic erosion refers to the loss of genetic diversity within a species, particularly in agricultural crops. This phenomenon can occur due to various factors, including deforestation, shifting cultivation, and the adoption of genetically uniform varieties. Let’s explore how each of these contributes to genetic erosion.

Deforestation
- Deforestation leads to habitat loss, which can diminish the number of plant and animal species in a region.
- The destruction of forests affects the genetic diversity of wild relatives of crops, which are crucial for breeding programs and resilience against pests and diseases.

Shifting Cultivation
- Shifting cultivation involves the practice of rotating fields to maintain soil fertility.
- While it can be sustainable, if done unsustainably, it may lead to land degradation and a decline in diverse plant species that local communities rely on, thus reducing genetic variation.

Adopting Genetically Uniform Varieties
- The widespread adoption of genetically uniform crop varieties aims for high yields and disease resistance but reduces genetic diversity.
- This uniformity makes crops more vulnerable to pests and diseases, as a single pathogen can potentially wipe out large areas of crops.

Conclusion
- The combination of these factors results in a significant decline in genetic diversity, which is vital for food security and ecosystem resilience.
- Thus, the correct answer being option 'D', encompasses all these practices that contribute to genetic erosion, highlighting the need for sustainable agricultural practices to preserve biodiversity.

Genetic erosion is a process, where by an already limited gene pool of an endangered species of plant and animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population


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