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Abstract Detail


Integration of Spatial and Ecological Data in Evolutionary Studies

Dillon, Michael O. [1].

El Niño Mediated Evolutionary Patterns: Can trees illuminate climate influenced speciation?

The lomas formations of coastal Peru and northern Chile are isolated and strictly delimited ecosystems, unique within the context of South American floristic composition and ecological preferences. These highly endemic communities exist as a linear, terrestrial archipelago of vegetation islands within a 3500 km sea of hyper-arid desert. Long-term aridity, dating from the late Jurassic, makes this the oldest and driest desert on Earth. Recent studies have reconstructed phylogenetic relationships with molecular sequence data within nearly a dozen genera with lomas formation representatives. While much more data remain to be gathered, initial studies allow for speculation on processes that have led to adaptations in these harsh environments. Could it be that climate fluctuations, specifically El Niño phenomena, are responsible for driving speciation within the lomas formations? Unpredictable, but recurrent El Niño events generate abnormal available moisture which has observable impacts upon the desert biota. El Niño has been implicated in shifts in selection pressures, population expansions, vicariance events, and founder effects involving seedling establishment, and seed-bank maintenance. An El Niño free regime would negatively impact taxa that require El Niño moisture for their existence and render range expansion difficult. Our ability to divine causal agents from phylogenies built upon one or a few gene-trees is limited. Trees may allow for the recognition of allopatric and secondary sympatic distributional patterns. Calculating the influence of any specific climate element is more difficult. The historical establishment of El Niño, its temporal duration, and intensity levels are controversial subjects. Further, the interplay of Cenozoic glacial cycles at ~40 kyr intervals, collisional tectonics, and associated sea-level changes can not be ignored.


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1 - Field Museum of Natural Hististory, Department of Botany, 1400 South Lake Shore Drive, Roosevelt Rd At Lake Shore, Chicago, Illinois, 60605-2496, USA

Keywords:
Biogeography
Chile
coastal deserts
lomas
Peru
phylogenetics.

Presentation Type: Symposium or Colloquium Presentation
Session: C02
Location: Stevens 2/Hilton
Date: Wednesday, July 11th, 2007
Time: 11:00 AM
Number: C02010
Abstract ID:1190


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