Under what conditions is a species considered extinct?

A species is considered extinct when there are no known surviving members of that species. This can occur for a variety of reasons, including:

* Habitat destruction: When a species' habitat is destroyed, it can lose access to the resources it needs to survive, such as food, water, and shelter. This can lead to a decline in the population and eventually extinction.

* Overexploitation: When a species is hunted, fished, or otherwise harvested at an unsustainable rate, its population can decline rapidly and eventually collapse. This is a major cause of extinction for many species.

* Climate change: As the climate changes, many species are unable to adapt and their populations decline. This is a growing threat to biodiversity and is expected to cause many more species to go extinct in the future.

* Disease: Diseases can spread rapidly through a population and cause a sharp decline in its numbers. This can be a major factor in the extinction of species, especially those that are already vulnerable due to other threats.

* Invasive species: Invasive species can compete with native species for resources, such as food and habitat. This can lead to a decline in the population of the native species and eventually extinction.

The extinction of a species is a serious problem, as it represents a loss of biodiversity and can have a ripple effect on the entire ecosystem. It is important to take steps to protect endangered species and prevent them from going extinct.