First phylogeographic study of a rainforest tree
In species-rich rainforests of the New World tropics most trees have broad geographic distributions–from Mexico to Bolivia and sometimes to the West Indies. Either they have excellent dispersal abilities, or they established broad ranges prior to the formation of present geographic barriers. In a study featured in American Naturalist, Christopher Dick, Kobinah Abdul-Salim and Eldredge Bermingham address these questions in the first phylogeographic study of a rainforest tree.
The morphology of the study species, Symphonia globulifera (Clusiaceae) is uniform across a natural range that includes the New World tropics and Africa. Symphonia globulifera also has a detailed fossil pollen record, which the authors used to calibrate a molecular clock for DNA sequences obtained from African and Neotropical populations and to estimate when these populations were separated. The study revealed that, although trees from different populations look the same, the evolutionary history of these populations is probably quite distinct.
Although marine dispersal of S. globulifera is considered improbable because it has salt-intolerant seeds, the authors demonstrate that Symphonia expanded into Mesoamerica, the Amazon basin and the West Indies via oceanic currents at least three times. The three major New World clades – found in Mesoamerica, the Amazon basin, and the West Indies – diverged over 15 million years ago, and appear to have been genetically isolated ever since, giving Symphonia globulifera the status of "living fossil".
Panama contained the largest number of genetically distinctive populations, in contrast to Amazon basin Symphonia, which displayed no genetic differentiation across 2500 km of lowland forest. The authors suggest that strong phylogeographic structure in the Panamanian Isthmus stems from its history as a land bridge between Central America, South America, and the proto-Isthmian archipelago of islands, which were connected approximately 3 million years ago.
The authors suggest that same history may explain the high level of beta diversity (changes in species composition among sites) of rainforest trees in Panama, in contrast to western Amazon (Condit et al. Science 2002 v292, 666-669). While ecologists attribute the beta diversity in Panama to local adaptations to varied habitats, the diversity may also reflect the incomplete mixing of independently evolved floras during the Great American Biotic Interchange across the Isthmus of Panama.
Ref. Molecular systematics reveals tertiary diversification of a widespread tropical rainforest tree. Christopher Dick, Kobinah Abdul-Salim, and Eldredge Bermingham. American Naturalist, December, 2003.
Christopher Dick | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...