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domingo, 25 de octubre de 2015

NSF : Ancient fossils show effect of humans on Caribbean wildlife .- Fósiles antiguos muestran el efecto de los seres humanos en la vida silvestre del Caribe

Hola amigos: A VUELO DE UN QUINDE EL BLOG., Cerca de 100 especies de fósiles hallados en una cueva inundada en la isla de Abaco en las Bahamas revelan una historia de persistencia a pesar de todo - al menos hasta que los seres humanos de tiempo puesto un pie en las islas.Los investigadores dicen que el descubrimiento, detallado en un artículo publicado esta semana en las Actas de revista de la Academia Nacional de Ciencias, muestra que las actividades humanas representan una amenaza para el futuro de la biodiversidad de las islas, con el cambio climático moderno no es necesariamente el factor más importante."Los resultados de este proyecto ofrecen otra perspectiva sobre las formas en las fuerzas naturales y humanos han interactuado con el tiempo y el espacio", dice Tom Baerwald, director del programa de geografía en la National Science Foundation (NSF), que financió la investigación. "A pesar de centrarse en un escenario, este proyecto amplía nuestros conocimientos sobre-naturaleza humana interacciones para las regiones cercanas, incluyendo muchas partes de los EE.UU."Baerwald añade: "La rica variedad de materiales descubierto, y su valor en ayudar a interpretar las condiciones ambientales del pasado, ayudó a llevar a la inclusión de estos sitios en los nuevos parques nacionales y reservas marinas en las Bahamas".
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Fossils found in flooded cave tell new story about nature-human interactions
person sitting next to a lake formed in a flooded sinkhole
Sawmill Sink, the flooded sinkhole from which fossils of almost 100 vertebrate species were found.
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October 20, 2015
Nearly 100 fossil species found in a flooded cave on Abaco Island in the Bahamas reveal a story of persistence against all odds--at least until the time humans stepped foot on the islands.
Researchers say the discovery, detailed in a paper published this week in the journal Proceedings of the National Academy of Sciences, shows that human activities pose a threat to the future of island biodiversity, with modern climate change not necessarily being the most important factor.
"The results of this project provide another perspective on the ways natural and human forces have interacted over time and space," says Tom Baerwald, geography program director at the National Science Foundation (NSF), which funded the research. "Although focusing on one locale, this project expands our insights into nature-human interactions for nearby regions, including many parts of the U.S."
Baerwald adds, "The rich array of materials discovered, and their value in helping interpret past environmental conditions, helped lead to the inclusion of these sites in new national parks and marine reserves in the Bahamas."
Some species more adaptable
Exploring why some species were more flexible than others in the face of climate and human-driven changes could alter the way we think about conservation and restoration of species today.
Scientists fear that activities like habitat alteration and the introduction of invasive species could pose the greatest risk to island species, says lead paper author David Steadman, ornithology curator at the Florida Museum of Natural History.
Abaco Island has lost 39 of the species in the study. Of those, 17 species of birds likely fell victim to changes in climate and rising sea levels around the end of the Ice Age, about 10,000 years ago.
The 22 other species of reptiles, birds and mammals persisted through dramatic environmental changes, only to vanish when humans first arrived on the island 1,000 years ago.
"What we see today is just a small snapshot of how species have existed for millions of years," Steadman says. "The species that existed on Abaco until people arrived were survivors. They withstood a variety of environmental changes, but some could not adapt quickly or drastically enough to what happened when people showed up. There must be different mechanisms driving these two types of extinctions. What is it about people that so many island species could not adapt to?"
Steadman and colleagues, including Janet Franklin of Arizona State University, hope to answer that question later this year when they return to the Bahamas with a National Science Foundation grant that will allow further exploration of caves on Caribbean islands.
Which species went, which remained?
The research will expand the picture of the species that disappeared when humans arrived versus those that survived.
For species that were lost at the end of the Ice Age, climate change, habitat change, and rising seas (with resulting smaller islands) may have caused their populations to become too small to remain genetically viable, resulting in inbreeding.
Some of the species that persisted until people arrived were depleted by human activities that altered forest habitats.
The research also shows how quickly humans can modify habitats. Unlike during the Ice Age, modern climate change and other human-driven changes often go hand-in-hand.
Future research will explore whether there are genetic differences between the Bahamas species that persisted and those that were lost when humans arrived. The scientists hope to learn whether there's a genetic basis for adaptability.
"The answer could help us predict what animals will be affected most by a changing climate, and by humans," Steadman says.
Steadman's and Franklin's research is also funded by NSF's Division of Environmental Biology.
-- Cheryl Dybas, NSF (703) 292-7734
-- Stephenie Livingston, University of Florida (386) 855-0252
Investigators Patricia Fall
David Steadman
Janet Franklin
Related Institutions/Organizations University of Florida
Arizona State University
Related Programs MacroSystems Biology
Geography and Spatial Sciences Program
Related Awards #1118340 Collaborative Research: Long-Term Dynamics and Resilience of Terrestrial Plant and Animal Communities in the Bahamas
#1461496 Avifauna Persistence and Vulnerabilities: Island Biogeography Across Long Time Scales
#1065826 Collaborative Research: Do Microenvironments Govern Macroecology?

A green sea turtle shell that was recovered from Sawmill Sink in very good condition.
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Bones and shells of extinct tortoises
Bones and shells of extinct tortoises were found with crocodile bite marks on them.
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Bahamas parrots sitting in a tree
The Bahamas, or rose-throated, parrot, was identified from fossils dated back to the Ice Age.
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Hairy woodpecker in a tree
Hairy woodpeckers near Sawmill Sink have been there as a species at least since the Ice Age.
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two people in a pine forest
The fossil discoveries led to a new protected area, including a pine woodland with many birds.
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the National Science Foundation (NSF)
Guillermo Gonzalo Sánchez Achutegui
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