Question

when no number of the species remains alive anywhere in the world ;this is

Answer 1

DODO BIRD ARE EXTINCT AND DINOSAURS ALIVE

Answer 2

The several threatening perspectives of the decline of biodiversity is the extinction of varieties of animals after been declared as Endangered. Once a class of animals declared as an extinct,  further evolution of that particular species is not possible because its kind does not exist. A species is estimated to be dead then no member of its classes continues to be alive anywhere in the world. If individuals of a species remain to be viable only in detainment or other situations controlled by humans, species are assumed to be terminated in the world. In above-mentioned conditions, the species would be acknowledged as globally extinct.