Tales From the Cryptic Species – Shelf Life #16


[MUSIC PLAYS]>>EVON HEKKALA: I like to think of myself
as a creative thinker about museum collections. [SWITCH CLICK, ELECTRIC SIZZLE]>>HEKKALA: I was doing my dissertation research on crocodiles, and I started to collect data. [SCRAPING]>>HEKKALA: And as I started collecting DNA, I realized
that there were a lot of places where you couldn’t get samples anymore because crocodiles
had gone extinct in those sites. And so I thought maybe I can use museum specimens
to fill in some of these gaps. [STEAM WHISTLE, CHURNING WATER]>>HEKKALA: I found that there was this expedition to
the Congo from 1909 to 1915, conducted by the American Museum of Natural History, and
those explorers had collected crocodile specimens from the Upper Congo. I extracted samples and I was dumbfounded
when I looked at the DNA sequence. I’m Evon Hekkala and I am a research associate
at the American Museum of Natural History. [MUSIC PLAYS]>>JOEL CRACRAFT: Scientists have named and
described approximately one and a half million species of organisms. Yet, everybody agrees that that is a tiny
portion of the biodiversity that’s out there. I’m Joel Cracraft. I’m a curator of ornithology here at the American
Museum of Natural History. The knowledge that we have about the rainforests
around the world has been basically built up over the last 100 years or more of exploration. But now, new, younger scientists are going
out and they are looking at diversity in these forests from a genetic point of view.>>HEKKALA: So, this site right here—Faradje—is
where they collected two specimens of crocodiles on either side of this little river. And it turned out that one specimen had one
DNA sequence and the other specimen had another DNA sequence. And they were completely different. And I started thinking there must be a cryptic
species here.>>CRACRAFT: Two very distinct species can
look exactly the same, but when you look at them genetically, then you find out that,
in fact, they’re very different. And so, we call those things cryptic species. And we are finding that we’ve underestimated
species diversity in virtually all organisms in these forests.>>HEKKALA: It turned out that one specimen
represents the Nile crocodile species that we all know and love, from the Nile. And the other represents a completely separate
species of crocodiles. In fact, they’re so distinct they’re not even
each other’s closest relatives. They haven’t exchanged genes in millions of
years. Once I started looking into the documentation
that went along with those crocodiles, I realized there must be other specimens from their expedition
that also represent cryptic species. This is a great opportunity for species discovery. So we started looking at tortoises, and we started looking at monitor lizards. We started finding similar patterns there. We were planning on looking into pangolins, the okapi, elephant shrews. But the one that sort of jumped out at me right away was the African leopard. Everyone’s assumed that they’re all one species, recently, but in the Lang-Chapin field notes, they describe differences in the coat texture, and pattern, differences in the distribution and the sizes, and so, we thought that would be a really good target species. The most exciting thing with what we found in the leopard data—and it’s also the most concerning— is that our molecular data suggest that one of the leopard subspecies is found only in a tiny, little pocket in the forest, in the Upper Congo. If we lose this unique little slice of genetic diversity, we’re actually losing global biodiversity.>>CRACRAFT: Biological diversity is many things to many people. One of it is the obvious—how many different kinds of organisms are there out there. Another way they look at it is how much genetic diversity does a habitat contain.>>HEKKALA: Having a distinct genetic identity may not necessarily mean that you’re a distinct species, But having a distinct characteristic of your DNA may be incredibly important because more variation tends to be better in the face of a changing world. And when populations get small and isolated, they don’t have the necessary ability to be resilient in the face of change.>>CRACRAFT: The pressures on the forest have increased dramatically. Knowing what’s out there is the first step in saving what’s out there. And managing the genetic diversity is a key component to managing endangered species everywhere in the world right now.>>HEKKALA: One of the reasons that these historical collections are so valuable and important is because today conflict, deforestation, habitat loss, poaching—these are all devastating the flora and fauna of the Congo basin. So, these specimens represent an irreplaceable resource that can never be reacquired. [MUSIC PLAYS]

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