Hotspots require two main criteria: At least 1,500 vascular plant species with over half endemic to the region, or found only there, the Christian Science Monitor reported quoting the US-based nonprofit organization.

Amazon Rain Forest: The Amazon wilderness, which spans nine countries, is home to 40,000 plant species, of which the majority are not found anywhere else.

It is also home to more primate species anywhere in the world, possibly more insects as well. The Brazilian government said in December 2011 that deforestation rates in the Amazon, the world's largest rainforest, had fallen to the lowest levels since 1988.

Congo Basin: Second only to the Amazon in terms of area, the Congo Basin is home to biologically important species from large mammals - antelopes, elephants, and most famously, gorillas - as well as human communities and old growth forests. With a reach across seven African nations, it is only 11 percent protected - largely through national parks.

New Guinea: Islands often have exceptionally rich biodiversity as does New Guinea - it is the world's highest and second largest behind Greenland, located in the Southwest Pacific. A total of 1,000 species were discovered since 1998 - from birds, butterflies, coral, dolphins, fish, orchids, reptiles, and sharks.

North American deserts: The Mojave, Colorado, Chihuahua, Sonoran, and Baja California deserts that stretch from the southwestern US to Mexico are some of the most biologically diverse in the world, with 6,000 vascular plant species, as well as other special types of animals who have adapted to the climate, from bighorn sheep, desert tortoises, kangaroo rats, jackrabbits, roadrunners, and wild horses.

Southern Africa: The Miombo-Mopane woodlands and savannahs stretch across 10 countries in central southern Africa from Angola to Mozambique. They are home to animal species including the endangered black rhinoceros and almost 80 percent of all African elephants.

This wilderness area is threatened by climate change, drought, development and the need to balance the survival needs of the people who live there with conservation efforts.