I celebrated Charles Darwin's 200th birthday on Rota, a beautiful small island (85 square kilometers) of the Commonwealth of the Northern Marianas Islands. Rota is a fine place to think about evolution, speciation, and also conservation. This is because Rota is home to several endemic species. The Mariana Crow (Corvus kubaryi) previously inhabited Guam but fell victim to the Brown Tree Snake and is now consider critically endangered on Rota with at most 150 individuals. The Rota White-Eye (Zosterops rotensis) divereged from the more common Bridled White-Eye (Zosterops conspicillatus) which inhabits neighboring islands, some of which can been seen from Rota on a clear day. Also the Mariana Fruit Bat (Pteropus mariannus) has been hunted to extinction on other islands and is at risk of going extinct on Rota as well. When I think about the conservation of these rare species I can't help the think about the evolutionary forces that created these unique populations. Because when we talk about the conservation of a species we are talking about preserving a piece of evolutionary history--collections of beautifly crafted genes sculpted (and still being improved upon) by the natural environment they live in. In the Origin of Species Darwin says: "How fleeting are the wishes and efforts of man! how short his time! and consequently how poor will his products be, compared with those accumulated by nature during whole geological periods". I think it is clear from this that if Darwin were alive today he would be an ardent conservationist!
The natural history that Darwin (and Wallace as well) observed on islands was critical for their formation of their theories of evolution. The combination of unique ecological scenarios and isolation makes islands supreme for the creation of new species. But island species also suffer from small population sizes and, again, unique ecological scenarios which make them vulnerable to extinctions. Something like 80% of avian extinctions in recent times were island species. In this modern age of extinction I think islands are a still a great place to get excited about evolution, but perhaps more important for encouraging conservation!
I have had the great pleasure to hang out with Ken Levenstein and Julia Boland. Ken is a postdoc from the University of Washington who is currently studying the Mariana Crow and the Rota White-Eye. He did his PhD in the Galapagos and stayed at Darwin's camp site. Julia is a biologists with the Division of Fish and Wildlife studying the Mariana Fruit Bat, and is working to reduce poaching on the island. It is refreshing to meet people out in this isolated world in the Pacific who are thinking about ecology and evolution and are out here trying to preserve some of evolution's beautiful creations. Darwin would be happy to see it.
Happy Birthday
Monday, February 16, 2009
Wednesday, February 4, 2009
In the Mariana Islands--Looking for big changes in small places.
The brown tree snake (Boiga irregularis) is famous for having caused the extirpation of Guam's avifauna. Agreed to be a tragic and saddening story of invasion. Think, a beautiful tropical island without birds! A scary thought in itself. But what most people do not think of is the ecological effect losing birds. How will the loss of birds change the native forests of Guam?
I am currently working as a field technician on a project that is attempting to answer this question. With funding from NSF and USDA, PI's Joshua Tewksbury, Janneke HilleRisLambers, Ross Miller and Grad student Haldre Rogers are using the Mariana Islands as a huge natural experiment to understand the ecological role of birds in forest systems. The islands north of Guam (Rota, Saipan, and Tinian) still have healthy populations of birds, thus comparisons can be made between the northern islands and Guam. It is the type of experiment ecologist would dream of designing, but could never ethically create.
We are currently focusing on seed dispersal in an attempt to understand how spatial distributions of seed rain vary between the islands. Since birds are the primary disperser of seeds in Guam's forests, the effects of bird loss are predicted to be quite drastic. To measure how far seeds get away from their parent tree, we have hung seed traps in the jungle underneath fruiting trees at 1, 5, 10 and 20 meters away. These traps collect everything that falls into them--which mostly consists of leaves, sticks, frass, etc. We really just want the seeds.
Initially we sorted through all of the samples by hand, individually picking out each leaf and twig until it was possible to find the seeds. This was terribly time consuming. Luckily there are sophisticated machines that separate seeds out from various undesirables--complete with agitators, variable sized sieves, wind chambers and aspirator fans. But as you might imagine they are too spendy for ecologists. So we got creative. Inspired by the designs of seed sorting machines in agriculture we designed and built Kogia sima, our friend, our coworker, our invention. It is quite ingenious if I do say so myself. Kogia sima is not a dwarf sperm whale as the name implies, rather it is a seed sorting machine made of PVC pipe, 2x4's, a tupperware container, an old T-Shirt, and--the heart of the beast--a hair dryer. Dried samples from the seed traps go into the bottom of Kogia sima. The hair dryer blows unwanted leaves out the top like the spray from a blowhole, leaving the seeds down below. Although we still have to sort and identify the different species of seeds, Kogia sima greatly lessens the work load by removing all of the leaves and other light weight debris, which is helping us understand how changes in the dispersal of seeds by birds may impact the forest of Guam over time.
I am currently working as a field technician on a project that is attempting to answer this question. With funding from NSF and USDA, PI's Joshua Tewksbury, Janneke HilleRisLambers, Ross Miller and Grad student Haldre Rogers are using the Mariana Islands as a huge natural experiment to understand the ecological role of birds in forest systems. The islands north of Guam (Rota, Saipan, and Tinian) still have healthy populations of birds, thus comparisons can be made between the northern islands and Guam. It is the type of experiment ecologist would dream of designing, but could never ethically create.
We are currently focusing on seed dispersal in an attempt to understand how spatial distributions of seed rain vary between the islands. Since birds are the primary disperser of seeds in Guam's forests, the effects of bird loss are predicted to be quite drastic. To measure how far seeds get away from their parent tree, we have hung seed traps in the jungle underneath fruiting trees at 1, 5, 10 and 20 meters away. These traps collect everything that falls into them--which mostly consists of leaves, sticks, frass, etc. We really just want the seeds.
Initially we sorted through all of the samples by hand, individually picking out each leaf and twig until it was possible to find the seeds. This was terribly time consuming. Luckily there are sophisticated machines that separate seeds out from various undesirables--complete with agitators, variable sized sieves, wind chambers and aspirator fans. But as you might imagine they are too spendy for ecologists. So we got creative. Inspired by the designs of seed sorting machines in agriculture we designed and built Kogia sima, our friend, our coworker, our invention. It is quite ingenious if I do say so myself. Kogia sima is not a dwarf sperm whale as the name implies, rather it is a seed sorting machine made of PVC pipe, 2x4's, a tupperware container, an old T-Shirt, and--the heart of the beast--a hair dryer. Dried samples from the seed traps go into the bottom of Kogia sima. The hair dryer blows unwanted leaves out the top like the spray from a blowhole, leaving the seeds down below. Although we still have to sort and identify the different species of seeds, Kogia sima greatly lessens the work load by removing all of the leaves and other light weight debris, which is helping us understand how changes in the dispersal of seeds by birds may impact the forest of Guam over time.
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