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Biological evidence supports an early and complex emergence of the Isthmus of Panama

Artikel i vetenskaplig tidskrift
Författare Christine D. Bacon
Daniele Silvestro
C. Jaramillo
B. T. Smith
P. Chakrabarty
Alexandre Antonelli
Publicerad i Proceedings of the National Academy of Sciences of the United States of America
Volym 112
Nummer/häfte 19
Sidor 6110-6115
ISSN 0027-8424
Publiceringsår 2015
Publicerad vid Institutionen för biologi och miljövetenskap
Sidor 6110-6115
Språk en
Länkar dx.doi.org/10.1073/pnas.1423853112
Ämnesord biogeography, evolution, neotropics, fossil, migration, AMERICAN BIOTIC INTERCHANGE, NORTHWESTERN SOUTH-AMERICA, WESTERN PANAMA, NORTH-AMERICA, MIOCENE, COLLISION, HISTORY, CLOSURE, ARC, EVOLUTION, Multidisciplinary Sciences
Ämneskategorier Geologi

Sammanfattning

The linking of North and South America by the Isthmus of Panama had major impacts on global climate, oceanic and atmospheric currents, and biodiversity, yet the timing of this critical event remains contentious. The Isthmus is traditionally understood to have fully closed by ca. 3.5 million years ago (Ma), and this date has been used as a benchmark for oceanographic, climatic, and evolutionary research, but recent evidence suggests a more complex geological formation. Here, we analyze both molecular and fossil data to evaluate the tempo of biotic exchange across the Americas in light of geological evidence. We demonstrate significant waves of dispersal of terrestrial organisms at approximately ca. 20 and 6 Ma and corresponding events separating marine organisms in the Atlantic and Pacific oceans at ca. 23 and 7 Ma. The direction of dispersal and their rates were symmetrical until the last ca. 6 Ma, when northern migration of South American lineages increased significantly. Variability among taxa in their timing of dispersal or vicariance across the Isthmus is not explained by the ecological factors tested in these analyses, including biome type, dispersal ability, and elevation preference. Migration was therefore not generally regulated by intrinsic traits but more likely reflects the presence of emergent terrain several millions of years earlier than commonly assumed. These results indicate that the dramatic biotic turnover associated with the Great American Biotic Interchange was a long and complex process that began as early as the Oligocene–Miocene transition.

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