What does the term "bottleneck effect" refer to in evolutionary biology?

The term "bottleneck effect" in evolutionary biology specifically refers to a sharp reduction in population size due to environmental events, such as natural disasters (e.g., earthquakes, floods) or human activities (e.g., habitat destruction, overhunting). When a population experiences such a dramatic decrease, it typically results in a loss of genetic diversity because only a limited number of individuals survive to repopulate. This reduced genetic variation can impact the population’s ability to adapt to environmental changes or pressures, leading to long-term effects on the population's evolutionary trajectory. The bottleneck effect highlights how random events can significantly influence the genetic composition of future generations, often resulting in a population that is less resilient to new challenges.