Island Biodiversity Race

Category: Biodiversity, Gulf of Guinea, Sao Tome, biogeography, frogs, principe, snakes | Date: May 03 2008 | By: islandbiodiversityrace

We are still on Principe and down to the hard corps: me, Wes and Josef. The mushroom and plant folks, Dennis, Brian, Tom and Rebecca are home in San Francisco by now. So it is time to tell you a little about my own research interests. Cobra Jita is a snake and we have been looking for it all week; in order to explain why, I need to tell you a frog story.

Josef Uyeda on Principe. Weckerphoto GGIII

As I have said, the fact that there are amphibians here at all is astounding; amphibians, along with primary freshwater fish, are among the poorest dispersers across saltwater barriers known. They are the last kinds of critters one would expect to find on an oceanic island…. Think of the Hawaiian Islands and the Galapagos, perhaps the two most intensely studied oceanic archipelagos in the world… no frogs or other amphibians, right? But here on Sao Tome and Principe we have seven amphibian species, one of which is the famous caecilian, Schistometopum thomense. How can this be? How did they get here? More on this later, but one of the keys is time: remember that Sao Tome is at least 15 million years old, and Principe is more than double that, perhaps 31 million years. Hawaii and the Galapagos are but 5 million years max.

During GG I, we collected series of little brown frogs of the genus Phrynobatrachus from various locations on both islands; at the time all of them were considered the same species, P. dispar, originally described from Principe over 100 years ago. In 2005, a bright young intern from Willamette University named Josef Uyeda, spent the summer in my lab studying these preserved specimens and concluded that the frogs were quite different. Josef joined GG II and did a lot of collecting on both islands, recorded calls, did dissections and comparisons of DNA from the critters on both islands. The results are that the two island frogs are VERY different; in fact, there is nearly 21% DNA sequence difference between the two; indicating that they have not interbred in many millions of years, possibly predating the existence of Sao Tome (yet they still look virtually identical!). Moreover the two together appear to be more closely related to East African species than to more nearby West African species, but more on that later. In 2007, Josef, I and Breda Zimkus of Harvard described the Sao Tome brown frogs as a new species, Phrynobatrachus leveleve.

Phrynobatrachus leveleve. Sao Tome. Weckerphoto GGIII

Phrynobatrachus dispar Principe. Weckerphoto GGIII

from Uyeda et al. 2007. Proc. Calif. Acad. Sci. 58

This brings me to cobra jita (pronounced “zheetah” – it means snake slow, as opposed to the other Principe snake, cobra sua sua, which means snake fast!). Here we have the same situation as we had with the small brown frogs, Phrynobatrachus. Jita (more properly known as Lamprophis lineatus bedriagae, or lined house snake) has always been considered to be the same species on both islands. After our frog studies, I am not so sure! They look different – regrettably I will have to post a picture of the Sao Tome form later… didn’t bring one in my zip drive—the Principe form is much more obviously patterned than the Sao Tome snake. During GG I and GG II we got very good samples of the Sao Tome population, but for some reason, only one specimen from Principe.

Lamprophis from Bombom Id, Principe. Weckerphoto GGIII

Lamprophis from Sao Tome. D. Lin photo. GGII

Josef is now a PhD candidate at Oregon State University and joined us a couple of weeks ago in our search for Jita (among other things I will describe later). Snakes, as you probably know, are where you find them… as primary predators, they are never very common but always around, and such has been the case here on Principe. It has taken us six days of trekking around in the forest, turning over logs, etc. to find six snakes. But I am delighted. This is certainly enough now to estimate the genetic distance between the two populations, and given the age of these islands, I will not be surprised at all to learn that they are distinct at the species level.

Josef and I looking for Jita on Bombom Id. Weckerphoto. GGIII

We have learned a lot about this critter. On Sao Tome, Jita is primarily nocturnal while the daylight hours on that island seem to be dominated by the endemic Sao Tome green bush snake, Philothamnus thomensis. This is the situation we would predict using island biogeographic theory—no niche overlap – they both seem to eat frogs and skinks, but at different times. But here on Principe, all of the jitas we have caught have been during the daylight hours, as was the single individual caught during GG II in 2006. Moreover, the green snake of Principe (yes there is a green sua sua here as well, but not related to the Sao Tome species) also seems to be diurnal! They are incredibly fast; we have seen two of them and missed both. So until we can look at stomach contents, we seem to have an ecological mystery.

Me, Josef and Ramos on Bombom Id. Weckerphoto GGIII

Our search has been greatly aided by an amazingly bright local naturalist; Jose Ramos Maria Vital Pires, or Ramos for short. Ramos has led us around this island searching for the elusive jita we have been blown away by his keen perception and observations of the local flora and fauna, and his delightful smile and sense of humor. The thing is everyone knows about this snake, most of the locals are to say the least, not exactly fond of snakes and one referred to as a “house snake” frequently comes a little too close for comfort, as you might imagine. But finding a snake when you are looking for it is entirely different matter. Our first success occurred on Bom Bom Island (not really and island, but sort of). I had just commented that the area Ramos was leading us through was too steep to find a snake, when he began excitedly shouting “snake!” only meters away. Within moments we had bagged our first jita.

There have been some rather ignominious moments for me personally. My two young compadres, Wes and Josef are willing to give me credit for catching but one jita, a dead one. The specimen had, in fact, been killed two hours earlier by a local woman who was delighted to have us remove it from along the road. This morning was the last straw. We had been combing Bom Bom Island again; Josef and Wes had taken a lower route than I and about an hour in, I heard Josef yell that they had caught a snake in the act of ripping a tail off a skink. Well and good, I thought, but where’s mine? So I am walking along, seeing snake food like skinks all over the place, when Wes and Josef come down the trail towards me. We stopped, admired the snake Josef had already bagged and the photos Wes took of it eating its skink tail, all three of us turned around…Josef stooped over and grabbed our largest jita of the expedition, about a foot behind me. I must have stepped right over it a moment beforehand. Perhaps it is not necessary to tell you that there has been much snickering among the younger members of this outfit ever since… Argh.

Josef collecting a jita on Bombom. Weckerphoto GGIII

Nova Cuba, near Santo Antonio, Principe. Weckerphoto GGIII

PARTNERS We gratefully acknowledge the support of the Research Investment Fund of the California Academy of Sciences, the Société de Conservation et Développement  (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/ and especially the generosity of three private individuals, George F. Breed, Gerry F. Ohrstrom and Timothy M. Muller, for making GG III possible. More anon.

Tags: 1293, 1294, 1295, 708

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Category: Biodiversity, Gulf of Guinea, Island endemics, Sao Tome, flowers, principe | Date: May 02 2008 | By: islandbiodiversityrace

As I mentioned yesterday, the first two botanists to join one our GG expeditions are Dr. Tom Daniels of CAS Botany Department and one of his graduate students, Rebecca Wenk. Both are specialists on a large family of tropical herbs called the Acanthaceae. Can’t give you a common name, sorry.

Rebecca and Tom among the baobabs at Lagoa Azul. Weckerphoto

GGIII.
There is already a book on the flora of the islands written by a man named A.W. Exell many years ago but there are still many groups that are poorly known on Sao Tome and Principe, including Tom’s and Rebecca’s acanths, and there is always the possibility of finding something new. Although these data are old, it is estimated that the flowering plants of Sao Tome and Principe are between 8 and 14% endemic, found nowhere else in the world. The numbers are a range because it depends upon which island and plant family you are talking about, but the endemicity is high.

Brillantasia, Sao Tome. Weckerphoto, GGIII
Tom and Rebecca have been working side by side with the cugumelo team but have been pressing and drying their plants at the small herbarium at Bom Sucesso, which is at about 1000 meters on the island of Sao Tome. The herbarium and delightful botanical gardens of Bom Sucesso were first built with support by ECOFAC, but now run by a local NGO called Monte Pico; their specialty is the endemic orchids, and there are guides for tours of the gardens, as well as guides available for hikes up into the “real” primary vegetation above. Our old friend, Bastien Loulomb, has been an advisor to Bom Sucesso and Monte Pico for a long time and has been of consistent help to me on the GG II and GG III expeditions.

GGIII team at Bom Successo, Sao Tome. Weckerphoto GGIII
I have always teased my botanical colleagues about the funny hats they wear in the field, and the fact that they never seem to get dirty like us herpetologists. Well, funny hats are a given (see the photo) but Tom and Rebecca get just as dirty as the rest of us. So far they seem to have collected whole samples, tissue for DNA and for karyotyping of all of the known endemics of their group, but have also collected great samples of a lot of other peculiar things, including the world’s largest Begonia, B. ebaccata, which grows to nearly 10 meters on Sao Tome. All duplicates collected by our botanists will reside at Bom Sucesso in the Herbarium.

Begonia baccata, largest in the world - Lagoa Amelia, Sao TomeWeckerphoto, GGIII

Tom at Bom Successo. Weckerphoto GGIII
A high point was when Rebecca finally found an example of her “questing beast,” a tiny little acanth growing along the side of track up Pico Papagaio on Principe. She let out a loud shriek and dove to the ground. I wish I could remember the name of the thing, but Tom and Rebecca are on there way back the US as I write. Apparently, she needed sequence data from this little plant critter in order to “root the tree” of her current MSc thesis (the scientists among you will understand). Here’s a photo of her with her discovery.

Rebecca Wenk with her “questing beast.” Weckerphoto GGIII

Rebecca’s acanth crittter (Elytraria marginata).  Weckerphoto, GGIII

Finally, thanks to SCD a couple of weeks ago, we were offered a boat ride to the inaccessible southwest coast of Principe The southwest exposures of all of the islands in this chain, Bioko, Principe, Sao Tome and Annobon are inaccessible by land because they receive the brunt of the incoming weather, hence erosive force comes from the southwest. For the same reason the Portuguese were unable to cultivate these areas during their 500 years of colonization here and on each island these exposures are pretty much untouched by man. In one sense the trip was a near disaster; our small rubber dingy flipped and a lot of our equipment was compromised, most of it temporarily. But the mushroom guys were able to collect a bunch of stuff on a virtually untouched steep slope, and Tom and Rebecca were able to establish that the dominant plant group in the southwest of Principe is the Rubiaceae, members of the coffee family.

A melastome from Sao Tome.  Weckerphoto GGIII

We are posting a bunch of images, mostly by Wes Eckerman, that are unlabeled. The reason for this is that in many cases we do not know yet what the stuff is. Stay tuned.

Fisherman at Lagoa Azul. Weckerphoto GGIII

PARTNERS We gratefully acknowledge the support of the Research Investment Fund of the California Academy of Sciences, the Société de Conservation et Développement  (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/ and especially the generosity of three private individuals, George F. Breed, Gerry F. Ohrstrom and Timothy M. Muller, for making GG III possible.
Next will be posting on my stuff, the creepy crawlies.

Tags: 1293, 1294, 1295

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