New global map of ant biodiversity reveals areas that may be hiding undiscovered species

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An ant (species: Ectatomma tuberculatum) photographed in Costa Rica. Ants make up a large portion of the total animal biomass in most terrestrial ecosystems, but researchers say there is a lack of understanding of their global diversity. This new study provides a high-resolution map that estimates and visualizes global ant diversity. Photo credit: Dr. Benoit Guénard

They are hunters, farmers, harvesters, gliders, herders, weavers and carpenters. They are ants and they make up a large part of our world, comprising over 14,000 species and much of the animal biomass in most terrestrial ecosystems.

Like other invertebrates, ants play a vital role in the functioning of ecosystems, from aerating soils and dispersing seeds and nutrients to cleaning and hunting other species.

However, a global vision of their diversity is lacking.

But an international team of researchers led by the Okinawa Institute of Science and Technology and including an ecologist from the University of Michigan has developed a high-resolution map that combines existing knowledge with machine learning to estimate and visualize diversity. world of ants.

The team’s findings were published online August 3 in Science Advances.

Map highlighting species rarity - areas with many ant species with very small ranges.  The colored areas all indicate important regions for ant species with small ranges.  Red indicates areas that are relatively more studied than other areas, which could artificially increase their importance.  The purple areas are both significant based on current knowledge and will likely remain so after future sampling.  The blue areas are predicted by machine learning to harbor concentrations of undiscovered small-range ant species, giving scientists a treasure map to guide future exploration.  This image is a modified version of a figure that appeared in Kass et al., Science Advances, August 2022.
Map highlighting species rarity – areas with many ant species with very small ranges. The colored areas all indicate important regions for ant species with small ranges. Red indicates areas that are relatively more studied than other areas, which could artificially increase their importance. The purple areas are both significant based on current knowledge and will likely remain so after future sampling. The blue areas are predicted by machine learning to harbor concentrations of undiscovered small-range ant species, giving scientists a treasure map to guide future exploration. This image is a modified version of a figure that appeared in Kass et al., Science Advances, August 2022.

“This study helps add ants, and terrestrial invertebrates in general, to the discussion on biodiversity conservation,” said Evan Economo of the Biodiversity and Biocomplexity Unit at the Okinawa Institute of Science and Technology. “We need to know the locations of centers of high-diversity invertebrates in order to know areas that can be the focus of future research and environmental protection.”

The resource will also serve to answer many biological and evolutionary questions, such as how life has diversified and how patterns of diversity have arisen, said Economo, who was a Michigan Fellow at the 2009 UM. to 2012.

“Early naturalists recognized large-scale patterns of biodiversity, but primarily for vertebrates and plants,” said UM ecologist and study co-author Nate Sanders. “This impressive collaboration provides the first high-resolution biodiversity map of where the engines and shakers of ecology are – the ants.”

The decade-long project began when study co-first author and former OIST postdoctoral researcher Benoit Guénard (now at the University of Hong Kong) worked with Economo to create a database from online repositories, museum collections and approximately 10,000 scientific publications on where different species of ants are located.

Researchers around the world contributed and helped identify the errors. Over 14,000 species were examined, and they varied greatly in the amount of data available.

The vast majority of these records, while containing a description of the sampled location, lacked the precise coordinates needed for mapping. To solve this problem, co-author Kenneth Dudley of the Environmental Informatics Section of OIST built a computational workflow to estimate coordinates from available data, which also checked all data for errors.

Together with Dudley and OIST research technician Fumika Azuma, OIST postdoctoral researcher and co-first author Jamie Kass made different range estimates for each ant species depending on the amount of data available. The researchers collated these estimates to form a global map, divided into a grid of 20 by 20 kilometer squares, which showed an estimate of the number of ant species per square (called species richness).

The centers of species richness identified by the researchers include locations in Mesoamerica, the Caribbean, the tropical Andes, the Guiana Shield in South America, the Atlantic Forest in Brazil, the Mediterranean, several regions from Africa, Madagascar, the Himalayas and northeast India, the Western Ghat Mountains in India, Sri Lanka, Southeast Asia, Melanesia and coastal Australia.

In the United States, centers of ant species richness are located in Florida, southern California, and southeastern Arizona.

The researchers also created a map that shows the number of ant species with very small ranges per square (called species rarity). In general, species with small ranges are particularly vulnerable to environmental changes.

However, there was another problem to overcome: sampling bias.

The researchers used machine learning to predict what would happen if they sampled all regions of the world equally, and in doing so identified areas where they believe there are many unknown and unsampled species.

“It gives us a sort of ‘treasure map,’ which can guide us to where we should explore next and look for new species with restricted ranges,” Economo said.

UM’s Sanders said the southern tropical Andes are “probably where most of the new ant biodiversity will be discovered. But the Western Ghats in India, much of Southeast Asia, and parts of New Guinea will likely also harbor new and undiscovered ant biodiversity.

The Atlantic Forest in Brazil, Thailand, Vietnam, many islands in the Philippines and Indonesia, the Solomon Islands and Vanuatu are also promising places, he said.

Map highlighting the centers of ant biodiversity in Asia - areas that are home to many ant species with small ranges.  The different colors indicate how the importance of each region may change with future searches around the world.  Red areas should decrease in importance, purple areas will remain among the most important regions even after more areas are surveyed, and blue indicates areas that should be targets for exploration as they should harbor hidden diversity.  This is a modified version of a figure from Kass et al, Science Advances, August 2022.
Map highlighting the centers of ant biodiversity in Asia – areas that are home to many ant species with small ranges. The different colors indicate how the importance of each region may change with future searches around the world. Red areas should decrease in importance, purple areas will remain among the most important regions even after more areas are surveyed, and blue indicates areas that should be targets for exploration as they should harbor hidden diversity. This is a modified version of a figure from Kass et al, Science Advances, August 2022.

When researchers compared the rarity and richness of ant distributions to relatively well-studied amphibians, birds, mammals, and reptiles, they found that ants were about as different from these vertebrate groups as the vertebrate groups the were from each other, which was unexpected given that ants are evolutionarily far removed from vertebrates.

“This means that targeted conservation efforts aimed at protecting a diversity of rare vertebrates could also protect the diversity of rare species of ants and other insects,” said Sanders, a professor in the department of ecology and evolutionary biology at UM and Director of UM. s Reserve ES George.

The researchers looked at how well protected these areas of high ant diversity are. They found that only a small percentage had some sort of legal protection, such as a national park or reserve.

“What excites me the most is the treasure map,” Sanders said. “We really need mud-booted biologists to explore these unexplored places to document the diversity of ants – and other things – before they are lost to habitat destruction or climate change in Classes.”

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