Newly Discovered Flower Makes Fake Pollen to Fool Bees

"I was certain it was something new when I saw it," says Chris Martine of the bush tomato species he discovered in the Australian outback. It's a scrappy, spiny shrub with crinkly purple flowers that thrives on fire. It also uses treachery to survive, disguising its female flowers with fake male parts and even fake pollen.

A botanist and biodiversity scientist at Bucknell University, Martine explains that the new plant "was on the radar of a few local botanists as being an oddball." Martine had been studying related species for a decade, so when his lab analyzed this plant's DNA, he recognized that it was something different. He went to Australia to document the species in person and dubbed it Solanum cowiei after botanist Ian Cowie at the Northern Territory Herbarium, who first introduced him to the plant.

The diverse Solanum genus includes plants ranging from potatoes and tomatoes to eggplant and nightshade. The Australian bush tomatoes that Martine studies grow little fruits that can be edible or quite poisonous, depending on the species.

Martine discovered that compared to its relatives, S. cowiei is especially well adapted to the fires that sometimes sweep through its habitat. The plants live in large groups of clones tied together by underground root systems. In an area that had recently been burned clear, Martine found S. cowiei plants springing up and blooming while other species lagged behind. This means that after a fire, these plants have a competitive edge over all their neighbors in getting to pollinators.

The new species's method of reaching those pollinators is a weird one. S. cowiei grows separate male and female flowers, and like about a dozen of its close relatives, it disguises the female flowers with fake male parts and pollen. Under an electron microscope, the false pollen grains look like brand-new tennis balls. Real pollen grains are closer to old ping-pong balls, with large dents or grooves on their surface—these are the weak spots where a narrow tube may later burst out of the wall of the pollen grain, carrying the plant's sperm to an egg.

Why bother with the ruse? Solanum flowers don't have any attractive fragrance to lure their pollinators, or nectar for insects or birds to drink while they're dusted with pollen. Instead, these plants rely on pollinators that want to eat the pollen itself. Certain foraging bees use pollen to feed their young, Martine says. "So if you want one of these bees to visit your flowers, you have to have to have the visual cue of the anthers," a flower's male parts. "And if you want them to come back to flowers like yours again, you have to give them some reward to take away."

Martine and his collaborators are now studying whether this fake pollen is any better or worse for young bees to eat than the real stuff. "Is there a difference in what they are getting?" he says. "Can they tell?"

The "oddball" bush tomato isn't the only plant Martine finds intriguing. He produces an online video series called "Plants Are Cool, Too!" ("Can an animal make its own food? No! Can an animal feed the whole world? No!" the theme song declares.) Martine started this series after working with kids who were interested in science and realizing that they knew a lot about animals, but not so much about plants. People browsing online are more likely to encounter a cute cat video, after all, than one about cattails. So he started putting together episodes that highlight some of the "coolest" plants, along with the botanists who study them.

The next full episode should be out in January, he says, and it includes an especially cool moment: a new species of mustard plant being discovered. "Our guest expert looked down during shooting and said, 'Hey, wait a minute,'" he says. "I don't know how often new species are discovered while a camera is running, but it can't be very common."

Photo by Kym Brennan.

Christopher T. Martine, David E. Symon, & Elizabeth C. Evans (2013). A new cryptically dioecious species of bush tomato (Solanum) from the Northern Territory, Australia. PhytoKeys DOI: 10.3897/phytokeys.30.6003

Bats, like Batman, Thrive in a Post-Apocalyptic Environment

Without plagues, earthquakes, and unhinged criminal masterminds, the residents of Gotham might never need to put up the bat signal. Real bats, of course, are less concerned with responding to emergencies than with eating bugs. But like Batman, they do just fine—if not better than ever—in recently devastated environments. Specifically, forests that have burned down.

For five weeks in the summer of 2002, a wildfire tore through national forests in the Sierra Nevada mountains. The McNally Fire was started by a careless human, and ended with over 150,000 acres burned. A year later, scientists came by to see how the bats were doing.

"Bat ecologists have known for a while now that bats respond favorably to controlled, low intensity fires," says Michael Buchalski of Western Michigan University, one of the study's authors. "We were more interested in the effects of large, natural fires." These blazes can completely destroy the forest canopy, leaving an area unrecognizable.

Researchers visited 14 sites in the woods, half in burned areas and half in areas that were untouched. They left devices that recorded the ultrasonic cries of echolocating bats at night. Since tallying up all the bat activity they heard could be misleading—one flourishing species of bats might mask the disappearance of another—they divided the recordings into groups of similar-sounding calls, representing groups of bat species.

The researchers estimated how plentiful each type of bat was based on how often they heard its calls. Comparing burned and unburned areas, they found that no bat group was bothered by the fire. Instead, every group of bats was at least as plentiful in the fire-scorched areas—and some were doing even better than usual.

Despite the absence of costumed criminals, a few factors might account for bats' increased activity in a scorched landscape. Bats hunt by swooping through the air and searching for insects below. With much of the vegetation cleared out by fire, insects have fewer places to hide, and hunting bats have a clearer view for their echolocation.

Additionally, the first plant regrowth after a fire leads to a boom in insect species. This means there's more prey than ever available for hungry bats. "One-stop shopping!" says coauthor Joseph Fontaine of Murdoch University. Those bats may find new places to roost—or, if you prefer, build their secret lairs—inside dead trees.

Buchalski and Fontaine say bats probably need a mix of landscapes to thrive, including areas that have recently burned. Carefully allowing forests to burn more like they did in the past could lead to "healthier forests and healthier wildlife populations," Buchalski says. "However, this is a very contentious issue within the field of forestry management."

"We have spent the majority of the last century suppressing and excluding fire," Fontaine adds. "More fire right now is probably not a bad thing whatsoever." (For non-human animals, anyway.) With climate change increasing the potential for drought and wildfire, the authors say that understanding how different species deal with fire is becoming more important.

Bats aren't the only animals that appreciate a fire. Fontaine says deer mice and other short-lived rodents respond very well to fire, and deer and elk like to chew on the soft new shrubs that have regrown a few years later. Several types of woodpeckers, he adds, rely on fires. Many bird species that forage in the open and don't need living trees to make their nests have a similar response to the bats.

Although forest fires are a boon for many species, the robin doesn't seem to be among them.


Buchalski, M., Fontaine, J., Heady, P., Hayes, J., & Frick, W. (2013). Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0057884

Image from public domain files at Wikia.

Dinosaur Age Not Dramatic Enough? Add Fire

As if a world dominated by hungry, house-sized lizards weren't sufficiently exciting, scientists have added another set piece to our image of the Cretaceous: raging wildfires.

The Cretaceous period, which ended about 65 million years ago with the extinction of the dinosaurs, was hot. That's thanks to volcanos that pumped carbon dioxide into the atmosphere and created a greenhouse effect. Researchers from London and Chicago now say it was also a "high-fire" world. Frequent blazes may have kept animals on the run, created some of the fossil beds we study today, and helped determine which plant species survived into the next era.

Led by graduate student Sarah Brown from the Royal Holloway University of London, the researchers tracked the appearance of charcoal in ancient sediments. Like a set of sooty footprints right through the fossil record, the charcoal evidence showed when and where fires had occurred.

The team saw that wildfires had increased during the Cretaceous period. These fires were probably sparked by lightning, and their flames were fanned by the high concentration of oxygen in the ancient atmosphere. Today, oxygen makes up about 21% of our air. But during the Cretaceous, it may have risen as high as 25% or more.

This high oxygen content, the authors say, would have allowed plants to burn without being bone dry. A spark in a green forest, instead of dying out as it would today, might become a full-blown fire.

Brown and her coauthors did not find any evidence that these fires contributed to killing off the dinosaurs. But they note that after a fire burns through a piece land, erosion is likely. There may be rapid flooding or mudslides. In the Cretaceous, these events might have trapped and killed dinosaurs and other animal life--and helped preserve their bones.

The authors point to certain fossil beds that lie in floodplains and contain charcoal, as well as plant and animal remains. These could be sites where wildfires triggered flooding, conveniently sweeping lots of informative fossils into one place for future scientists to find.

Charred plant remains in these fossil beds provide another clue about the effect of fire. As the Cretaceous went on, the types of plants being fossilized gradually changed. Flowering plants, called angiosperms, became more and more common. Gymnosperms--the more ancient, flowerless species such as cone-bearing trees, cycads, and ginkgos--faded into the background.

A charred flower fossil from the Late Cretaceous.

Frequent fires may have given an added edge to the angiosperms. The new types of plumbing these plants had invented let them grow faster and more efficiently. Rather than trees, the flowering plants growing during the Cretaceous seem to have been weedy and shrubby types. After a fire, they could regrow faster than the gymnosperms. And their new growth provided fresh fuel for wildfires, creating a cycle that encouraged the growth of flowering plants and left older models in the dust.

Though fire didn't do in the dinosaurs, then, it may have helped set the stage for the dominant plants of the modern age. (As if we needed any more drama.)

Brown, S., Scott, A., Glasspool, I., & Collinson, M. (2012). Cretaceous wildfires and their impact on the Earth system Cretaceous Research DOI: 10.1016/j.cretres.2012.02.008


Images: Gorgosaurus from Nobu Tamura/Wikimedia Commons; flower fossil from Brown et al.

Make Mine Well-Done (with a Side of Calories)

Unless you enjoy your beef patties uncooked and straight from the fridge, there may be more calories hiding in that hamburger than you think. Harvard researcher Rachel Carmody says that our standard method of measuring calorie content doesn't account for the ways heat changes food. Cooking adds calories, Carmody says, and she's got some Atkins-adherent mice to back her up.

The calorie numbers on food labels are calculated according to how many grams of fat, carbohydrate, and protein the food contains, and how calorie-dense each of those nutrients is. It's simple math and chemistry. But since calories are a unit of energy--how much energy you, as an eating animal, manage to extract from your meal--biology should be a part of the equation, too. Our standard calorie math doesn't consider how much energy we expend chewing and digesting our food, or what components of our meal go toward feeding our gut microbes instead of our bodies. It also ignores the effect of cooking: heat breaks down starches and unravels proteins, making those molecules easier for our bodies to absorb.

Carmody used mice to study the effects of an all-cooked or all-raw diet. Mice, like humans, are natural omnivores. Unlike humans, they will allow you to feed them nothing but raw sweet potato for four days.

Adult male mice were put on a diet of either sweet potato or beef, raw or cooked. (The researchers also studied the effect of pounding the food, which makes it easier to chew but doesn't otherwise have much effect.) The mice could eat as much of their one food as they wanted. They were also free to exercise, running on magnetic wheels that recorded how much use they got. The researchers measured how much food their subjects ate, how much they exercised, and how much weight they had gained or lost after four days.

Since previous research had shown that cooked starches provide more energy, the potato-eating mice were expected to get more calories from their food when it was cooked. Obligingly, the mice maintained their original weights on a cooked-potato diet but lost weight on a diet of raw potato. Besides getting more energy out of each bite of food, the cooked-potato mice also ate more. The raw-diet mice, on the other hand, apparently weren't able to choke down enough sweet potato to keep up their weight. Both groups of mice exercised the same amount.

Mice being fed lean beef were also expected to lose weight, lacking necessary fat and carbohydrates in their diet. (The authors point out that in humans, eating nothing but lean meat leads to a condition called "rabbit starvation." You can go ahead and cross that all-rabbit diet off your list of resolutions for 2012, because it's said to cause diarrhea, headache, and "vague discomfort.")

All of the meat-eating mice lost weight. But those mice eating cooked meat lost significantly less weight, demonstrating that they were able to get more calories out of their food. Their amount of exercise was the same as the raw-meat mice. And unlike the mice fed on sweet potato, the meat-eating mice actually ate less of their food when it was cooked. This suggests that they weren't enjoying their diet very much, but it also suggests that the cooked beef was even more calorie-rich than the weight results would imply. If the mice eating cooked beef had swallowed the same quantities as their raw-diet counterparts, they might have lost even less weight, or not lost weight at all.

There are several factors that could make cooked meat more energy-rich. High heat unwinds (or "denatures") protein molecules, making them easier to digest. Since cooked meat is usually softer, we need to expend less energy chewing it up and breaking it down inside our bodies. Additionally, cooking kills the pathogens that like to hang out on raw meat. When we ingest E. coli or Salmonella along with our meal, we have to divert extra energy to our immune systems to keep those bacteria at bay. Calories spent chewing, breaking down, or disinfecting our food cancel out the calories of energy we're taking out of it.

We started using fire at least 300,000 or 400,000 years ago. For reference, that's before modern humans even existed. As long as we've been Homo sapiens sapiens, we've lived with fire. Once we figured out how to cook our food, which included a lot of meat, we would have seen the benefits: more energy for making tools, raising families, and growing those big brains.

Now that meat is available to many of us in the form of daily Double Whoppers, and not just the occasional mastodon steak, the question of how many calories are really in our food isn't a trivial one. Even the most careful calorie counters may be taking in more energy than they think. A fast-food taco, or a trough of starchy pasta at a restaurant, could hold even more calories than the menu says.

We need better math, for everyone's sake. For starving and malnourished populations, understanding how cooking increases calorie content could help people glean more sustenance from their limited resources. For populations struggling with obesity, better food labeling could allow people to take control of their calorie intake before we all have to go on a rabbit diet.


Carmody, R., Weintraub, G., & Wrangham, R. (2011). Energetic consequences of thermal and nonthermal food processing Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1112128108


Image: Carmody et al. 10.1073/pnas.1112128108