Define 'biodiversity hotspot.'

A biodiversity hotspot is defined as a region that is both biologically rich and threatened. This concept is significant in conservation biology, as it identifies areas that are not only home to a large number of unique species but also face substantial risks from human activities or environmental changes. By emphasizing regions that are rich in biodiversity, the term highlights the importance of protecting these areas to preserve the myriad species they host, including many that may be endemic, meaning they are found nowhere else on Earth.

In contrast, a region with no endemic species would not qualify as a hotspot since it lacks the uniqueness that characterizes significant biodiversity. High urbanization typically leads to habitat destruction and fragmentation, which can threaten biodiversity rather than enhance it. While climate can influence biodiversity, defining a region solely by its climate overlooks other critical aspects such as species diversity and ecosystem health that contribute to a region's status as a biodiversity hotspot. Thus, the correct answer encapsulates both the richness and the necessity for conservation in these vital areas.