ऐसी प्रजातियाँ जिनका वितरण एक बहुत ही सीमित भौगोलिक क्षेत्र तक ही सीमित होता है, क्या कहलाती हैं?

Which level of biodiversity is specifically characterized by the variation and differences in genes within individuals of a single species?

Out of the estimated millions of species on Earth, approximately how many species have been scientifically identified and described to date?