Vulnerable species are often characterized by what trait?

Vulnerable species are often characterized by small population sizes, which is a significant factor in their risk of extinction. Small populations can be more susceptible to various threats, including habitat loss, climate change, disease, and random events that may disproportionately affect them, such as natural disasters. The genetic diversity within small populations is typically reduced, leading to inbreeding and a decrease in resilience against environmental pressures.

In contrast, high reproductive rates allow species to recover more rapidly from declines, while limited geographic distribution can be a vulnerability but does not encompass the broader range of risks faced by small populations. Environmental adaptability refers to a species' ability to adjust to changes in their habitat or climate, which can enhance survival chances and is not inherently tied to a species' vulnerability. Therefore, focusing on small population sizes provides a clear understanding of why a species might be at risk, reflecting on the challenges they face in sustaining their numbers over time.