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Caribbean frog populations started with single, ancient voyage on south american raft |
| TheAllINeed.com |
(NC&T/NSF) Similarly, the scientists found that the Central American relatives of these Caribbean amphibians also arose from a single species that arrived by raft from South America.
"This discovery is surprising because no previous theories of how the frogs arrived had predicted a single origin for Caribbean terrestrial frogs, and because groups of close relatives rarely dominate the fauna of an entire continent or major geographic region," said Blair Hedges of Penn State, an evolutionary biologist who directed the research. "Because connections among continents have allowed land-dwelling animals to disperse freely over millions of years, the fauna of any one continent is usually a composite of many types of animals."
The results were published in the June 12, 2007 issue of the Proceedings of the National Academy of Sciences and posted in the journal's online early edition this week.
The field work for the study required nearly three decades to complete because many of the species are restricted to remote and isolated mountain tops or other inaccessible areas. Some species included in the study are believed to be extinct because of habitat degradation and other causes.
"This study is a valuable contribution to our understanding of the evolutionary and biogeographic history of one of the world's most complicated places geographically, the Caribbean," said Patrick Herendeen, program director in the National Science Foundation's division of environmental biology, which funded the research. "The research presents strong evidence that this group of frogs reached the Caribbean islands by dispersal."
 | | This frog sits on a tree in Haiti. It is the species Eleutherodactylus eunaster. (Photo: Eladio Fernandez) |
A recent global assessment of amphibians found that the Caribbean Islands have the highest proportion of amphibian species threatened with extinction.
The anatomy of Caribbean frogs previously had led scientists to conclude that species in Cuba and other western-Caribbean islands were related to different mainland species than were the species on Puerto Rico and other eastern-Caribbean islands, regardless of how they got there.
"Discovering a single origin for all of these species throughout the Caribbean islands was completely unexpected," Hedges said.
To make their discovery, the researchers sequenced the DNA of nearly 300 species of Caribbean, Central American, and South American frogs.
The study's DNA research revealed that, while many ocean dispersals may have occurred over time, only two led to the current faunas: one for the Caribbean islands and another for Central America.
The original frogs that successfully colonized the Caribbean islands likely hitched a ride on floating mats of vegetation called flotsam, the method typically used by land animals to travel across salt water. It's not likely that the frog species dispersed simply by swimming because frogs dry out easily and are not tolerant of salt water.
In addition to the study's discoveries about Caribbean and Central American frogs, the research also revealed an unusually large and unpredicted number of frog species in South America.
"The South American frog group may have more than 400 species, and is mostly associated with the large Andes mountains of South America," Hedges said.
Hedges and coauthor William Duellman of the University of Kansas conducted much of the field work. A third co-author is Penn State graduate student Matthew Heinicke, who performed DNA sequencing and analysis. The research was also supported by the NASA's Astrobiology Institute.
How to make your home heating and cooling system cost effective? By: Ophelia Smith
Did your heating bill again knock your socks off? Why not mine? I have a 2100 plus square foot house but my heating system costs only $200 per month. As compared to me, your bill may be even more than $500. Why is there such a big difference? Let's know the basics to minimize this intolerable difference.
When it comes to my house, its visage is southern and obtains a good heat in winter seasons which turns into shade in summer. Most importantly, it is earth sheltered and on ground floor it is heated by propane heater. Additionally I have a wood stove for wintry days and even it is used for cooking whenever power is off. Higher altitude of mountainous location gives my home an appreciable air conditioning for free.
Now let's look on possible problems in your house. First of all your house may be in city where it gets little sun heat. Even though your house might be new and expensive but still I think insulation may be poor. Additionally you may have conventional gas heating and electric cooling system, both of which are expensive. In this way your house is sucking some extra money from your pocket. Obviously most of the houses in US are power controlled. So what you should do to save money? Here are three valuable strategies to do it efficiently.
1. Make sure to use less gas and power in extra efficient systems like air conditioners, hot water heaters and thermostats.
2. Insulation makes a big difference. You should try to increase insulation in structures which are not properly insulated. Cover all cabinets and shelves in the wall with doors. Also build a porch to shade the windows which will serve to save your home from hot sun. Investment in new sheet rock and insulation is required only once but your bill will come every month. Surely these are old ideas but we need to bring these ideas back to save some useful money.
3. While building your house you should ensure good science. Many builders avoid learning and doing something new so they use conventional ideas which are surely sucking our resources. Also poor quality systems are embedded in these extra large and too fragile houses. For this you need to learn all the basics so you become able to ask your builder for a higher quality.
Always remember houses built on small footprints have proved more energy efficient. Experiences have proved that smaller houses are cheaper to have proper heating and cooling system. Another way of proper heating and cooling is to stack the floors over each other. This way they work more efficiently and save some extra money. Similarly, earth sheltering is another useful approach. By this approach the under ground temperature remains 55 degree and it requires only a small amount of heating and dehumidifying. However some of these structures my not need any cooling or heating but still best thing about them is storm and fire resistance capability. Another option can be the addition of solar collectors to your yard and house. The idea of fireplace can be excellent in cold climates to have good heating environment in your house.
Does all this sounds good for you? Surely, if we go for good science rather than fashion, valuable money can be saved to invest some where else!
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I want to get a tatoo of myself on my entire body, only 2 taller. -- Steven Wright
I think you should defend to the death their right to march, and then go down and meet them with baseball bats.-Woody Allen, on the KKK
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