Why is low genetic variability so bad for a population?

Low genetic variability is detrimental to a population because it reduces its ability to adapt to changing environmental conditions and increases vulnerability to diseases and parasites. With fewer genetic options, the population may struggle to survive under stressors such as climate change or habitat loss. This lack of diversity can also lead to inbreeding, which can further decrease fitness and reproductive success. Overall, low genetic variability undermines the resilience and long-term survival of the population.