The tiny, diligent gardeners of the Amazon

The gardeners described here are not concerned with trimmed topiaries or manicured lawns—though, like designers of landscape gardens, these workers are exceptionally picky. And they have to be if they are going to survive. That is, ants such as Myrmelachista schumanni and Camponotus femoratus of South America depend on certain plants for shelter, and in return, they offer these plants nutrients and protection from predators. As a result, they have developed a mutualistic relationship that has led to an incredible resilience for both species. For example, the ant M. schumanni has kept the plant Duroia hirsute alive in one area of the Amazon, known as a devil’s garden to locals, for more than 800 years. This particular type of ant-plant dependency is plentiful in the Amazon and it creates eerie patches of monoculture gardens amidst the rest of the lush, diverse rainforest. As biologist and photographer Alex Wild described in a recent Myrmecos blog post (complete with photos): I had been following an army ant raid for half an hour through dense tropical forest when the trees unexpectedly parted to reveal a small clearing. Sun broke through the canopy and fell on a low tangle of furry plants. It was a monoculture, looking as though planted by a reclusive sort of gardener. I had stumbled into a Devil’s Garden. Local lore holds that malevolent forest spirits create these unnatural crop circles, but the truth is just as weird. Devil’s Gardens are [cultivated] by ants. The plant species that compose these gardens—mostly in the genera Tococa, Clidemia, and Duroia—sport swollen structures filled by the nests of tiny Myrmelachista ants no more than 3 millimeters long. The ants are meticulous about caring for their hosts, removing [pesky] herbivores and injecting formic acid into the saplings of competing plants. Another ant species, C. femoratus, gathers the seeds of particular plants to cultivate in its nests, called ant gardens, and made of a mixture of animal feces, digested plants and other organic material. These nests are attached to vines, the sides of trees and even high up in the tree canopy. As Elsa Youngsteadt explained in the podcast Curiouser and Curiouser, ants followed chemical signals given off by seeds of certain plants, collected the seeds, carried them back and embedded them in the walls of the nests. The plants benefitted from the fertilizer mixed in the nest, and in turn, the roots helped to add structure to the ant garden. In addition, the leaves protected it from heavy rains that would otherwise have caused the material to disintegrate. “There are about ten plant species that are in ant gardens regularly that you don’t...

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Army ants, beard microbes and ant-mimicking jumping spiders

Army ant week: Biologist and photographer Alex Wild reported on army ants all last week  in a series of posts on his blog Myrmecos. In one post, he described how army ants link with one another using hooks on their feet: “When the time comes to encamp, they can string together living curtains of ants in a matter of minutes. Army ant bivouacs are made from the ants themselves, a vibrant structure that protects the vulnerable brood and maintains temperature within a single degree of optimal.” Read more or view photos at “Army Ants as Living Legos.” Funky pheromones: Chemical signals, as ecologist and blogger Tracey Switek put it in a recent post on The Olive Tree, “don’t have to just be scents that waft through the air…They can be toxins, which send a very clear signal either because they make the plant taste bad or outright kill or injure anything that tries to eat. We’re all familiar with the culinary herbs such as basil, mint, thyme, cilantro and sage… But the real purpose of those pungent chemicals is to discourage insect predation.” Chemical signals can change the behavior of a species in many ways—for example, pheromones on squid eggs can cause males to become aggressive at the slightest touch (see above video). Read more at “Everybody Stinks: Chemical Signaling in the Undergrowth” and at “Rage-inducing chemical on squid eggs turns males into violent thugs” by Not Exactly Rocket Science. Woody vines: Stefan Schnitzer from the University of Wisconsin in Milwaukee and colleagues gathered data on the abundance of woody vine growth in American tropical and subtropical forests, and the cascading effects they had on biodiversity and water supply. According to a recent Live Science article, “It’s possible an increase in woody vines could change the nutrient dynamics of forests, in part because of differences between their leaves and the leaves of tropical trees, all of which ultimately fertilize the forest floor.” Read more at “Twisted Tropics: Growth of Vines Imperils Ecosystem.” Ant-mimicking spider: Michael Bok described the jumping spider, Myrmarachne plataleoides, in his blog Anthropoda. At first glance, the spider appears to be a red ant, but upon further examination, the  four pairs of legs become noticeable (see above video). “It makes up for a lack of antennae, and an overabundance of legs, by holding its forelegs up, alongside the head,” he wrote. “Its huge anterior medial eyes are colored to match the head when not viewed directly, and the posterior lateral eyes are enlarged, with darkened pigment around them to mimic an ant’s eyes. Also, the cephalothorax and abdomen are deformed and narrowed considerably.” Read more at...

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Those gibbons sure can wail

Birds are not the only animals that communicate by singing—gibbons, apes more closely resembling monkeys in size, sing to strengthen social relationships, announce their territory and find a mate. Crested gibbons in the genus Nomascus live in the Asian rain forests of China, Laos, Cambodia and Vietnam and sing for a specific purpose. “The songs are specifically adapted to travel over long distances through the dense vegetation of the rain forest by concentrating all of the energy into a single frequency, similar to the calls used by rain forest birds,” wrote Jennifer Welsh in a Live Science article. The coloration in gibbons varies by individual, making it difficult for researchers and conservationists to distinguish between species. But as Sarah Zielinski reported in yesterday’s Surprising Science post, scientists from the German Primate Center in Goettingen examined the songs of seven species of crested gibbons and found that each species had its own distinct dialect. “The researchers found that the songs of the two northern species, N. nasutus and N. concolor, were significantly different from those of the four southern species, and the songs of the four southern species were all subtly different from one another. And the more closely related two species or populations songs were, the more alike was their mitochondrial DNA.” The findings, said the researchers, could help to monitor gibbon populations through song, as opposed to visual, recognition. In addition, continued Welsh, “[t]he gradation of song similarity between the northern and southern populations supports the idea that the genus began in the north and migrated toward the south.” Read more at “Crested Gibbons Sing in Different Dialects.” Photo Credit: Tim...

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EcoTone sheds its exoskeleton

Frequent visitors to EcoTone might notice a few changes to the look and layout of the blog.  Instead of one long list of posts, for example, the most recent posts are now presented with a photo and brief summary. That way, all of the news in ecology is together on one page for easy browsing. Sharing links with friends and colleagues on Facebook and Twitter is also simpler thanks to new social media buttons. Over the last few years—with the guidance of former ESA Communications Officer Christine Buckley and other blog moderators—EcoTone has evolved into a top resource for the latest news in ecological science. Readership has grown substantially within the last year and it is apparent that the blog is viewed as a resource in topics ranging from iron-plated snails to science expressed through art. EcoTone is molting, one might say, in order to make room for growth—in this case, allowing more opportunities for sharing and producing fresh content. The Ecological Society of America’s blog has come a long way since its creation in 2006, but the goals remain the same: to share the diverse aspects of ecological science and to encourage conversations about ecology within and between communities. So with multimedia options, technological advances and exciting online resources in ecology emerging, it’s on to the next stage! What do you think of EcoTone? If you have any suggestions for posts, design additions or any other ideas, please share your insights. Email Katie Kline, moderator of EcoTone, at esablog@esa.org or contribute your thoughts in the comments section. Thank you for your readership and contributions! Photo Credit: Roger...

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Fear as an ecosystem engineer

This post contributed by Cristina Eisenberg, conservation biologist at Oregon State University Over the past three years I have conducted thirteen hundred focal animal observations on elk in the northern and southern Rocky Mountains. This involves patiently watching one animal at a time for up to twenty minutes and recording its wariness–that is, the amount of time it spends with its head down feeding versus head up, scanning for predators. Prey group size and a host of environmental factors can influence vigilance behavior. My research questions have to do with whether the vigilance of ungulates—such as elk, deer and other hooved animals— varies based on wolf population dynamics or other environmental factors that can influence predation risk. For example, would lone wolves passing through an area occasionally, but not denning there (as is the case with a returning wolf population in the Southern Rocky Mountains) have the same effect as several well-established packs using an area? Do terrain features such as downed wood, which may make it more difficult for an elk to escape a wolf, increase elk wariness? And could fear-based behavior vary by season, age and sex of the animals observed, herd size or human management of wolves? Termed the ecology of fear by ecologist Joel Brown, these predator-driven dynamics can have far-reaching effects on ecosystems via trophic cascades. Trophic cascades are the direct and indirect effects of an apex, or top, predator in a food web. In 1974 in the Aleutian archipelago, Jim Estes and his colleagues found that removing sea otters releases their primary prey, sea urchins, from predation. As sea urchins explode in number, they consume vegetation unsustainably, thereby reducing habitat for other species such as fish. The presence of a predator, such as the wolf, affects prey foraging behavior as prey try to balance the need to detect predators with meeting their  nutritional needs. These behavioral effects have been observed between spiders and their grasshopper prey by Oswald Schmitz and colleagues, as with sea urchins in terrestrial systems: Intensive browsing can lead to herbivores literally eating themselves out of house and home and, consequently, to a loss of biodiversity and ecosystem destabilization. Lacking apex predators to keep ungulates in check, ecosystems can support fewer species, such as birds and butterflies , because the plants that create habitats for these species have been over-browsed. Some predators and their prey naturally fluctuate in population size; this cycling can leave noticeable marks on the landscape. However, scientists are finding that these interactions are complex beyond the typical ebb and flow of predator and prey numbers. Assessing ungulates and large carnivores in the northern hemisphere, conservation biologist...

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