"The history of all past society has consisted in the development of class antagonisms…the exploitation of one part of society by the other". – Karl Marx and Frederick Engels, The Communist Manifesto.
Although diversity in social groups can increase group well being, it also may increase the potential for conflict. All societies are characterized by struggles for control: which individuals gain the spoils and which toil in the fields. In colonies of social insects this struggle is embodied by a reproductive division of labor. Some individuals (the queens) reproduce, while the workers provide the labor that maintains colony function. In many social insects queens enjoy nearly complete control over reproduction and workers have diversified in form and function to increase their efficiency at performing different labors.
How, then, is it determined which individuals, as developing larvae, becoming queens or different types of workers? A collaborative research team of scientists at four universities has found that caste determination in the Florida harvester ant is much more than meets the eye. Larvae become different castes (small workers, large workers, or new queens) based largely on the nutrition they receive. Those fed more insects than seeds are more likely to become larger individuals (queen>large worker>small worker). However, genetic differences also contribute and bias the larva's developmental pathway. Even once caste is determined, nutritional, social (colony size), and genetic factors all contribute, but in different ways, to how big an individual grows. "Caste determination in most social insects likely involves both nature and nurture, but most interestingly in this species, these two forces contribute differently in different castes," says lead researcher Chris R. Smith of the University of Illinois. Although genetic factors contribute to what caste an individual becomes, the environment of the larva is controlled by the workers. Quite generally, ant colonies are supreme examples of both conflict and cooperation – each extreme of the nature-nurture continuum.
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"Caste determination in a polymorphic social insect: nutritional,
social, and genetic factors" by C.R. Smith (University of Illinois
Urbana-Champaign), K.E. Anderson (University of Arizona), C.V. Tillberg
(Linfield College), J. Gadau (Arizona State University), and A.V.
Suarez (University of Illinois Urbana-Champaign). American Naturalist (2008) 172:497-507
DOI: 10.1086/590961
University of Chicago Press Journals
Molecular biologists have decoded the genome of a nematode living in beetles.
Scientists at the Max Planck Institute for Developmental Biology, together with American colleagues, have decoded the genome of the Pristionchus pacificus nematode, thereby gaining insight into the evolution of parasitism. In their work, which has been published in the latest edition of Nature Genetics, the scientists from Professor Ralf J. Sommer’s department in Tübingen have shown that the genome of the nematode consists of a surprisingly large number of genes, some of which have unexpected functions. These include a number of genes that are helpful in breaking down harmful substances and for survival in a strange habitat: the Pristionchus uses beetles as a hideout and means of transport, feeding on the fungi and bacteria that spread out on their carcasses once they have died. It thus provides the clue to understanding the complex interactions between host and parasite. (Nature Genetics, September 22, 2008)
The Nematode Pristionchus Pacificus (left) and its host, the dung beetle (right).
With well over a million different species, nematodes are the largest group in the animal kingdom. The worms, usually only just one millimetre in length, are found on all continents and in all ecosystems on Earth. Some, as parasites, are major pathogens to humans, animals and plants. Within the group of nematodes, at least seven forms of parasitism have developed independently from one another. One member of the nematode group has acquired a certain degree of fame: due to its humble lifestyle, small size and quick breeding pattern, the Caenorhabditis elegans is one of the most popular animals being used as a model in biologists’ laboratories. It was the first multicellular animal whose genome was completely decoded in 1998.
Ten years later, a group of scientists from the Max Planck Institute for Developmental Biology in Tübingen, together with researchers from the National Human Genome Research Institute in St. Louis (USA), have now presented the genome of another species of nematode, the model organism Pristionchus pacificus. Pristionchus species have carved out a very particular habitat for themselves: they live together with May beetles, dung beetles and potato beetles in order to feast on the bacteria and fungi that develop on the carcasses of these beetles after they die. The nematodes therefore use the beetles as a mobile habitat that offers them shelter and food.
When they move from the land to the beetle, the nematodes’ habitat changes dramatically. The nematodes have to protect themselves against toxic substances in their host, for example. The methods they employ to cope with the conditions in the beetle are worthy of closer attention, as this life form can possibly be regarded as the precursor to real parasites. At least, this is what researchers have suspected for a long time.
The sequencing of the genome of the P. pacificus has now confirmed this suspicion: the genome, consisting of around 170 megabases, contains more than 23,500 protein-coding genes. By comparison, the model organism of C. elegans and the human parasite Brugia malayi (the genome of this was sequenced in 2007) only have about 20,000 or 12,000 protein-coding genes respectively. "The increase in P. pacificus is partly attributable to gene duplications," explained Ralf Sommer. "These include a number of genes that could be helpful for breaking down harmful substances and survival in the complex beetle ecosystem."
Surprisingly, the Pristionchus genome also has a number of genes that are not known in C. elegans, although they have been seen in plant parasites. Genes for cellulases - enzymes that are required to break down the cell wall of plants and microorganisms - have aroused particular interest among scientists. "The really exciting questions are still to come", said Sommer. "Using the sequence data, we can test how the Pristionchus has adapted to its specific habitat. And this will undoubtedly give us new insight in to the evolution of parasitism.
"Beware: exploding lungs" is not a sign one would expect to see at a wind farm. But a new study suggests this is the main reason bats die in large numbers around wind turbines.
The risk that wind turbines pose to birds is well known and has dogged debates over wind energy. In fact, several studies have suggested the risk to bats is greater. In May 2007, the US National Research Council published the results of a survey of US wind farms showing that two bat species accounted for 60% of winged animals killed. Migrating birds, meanwhile, appear to steer clear of the turbines.
Why bats - who echolocate moving objects - are killed by turbines has remained a mystery until now. The research council thought the high-frequency noise from the turbines' gears and blades could be disrupting the bats' echolocation systems.
In fact, a new study shows that the moving blades cause a drop in pressure that makes the delicate lungs of bats suddenly expand, bursting the tissue's blood vessels. This is known as a barotrauma, and is well-known to scuba divers.
"While searching for bat carcasses under wind turbines, we noticed that many of the carcasses had no external injuries or no visible cause of death," says Erin Baerwald of the University of Calgary in Canada. Internal injuries
Baerwald and colleagues collected 188 dead bats from wind farms across southern Alberta, and determined their cause of death. They found that 90% of the bats had signs of internal haemorrhaging, but only half showed any signs of direct contact with the windmill blades. Only 8% had signs of external injuries but no internal injuries.
The movement of wind-turbine blades creates a vortex of lower air pressure around the blade tips similar to the vortex at the tip of aeroplane wings. Others have suggested that this could be lethal to bats, but until now no-one had carried out necropsies to verify the theory.
Baerwald and her colleagues believe that birds do not suffer the same fate as bats - the majority of birds are killed by direct contact with the blades - because their lungs are more rigid than those of bats and therefore more resistant to sudden changes in pressure.
Bats eat nocturnal insects including agricultural pests, so if wind turbines affected their population levels, this could affect the rest of the local ecosystems. And the effects could even be international. "The species being killed are migrants," says Baerwald. "If bats are killed in Canada that could have consequences for ecosystems as far away as Mexico." Windy day
One solution could be to increase the minimum wind speed needed to set the blades in motion. Most bats are more active in low wind.
The study was funded by a number of bat conservation groups together with energy companies with a financial interest in wind energy, such as Shell Canada and Alberta Wind Energy.
Here is a little video of the Cuttlefish and its flamboyent colours
This species is well worth highlighting for its beauty and rarity. They are highly prized on a divers must see list. Distribution, central indo region, southern Philippines to Northern Australia.
Once discovered, instead of leaving the area they will usually stay in the same place for some months so revisiting is possible. Rather than seeing this species swimming they prefer to walk the substrate on two front tentacles and two skin flaps located on the underbelly, this is clearly illustrated within our field guide images. Look for the sandy appearance on the "walking" front tentacles and the underbelly skin flaps, this is where the creature makes contact with the substrate.
They are active in daylight hours and their coloration is generally brown to match the substrate (darker in Indonesia due to darker sand).
They show flamboyant displays of red, yellow, white and pink chevrons that move up and down their bodies pulsating in a mesmerizing rhythm. Like other cuttlefish they produce instant colour changes.
Their elaborate coloration may indicate a poisonous bite like its cousin the Blue Ringed Octopus.
Their maximum size is approx. 10cm. Imperial Partner Shrimps live a symbiotic relationship with many creatures including cuttlefish for more information please visit our Marine Biology Crustacean page.
University of Florida College of Pharmacy researchers have
discovered a marine compound off the coast of Key Largo that inhibits
cancer cell growth in laboratory tests, a finding they hope will fuel
the development of new drugs to better battle the disease.
The
UF-patented compound, largazole, is derived from cyanobacteria that
grow on coral reefs. Researchers, who described results from early
studies today (Aug. 7) at an international natural products scientific
meeting in Athens, Greece, say it is one of the most promising they've
found since the college's marine natural products laboratory was
established three years ago.
An initial set of papers in the Journal of the American Chemical Society
also has garnered the attention of other scientists, and the lab is
racing to complete additional research. The molecule's natural chemical
structure and ability to inhibit cancer cell growth were first
described in the journal in February and the laboratory synthesis and
description of the molecular basis for its anticancer activity appeared
July 2.
"It's exciting because we've found a compound in
nature that may one day surpass a currently marketed drug or could
become the structural template for rationally designed drugs with
improved selectivity," said Hendrik Luesch, Ph.D., an assistant
professor in UF's department of medicinal chemistry and the study's
principal investigator.
Largazole, discovered and named by
Luesch for its Florida location and structural features, seeks out a
family of enzymes called histone deacetylase, or HDAC. Overactivity of
certain HDACs has been associated with several cancers such as prostate
and colon tumors, and inhibiting HDACs can activate tumor-suppressor
genes that have been silenced in these cancers.
Although
scientists have been probing the depths of the ocean for marine
products since the early 1960s, many pharmaceutical companies lost
interest before researchers could deliver useful compounds because
natural products were considered too costly and time-consuming to
research and develop.
Many common medications, from pain
relievers to cholesterol-reducing statins, stem from natural products
that grow on the earth, but there is literally an ocean of compounds
yet to be discovered in our seas. Only 14 marine natural products
developed are in clinical trials today, Luesch said, and one drug
recently approved in Europe is the first-ever marine-derived anticancer
agent.
"Marine study is in its infancy," said William Fenical,
Ph.D., a distinguished professor of oceanography and pharmaceutical
sciences at the University of California, San Diego. "The ocean is a
genetically distinct environment and the single, most diverse source of
new molecules to be discovered."
The history of pharmacy
traces its roots back thousands of years to plants growing on Earth's
continents, used by ancient civilizations for medicinal purposes,
Fenical added. Yet only in the past 30 years have scientists begun to
explore the organisms in Earth's oceans, he said. Fewer than 30 labs
exist worldwide and research dollars have only become available in the
past 15 years.
HDACs are already targeted by a drug approved
for cutaneous T-cell lymphoma manufactured by the global pharmaceutical
company Merck & Co. Inc. However, UF's compound does not inhibit
all HDACs equally, meaning a largazole-based drug might result in
improved therapies and fewer side effects, Luesch said.
Since
2006, Luesch and his team of researchers have screened cyanobacteria
provided by collaborator Valerie Paul, Ph.D., head scientist at the
Smithsonian Marine Station in Fort Pierce. They check the samples for
toxic activity against cancer cells and last year encountered one
exceptionally potent extract — the one that ultimately yielded
largazole.
To conduct further biological testing on the
compound, Luesch and his team have been collaborating with Jiyong Hong,
an assistant professor in the department of chemistry at Duke
University, to replicate its natural structure and its actions in the
laboratory.
Luesch said that within the next few months he plans to study whether largazole reduces or prevents tumor growth in mice.
Luesch has several other antitumor natural products from Atlantic and Pacific cyanobacteria in the pipeline.
"We
have only scratched the surface of the chemical diversity in the
ocean," Luesch said. "The opportunities for marine drug discovery are
spectacular."
A little eight-legged pickpocket that darts around acacia trees could be the first known vegetarian
spider.
Bagheera kiplingi belongs among the big-eyed, athletic predators in the family of jumping spiders and gets its name from a panther in a Rudyard Kipling story. Yet a population of these spiders in Mexico mostly eats bits of the acacia trees, says Christopher Meehan of Villanova University in Pennsylvania.
A few other spider species do taste vegetable matter now and then, says Yael Lubin of Ben-Gurion University in Sede Boqer, Israel. Male crab spiders that spend their brief mating-oriented adult lives sitting on flowers will sip nectar for a little energy boost. And some baby spiders eat spores that have stuck to a web. But on hearing about spiders specializing in stealing vegetarian food, “I was absolutely floored,” Lubin says.
These arachnid herbivores are no wimps. “The tree is full of biting, vicious ant guards,” Meehan said during the 12th International Behavioral Ecology Congress meeting August 9 through 15 at Cornell University. The little spider spends its life dodging patrols of ants and stealing their (vegetarian) lunches.
Acacia trees and their resident ants have become a textbook example of a mutually beneficial partnership. Tree thorns grow swollen bases the right size to shelter ants. Glands at the base of the leaves ooze nectar, far from flowers but just at the spot to offer refreshment for ants. Acacia leaflet tips sprout nubbins of protein and fat suitable for ant snacks.
Certain ant species take full advantage of these comforts and defend their home trees against all comers. In the course of their vigilance, the ants get rid of caterpillars and other invaders that might chew on the tree.
Meehan says the spiders manage to dodge the ants, perching on leaf tips and nesting in mature leaves, which aren’t as heavily patrolled as other tree parts.
Ecologists have studied the partnership for years, but “people who look at ant acacias — they look at the ants,” Lubin says. “It took the eyes of a student naturalist to see this.”
That fresh observer was Meehan, who, along with his Villanova colleague Robert Curry, noticed the spiders dining on the leafy snacks of acacias in Mexico. In videos of 140 spider meals, the researchers counted 136 acacia protein-fat snacks with a few nectar sips. On four occasions the spiders did turn to meat as they tugged away ant larvae from a passing nursemaid and ate the youngsters.
In Costa Rica, the spiders also steal ant food, though to a lesser extent, according to observations from Eric Olson of Brandeis University. He independently discovered the spiders eating tree snacks in Costa Rica in 2001 and is working with the Villanova team on a report on the species.
Those meat moments don’t happen often, according to studies done in collaboration with Matt Reudink and others of Queen’s University in Kingston, Canada. The team checked spider tissue for the heavier form of nitrogen, N15, which becomes more concentrated as animals eat animals that have eaten other animals.
That carnivore signal does not show up in the acacia-tree spiders, which carry a relatively light concentration of N15, one that is typical of plant-eaters, according to the team’s data. He also found that the concentration of the heavier form of carbon, C13, also looks typical for a vegetarian.
Long a problem in the western U.S., the New Zealand mud snail
currently inhabits four of the five Great Lakes and is spreading into
rivers and tributaries, according to a Penn State team of researchers.
These tiny creatures out-compete native snails and insects, but are not
good fish food replacements for the native species.
"These snails have an operculum, a door that closes the
shell," says Edward P. Levri, associate professor of biology at Penn
State's Altoona Campus. "They can be out of the water for longer than
other snails and when fed to fish, they are not digested and sometimes
come out alive. This has a potential to alter the salmon and trout
fisheries because they alter the food chain."
The New Zealand mud snail grows to a maximum of a quarter of
an inch and is more normally a sixteenth to an eighth of an inch in
length. The hard shell is capable of sealing off the soft animal from
outside influences. In New Zealand, the snails reproduce asexually,
resulting in identical clones, or sexually. However, in invaded areas,
asexual cloning is the only mode of reproduction.
This mud snail spread to England as early as 1850 and Europe
in the late 1800s. It is found in Japan, but when the snail arrived
there is unknown. The first mud snail found in the U.S. was in 1987 in
the Snake River, Idaho, but the species did not appear in the east
until 1991 in Lake Ontario. The western and eastern U.S. populations
are separate episodes of introduction, because they represent different
clones; in each case, only one snail needed to be introduced to begin
the invasion. The snails in the Great Lakes region appear to be the
same as one clone found in Europe.
"In the western U.S., this species is of special concern
largely because of their ability to modify ecosystems," Levri told
attendees today (Aug. 8) at the Ecological Society of America's annual
meeting in Milwaukee.
The snails in western streams alter the nitrogen and carbon
cycling. They are primarily grazers and detritus eaters with very wide
food preferences. In some places in streams in Yellowstone National
Park, they reach population densities of 323 individuals per square
inch. Levri, working with undergraduates Warren J. Jacoby, Shane J.
Lunen, Ashley A. Kelly and Thomas A. Ladson, found that densities in
the Great Lakes are not anywhere near that in the West.
"In our most recent survey, we were lucky if we found a few
hundred per square meter," says Levri. "In Lake Erie they are not very
abundant, but it is unclear what they are doing 100 feet below the
surface."
In New Zealand, the mud snails are not a problem because of
native trematodes -- flukes -- that infect the snails and controls
their population and reproduction. Some people have suggested that
those who want to control the snail introduce this trematode to the
U.S. to control the snails.
"There are two problems with introducing these trematodes,"
says Levri. "The first is that any introduction of a nonnative species
can cause worse problems than they were expected to cure. The second is
that these flukes have a multiple-host life cycle, infecting ducks that
are apparently not affected before infecting the snails. This might
work in the west where the snails are in shallow water, but no duck is
going to dive 100 feet to get snails."
Levri and his team found that in Lake Ontario, the densities
of the snails peak between 50 and 82 feet and they were rarely found in
water less than 16 feet.
"What we can do is limit their expansion," says Levri. "That
means that recreational water users must be very careful moving from
one place to another. We advise anglers to freeze waders and fishing
gear, or use Formula 409 or something like that to kill the snails."
He notes that signs are beginning to mark areas in New York where the snail is found to warn people to clean their gear.
The
Penn State researcher warns that the snails are difficult to control,
noting "I have frozen them for 12 hours at a time and about 50 percent
of them survive."
Deep in the hinterlands of the Republic of the Congo lies a secret ape paradise that is home to 125,000 western lowland gorillas, researchers announced today.
The findings, if confirmed, would more than double the world's estimated population of gorillas.
Western lowland gorillas are a subspecies classified as critically endangered by the International Union for Conservation of Nature (IUCN).
Their numbers have been devastated in recent years by illegal hunting for bush meat and the spread of the Ebola virus. Just last year scientists projected the animals' population could fall as low as 50,000 by 2011.
Now those predictions may have to be dramatically reworked to incorporate findings released today by the Wildlife Conservation Society (WCS).
A first ever ape census in northern Congo found 73,000 of the gorillas in that country's Ntokou-Pikounda region and 52,000 more in the Ndoki-Likouala area.
The Ndoki population includes an obscure group of nearly 6,000 gorillas living in close quarters in isolated swamps near Lac Télé.
"We knew there were apes there, we just had no idea how many," said WCS's Emma Stokes, one of the lead researchers in the two-year project.
The gorillas have thrived thanks to their remoteness from human settlements, food-rich habitats, and two decades of conservation efforts in one of the world's poorest countries, Stokes said.
Shy, But Plentiful
Lowland gorillas are more common than their mountain cousins. The animals are found in tropical forests and swamps in Angola, Cameroon, the Central African Republic, Congo, the Democratic Republic of the Congo, Equatorial Guinea, and Gabon.
Each group of lowland gorillas has a range of about 7.7 square miles
(20 square kilometers), and the animals build the nests to sleep in
each night before moving on in the morning.
The census work involved crossing hundreds of miles to count
nests, then loading data into a mathematical model that estimated the
number of gorillas living within a defined area.
In the 17,400-square-mile (28,000-square-kilometer)
Ndoki-Likouala region, for example, the nest census found an estimated
population density of 1.65 gorillas per square kilometer (equal to
about 0.3 square mile).
This means that about 46,200 western lowland gorillas likely
live in the area, which runs west of the Sangha River to the border of
the Central African Republic.
An additional 6,000 gorillas reside in the region's 646-square-mile
(1,040-square-kilometer) Batanga swamps. These wetlands, which are
inaccessible to humans for more than half the year, house an estimated
five to six apes per square kilometer.
"That's the highest density I've seen," Stokes said, adding
that the data suggest Ndoki-Likouala is the subspecies' "largest
remaining stronghold."
The discovery "shows that conservation in the Republic of Congo is working," said WCS president Steven Sanderson.
Almost half the surveyed area lies within officially protected
zones or inside timber concessions where logging companies have banned
transport of protected animals and weapons on their roads.
Researchers hope the latest census will encourage the
government of Congo to establish a new national park in the
Ntokou-Pikounda region.
The census was presented today at the International Primatological
Society conference in Edinburgh, Scotland, and some of the data will
appear in an upcoming issue of the conservation journal Oryx.
Perils of Counting Apes
Several experts greeted the survey findings with a mix of excitement and caution.
"If these new gorilla census figures are confirmed by further surveys,
it would be the most exciting ape conservation news in years," said
Craig Stanford of the Jane Goodall Research Center at the University of
Southern California.
"Nest census data are notorious for varying from one method to
the next, however, and I think we should be cautious before assuming
the world's known gorilla population has just doubled."
Nesting data were among the factors used in a 2007 IUCN
population assessment that placed the western lowland gorilla on the
organization's Red List of Threatened Species.
IUCN estimated the gorillas had declined by more than 60 percent over
the past 25 years, and its scientists projected the apes' population
could fall to 50,000 as the deadly Ebola virus penetrated deeper into
their habitat.
That report came with a caveat about the reliability of nest counts:
"Technical problems with the conversion of ape nest density to
estimates of gorilla density preclude a rigorous estimate of range-wide
gorilla abundance."
Peter Walsh of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, led the 2007 IUCN assessment. He
repeated those concerns when he learned of WCS's findings in northern
Congo.
"It is not that I think that the numbers are necessarily too high,"
Walsh said. "It is just that I do not trust the assumptions made by the
estimation models that are being used."
Nature's Secrets
John Oates, professor emeritus of anthropology at Hunter College
in New York, noted that "what does seem clear is that there are still
plenty of western gorillas in northern Congo."
He remains cautious, however, about whether the new research should signal a change in status for the great apes.
In addition to habitat loss and hunting, in recent years Ebola
has ravaged gorilla habitats bordering the Ntokou-Pikounda survey area,
killing 60 percent of the apes in nearby Odzala National Park.
While WCS's Stokes said her survey found "no evidence of Ebola
in Ntokou-Pikounda, our general philosophy is Ebola can hit anywhere,
anytime."
And with a 90 percent mortality rate among infected gorillas,
Stokes thinks the animals deserve all the protection they can get.
In general, the WCS findings demonstrate that our intensely observed
planet still has its biological secrets, added Richard Bergl, curator
of research at the North Carolina Zoo.
"It is extraordinary that in this day and age," he said, "there
could be a population of a hundred thousand or more gorillas that were
essentially unknown to science."
