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Osos pardos del Pleistoceno en el medio continente de América del Norte
Paul Matheus1, James Burns, Jaco Weinstock
1Alaska Quaternary Center, University of Alaska Fairbanks, Fairbanks, AK, USA. ffpem1@uaf.edu
Science (New York, N.Y.)
|November 13, 2004
Resumen
Un fósil de oso pardo de Alberta de hace 26.000 años desafía los modelos de migración. Los modernos osos pardos probablemente descienden de poblaciones que persistieron al sur de las capas de hielo durante el Último Máximo Glacial.
Área de la Ciencia:
- Paleontología Paleontología.
- Genética La genética.
- La biogeografía es la biogeografía.
Sus antecedentes:
- Los modelos actuales sugieren que la migración del oso pardo (Ursus arctos) a América del Norte ocurrió hace 100-50 mil años, con una expansión hacia el sur después de hace 12 mil años a través de un corredor libre de hielo.
- Estos modelos carecen de evidencia de presencia de osos al sur de Beringia durante el Último Máximo Glacial.
Objetivo del estudio:
- Investigar el momento y las rutas de la migración del oso pardo hacia el Nuevo Mundo.
- Para determinar si las poblaciones persistieron al sur de los márgenes glaciales durante el Último Máximo Glacial.
Principales métodos:
- Datamiento radiométrico de un fósil de oso pardo.
- Análisis del ADN mitocondrial (mtDNA) del espécimen fósil.
Principales resultados:
- Un fósil de oso pardo de hace 26.000 años fue descubierto en el centro de Alberta, significativamente al sur de Beringia.
- El análisis de ADN mitocondrial reveló que el fósil pertenece al mismo clado que los modernos osos pardos en el sur de Canadá y el norte de Estados Unidos.
- Este hallazgo sugiere que los osos pardos habitaban áreas al sur de las capas de hielo durante el Último Máximo Glacial.
Conclusiones:
- El descubrimiento desafía la línea de tiempo establecida de la migración del oso pardo al Nuevo Mundo.
- Las poblaciones modernas de osos pardos en el sur de Canadá y los Estados Unidos probablemente se originaron de poblaciones que sobrevivieron al sur del margen glacial durante el Último Máximo Glacial.
- Esto sugiere una presencia más compleja y más temprana de osos pardos en el Nuevo Mundo de lo que se suponía anteriormente.
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