Estudo descobre elo entre algas marinhas e diversidade em baleias ao longo de 30 milhões de anos

terça-feira, fevereiro 23, 2010

Link Between Marine Algae and Whale Diversity Over Last 30 Million Years, Study Finds

ScienceDaily (Feb. 22, 2010) — A new paper by researchers at George Mason University and the University of Otago in New Zealand shows a strong link between the diversity of organisms at the bottom of the food chain and the diversity of mammals at the top.
Humpback Whale. (Credit: iStockphoto/Josh Friedman)

Mark D. Uhen, a geologist at Mason, says that throughout the last 30 million years, changes in the diversity of whale species living at any given time period correlates with the evolution and diversification of diatoms, tiny, abundant algae that live in the ocean. In the paper, published in the latest issue ofScience, Uhen and co-author Felix G. Mark of Otago show that the more kinds of diatoms living in a time period, the more kinds of whales there are.

Looking at thousands of published accounts of whale fossil records, the researchers assembled the records in a database to analyze and pinpoint the various fossils. The fossil records show a direct link between the productivity of the ocean and the variety of whale fossils. Uhen says they also found a correlation between global changes and fossil variety.

"This study shows that if we look at the bottom of the food chain, it might tell you something about the top," says Uhen. "Diatoms are key primary producers in the modern ocean, and thus help to form the base of the marine food chain. The fossil record clearly shows that diatoms and whales rose and fell in diversity together during the last 30 million years."

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Science 19 February 2010:
Vol. 327. no. 5968, pp. 993 - 996
DOI: 10.1126/science.1185581

Climate, Critters, and Cetaceans: Cenozoic Drivers of the Evolution of Modern Whales

Felix G. Marx1,2,* and Mark D. Uhen3

Modern cetaceans, a poster child of evolution, play an important role in the ocean ecosystem as apex predators and nutrient distributors, as well as evolutionary "stepping stones" for the deep sea biota. Recent discussions on the impact of climate change and marine exploitation on current cetacean populations may benefit from insights into what factors have influenced cetacean diversity in the past. Previous studies suggested that the rise of diatoms as dominant marine primary producers and global temperature change were key factors in the evolution of modern whales. Based on a comprehensive diversity data set, we show that much of observed cetacean paleodiversity can indeed be explained by diatom diversity in conjunction with variations in climate as indicated by oxygen stable isotope records (18O).

1 Department of Geology, University of Otago, 360 Leith Walk, Post Office Box 56, Dunedin, Otago 9016, New Zealand.

2 Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK.

3 Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, MS 5F1, Fairfax, VA 22030, USA.

* To whom correspondence should be addressed. E-mail:


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