00:00This thing I have in my hands could be a very powerful tool for scientists.
00:05Wait a moment and I'll explain.
00:07A one-liter water sample like this, but taken from an ecosystem,
00:11It allows scientists to know what species of animals live there without having to capture them.
00:17More precisely, this technique is known as environmental DNA.
00:21And a few weeks ago, a group of scientists, including two Colombian researchers,
00:27They published the most comprehensive study ever done on environmental DNA in South America
00:32to describe the biodiversity of aquatic and terrestrial vertebrates in underground ecosystems of a country
00:38And they did it in caves and caverns in Colombia.
00:42The first part of this technique is water collection.
00:45What comes next, explained Susana Caballero, a Colombian biologist
00:50And one of the pioneers in the use of environmental DNA in the country is the filter.
00:54Using syringes, researchers pass water samples through very tiny, special filters.
01:00in which they create particles of genetic material from animals, such as feces, urine, or saliva.
01:07These filters are treated with a preservation solution and sent to specialized laboratories.
01:13In the specific case of the recent study, the researchers took 7 one-liter samples of water
01:18in each of the 21 caves they accessed, from San Andrés Island to the Amazon.
01:24An unprecedented effort.
01:27It turns out that caves, caverns, grottos, among others, are orphaned ecosystems.
01:33as described by biologist Carlos Lazo, a researcher at the Humboldt Institute,
01:37since they have been forgotten by the major ecosystem studies in the country.
01:40This is where environmental DNA becomes key to studying these ecosystems, which are difficult and expensive to access.
01:47access.
01:48To give you an idea, in addition to the logistical, economic, and physical challenges,
01:53since one has to crawl and descend or ascend in the dark,
01:56Those who venture into caves or caverns face sudden increases in blood pressure or health problems.
02:02such as pulmonary histoplasmosis, a respiratory infection caused by inhaling spores
02:07of a fungus present in the excrement of birds and bats.
02:10Animals common in these ecosystems.
02:13For researchers like Lazo, having to enter caves to take water samples like this,
02:18It saves work, exposes them to fewer risks, and they can achieve great results.
02:24At this point, a second technique known as metabarcoding or genetic barcoding appears.
02:31Basically, biologist Caballero told us, it's like a barcode at the supermarket.
02:36Species can be identified according to the order of the nucleotides, or the letters that make up DNA.
02:43And to complete this part, publicly accessible genetic databases are key.
02:49After this entire process, the researchers identified 82 genera and 111 species in those 21 sampled caves.
02:56In the group of fish, for example, they identified 13 orders, 22 families, 32 genera and 51 species.
03:04They also identified 8 species of amphibians, 3 of reptiles, 13 of birds, and 32 of mammals.
03:10It is a baseline of biodiversity in these underground ecosystems, as they themselves define it.
03:16The results also allowed researchers to identify new distributions that were previously unknown.
03:24Daniela Martínez Limarín, biologist, microbiologist and lead author of the recent study, highlights the case of the oilbird.
03:31A nocturnal bird with a distribution in the Andes, but which in this study was also found in San Andrés.
03:37A distribution that had not been recorded until now.
03:40However, the work also raised some concerns about invasive species, such as the Asian catfish.
03:47Although it would be too early to confirm the presence of this invasive species in the country's underground ecosystems,
03:52The fact that it appeared in the results indicates that it is being consumed by populations in places near the caves.
04:00If you want to know more about this work, a pioneering effort for the country and the region, you can find the article in the
04:06Spectator Environment section.
04:08And if you don't want to miss more fascinating stories about Creole science, don't forget to follow us on all our social media.
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