Why is the conservation of biodiversity considered an international issue?

Identify the odd one out regarding recent extinctions.

The impacts of loss of biodiversity may lead to:
$I$. Lowered resistance to environmental perturbation
$II$. Decrease in plant production
$III$. Increased variability in ecosystem processes like water use,pest/disease cycle,and plant productivity
$IV$. Increase in plant production
Choose the correct option.

Provide information on the history of species extinction and state its effects.

According to the $IUCN$ Red List $(2004)$,how many species have become extinct in the last $500$ years?

Presently,$....A....\%$ of all mammal species and $....B....\%$ of all gymnosperm species in the world face the threat of extinction.