Pollination from the plant’s perspective

If plants had a perspective, they would probably think of pollinators as more than just extra-friendly house guests. That is, plants would be more likely to view pollinators as the mutual friend who likes to set up blind dates. Bees might limit pollen to its use as a protein source for the hive, and birds might devour the flesh of a fruit and eliminate the seed as waste. However, many flowering plants, as Bug Girl pointed out in a post in honor of National Pollinator Week, have evolved alongside these pollinators for only one purpose: reproduction. “Sure, you can toss your pollen out on the wind and hope it lands in the right place. And for a lot of plants, evergreens in particular, this works just fine,” she wrote. “That methodology results in a lot of wasted gametes (plant sperm) though, so for nearly all flowering plants, insects or other pollinators are needed for plant nookie.” Sometimes the pollinator-plant relationship is mutualistic, and in many cases, one species or another is dependent upon the other for its survival. Take the agave plant. Probably the most well-known species is the blue agave plant (Agave tequilana), the nectar of which is used as a granular sugar substitute and to make tequila (one of the “finer” products of pollination, along with chocolate and coffee, mentioned by Bug Girl ). Leptonycteris nivalis, known as the greater long-nosed bat or Mexican long-nosed bat, and the lesser long-nosed bat (Leptonycteris curasoae), are the primary pollinators of this economically and ecologically valuable plant. This agave-bat relationship is mutually beneficial. The bats, hovering in place like a hummingbird, use their long muzzles to feed on the high-fructose nectar of the agave. At the same time, the plants’ pollen collects on the bats’ fur. The bats then travel from plant to plant, spreading pollen as they drink from the nectar-filled stalks that bloom each night across the southwestern U.S. and Mexico. The bats also migrate based on the blooming time of these plants. They arrive in Texas—particularly in Big Bend National Park, where a single colony resides in the Chisos Mountains—shortly after agave plants, such as the century plant (Agave havardiana), begin to bloom. Unfortunately, the lesser long-nosed bat and the Mexican long-nosed bat are endangered—and as their numbers decline, agave plant reproduction becomes more limited. A little farther north, however, some species of agave plants—those that are not harvested for tequila— have evolved to attract both bats and moths to serve as pollinators. Agave plants have several ways of advertising their nectar: the scent, the color of the flower and the shape, or morphology, of the structure...

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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...

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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...

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Zebra finches practice singing for the ladies

The male zebra finch (Taeniopygia guttata) learns to sing in private before performing for a female audience, according to Satoshi Kojima and Allison J. Doupe from the University of California, San Francisco. In addition, juvenile male finches seem to step up the quality of their singing, despite their immaturity, when in the presence of potential mates. As described in the blog Talking Science, part of National Public Radio’s Science Friday Initiative, “Male finches, by the time they are sexually mature, typically know two different forms of song: undirected, which is performed in isolation, and directed, which is performed for a female audience. Young males learn undirected song first, which characteristically sounds immature and is of variable quality. As adults, they become experts in directed song, a talent they refine specifically for the purpose of courting females.” As the researchers reported in the Proceedings of the National Academy of Sciences study, the juveniles, when performing for females, seemed to focus on the best parts of the songs that they practiced in private. Kara Rogers wrote in Talking Science, “The discovery reveals that the undirected song of young male finches disguises the actual extent of the birds’ song-learning capabilities…” In other words, despite their inexperience, immature male finches were able to sing at the level of mature finches in the appropriate social conditions: When there was a chance to  mate. Read about the zebra finch genome in Nature or take the songbird call challenge at enature.com. Photo Credit: Patricia van...

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Wet or dry: Butterflies reverse sex roles in extreme seasons

In the case of the African butterfly Bicyclus anynana, females develop ornate wings and court males if they spend the larval stage in a dry, cool environment. The reverse occurs, according to Kathleen Prudic from Yale University and colleagues, when the butterflies are exposed to wetter, warmer environments. “As expected, female Bicyclus anynana in warmer moister conditions that mimic the wet season in the native African range were more likely to mate with males with ornamented wings,” explained a Yale University press release. “However, the roles were reversed in cooler drier climates. Females played the role of suitors and flashed their eye spots to choosy males. When scientists studied the wing spots, which reflect light in the UV range, invisible to humans, they found they were brighter in the courting females relative to the males of that same season, or relative to females raised in the hotter season.” In a study published today in Science magazine, Prudic and colleagues suggested that the reversal is brought about by the environmental conditions. When transferring sperm, the male butterflies also administer nutrients, increasing the females’ chances of surviving the harsh conditions of a warm, dry season. Therefore, it is in the best interest of the female butterflies to attract males for their supply of nutrients, whereas males will be more selective in choosing females since they are limiting their own chances of survival by mating. As a result, the females that flash their showy spots are more likely to be chosen. Photo Credit: South African...

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