(Shouldn't "taxons" be "taxa"?) The URL of the corresponding map is given in the
tag. Append this to "http://data.gbif.org/, and you have the URL for the image of the map. For example, here's the map for Apus apus.
I've added code to do this to iSpecies, so it now features maps from from GBIF. I've also finally tweaked the Google code to stop mangling UTF-8 characters.
Thursday, August 30, 2007
Authors: Tobias Reichenbach, Mauro Mobilia & Erwin Frey
Biodiversity is essential to the viability of ecological systems. Species diversity in ecosystems is promoted by cyclic, non-hierarchical interactions among competing populations. Central features of such non-transitive relations are represented by the 'rock–paper–scissors' game, in which rock crushes scissors, scissors cut paper, and paper wraps rock. In combination with spatial dispersal of static populations, this type of competition results in the stable coexistence of all species and the long-term maintenance of biodiversity. However, population mobility is a central feature of real ecosystems: animals migrate, bacteria run and tumble. Here, we observe a critical influence of mobility on species diversity. When mobility exceeds a certain value, biodiversity is jeopardized and lost. In contrast, below this critical threshold all subpopulations coexist and an entanglement of travelling spiral waves forms in the course of time. We establish that this phenomenon is robust; it does not depend on the details of cyclic competition or spatial environment. These findings have important implications for maintenance and temporal development of ecological systems and are relevant for the formation and propagation of patterns in microbial populations or excitable media.
Posted by Kari T. Ryder Wilkie at 4:36 PM
Wednesday, August 29, 2007
I love it when people use new technology to accomplish classic research:
Researchers at MIT are using mobile phones to help count owls in forests. Professor Eben Goodale and his colleagues placed tricked-out cell phones in various parts of a forest. When Goodale dials the owls' numbers, the mobile phones play owl calls from their speakers and record the responses. From The Telegraph:One use has been to track great horned owls in Louisiana and their effects on local swallow tailed kite populations. In the new study, they show that Barred Owls and the Eastern screech owl are also happy to take a call on the mobile.
Traditionally, bird surveys rely on people standing in the woods, playing a CD of bird calls, and taking note of the birds they hear responding. It can be labour intensive and inexact.
The researchers now plan to compare a survey conducted with 65 phones with one that relies on CD recordings used by 250 volunteers from the Audubon Society in Maine to see if the mobiles do as well. The advantage is that the new method allows ornithologists to dial up birds anywhere on the planet, and to cover a large area at the same time.
Posted by Kari T. Ryder Wilkie at 8:59 AM
Tuesday, August 28, 2007
Marc van Roosmalen is a world-renowned primatologist whose research in the Amazon has led to the discovery of five species of monkeys and a new primate genus. But precisely because of that work, Dr. van Roosmalen was recently sentenced to nearly 16 years in prison and jailed in Manaus, Brazil. Earlier in August, his lawyers managed to get him freed while they appeal his conviction on charges stemming from an investigation into alleged biopiracy. But scientists here and abroad are outraged, and they describe the case as only the most glaring example of laws and government policies they say are xenophobic and increasingly stifling scientific inquiry.
“Research needs to be stimulated, not criminalized,” said Enio Candotti, a physicist who has been the president of the Brazilian Society for the Progress of Science, the country’s leading scientific body, for the last four years. “Instead, we have a situation in which overzealous bureaucrats consider everyone guilty unless they can prove their innocence.”
At a biologists’ conference in Mexico last month, 287 scientists from 30 countries signed a petition saying that the jailing of Dr. van Roosmalen was “indicative of a trend of governmental repression of scientists in Brazil.”
The treatment of him, they warned, is unduly harsh and is “already discouraging biological research in Brazil, both by Brazilian scientists and by potential international donors.”
Brazil’s government officials say they have no vendetta against the scientists and are merely trying to protect the nation’s natural and genetic patrimony; they also declined to talk about the van Roosmalen case.
Read rest of article here
Posted by Kari T. Ryder Wilkie at 5:48 PM
Sunday, August 26, 2007
I know, I should be ashamed for that one.
If you ever felt like one of the “ants” in a Dave Matthews song while marching through Phoenix Sky Harbor International Airport, there might be something to it.
Southwest Airlines researchers trying to mimic the efficiency of marching ants tested a computer simulation at the airport in 2004, trying to get airplanes through the gates faster.
Meanwhile, in Australia, researchers studying swarm behavior are finding:
A panicking crowd can be evacuated faster by placing certain types of obstacles in its path, according to Australian researchers who say we can learn from the masters of crowd control: ants.
Associate Professor Martin Burd from Monash University is using Argentine ants (Linepithema humile) to model the behaviour of panicking crowds.
Posted by Kari T. Ryder Wilkie at 7:01 PM
On September 2nd this year go out somewhere: into your backyard, or the woods, or the bottom of the sea, and turn a rock or two or three. Take pictures of what you find underneath. Perhaps you'll find earthworms, or pillbugs, or beetles. Or a starfish. Maybe even a snake. Perhaps even a snake guarding the entrance to Dick Cheney's Undisclosed Location. If you turn a rock in Iraq and find WMDs please let us all know as that would be the biggest scoop in the history of the blogosphere (good luck with that one, though).
Post your pictures on your blog and send Bev the URL, or post them on this Flickr tag, or send them to Bev at bev (at) magickcanoe (dot) com (with "Rock Flipping" in the subject line). Then sit back and watch the collection grow. See what others find under the rocks on that day. Post a link on your blog as well.
Posted by Kari T. Ryder Wilkie at 6:56 PM
Rapid inventory of the ant assemblage in a temperate hardwood forest: species composition and assessment of sampling methods
Ants are key indicators of ecological change, but few studies have investigated how ant assemblages respond to dramatic changes in vegetation structure in temperate forests. Pests and pathogens are causing widespread loss of dominant canopy tree species; ant species composition and abundance may be very sensitive to such losses. Before the experimental removal of red oak trees to simulate effects of sudden oak death and examine the long-term impact of oak loss at the Black Rock Forest (Cornwall, NY), we carried out a rapid assessment of the ant assemblage in a 10-ha experimental area. We also determined the efficacy in a northern temperate forest of five different collecting methods-pitfall traps, litter samples, tuna fish and cookie baits, and hand collection-routinely used to sample ants in tropical systems. A total of 33 species in 14 genera were collected and identified; the myrmecines, Aphaenogaster rudis and Myrmica punctiventris, and the formicine Formica neogagates were the most common and abundant species encountered. Ninety-four percent (31 of 33) of the species were collected by litter sampling and structured hand sampling together, and we conclude that, in combination, these two methods are sufficient to assess species richness and composition of ant assemblages in northern temperate forests. Using new, unbiased estimators, we project that 38-58 ant species are likely to occur at Black Rock Forest. Loss of oak from these forests may favor Camponotus species that nest in decomposing wood and open habitat specialists in the genus Lasius.
Environ Entomol. 2007 Aug;36(4):766-75
Ellison AM, Record S, Arguello A, Gotelli NJ
Posted by Kari T. Ryder Wilkie at 12:24 AM
Thursday, August 23, 2007
Via Charlie Rose on Google Video:
Segment 1: A discussion about theoretical physics with Harvard professor Lisa Randall. Her book is called "Warped Passages: Unraveling the Mysteries of The Universe's Hidden Dimensions".
Segment 2: We conclude with Harvard biology professor Edward O. Wilson. His latest book is "The Creation: An Appeal to Save Life on Earth".
Posted by Kari T. Ryder Wilkie at 11:48 PM
Spatio-temporal patterns of ground-dwelling ant assemblages in a lowland rainforest in southeast Cameroon
From the August issue of Insectes Sociaux:
Abstract. We studied the spatio-temporal patterns of ground-dwelling and -foraging ant assemblages in a continuous mixed secondary lowland rainforest on the northern periphery of the Dja Biosphere Reserve in southeast Cameroon. The effect of season and of the interaction of season with vegetation type on ant species density, activity and composition were investigated. We also checked for a possible impact of army ant activity on the ant assemblage. Ants were collected by pitfall trapping in seven vegetation types in each of three seasons during 12 months in 2003 and 2004–2005. Season significantly influenced the ground-dwelling ant assemblage. The late wet season had the lowest ant species density and a different species composition than the early wet and the dry season. Also inter-annual variation in ant species density and composition was detected and could partly be explained by an influence of Dorylus activity. In general, vegetation type and inter-annual variation had a larger influence on the ground-ant assemblage than season. Significant effects of interactions between season, year, vegetation type and army ants on the ant assemblage confirm that also in African rainforests ant assemblages are extremely dynamic and depend on a complex combination of availability of food resources, nest sites and predators.
Posted by Kari T. Ryder Wilkie at 11:21 PM
The fungus-growing ant–microbe mutualism is a classic example of organismal complexity generated through symbiotic association. The ants have an ancient obligate mutualism with fungi they cultivate for food. The success of the mutualism is threatened by specialized fungal parasites (Escovopsis) that consume the cultivated fungus. To defend their nutrient-rich garden against infection, the ants have a second mutualism with bacteria (Pseudonocardia), which produce antibiotics that inhibit the garden parasite Escovopsis. Here we reveal the presence of a fourth microbial symbiont associated with fungus-growing ants: black yeasts (Ascomycota; Phialophora). We show that black yeasts are commonly associated with fungus-growing ants, occurring throughout their geographical distribution. Black yeasts grow on the ants' cuticle, specifically localized to where the mutualistic bacteria are cultured. Molecular phylogenetic analyses reveal that the black yeasts form a derived monophyletic lineage associated with the phylogenetic diversity of fungus growers. The prevalence, distribution, localization and monophyly indicate that the black yeast is a fifth symbiont within the attine ant–microbe association, further exemplifying the complexity of symbiotic associations.
Posted by Kari T. Ryder Wilkie at 11:08 PM
Posted by Kari T. Ryder Wilkie at 10:45 PM
Wednesday, August 22, 2007
Social parasites are involved in a coevolutionary arms race, which drives increasing specialization resulting in a very narrow host range. The Formicoxenus ants are a small group of social parasites with a xenobiotic lifestyle. Formicoxenus quebecensis and Formicoxenus provancheri are highly specialized ants using chemical mimicry to blend into their respective Myrmica ant host colonies. However, Formicoxenus nitidulus is unique in being able to survive in over 11 different ant host species. We observed that when live or dead F. nitidulus adults are seized by their host they are immediately dropped undamaged, despite possessing a cuticular hydrocarbon profile that differs markedly from its host. Hexane extracts of the F. nitidulus cuticle made previously acceptable prey items unattractive to their Formica host, indicating a chemical deterrent effect. This is the first time that a social parasite has been shown to exploit the generalized deterrence strategy to avoid host aggression over long periods of time. This supports the idea that coevolved and generalist diseases or parasites require fundamentally different defence mechanisms. We suggest that F. nitidulus uses its cuticular chemistry, possible alkadienes, as a novel deterrent mechanism to allow it to switch hosts easily and so become a widespread and abundant social parasite.
Stephen J. Martin, Edward A. Jenner, Falko P. Drijftout
Image: Worker of Formicoxenus nitidulus, antbase.net
Posted by Kari T. Ryder Wilkie at 8:06 AM
Monday, August 20, 2007
Posted by Kari T. Ryder Wilkie at 10:55 PM
In the somewhat obscure world of animal art -- where chimps, horses and elephants learn to grip paint-laden brushes and thrash randomly at a canvas to create abstract paintings -- Steven Kutcher's "bug art" stands out. Commanding a team of animal artists far too small to hold any paintbrush, Kutcher uses insects as living, moving paintbrushes to fashion his art.
"I'll take a bug in my hand and, leg by leg, load the paint onto each leg," says Kutcher, 63, from his Los Angeles home. The bugs -- flies, cockroaches and beetles -- are then let loose on a prepared canvas to scratch out their "masterpieces."
A keen environmentalist, Kutcher ensures his paint-soaked insects are unharmed by the ordeal. "I use water-based, nontoxic paints that easily wash off," he says. "I have to take good care of them. After all, they are artists!"
Posted by Kari T. Ryder Wilkie at 3:11 PM
Most of us are aware that we share our lives and our homes with countless tiny creatures, plants, fungi and bacteria. Our bodies alone present an amazing array of extreme, bizarre environments, and our homes provide convenient, secure hiding places with an abundant source of food. Many of our "Unseen Companions" are so small that they do not even attract our attention; many are benign or even helpful to us; but some are unwelcome guests because they bite, sting or carry disease. Whether friend or foe, these creatures are beautiful and fascinating in their own right, leading complex, highly specialised lives. This book reveals, at the turn of every page, the spectacular microscopic world, both inside and on the surface of our bodies, together with the artificial habitats that we provide in our homes and our gardens. It will delight, horrify, or maybe both, but the text helps us to understand the fascinating life cycles, habits and interactions that contribute to a curious biological balance.
Posted by Kari T. Ryder Wilkie at 2:52 PM
"The National Science Foundation, Public Library of Science and the San Diego Supercomputing Center have partnered to set up what can best be described as a "YouTube for scientists", SciVee". Scientists can upload their research papers, accompanied by a video where they describe the work in the form of a short lecture, accompanied by a presentation. The formulaic, technical style of scientific writing, the heavy jargonization and the need for careful elaboration often renders reading papers a laborious effort. SciVee's creators hope that that the appeal of a video or audio explanation of paper will make it easier for others to more quickly grasp the concepts of a paper and make it more digestible both to colleagues and to the general public."Link
Posted by Kari T. Ryder Wilkie at 2:27 PM
Sunday, August 19, 2007
From Ant Visions:
For a while I have been thinking of setting up my ant photographs in one place rather than having sample shots!! Finally I have set up an image gallery here. I am currently in the middle of digging out images from my backup drives. The first batch of pictures are up: Anoplolepis, Camponotus, Crematogaster, Diacamma, Leptomyrmex, Melophorus, Myrmecia, Oecophylla, Polyrhachis, Rhytidoponera, Solenopsis and ant-mimics.
Posted by Kari T. Ryder Wilkie at 11:57 AM
Tuesday, August 14, 2007
The remarkable ability of ants and other social insects to divide the work in a colony is a result of many factors: genes, age, social interactions, even size or other physical attributes.
But might individual experience be involved as well? Might those who turn out to be good at a task end up specializing in that task, and those that aren’t go on to something else?
These are questions that Fabien Ravary and Emmanuel Lecoutey of the University of Paris-North in Villetaneuse, France, and colleagues sought to answer. To do so, they chose an ant, Cerapachys biroi, that allowed them to focus on experience to the exclusion of everything else. These ants produce a new generation of workers all at once, so they are of precisely the same age and size and are raised under the same conditions.
The researchers allowed workers to forage for food, with different outcomes. Half were given prey on every trip, while the others never obtained prey. As described in Current Biology, the successful ants foraged more and more, while the unsuccessful ones foraged less and less. After 30 days, the successful foragers were still foraging, while the unsuccessful ones were doing another task: caring for the brood.
The researchers say their work suggests that while the division of labor within a colony is a function of many factors, it can be influenced by positive (or negative) reinforcement of individuals based on their experiences.
By HENRY FOUNTAINPublished: August 14, 2007
Posted by Kari T. Ryder Wilkie at 9:56 AM
Monday, August 13, 2007
Sunday, August 12, 2007
Thursday, August 09, 2007
Now that I am a Derby Dame, I know a lot more people with tattoos. Very few of them are science-related, though. Today I was pointed towards a gallery of science related tattoos. (update: this page has now been moved to: http://carlzimmer.typepad.com/sciencetattoo/). Some of them are pretty cool, but I, of course, immediately thought of Corrie Moreau's ant tattoos, which I love, and wanted to submit a picture of them. I don't have a good shot, though. The image below is from her Harvard webpage. You can see all the tats, just not specifically what they are. BTW, they are spectacular. And morphologically detailed enough that you can ID them to genus (at least). If you get a chance to meet her, test out your identification skills on her (I think I got one wrong, but I can't remember which one).
Posted by Kari T. Ryder Wilkie at 10:54 AM
Wednesday, August 08, 2007
Insects are a major force in most ecosystems, yet in studies of biodiversity they often receive less attention than birds, mammals and plants. Two papers this week redress the balance. Novotny et al. studied some 500 species of lepidopteran caterpillars, beetles and fruit flies across 75,000 km2 of rain forest in Papua New Guinea. They found that most species of herbivorous insects were widely distributed. Species richness was high, as expected in the tropics, but the species found did not alter much even over hundreds of kilometres. Dyer et al. reached rather different conclusions from their work on hundreds of thousands of host-specificity feeding records for butterfly and moth caterpillars from areas ranging from Canada to Brazil. They found that the average number of tree species on which an insect species feeds was fewer in the tropics than in temperate parts of the New World, a confirmation of the latitudinal gradient in ecological specialization much discussed by biologists since the time of Darwin and Wallace. With apparently contradictory results such as these two reports, though, the discussion may run and run.
News and Views: Biodiversity: World of insects
When it comes to understanding patterns of biodiversity, ours is a little-known planet. Large-scale sampling projects, as carried out in two investigations of insect diversity, show a way forward.
Nigel E. Stork
Letter: Low beta diversity of herbivorous insects in tropical forests
Vojtech Novotny, Scott E. Miller, Jiri Hulcr, Richard A. I. Drew, Yves Basset, Milan Janda, Gregory P. Setliff, Karolyn Darrow, Alan J. A. Stewart, John Auga, Brus Isua, Kenneth Molem, Markus Manumbor, Elvis Tamtiai, Martin Mogia & George D. Weiblen
Letter: Host specificity of Lepidoptera in tropical and temperate forests
L. A. Dyer, M. S. Singer, J. T. Lill, J. O. Stireman, G. L. Gentry, R. J. Marquis, R. E. Ricklefs, H. F. Greeney, D. L. Wagner, H. C. Morais, I. R. Diniz, T. A. Kursar & P. D. Coley
Posted by Kari T. Ryder Wilkie at 11:41 PM
For numerous taxa, species richness is much higher in tropical than in temperate zone habitats1. A major challenge in community ecology and evolutionary biogeography is to reveal the mechanisms underlying these differences. For herbivorous insects, one such mechanism leading to an increased number of species in a given locale could be increased ecological specialization, resulting in a greater proportion of insect species occupying narrow niches within a community. We tested this hypothesis by comparing host specialization in larval Lepidoptera (moths and butterflies) at eight different New World forest sites ranging in latitude from 15° S to 55° N. Here we show that larval diets of tropical Lepidoptera are more specialized than those of their temperate forest counterparts: tropical species on average feed on fewer plant species, genera and families than do temperate caterpillars. This result holds true whether calculated per lepidopteran family or for a caterpillar assemblage as a whole. As a result, there is greater turnover in caterpillar species composition (greater diversity) between tree species in tropical faunas than in temperate faunas. We suggest that greater specialization in tropical faunas is the result of differences in trophic interactions; for example, there are more distinct plant secondary chemical profiles from one tree species to the next in tropical forests than in temperate forests as well as more diverse and chronic pressures from natural enemy communities.L. A. Dyer, M. S. Singer, J. T. Lill, J. O. Stireman, G. L. Gentry, R. J. Marquis, R. E. Ricklefs, H. F. Greeney, D. L. Wagner, H. C. Morais, I. R. Diniz, T. A. Kursar & P. D. Coley
Nature 448, 696-699(9 August 2007)
Posted by Kari T. Ryder Wilkie at 11:38 PM
Recent advances in understanding insect communities in tropical forests1, 2 have contributed little to our knowledge of large-scale patterns of insect diversity, because incomplete taxonomic knowledge of many tropical species hinders the mapping of their distribution records3. This impedes an understanding of global biodiversity patterns and explains why tropical insects are under-represented in conservation biology. Our study of approximately 500 species from three herbivorous guilds feeding on foliage (caterpillars, Lepidoptera), wood (ambrosia beetles, Coleoptera) and fruit (fruitflies, Diptera) found a low rate of change in species composition (beta diversity) across 75,000 square kilometres of contiguous lowland rainforest in Papua New Guinea, as most species were widely distributed. For caterpillars feeding on large plant genera, most species fed on multiple host species, so that even locally restricted plant species did not support endemic herbivores. Large plant genera represented a continuously distributed resource easily colonized by moths and butterflies over hundreds of kilometres. Low beta diversity was also documented in groups with differing host specificity (fruitflies and ambrosia beetles), suggesting that dispersal limitation does not have a substantial role in shaping the distribution of insect species in New Guinea lowland rainforests. Similar patterns of low beta diversity can be expected in other tropical lowland rainforests, as they are typically situated in the extensive low basins of major tropical rivers similar to the Sepik–Ramu region of New Guinea studied here.Vojtech Novotny, Scott E. Miller, Jiri Hulcr, Richard A. I. Drew, Yves Basset, Milan Janda, Gregory P. Setliff, Karolyn Darrow, Alan J. A. Stewart, John Auga, Brus Isua, Kenneth Molem, Markus Manumbor, Elvis Tamtiai, Martin Mogia & George D. Weiblen
Posted by Kari T. Ryder Wilkie at 11:24 PM
Pirate ants (Polyergus breviceps) and sympatric hosts (Formica occulta and Formica sp. cf. argentea): host specificity and coevolutionary dynamics
Abstract: The pace and trajectory of coevolutionary arms races between parasites and their hosts are strongly influenced by the number of interacting species. In environments where a parasite has access to more than one host species, the parasite population may become divided in preference for a particular host. In the present study, we show that individual colonies of the pirate ant Polyergus breviceps differ in host preference during raiding, with each colony specializing on only one of two available Formica host species. Moreover, through genetic analyses, we show that the two hosts differ in their colony genetic structure. Formica occulta colonies were monogynous, whereas Formica sp. cf. argentea colonies were polygynous and polydomous (colonies occupy multiple nest sites). This difference has important implications for coevolutionary dynamics in this system because raids against individual nests of polydomous colonies have less impact on overall host colony fitness than do attacks on intact colonies. We also used primers that we designed for four microsatellite loci isolated from P. breviceps to verify that colonies of this species, like other pirate ants, are comprised of simple families headed by one singly mated queen.
Authors: JEREMY M. BONO, RUMSAIS BLATRIX, MICHAEL F. ANTOLIN, and JOAN M. HERBERS, Colorado State University, Fort Collins, CO, USA
Image: poster from the animated film Bad Bug Bee and the Pirate Ants. Coincidentally, while searching for this image, I discovered that there apparently is a rugby team in Kolkata, India, that is named the Pirate Ants. Frickin' awesome!
Posted by Kari T. Ryder Wilkie at 10:54 AM
Via Ant Visions:
An article on the Japanese ant Cerapachys biroi shows that success or failure of a foraging individual (~7 successive experiences) can determine if the ant would continue as a forager or would decide to nurse the brood. A really simple strategy that could structure division of labour in insect societies. It is interesting to note the authors mention that an unsuccessful individual spends more time with the brood and hence could end up caring for the brood instead of foraging. Virgin workers of this species produces diploid eggs through thelytokous parthenogenesis. It would be interesting to see how insects with different grades of recruitment fare with this current finding.Read the article here:
Image: Cerapachys biroi, AntWeb, Photographer: April Nobile
Posted by Kari T. Ryder Wilkie at 10:50 AM
Tuesday, August 07, 2007
Rodrigo Feitosa (Museum of Zoology of the University of São Paulo, Brazil) is currently revising the ant genera Acanthoponera, Heteroponera, Probolomyrmex and Lachnomyrmex. So, if you have specimens from these genera, he would be happy to take a look at them.
More details here
Posted by Kari T. Ryder Wilkie at 7:55 PM
Mandibles triangular, smooth and shiny. Eyes small. Antennal scapes short, not surpassing margin of vertex. Pronotal suture present. Propodeal suture absent. Anteroventral subpetiolar process square cut. Petiole posteriorly inclined with the anterior face and dorsal face joining through a small convexity, whereas the dorsal face and posterior face join at a sharper angle. The posterior face is perpendicular, not concave. The most striking thing about this species is the sculpturing which is very fine and appears beaded, like tiny strings of pearls. Very pretty.The second is KTRW-001:
Mandibles triangular and distinctly striate. Antennal scapes very long, clearly surpassing the margin of the vertex by a large margin. Anteroventral subpetiolar process not square cut, posterior edge somewhat rounded. Pronotal costulae semi-circular, propodeal costulae longitudinal, metanotal costulae transverse. I thought at first that this was bisulca, but now believe that what I thought were the pronotal and propodeal sutures, are simply the sculpturing. I believe it is in the striatula group.The other species I have are: concinna, haenschi, horni, kempfi, mediatrix, minuta, pleurodon, regularis, simulans, striatula, sulcata.
Gnamptogenys of Tiputini
Posted by Kari T. Ryder Wilkie at 6:52 PM
Sunday, August 05, 2007
ScienceHack is a search engine for science videos. All of the videos have been screened by a scientist for accuracy. Looks like a nice idea, although it is pretty small at the moment. I submitted a few videos about ants to get them on the right track....
Posted by Kari T. Ryder Wilkie at 10:48 PM
Wednesday, August 01, 2007
Abstract. 1. Atta (Hymenoptera: Formicidae) leafcutter ants display the most polymorphic worker caste system in ants, with different sizes specialising in different tasks. The largest workers (majors) have large, powerful mandibles and are mainly associated with colony defence.
2. Majors were observed cutting fallen fruit and this phenomenon was investigated in the field by placing mango fruit near natural Atta laevigata and Atta sexdens colonies in São Paulo State, Brazil.
3. Ants cutting the fruit were significantly heavier (mean = 49.1 mg, SD = 11.1 mg, n = 90) than the ants carrying the fruit back to the nest (mean = 20.9 mg, SD = 9.2 mg, n = 90).
4. Fruit pieces cut by majors were small (mean = 15.9 mg), approximately half the weight of leaf pieces (mean = 28.5 mg) cut and carried by media foragers. It is hypothesised that it is more difficult to cut large pieces from three-dimensional objects, like fruit, compared to two-dimensional objects, like leaves, and that majors, with their longer mandibles, can cut fruit into larger pieces than medias.
5. The study shows both a new role for Atta majors in foraging and a new example of task partitioning in the organisation of foraging.
SOPHIE E. F. EVISON, FRANCIS L. W. RATNIEKS
New role for majors in Atta leafcutter ants
Ecological Entomology (OnlineEarly Articles).
Image: Atta Cephalotes; photograph © Alex Wild 2004
Posted by Kari T. Ryder Wilkie at 10:32 AM