NEWS BRIEFS - POSTED THURSDAY, JANUARY 11, 2007
Giant Stinky Mystery Flower is Classified…and has surprisingly normal relatives
Rafflesia (Rafflesiaceae)—a parasitic plant whose flower weighs more than a bowling ball and reeks of rotting flesh—has finally found its family, according to a Brevia published in the journal Science.
Found on rainforest floors in southern Asia, rafflesia has baffled botanists for two centuries. It is hard to classify because it is rootless, shootless and leafless; it only has a sinewy stem which it uses to siphon the nutrients and water it needs from the host plant it parasitizes.
“Very few botanists have been brave enough to speculate on their closest relatives,” said Charles Davis, assistant professor of Organismic and Evolutionary Biology and co-author on the paper. “And the flowers are totally out to lunch,” he adds. “They really look extra-terrestrial."
Further complicating classification, this plant no longer photosynthesizes, so it ditched the parts of its genome needed for that process. And those genes are often used to classify plants.
So instead, Davis and his colleagues delved deeper, analyzing 11,500 base pairs of DNA from another region of the genome. “The breakthrough has been tapping a different part of the genome: in particular, mitochondrial genes and nuclear genes. That was the contribution here,” Davis explains. The data showed that rafflesia belongs to a faimly whose flowers are nearly all tiny--Euphorbiaceae. Among its closest relatives are poinsettias and rubber trees.
How did this “charismatic mega-flora”, as Davis calls it, evolve from its dainty blossomed ancestors? The study showed that the flower increased in size by 79-fold over 46 million years. The change would be equivalent to a human growing to 146 meters tall—the height of the Great Pyramid of Giza—Davis points out. Davis believes the size change occurred over a short period of time. “I would tend to argue that the change almost certainly happened very quickly in its early evolution,” he says. “There was probably strong selective pressure to evolve large flowers early on.”
If researchers discover exactly which genes or gene is responsible for the gigantism, Davis believes there will be wide applications. “You can envision using a gene in every number of ways.” High protein grains or 15-pound roses, for example.
The technique Davis used to uncover the flower’s genetic identity may allow scientists to classify other mystery plant life. “With organisms like these that are so bizarre, we’ve just been at a standstill. Molecular genetics came through like gangbusters.”
Birds with bigger brains relative to their body size had a higher survival rate than those with smaller brains, according to a study published in Proceedings of the Royal Society B: Biological Sciences this week. After sorting out the other factors that can affect mortality, researchers showed for the first time in any animal that brain size is correlated with survival.
This study provides evidence for the cognitive buffer hypothesis--that brain size is linked to the ability to learn and innovate. And bigger-brained animals may respond better to changes in habitat. Louis Lefebvre, co-author on the study and a professor of Biology at McGill University in Canada, says, “Some animals can learn about predators, if there is no water or food; some animals innovate in food searching behavior. Others just can’t cope with it.”
Past studies in primates have shown that if the neocortex region of the brain is bigger, the primate is better able to use tools. In birds, if a region of the brain called the mesopallium is bigger, that species is better able to respond to changes in habitat. Although the neocortex and mesopallium are organized differently, they serve as integrative centers, says Lefebvre. Both take information not just from the sense organs, but other parts of the brain and put it together.
Crows score high when it comes to brain-power. While pigeons—despite being masters of exploiting the built environment—are surprisingly small-brained.
So why are small-brained birds still around if survival is linked to big brains? “There must be compensation there somewhere,” Lefebvre says. It's possible that small-brained animals compensate by having more offspring, he says. In fact, although survival is lower for small-brainers, a species' vulnerability to extinction does not seem to be linked. It can’t be as simple as big brains are better; if that were the case, says Lefebvre, “there shouldn’t be any partridges around any more.”
But as the climate changes, the ability to adapt to a new environment could be more highly prioritized. “Presumably the flexible animals might cope better with changes, says Lefebvre, “But in 10,000 years is it just going to be descendents of crows? We can’t go that far.”
How far can we extrapolate the findings – should we humans be looking for mates with big heads? Lefebvre answers: “No, we can’t extrapolate bird brains to humans. I personally don’t base my decisions on my findings in birds.”
Annual plants, including most weeds, may be better equipped to deal with changes in climate than longer-lived perennials, according to a study published in the Proceedings of the National Academy of Sciences. Annuals reproduce and die each year, giving them more chances to adapt than plants with longer generation times.
The researchers compared a population of mustard plants before and after a multi-year drought by resurrecting old seeds that had been collected before the drought took place.
In this study, pre-drought seeds and their post-drought descendents were grown side-by-side in a greenhouse. The researchers found that the post-drought mustard plants flowered as many as eight days earlier than the pre-drought plants. Early flowering is advantageous in a drought period: those plants that wait to flower often wither before producing a single seed.
Steven Franks, a post-doctoral research associate in the Department of Ecology and Evolutionary Biology at the University of California Irvine and first author on the study, says, “This shows that it is possible for annual plants to adapt pretty fast to changing climactic conditions.”
But even for annuals, there is a limit. “Even weedy species may run out of existing genetic variation.” Physiological constraints also put a cap on flowering time—there have to be roots and leaves and a stem in place for there to be a flower.
To facilitate this method used in this study in the future, co-author Arthur Weis has started Project Baseline, which aims to collect seeds from today’s plants, so that scientists years from now will be able to compare future populations with those that exist today.
McNaught's comet, originally discovered by astronomer Robert McNaught in August 2006, has become much brighter over the past several nights, according to Space.com columnist, Joe Rao, a broadcast meteorologist and lecturer at New York’s Hayden Planetarium.
The comet will be closest to the sun on Friday afternoon. It is expected to reach its peak brightness by Friday or Saturday, Rao says. “This could very well turn out to be the most brilliant comet in more than 30 years,” Rao says.
According to Discovery Channel News, look just left of due west during early evening to catch a glimpse of the comet. The further north you are the better you’ll be able to see it.
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