Cincinnati -- DNA probes similar to those used to solve criminal cases and paternity suits could find a new use by conservations trying to preserve the health of the world's tropical rainforests.
UC biologist Steven Rogstad, former graduate student Daniel Busemeyer, mathematician Stephan Pelikan and Robert Kennedy of the Cincinnati Museum of Natural History report in the Journal of Tropical Ecology used DNA fingerprinting probes to examine the genetic diversity of a common Philippine shrub, Rubus moluccanus. The researchers found that populations on different islands had a distinctly different genetic makeup.
"This has implications for tropical rainforest diversity," said Rogstad. "It demonstrates that all of the genes in a species are not necessarily found in every population. So, it becomes important to survey and preserve as much genetic variation as possible."
Conservation biologists have recognized recently that not only must species be preserved, but an array of genetically diverse populations should be preserved to ensure their evolutionary success in the future.
Rogstad and Busemeyer used two synthetic DNA probes to look at genetic diversity in stretches of DNA known as VNTRs (variable number of tandem repeats). Their results indicated that none of the plants was genetically identical to any other plant, which means the plants were not reproducing asexually or by cloning. That is also an important finding when planning conservation efforts, especially for plants which are often extensively clonal.
"If tropical rainforest trees have a long history of outbreeding and we force them to inbreed by reducing the amount of areas forested, you often see greatly increased rates of deleterious effects. Those are the ones we worry about," said Rogstad.
The plants studied came from one population on the island of Luzon and three isolated populations on the island of Mindanao. As expected, the plants on Luzon were most different when compared with the Mindanao populations. However, there were also significant differences among the Rubus populations on the same island.
To document the differences within a single population and between populations, the researchers used a software package developed by Pelikan and Rogstad called "GELSTATS." Only two populations (on Mount Apo and Mount Busa) appeared genetically similar. Not surprisingly, the greatest differences appeared in the populations which were the greatest distance apart.
One explanation for the differences, according to Busemeyer, is the reliance on bees for pollination. "Many bees do not forage at great distances from the hive," according to Busemeyer, "so it is probably unlikely that they would move between populations."
The researchers say their findings indicate that a large number of individuals from various populations would have to be protected to conserve the maximum genetic diversity in a species such as Rubus.
The research findings will be published in the Journal of
Tropical Ecology. The project was supported in part by the
National Science Foundation with assistance from the Cincinnati
Museum of Natural History and the Philippines Biodiversity
Inventory of the National Museum of the Philippines.