Big seeds produced by tropical trees such as black palms were probably once ingested and then left whole by huge mammals called gomphotheres.
Gomphotheres weighed more than a ton and dispersed the seeds over large distances.
But these Neotropical creatures disappeared more than 10,000 years ago. So why aren't large-seeded plants also extinct?
A paper published this week in the journal Proceedings of the National Academy of Sciences (PNAS) suggests that rodents may have taken over the seed-dispersal role of gomphotheres.
"The question has been: how did a tree like the black palm manage to survive for 10,000 years, if its seed-dispersers are extinct?" asks Roland Kays, co-author of the paper and a zoologist at North Carolina State University and the North Carolina Museum of Natural Sciences.
"This research solves a long standing puzzle in ecology," says Alan Tessier, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research.
"How did plant species that seem to be dependent on Pleistocene megafauna for seed-dispersal survive the extinction of that megafauna?"
Now, says Kays, scientists may have an answer.
By attaching tiny radio transmitters to more than 400 seeds, Patrick Jansen, a scientist at the Smithsonian Tropical Research Institute (STRI) and Wageningen University and colleagues found that 85 percent of the seeds were buried in caches by agoutis, common rodents in tropical lowlands.
Agoutis carry seeds around in their mouths and bury them for times when food is scarce.
Radio-tracking revealed a surprising finding: when the rodents dig up the seeds, they usually don't eat them, but instead move them to a new site and bury them, often many times.
One seed in the study was moved 36 times.
Researchers used remote cameras to catch the animals digging up cached seeds. They discovered t
|Contact: Cheryl Dybas|
National Science Foundation