Friday , January 31, 2014 - 5:58 PM
LOGAN — There’s a reason why gardeners spend summer months digging up hundreds of dandelions and not equal numbers of bristlecone pine trees.
Evolutionarily speaking, dandelions spend their energy on simple, sappy leaves that shoot up quickly, and flowers that make hundreds of tiny seeds that ride on the breeze. Bristlecone pine trees invest their energy in making fewer, larger seeds, and woody stems with more complex leaves, which form more slowly.
The pines can live hundreds of years, or more. Dandelions live months, at most.
“There are tradeoffs plants face,” said Peter Adler, Utah State University associate professor in the Department of Wildland Resources and the USU Ecology Center. “Some invest in a few big seeds with a good chance of making it, and others invest in a lot of little seeds.”
Adler, working with USU graduate student Aldo Compagnoni and university colleagues in Australia, Germany, California, South Africa and Great Britain, recently published a paper showing that simple morphological traits can explain variation in the life histories of plants.
Plant biologists and ecologists have long suspected that the size of seeds, the woodiness of stems and the complexity and thickness of leaves could be used to illuminate plant species’ evolutionary past, and the survival challenges they overcame, through natural selection.
“In a good year and a good location, small seeds do well,” Adler said. “In a bad year or location, small seeds have a tough go of it.”
Bristlecone pines use a “live long and prosper” strategy. Continuing the “Star Trek” analogy, dandelions reproduce faster than science-fictional Tribbles.
Ecologists have long believed that factors including seed size and plant structure could indicate species histories and the circumstances they overcame, Adler said, but lacked a way to generalize between individual species they studied.
“It’s hard to generalize,” Adler said. “It’s the Achilles heel of ecology.”
Adler and his team linked a global traits database with empirical population models for more than 200 species.
“We found strong relationships between functional traits and plant life histories,” he said. “We show that simple morphological measurements can predict where a species falls within the global range of life histories.”
Basically, they found that species with large seeds, long-lived leaves and dense wood have population growth rates influenced primarily by survival (live long and prosper).
Species with small seeds, short-lived leaves or soft wood, depend on fecundity — having lots of babies — for population growth and persistence.
“These results increase our ability to explain complex population processes with a few easily measured character traits,” Adler said. “If we can refine this approach, it could have important applications in conservation and natural resource management.”
Adler believes the data eventually could help determine the most cost-effective ways of controlling invasive species or protecting threatened species without spending years collecting demographic data.
The research, supported by the National Science Foundation, appeared in the Dec. 30, 2013, online Early Edition of the Proceedings of the National Academy of Sciences.
Contact reporter Nancy Van Valkenburg at 801-625-4275 or firstname.lastname@example.org. Follow her on Twitter at @S_ENancyVanV.
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