The story of the fig and its wasp

Inside the rounded fruit of a fig tree is a maze of flowers. That is, a fig is not actually a fruit; it is an inflorescence—a cluster of many flowers and seeds contained inside a bulbous stem. Because of this unusual arrangement, the seeds—technically the ovaries of the fig—require a specialized pollinator that is adapted to navigate within these confined quarters. Here begins the story of the relationship between figs and fig wasps. The queen of the fig wasp is almost the perfect size for the job—except, despite her tiny body, she often times will lose her wings and antennae as she enters through a tight opening in the fig. “The only link the fig cavity has to the outside world is through a tiny bract-lined opening at the apex of the fig, called the ostiole, and it is by means of this passage that the pollinating fig wasp gains access to the florets,” as described in Figweb, a site by Iziko Museums of Cape Town. Once inside, the queen travels within the chamber, depositing her eggs and simultaneously shedding the pollen she carried with her from another fig. This last task, while not the queen’s primary goal, is an important one: She is fertilizing the fig’s ovaries. After the queen has laid her eggs, she dies and is digested by the fig, providing nourishment. Once the queen’s eggs hatch, male and female wasps assume very different roles. They first mate with each other (yes, brothers and sisters), and then the females collect pollen—in some species, actively gathering it in a specialized pouch and in others, accumulating it inadvertently—while the wingless males begin carving a path to the fig’s exterior. This activity is not for their own escape but rather to create an opening for the females to exit. The females will pollinate another fig as queens. The males will spend their entire lifecycle within a single fruit. While this tree-wasp relationship may not be common knowledge to all fig-eaters, it is well-known to biologists as one of the most solid examples of coevolution. “One of the best activities to do with an introductory biology class is to pass around Fig Newtons, let them take a bite and then tell them the story of the fig wasp life cycle,” said tropical plant ecologist Greg Goldsmith as we recently hiked through a cloud forest in Monteverde, Costa Rica. “It’s a fascinating story.” After learning the story of the fig and its wasp, the most common question is, “Do we eat wasps when we eat figs?” The short answer is that it depends—that is, some figs are parthenocarpic, meaning they are...

Read More

The evolution of beer yeasts, seedy pants and vampire bat venom-turned medicine

Beer yeasts: Researchers at Lund University in Sweden tracked the history of two yeasts—Saccharomyces cerevisiae and Dekkera bruxellensis—used in alcohol fermentation to pinpoint their role in ethanol production. They found that, around 150 million years ago, competition with other microbes, and the overall increase in sugar-rich fruits, encouraged the yeasts to withstand high ethanol concentrations—an adaptation that would allow them to survive in places other microbes could not. “Now, scientists are closing in on just how and why yeast evolved to [ferment sugars into alcohol],” wrote John Roach in an MSNBC article. “No, it wasn’t to get humans drunk.” Read more at “The why of yeast’s buzz-giving ways” or the press release “Wine yeasts reveal prehistoric microbial world.” Camouflaged cuttlefish: “Cuttlefish are masters of camouflage. Like their relatives, the squid and the octopus, cuttlefish can change the colour of their skin to perfectly match a bed of pebbles, a clump of algae, or a black-and-white chessboard,” wrote Ed Yong of Not Exactly Rocket Science (see below video of previous research). Alexandra Barbosa from the University of Porto found that cuttlefish use visual cues to alter their appendages as well. In other words, when the cephalopods were placed against backgrounds of various striped patterns, they adjusted their tentacles to match the pattern that they saw. Read more and see photos at “Pocket Science – will all camouflaged cuttlefish please raise their tentacles?” Seedy pants: One of the most topical quotes this week—“I wish nature would stop getting it on in my eyeballs”—was uttered by a fellow allergy sufferer. Allergy season is in full force in temperate locales, such as some parts of the U.S. East Coast, as trees flood the air with pollen in the hopes of reaching a female counterpart. There are several ways that pollen travels, such as the wind, but most of us have probably never considered the role of pants in tree pollination. Yes, pants not plants. As quoted in a recent NPR article, “‘Because of his great mobility,’ [British botanist Edward] Salisbury wrote (projecting from his personal data set), ‘man is probably the most active agent—though usually an unconscious one—for [the] external transport of seeds.’” Read more at “Strange Things Happen To Guys Who Wear Pants.” Vampire bat venom: Scientists have tapped vampire bat saliva as a potential medication for treating stroke in humans, and the drug is actually called “Draculin.” It was announced this week that the drug would enter Phase 2 tests. “When vampire bats bite their victims, their saliva releases an enzyme called desmoteplase, or DSPA, into the bloodstream, which causes blood to flow more readily,” wrote Patrick Morgan on Discover’s blog...

Read More

Fungus makes zombie ants administer ‘death bite’ at noon

Researcher David Hughes has expanded research on a parasitic fungus and its carpenter ant host. As explained in an excerpt from a previous EcoTone post: Scientists have found that the parasitic fungus Ophiocordyceps unilateralis has possibly been invading carpenter ants (Camponotus) for 48 million years. The parasite not only infects the ant, but it manipulates the ant’s behavior, driving it to bite the underside of the leaf at the veins. Once the ant hits an optimal location, the fungus grows rapidly, killing the ant and preparing it to release a new spore. During this process, the ants leave distinct marks, also known as “death bites,” on the leaves as they bite the veins in search of a prime spot for fungal growth. It is this unique pattern that led researcher David Hughes to a 48 million year old leaf with similar markings. According to a Nature News article, Hughes contacted Conrad Labandeira, a palaeoecologist at the Smithsonian’s National Museum of Natural History, who, as it turns out, had noticed a leaf with similar markings. As Hughes said in the article, “It is not normal ant behavior to bite into the leaf vein because it has no real nutritional value to the ant and can in fact be toxic in some plant species.” This finding, as he explained in a Biology Letters study published [last year], indicated that the carpenter ants were infected with the parasitic fungus when the ant made the leaf marks. As reported in Discover Magazine’s blog 80beats, “If Hughes’ dating is correct, then the fungi have had plenty of time to fine-tune their zombifying practice into the ruthlessly efficient mind control we see today.” These findings were recently backed up in a study published by Hughes, now a researcher at Pennsylvania State University, and colleagues in the journal BMC Ecology this week. They found that the ants bit on the leaf veins around noon—a time that appeared to be specific for the fungus. As Hughes said in a Live Science article, “Synchronized arrival of zombie ants at the graveyards is a remarkable phenomenon. It adds a layer of complexity on what is already an impressive feat. However, although ants bite at noon they don’t in fact die until sunset. Likely this strategy ensures (the fungus) has a long cool night ahead of it during which time it can literally burst out of the ant’s head to begin the growth of the spore-releasing stalk.” The ants—in the case of the most recent study, Camponotus leonardi—live in the canopy of trees but come to the forest floor occasionally. It is here that they contract the fungus. It is...

Read More

Buffo the truffle-hunting dog, night-blooming balsa trees and fire-ant-made rafts

Truffle shuffle: According to a letter published in the April issue of Frontiers in Ecology and the Environment, Buffo the truffle-hunting dog made an unusual find: a one-pound Burgundy truffle in the forests of southern Germany in November. As lead author Ulf Büntgen said in a recent Wired Science article, “This wasn’t a small find, but a big and expensive truffle with lots of smaller ones around. It was strange to find it in an area where, so far, this truffle’s existence has never been reported…The season, early November, was also unusual. This led us to ask, ‘what is driving truffle growth here? Is it connected to climate?’” Read more at “Truffle-Hunting Dog Finds Jackpot in Unexpected Place.” Blooming balsa: Large, blooming balsa trees attract wildlife in the night with their nectar-laden blossoms. Natalie Angier elaborated in a National Geographic article: “When [the capuchin monkeys] look up again, their muzzles are speckled with pollen, which from the [balsa] tree’s perspective is the whole point of its flowers: to capture the attention of a pollinator long enough that the animal can’t help but be brushed with the plant’s equivalent of semen, which, if all goes well, the inadvertent matchmaker will eventually deliver to the female parts of another balsa tree’s flowers. The exchange is simple: You get drinks on the house, my gametes get a ride on your face.” Read more at “Panama’s Ochroma Trees.” Deepwater update: One year after the Deepwater Horizon explosion sent oil leaking into the Gulf of Mexico, scientists are still researching the longterm ecological impact of an incident that is unique in many ways. That is, “[t]he field of coral was just 11 kilometres from the Deepwater Horizon well head, which earlier in the year had spewed out more than 4 million barrels of oil and a similar amount of methane—the largest ever accidental release in the ocean,” wrote Mark Schrope in a Nature article. “The spill was unique in other ways, too. Located beyond the continental shelf and some 1,400 metres below the surface, it happened in deeper water than any other major spill in history.” Read more at “Oil spill: Deep wounds.” Peacock spots: Mate selection in peacocks may be more complex than previously thought. That is, the number of eyespots on a male peacock’s feathers is likely not the only factor responsible for female’s mate selection.“The threshold idea certainly makes sense at first glance, says Adeline Loyau, a peacock researcher at the CNRS research station in Moulis, France,” in a Science News article by Susan Milius. “The struggle to understand the long-familiar peacock, adds [Loyau], ‘suggests that we are still far from...

Read More

Ecosystem snapshot: reassessing the role of wolves in Yellowstone

Yellowstone National Park is home to more than 1,350 species of vascular plants and numerous species of mammals, amphibians, reptiles and birds—not to mention the natural landmarks such as Old Faithful Geyser. Among the inhabitants of Yellowstone is the famous quaking aspen, a deciduous tree that has significantly declined in the park since the 20th Century, due in large part to elk grazing.

Read More

From the Community: A week of ecology in mixed media

Video describing the challenges of male pregnancy, photo gallery of the oldest trees in the world, podcast outlining Earth’s environmental tipping points and an article on adapting to the anthropocene. Here is ecological news from the third week in March.

Read More

Can birds affect tree growth?

Growing conditions, such as water and nutrient supply, are the major determinates of tree growth, but insectivorous birds can also play an important role, say scientists in a study published in the January issue of Ecology. Under the right conditions, birds contribute to whole tree growth by preying on herbaceous arthropods, such as leafhoppers, caterpillars and grasshoppers…

Read More

Climate change doubles tree deaths

Tree deaths have more than doubled in the western U.S. in the past 20-30 years, and the culprit is climate change, according to a paper published Friday in Science. Warming has all kinds of consequences for species ranges.  Changes in temperature can narrow a species’ range or move it latitudinally through changes in average yearly temperatures and alterations of the growing or reproductive seasons. In the case of trees, other factors mitigated by climate change, such as bark beetles or forest fires, are often blamed for the most tree mortality. In this paper, the researchers collected historical data for more than 6,000 trees dating back to the 1920s. Areas covered in this paper include the Pacific Northwest, California, Idaho, Colorado and Arizona. The researchers say continued climate change alone at current rates will cause a 50 percent reduction in the average tree age in forests, trigger a potential reduction in average tree size and make many forests vulnerable to abrupt dieback. ESA member Nathan Stephenson, a researcher at the USGS Western Ecological Research Center and a corresponding author on the paper, thinks that in some cases, increasing tree deaths could indicate forests vulnerable to sudden, extensive die-back, similar to die-back seen over the last few years in parts of the southwestern states, Colorado, and British Columbia. “That may be our biggest concern,” he said in a press release from the USGS. “Is the trend we’re seeing a prelude to bigger, more abrupt changes to our forests?” Read the Science article here (subscription required to view full article); the Washington Post also had a nice article on...

Read More