Hello PLA:
If you’ll recall last week’s blog on the elfin forest in the Puerto Rican highlands, you might remember that I briefly mentioned the tragic case of the golden toad in the elfin forest in Monteverde, Costa Rica. Those toads, lost forever, have become a symbol of the current global amphibian crisis.
As a young herpetologist, its natural that I’m going to see nature through the prism of the taxa that I study: reptiles and amphibians. So it is with some hesitation that I sometimes wonder whether it really makes sense to focus too much on global amphibian declines, when really every sort of biodiversity is in major trouble. Is it missing the forest for the trees? No, it isn’t. What’s happening to amphibians is a microcosm (although perhaps that gives the wrong connotation – it isn’t happening on a small scale…) of what’s happening to other taxa.
- Golden toads alive and breeding in the elfin forest.
Here are the basics for my fellow PLA members so that I can get on to the case study that they might be half interested in. Amphibians are the most threatened group of vertebrates, and an absolutely unparallelled number of extinctions have occurred in the last twenty years. Now, there are much better blogs on the amphibian decline than this one, but I thought I would help summarize the causes for you: habitat loss, invasive species, and disease. These are all human mediated. How is disease human mediated? Well it turns out that the disease responsible for some of the most spectacular frog die-offs is itself an invasive species… Chytrid fungus is a skin infection that is destroying frog populations worldwide.
Now from what I know, Chytrid has its most devastating effects on frogs found at high altitude. As you guys might now recall from the elfin forest blog, high altitude communities tend to have more endemic species. Hence, entire species are going extinct – sometimes mountaintop by mountaintop.
This brings me to the golden coqui, Eleutherodactylus jasperi, and the Puerto Rican Sierra de Cayey. This sierra (mountain range) is a part of the Cordillera Central – the mountainous spine of Puerto Rico. It’s a region about an hour south of San Juan in the southeast quadrant of the island – and in 1973 four herpetologists, including young australian biologist Jasper Loftus-Hills, discovered a frog species unlike any other on the island. They knew it was a coqui – one of the small direct developing (no tadpoles – babies are born little froglets) species of the genus Eleutherodactylus common on the island. This genus of frogs is remarkable in its own right, and they have undergone a mind boggling adaptive radiation in the neotropics. Every island in the Greater Antilles has a set of Eleutherodactylus species – there are 16 alone recorded from Puerto Rico the last that I checked. The genus has since been split up (much of the work was done by former Penn State professor Blair Hedges) but at one time it was the most speciose vertebrate genus – with over 600 described species!
- A golden coqui in life. Photo by George Drewry.
This species, though, was different. Different not only from every other coqui on the island. Different not only because it was a light – almost transparent – golden color and because it has a unique call. This species is fundamentally different from every other species in the entire massive genus (sensu lato) because it gives birth. Those little froglets? They hatch from eggs laid by the female in every one of the other species. Golden coqui froglets emerge directly from their mother. This is truly incredible, and herpetology legend Marvalee Wake conducted a great study on the species’ reproductive biology where she explored possible reasons for the evolution of live birth.
Anyways, the species was discovered in this small mountainous forest in the Sierra de Cayey in 1973. The herpetologists who had discovered the species then worked diligently on describing it to science – this is a much more complicated and tedious process than you guys might be aware, and can frequently (almost always?) take years. Tragically, in 1974, one of those herpetologists – Jasper Loftus-Hills – was concurrently researching frog calls in Texas when he was killed by a hit and run driver. He was 28. To honor his memory, when the species was formally described in 1976 it was named Eleutherodactylus jasperi. Typically, when a species is named after someone the epithet is a form of their surname. I can only imagine, as they broke this tradition, that Drewry and Jones weren’t naming this species for a former colleague. They were naming it for their fallen friend.
Unfortunately, the story continues. Drewey and Jones described the golden coqui in 1976. In 1978 Wake published her study on the species’ reproduction. Then in 1981, in the Carite-Guavate State Forest, the species would be seen alive for the very last time. What caused the decline isn’t known for sure. The usual suspects remain: habitat loss from development, habitat alteration from fires in the area, and of course Chytrid. The rapid loss of this species – from an estimated population of a few thousand at the time of its description to none five years later – implicates Chytrid. This is especially true since Chytrid has been found on preserved Puerto Rican frogs from the mid 1970s. In fact, Chytrid fungus was found on the skin of the last ever collected specimen of Eleutherodactylus karlschmidti from El Yunque in 1971. That species along with another, E. eneidae, joins E. jasperi in the sad ranks of species presumed lost on the island. If they truly are extinct, then that brings the total number of Eleutherodactylus on Puerto Rico down to 13.
We’ll be based out of San Juan the week that we are there – returning from wherever we go each day to the hotel that night. I’ve looked at the itinerary and we have some free time, and so I’m going to try to get out to the Sierra de Cayey for at least one night’s worth of searching. Of course I know that I won’t find any jasperi, but I at least want to see the forest where they were and put in my 8-10 hours of survey effort. I’m not sure exactly why I have to do it – maybe as penance – but as a biologist, physically witnessing the absence of a recently lost species brings home the reality of the crisis in a way that reading doomed survey reports on google scholar doesn’t. Anybody in PLA that wants to spend a night sweating, getting eaten alive by mosquitos, and searching for an apparition is welcome to tag along.
MWH
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