食物网的古今差异不大

Researchers from the Santa Fe Institute and the Smithsonian Institution have pieced together a highly detailed¹ picture of feeding relationships among 700 mammal, bird, reptile², fish, insect, and plant species from a 48 million year old lake and forest ecosystem³. Their analysis of fossilized remains⁴ from the Messel deposit near Frankfurt, Germany, provides the most compelling evidence to date that ancient food webs were organized much like modern food webs. Their paper describing the research appears online and open access this week in Proceedings⁵ of the Royal Society B: Biological Sciences.

 

The researchers first compiled data about the more than 6,500 feeding relationships among 700 species found in the deposit, which dates to the Eocene epoch⁶（始新世）. Then they constructed two networks of feeding interactions -- one for the lake and one for the surrounding forest.

 

Next, they mathematically compared each food web's structural⁷ features with those of modern-day food web datasets -- matching up such indicators⁸ as fractions of cannibals（食人族）, herbivores, and omnivores（杂食者）; the distributions of generalist and specialist feeders; the mean lengths of feeding chains connecting pairs of taxa; and so on.

 

"What we found is that the Messel lake food web, with 94 taxa and 517 links, looks very much like a modern food web," says SFI Professor Jennifer Dunne. "This is despite the fact that 48 million years of species turnover⁹ and evolution separate the Messel lake ecosystem from modern ecosystems¹⁰."

 

Analysis of the Messel forest food web's structure was more challenging due to the high degree of species diversity represented in the Messel dataset -- 630 taxa and 5,534 feeding links -- far more than what datasets for modern webs include.

 

"Basically, we don't yet have examples of comprehensive modern terrestrial food web datasets that have the high resolution of plants, insects, and their interactions that we included in the Messel forest dataset," says Dunne.

分享到：