For all powerpoint presentation notes please refer to the "Ecology Resources" folder in Moodle. This site has additional notes and articles that I feel would help you to understand the ecological concepts better.

You have learned about food chains & food web and how when one of the animal/ plant is removed from the chain the ecosystem is affected in varying degree.

Colony Collapse Disorder

Many online websites and articles claim that Albert Einstein said that "If the bee disappears from the surface of the earth, man would have no more than four years to live." Even though the extinction of bees on earth would be catastrophic, there is no strong evidence that Einstein has made the remark. However, what would happen if the bee colonies start to collapse?

Can you predict what would happen?
Discuss this with your friend next to you quickly?


Read the article below and the link here


NY Times February 27, 2007

Honeybees Vanish, Leaving Keepers in Peril

By ALEXEI BARRIONUEVO

VISALIA, Calif., Feb. 23 — David Bradshaw has endured countless stings during his life as a beekeeper, but he got the shock of his career when he opened his boxes last month and found half of his 100 million bees missing.

In 24 states throughout the country, beekeepers have gone through similar shocks as their bees have been disappearing inexplicably at an alarming rate, threatening not only their livelihoods but also the production of numerous crops, including California almonds, one of the nation’s most profitable.

“I have never seen anything like it,” Mr. Bradshaw, 50, said from an almond orchard here beginning to bloom. “Box after box after box are just empty. There’s nobody home.”

The sudden mysterious losses are highlighting the critical link that honeybees play in the long chain that gets fruit and vegetables to supermarkets and dinner tables across the country.

Beekeepers have fought regional bee crises before, but this is the first national affliction.

Now, in a mystery worthy of Agatha Christie, bees are flying off in search of pollen and nectar and simply never returning to their colonies. And nobody knows why. Researchers say the bees are presumably dying in the fields, perhaps becoming exhausted or simply disoriented and eventually falling victim to the cold.
As researchers scramble to find answers to the syndrome they have decided to call “colony collapse disorder,” growers are becoming openly nervous about the capability of the commercial bee industry to meet the growing demand for bees to pollinate dozens of crops, from almonds to avocados to kiwis.

Along with recent stresses on the bees themselves, as well as on an industry increasingly under consolidation, some fear this disorder may force a breaking point for even large beekeepers.

A Cornell University study has estimated that honeybees annually pollinate more than $14 billion worth of seeds and crops in the United States, mostly fruits, vegetables and nuts. “Every third bite we consume in our diet is dependent on a honeybee to pollinate that food,” said Zac Browning, vice president of the American Beekeeping Federation.

The bee losses are ranging from 30 to 60 percent on the West Coast, with some beekeepers on the East Coast and in Texas reporting losses of more than 70 percent; beekeepers consider a loss of up to 20 percent in the off season to be normal.

Beekeepers are the nomads of the agriculture world, working in obscurity in their white protective suits and frequently trekking around the country with their insects packed into 18-wheelers, looking for pollination work.

Once the domain of hobbyists with a handful of backyard hives, beekeeping has become increasingly commercial and consolidated. Over the last two decades, the number of beehives, now estimated by the Agriculture Department to be 2.4 million, has dropped by a quarter and the number of beekeepers by half.
Pressure has been building on the bee industry. The costs to maintain hives, also known as colonies, are rising along with the strain on bees of being bred to pollinate rather than just make honey. And beekeepers are losing out to suburban sprawl in their quest for spots where bees can forage for nectar to stay healthy and strong during the pollination season.

“There are less beekeepers, less bees, yet more crops to pollinate,” Mr. Browning said. “While this sounds sweet for the bee business, with so much added loss and expense due to disease, pests and higher equipment costs, profitability is actually falling.”

Some 15 worried beekeepers convened in Florida this month to brainstorm with researchers how to cope with the extensive bee losses. Investigators are exploring a range of theories, including viruses, a fungus and poor bee nutrition. They are also studying a group of pesticides that were banned in some European countries to see if they are somehow affecting bees’ innate ability to find their way back home.

It could just be that the bees are stressed out. Bees are being raised to survive a shorter offseason, to be ready to pollinate once the almond bloom begins in February. That has most likely lowered their immunity to viruses.

Mites have also damaged bee colonies, and the insecticides used to try to kill mites are harming the ability of queen bees to spawn as many worker bees. The queens are living half as long as they did just a few years ago.

Researchers are also concerned that the willingness of beekeepers to truck their colonies from coast to coast could be adding to bees’ stress, helping to spread viruses and mites and otherwise accelerating whatever is afflicting them.

Dennis van Engelsdorp, a bee specialist with the state of Pennsylvania who is part of the team studying the bee colony collapses, said the “strong immune suppression” investigators have observed “could be the AIDS of the bee industry,” making bees more susceptible to other diseases that eventually kill them off.
Growers have tried before to do without bees. In past decades, they have used everything from giant blowers to helicopters to mortar shells to try to spread pollen across the plants. More recently researchers have been trying to develop “self-compatible” almond trees that will require fewer bees. One company is even trying to commercialize the blue orchard bee, which is virtually stingless and works at colder temperatures than the honeybee.

Beekeepers have endured two major mite infestations since the 1980s, which felled many hobbyist beekeepers, and three cases of unexplained disappearing disorders as far back as 1894. But those episodes were confined to small areas, Mr. van Engelsdorp said.

Today the industry is in a weaker position to deal with new stresses. A flood of imported honey from China and Argentina has depressed honey prices and put more pressure on beekeepers to take to the road in search of pollination contracts. Beekeepers are trucking tens of billions of bees around the country every year.

California’s almond crop, by far the biggest in the world, now draws more than half of the country’s bee colonies in February. The crop has been both a boon to commercial beekeeping and a burden, as pressure mounts for the industry to fill growing demand. Now spread over 580,000 acres stretched across 300 miles of California’s Central Valley, the crop is expected to grow to 680,000 acres by 2010.

Beekeepers now earn many times more renting their bees out to pollinate crops than in producing honey. Two years ago a lack of bees for the California almond crop caused bee rental prices to jump, drawing beekeepers from the East Coast.

This year the price for a bee colony is about $135, up from $55 in 2004, said Joe Traynor, a bee broker in Bakersfield, Calif.

A typical bee colony ranges from 15,000 to 30,000 bees. But beekeepers’ costs are also on the rise. In the past decade, fuel, equipment and even bee boxes have doubled and tripled in price.

The cost to control mites has also risen, along with the price of queen bees, which cost about $15 each, up from $10 three years ago.

To give bees energy while they are pollinating, beekeepers now feed them protein supplements and a liquid mix of sucrose and corn syrup carried in tanker-sized trucks costing $12,000 per load. Over all, Mr. Bradshaw figures, in recent years he has spent $145 a hive annually to keep his bees alive, for a profit of about $11 a hive, not including labor expenses. The last three years his net income has averaged $30,000 a year from his 4,200 bee colonies, he said.

“A couple of farmers have asked me, ‘Why are you doing this?’ ” Mr. Bradshaw said. “I ask myself the same thing. But it is a job I like. It is a lifestyle. I work with my dad every day. And now my son is starting to work with us.”

Almonds fetch the highest prices for bees, but if there aren’t enough bees to go around, some growers may be forced to seek alternatives to bees or change their variety of trees.

“It would be nice to know that we have a dependable source of honey bees,” said Martin Hein, an almond grower based in Visalia. “But at this point I don’t know that we have that for the amount of acres we have got.”

To cope with the losses, beekeepers have been scouring elsewhere for bees to fulfill their contracts with growers. Lance Sundberg, a beekeeper from Columbus, Mont., said he spent $150,000 in the last two weeks buying 1,000 packages of bees — amounting to 14 million bees — from Australia.

He is hoping the Aussie bees will help offset the loss of one-third of the 7,600 hives he manages in six states. “The fear is that when we mix the bees the die-offs will continue to occur,” Mr. Sundberg said.

Migratory beekeeping is a lonely life that many compare to truck driving. Mr. Sundberg spends more than half the year driving 20 truckloads of bees around the country. In Terra Bella, an hour south of Visalia, Jack Brumley grimaced from inside his equipment shed as he watched Rosa Patiño use a flat tool to scrape dried honey from dozens of beehive frames that once held bees. Some 2,000 empty boxes — which once held one-third of his total hives — were stacked to the roof.
Beekeepers must often plead with landowners to allow bees to be placed on their land to forage for nectar. One large citrus grower has pushed for California to institute a “no-fly zone” for bees of at least two miles to prevent them from pollinating a seedless form of Mandarin orange.

But the quality of forage might make a difference. Last week Mr. Bradshaw used a forklift to remove some of his bee colonies from a spot across a riverbed from orange groves. Only three of the 64 colonies there have died or disappeared.

“It will probably take me two to three more years to get back up,” he said. “Unless I spend gobs of money I don’t have.”



Understanding Relationships in Ecology



There are different types of direct relationships between individual organisms within ecological communities.
  1. Symbiotic relationships exist where one or more organisms live in close contact or live with one another.
    • Mutualism
    • Parasitism
    • Commensalism
  2. Predator – prey relationships or predation exist when one organisms consumes a second organism.
  3. Competitive relationships exist where organisms compete for an important resource such as food, shelter or possibly mates.
    • Intraspecific Competition
    • Interspecific Competition

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You can refer to Moodle's notes for the examples but we have looked into the fascinating relationship between the wasp and the fig to understand mutualism. Here we will look at the intriguing article by Carl Zimmer which may possibly make your stomach churn.

Do Parasites Rule The World? Parasites are more abundant than free-living organisms in the world. They may be found in nearly every phylum of animals, from protistan phyla to chordates, exhibit marvelous strategies for adaptation to their hosts. Parasitic diseases continue to be major threats to health for the world's population, have strong negative impacts on animal welfare and modern agriculture and are considered as biological indicators of environmental pollution. Parasites have pervasive influences in populations. They rule human and animal behavior, and affect a world history. By draining host nutrients, they alter how much energy and how many nutrients the population is withdrawing from the habitat. Weakened hosts are more vulnerable to predation and less attractive to potential mates. Some infections result in sterility. Some may alter the ratio of host males to females. In such ways, parasitic infections lower the birth...

Do Parasites Rule the World?

New evidence indicates our idea of how nature really works could be wrong
by Carl Zimmer
From the August 2000 issue, published online August 1, 2000

On a clear summer day on the California coast, the carpinteria salt marsh vibrates with life. Along the banks of the 120-acre preserve, 80 miles northwest of Los Angeles, thousands of horn snails, their conical shells looking like miniature party hats, graze the algae. Arrow gobies slip through the water, while killifish dart around, every now and then turning to expose the brilliant glint of their bellies. Fiddler crabs slowly crawl out of fist-size holes and salute the new day with their giant claws, while their bigger cousins—lined-shore crabs— crack open snails as if they were walnuts. Meanwhile, a carnival of birds— Caspian terns, willet, plover, yellowleg sandpipers, curlews, and dowitchers— feast on littleneck clams and other prey burrowed in the marsh bottom.

Standing on a promontory, Kevin Lafferty, a marine biologist at the University of California at Santa Barbara, watches the teeming scene and sees another, more compelling drama. For him, the real drama of the marsh lies beneath the surface in the life of its invisible inhabitants: the parasites. A curlew grabs a clam from its hole. "Just got infected," Lafferty says. He looks at the bank of snails. "More than 40 percent of these snails are infected," he pronounces. "They're really just parasites in disguise." He points to the snowy constellation of bird droppings along the bank. "There are boxcars of parasite biomass here; those are just packages of fluke eggs."

Every living thing has at least one parasite that lives inside or on it, and many, including humans, have far more. Leopard frogs may harbor a dozen species of parasites, including nematodes in their ears, filarial worms in their veins, and flukes in their kidneys, bladders, and intestines. One species of Mexican parrot carries 30 different species of mites on its feathers alone. Often the parasites themselves have parasites, and some of those parasites have parasites of their own. Scientists have no idea of the exact number of species of parasites, but they do know one fact: Parasites make up the majority of species on Earth. Parasites can take the form of animals, including insects, flatworms, and crustaceans, as well as protozoa, fungi, plants, and viruses and bacteria. By one estimate, parasites may outnumber free-living species four to one. Indeed, the study of life is, for the most part, parasitology.

Most of the past century's research on parasites has gone into trying to fight the ones that cause devastating illness in humans, such as malaria, AIDS, and tuberculosis. But otherwise, parasites have largely been neglected. Scientists have treated them with indifference, even contempt, viewing them as essentially hitchhikers on life's road. But recent research reveals that parasites are remarkably sophisticated and tenacious and may be as important to ecosystems as the predators at the top of the food chain. Some castrate their hosts and take over their minds. Others completely shut down the immune systems of their hosts. Some scientists now think parasites have been a dominant force, perhaps the dominant force, in the evolution of life.

Sacculina carcini, a barnacle that morphs into plantlike roots, is not the kind of organism that commands immediate respect. Indeed, at first glance Sacculina appears to slide down the ladder of evolution during its brief lifetime. Biologists are just beginning to realize that this backward-looking creature is a powerhouse in disguise.

Sacculina starts life as a free-swimming larva. Through a microscope, the tiny crustacean looks like a teardrop equipped with fluttering legs and a pair of dark eyespots. Nineteenth-century biologists thought Sacculina was a hermaphrodite, but in fact it comes in two sexes. The female larva is the first to colonize its host, the crab. Sense organs on the female Sacculina's legs catch the scent of a crab, and she dances through the water until she lands on its armor. She crawls along an arm as the crab twitches in irritation— or perhaps the crustacean equivalent of panic— until she comes to a joint on the arm where the hard exoskeleton bends at a soft chink. There she looks for the small hairs that sprout out of the crab's arm, each anchored in its own hole. She jabs a long hollow dagger through one of the holes, and through it squirts a blob made up of a few cells. The injection, which takes only a few seconds, is a variation on the molting that crustaceans and insects go through in order to grow. For example, a cicada sitting in a tree separates a thin outer husk from the rest of its body and then pushes its way out of the shell, emerging with a new, soft exoskeleton that stretches throughout the insect's growth spurt. In the case of the female Sacculina, however, most of her body becomes the husk that is left behind. The part that lives on looks less like a barnacle than like a microscopic slug.

The slug plunges into the depth of the crab. In time it settles in the crab's underside and grows, forming a bulge in its shell and sprouting a set of rootlike tendrils, which spread throughout the crab's body, even wrapping around its eyestalks. Covered with fine, fleshy fingers much like the ones lining the human intestine, these roots draw in nutrients dissolved in the crab's blood. Remarkably, this gross invasion fails to trigger any immune response in the crab, which continues to wander through the surf, eating clams and mussels.

Meanwhile, the female Sacculina continues to grow, and the bulge in the crab's underside turns into a knob. As the crab scuttles around, the knob's outer layer slowly chips away, revealing a portal. Sacculina will remain at this stage for the rest of her life, unless a male larva lands on the crab and finds the knob's pin-size opening. It's too small for him to fit into, and so, like the female before him, he molts off most of himself, injecting the vestige into the hole. This male cargo— a spiny, reddish-brown torpedo 1/100,000 inch long— slips into a pulsing, throbbing canal, which carries him deep into the female's body. He casts off his spiny coat as he goes and in 10 hours ends up at the bottom of the canal. There he fuses to the female's visceral sac and begins making sperm. There are two of these wells in each female Sacculina, and she typically carries two males with her for her entire life. They endlessly fertilize her eggs, and every few weeks she produces thousands of new Sacculina larvae.

Eventually, the crab begins to change into a new sort of creature, one that exists to serve the parasite. It can no longer do the things that would get in the way of Sacculina's growth. It stops molting and growing, which would funnel away energy from the parasite. Crabs can typically escape from predators by severing a claw and regrowing it later on. Crabs carrying Sacculina can lose a claw, but they can't grow a new one in its place. And while other crabs mate and produce new generations, parasitized crabs simply go on eating and eating. They have been spayed by the parasite.

Despite having been castrated, the crab doesn't lose its urge to nurture. It simply directs its affection toward the parasite. A healthy female crab carries her fertilized eggs in a brood pouch on her underside, and as her eggs mature she carefully grooms the pouch, scraping away algae and fungi. When the crab larvae hatch and need to escape, their mother finds a high rock on which to stand, then bobs up and down to release them from the pouch into the ocean current, waving her claws to stir up more flow. The knob that Sacculina forms sits exactly where the crab's brood pouch would be, and the crab treats the parasite knob as such. She strokes it clean as the larvae grow, and when they are ready to emerge she forces them out in pulses, shooting out heavy clouds of parasites. As they spray out from her body, she waves her claws to help them on their way. Male crabs succumb to Sacculina's powers as well. Males normally develop a narrow abdomen, but infected males grow abdomens as wide as those of females, wide enough to accommodate a brood pouch or a Sacculina knob. A male crab even acts as if he had a female's brood pouch, grooming it as the parasite larvae grow and bobbing in the waves to release them.

Sacculina's adaptations reflect a relatively simple life cycle for a parasite— it makes its way from one crab to another. But for many other parasites, the game is more complicated—they must journey through a series of animal species in order to survive and procreate. Such parasites exert extraordinary control over their hosts, transforming them into seemingly different creatures. They can change a host's looks or scent to appeal to a predator. They can even alter its behavior to force it into the next host's path.

The mature lancet fluke, Dicrocoelium dendriticum, nestles in cows and other grazers, which spread the fluke's eggs in their manure. Hungry snails swallow the eggs, which hatch in their intestines. The immature parasites drill through the wall of a snail's gut and settle in the digestive gland. There the flukes produce offspring, which make their way to the surface of the snail's body. The snail tries to defend itself by walling the parasites off in balls of slime, which it then coughs up and leaves behind in the grass.

Along comes an ant, which swallows a slime ball loaded with hundreds of lancet flukes. The parasites slide down into the ant's gut and then wander for a while through its body, eventually moving to the cluster of nerves that control the ant's mandibles. Most of the lancet flukes head back to the abdomen, where they form cysts, but one or two stay behind in the ant's head.

There the flukes do some parasitic voodoo on their hosts. As the evening approaches and the air cools, the ants find themselves drawn away from their fellows on the ground and upward to the top of a blade of grass. Clamped to the tip of the blade, the infected ant waits to be devoured by a cow or some other grazer passing by.

If the ant sits the whole night without being eaten and the sun rises, the flukes let the ant loosen its grip on the grass. The ant scurries back down to the ground and spends the day acting like a regular insect again. If the host were to bake in the heat of the direct sun, the parasites would die with it. When evening comes again, they send the ant back up a blade of grass for another try. After the ant finally tumbles into a cow's stomach, the flukes burst out and make their way to the cow's liver, where they will live out their lives as adults.

As scientists discover more and more parasites and uncover the extent and complexity of their machinations, they are fast coming to an unsettling conclusion: Far from simply being along for the ride, parasites may be one of nature's most powerful driving forces.At the Carpinteria salt marsh, Kevin Lafferty has been exploring how parasites may shape an entire region's ecology. In a series of exacting experiments, he has found that a single species of fluke— Euhaplorchis californiensis— journeys through three hosts and plays a critical role in orchestrating the marsh's balance of nature.

Birds release the fluke's eggs in their droppings, which are eaten by horn snails. The eggs hatch, and the resulting flukes castrate the snail and produce offspring, which come swimming out of their host and begin exploring the marsh for their next host, the California killifish. Latching onto the fish's gills, the flukes work their way through fine blood vessels to a nerve, which they crawl along to the brain. They don't actually penetrate the killifish's brain but form a thin carpet on top of it, looking like a layer of caviar. There the parasites wait for the fish to be eaten by a shorebird. When the fish reaches the bird's stomach, the flukes break out of the fish's head and move into the bird's gut, stealing its food from within and sowing eggs in its droppings to be spread into marshes and ponds.

In his research, Lafferty set out to answer one main question: Would Carpinteria look the same if there were no flukes? He began by examining the snail stage of the cycle. The relationship between fluke and snail is not like the one between predator and prey. In a genetic sense, infected snails are dead, because they can no longer reproduce. But they live on, grazing on algae to feed the flukes inside them. That puts them in direct competition with the marsh's uninfected snails.

To see how the contest plays out, Lafferty put healthy and fluke-infested snails in separate mesh cages at sites around the marsh. "The tops were open so the sun could shine through and algae could grow on the bottom," says Lafferty. What he found was that the uninfected snails grew faster, released far more eggs, and could thrive in far more crowded conditions. The implication: In nature, the parasites were competing so intensely that the healthy snails couldn't reproduce fast enough to take full advantage of the salt marsh. In fact, if flukes were absent from the marsh, the snail population would nearly double. That explosion would ripple out through much of the salt marsh ecosystem, thinning out the carpet of algae and making it easier for the snails' predators, such as crabs, to thrive.

Lafferty then studied the killifish. Initially, he found little evidence that flukes harmed or changed the fish they colonized; the fish didn't even mount an immune response. But Lafferty was suspicious. He figured that flukes sitting on the brain were in a good position to be doing something. So he plucked 42 fish from the marsh, dumped them into a 75-gallon aquarium in the lab, and gave his student Kimo Morris the laborious task of watching them. Morris would pick out one fish and stare at it for half an hour, recording every move it made. When he was done, he'd scoop the fish out and dissect it to see whether its brain was caked with parasites. Then he'd focus on another killifish.

What was hidden to the naked eye came leaping out of the data. As killifish search for prey, they alternate between hovering and darting around. But every now and then, Morris would spot a fish shimmying, jerking, flashing its belly as it swam on one side, or darting close to the surface— all risky things for a fish to do if a bird is scanning the water. It turns out that fish with parasites were four times more likely to shimmy, jerk, flash, and surface than their healthy counterparts.

Lafferty and Morris followed up with a marsh experiment in which they set up two pens, each filled with 53 uninfected killifish and 95 infected fish. To distinguish between the two groups, the researchers clipped the left pectoral fin of the healthy fish and the right fin of the parasitized ones. One pen was covered with netting to protect it from birds; the other was left open so birds could easily wade or land inside. After two days, a great egret waded into the open pen. It stepped slowly into the muddy water and struck it a few times, the last time bringing up a killifish. After birds had visited the pen for three weeks, Lafferty and Morris added up how many fish were alive. (The covered pen acted as a control for the researchers to see how many fish died of natural causes.) The results were startling: The birds were 30 times more likely to feast on one of the flailing, parasitized fish than on a healthy fish.

Predators are often very careful about the prey they eat, avoiding poisonous insects and frogs, for example. So why would birds pick so many fish that are guaranteed to pass on an energy-sucking intestinal parasite? The flukes do drain a bit of energy from the birds. But that is more than offset by the benefit they provide: They make finding food very easy for the birds.

Scientists have been stunned by the implications of these findings. The birds that frequent coastal wetlands depend on fish for much of their diet. Without parasites throwing prey their way, the birds of Carpinteria might have to put far more time and effort into eating and might reproduce at a lower rate. "Could we have so many birds out there if it were 30 times harder for them to get their food?" asks marine biologist Armand Kuris, also of the University of California at Santa Barbara. "Parasites don't just modify individual behavior, they're really powerful— they may be running a large part of the waterbird ecology."

The fluke that Lafferty studied is but one parasite, living in one salt marsh. There are a dozen other species of fluke that live in the snails of Carpinteria and other parasites that dwell in other animals of the marsh. Every ecosystem on Earth is just as rife with parasites that can exert extraordinary control over their hosts, riddling them with disease, castrating them, or transforming their natural behavior. Scientists like Lafferty are only just beginning to discover exactly how powerful these hidden inhabitants can be, but their research is pointing to a remarkable possibility: Parasites may rule the world.

The notion that tiny creatures we've largely taken for granted are such a dominant force is immensely disturbing. Even after Copernicus took Earth out of the center of the universe and Darwin took humans out of the center of the living world, we still go through life pretending that we are exalted above other animals. Yet we know that we, too, are collections of cells that work together, kept harmonized by chemical signals. If an organism can control those signals— an organism like a parasite— then it can control us. And therein lies the peculiar and precise horror of parasites.



For pictures of parasites do visit the Life Tree picture gallery.
[Warning, some of the parasite pictures may disturb you.]

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