Scientists have identified and named more than a million animal species, and there are millions more to be discovered across Earth’s seven continents. But which continent has the most animal species?
For hundreds of years, scientists have been cataloging and geolocating species around the globe. Before the digital age, most of our information about species distribution came from museum collections, he said. Victor Piacentinian ornithologist at the Federal University of Mato Grosso in Brazil. Today, the public is also contributing to this effort.
Over the past 20 years, there has been a “revolution” in citizen science, Piacentini told Live Science, and “scientists are using their data to fill in the gaps.”
Using this information, scientists can map the distribution of species around the world. In the late 1980s, scientist Norman Myers coined the term “biodiversity hotspot“to refer to places with an unusually high number of species for their surface area. From now 36 access points around the world, most are on continents that cross the equator, where the climate is hot and humid.
The reason for this has to do not only with animals, but also with plants. “Plants are the basis of species,” Barnabas Daruan applied ecologist at Stanford University, told Live Science. “If a place has a greater diversity of plants, it becomes easier for other organisms that depend on those plants to become more abundant.”
Related: Which group of animals has the most species?
Although plants can live in all types of conditions, most thrive in warm, humid places. Humidity and heat work together to provide essential moisture: warm air traps water molecules to create humidity. Heat is also better for many microorganisms, especially decomposers, which break down the dead material that plants harvest for nutrients.
On top of all that, insects, which pollinate many flowering plants, are better suited to warmer climates because they can’t regulate their own body temperature. Having more insects in the tropics means more pollination for plants and more food for hungry predators, Daru said.
But Piancentini noted that other factors are at play, too. To support many species, a continent must offer not only tropical conditions but also a variety of habitats. Places with high biodiversity have many potential niches for animals to occupy, Piacentini said. For example, tall trees or high mountains create vertical variation in temperature, sun exposure and terrain that allows more creatures to coexist without competing for the same resources or habitat.
Based on these factors and estimates using museum and citizen science data, most scientists agree that South America has the greatest number of animal species. From the Amazon rainforest, which has four layers of trees for animals to occupy, to the Andes mountains, with dozens of different microclimates, South America has the winning mix of heat and geography. “Everything is combined there,” said Piancentini, “and that’s why you have biodiversity [that it does].”
That said, South America’s biodiversity may not always be as vibrant as it is now. With loggingmercury mining and Climate ChangeSouth American animals are facing more threats than ever. There is still an opportunity to mitigate the damage, however.
“We will certainly lose many species,” Piacentini said, “but every effort we make to reduce our impact will also save us a lot.”
