Scientists have identified and named more than a million animal species, and millions more have yet to be discovered on Earth’s seven continents. But which continent has the most animal species?
For hundreds of years, scientists have cataloged and geolocated species around the world. Before the digital age, most of our information about species distribution came from museum collections, he said Wind Piacentini, an ornithologist at the Federal University of Mato Grosso in Brazil. Nowadays, the public also contributes to this effort.
The past 20 years have seen 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 exceptionally high number of species per area. Currently 36 active points worldwide, most are on continents that cross the equator, where the climate is warm and humid.
The reason is not only animals, but also plants. “Plants are the basis of species,” Barnabas Daru, an applied ecologist at Stanford University, told Live Science. “If a place has a higher diversity of plants, it makes it easier for other organisms that depend on those plants to become more abundant.”
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Although plants can live in all kinds of conditions, most thrive in warm and humid places. Humidity and heat work together to provide the necessary humidity: Warm air traps water molecules and creates humidity. Heat is also better for many microorganisms, especially decomposers that break down dead material that plants harvest into nutrients.
Additionally, insects that pollinate many flowering plants are better suited to warmer climates because they cannot 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 there are other factors at play. In order to accommodate a large number of species, the continent must offer not only tropical conditions but also diverse habitats. Sites with high biodiversity have many potential niches for animals to occupy, Piacentini said. For example, tall trees or tall mountains create vertical variations in temperature, sun exposure, and terrain that allow multiple animals 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 highest number of animal species. From the Amazon rainforest, which has four stories of trees for animals to occupy, to the Andes Mountains with dozens of different microclimates, South America has a winning combination of heat and geography. “Everything is combined there,” Piancentini said, “and that’s why it has biodiversity [that it does].”
This means that South America’s biodiversity may not always be as vibrant as it is now. WITH deforestationmercury mining and climate changeAnimals in South America face greater threats than ever before. However, there is still an opportunity to mitigate the damage.
“We’re definitely going to lose a lot of species,” Piacentini said, “but every effort we make to reduce our impact will also save us a lot.”