Making the Right Decision, If You’re A Rat

It’s Friday night and you have an exam on Monday. Between then and now, you would like to study, but you have also been invited to a party and have a date to go on. To decide how to spend your weekend, you will have to weigh the cost of a lower exam grade with the benefit of getting out with your main squeeze and partying.

A study by Ruud van den Bos has recently determined that Wistar rats have the ability to make decisions like this also. Van den Bos and his staff set up a T-shaped track, with the two arms of the T having treats in both. The rat was released in the bottom of the T and left to choose which arm it would enter to eat the treats there. The trick is in the varying difficulty between the arms. One arm would have a straight path to a single treat, the other barriers to scale to get to a larger amount of treats. In each successive test, the toughness of the path over the barriers was varied. The rats would have to determine how much energy they were willing to spend to get treats. When the barriers were small, the rats went over them most of the time to get the large reward. But when the path was harder, the rats more often went to the other arm for the one treat. This meant that the rats decided the energy cost was too high to scale the barriers when they were steep.

Van den Bos’s team noticed that rats seem to have a set amount of energy they are willing to spend on a certain activity. This standard may be predetermined by genetics and also past experiences and decision making on the part of the rat.

Posted by Natural K (8)

Pups Take a Long Time to Move Out

A recent study of Australian sea lions indicates several things about their juveniles, their population and its correlation to the frequency of dives and depth of dives. There are three levels of dives: epipelagic, mesopelagic and benthic which indicate the depth and size of prey the sea lions go for. The study shows it takes Australian juveniles longer to reach the depths of adults than other species of pinnipeds.

Pups are suckled for 17 months, one of the longest lactations periods of pinnipeds. It is observed that young pups don’t have much room to store oxygen, they use up more oxygen due to growth development and they have more drag due to their smaller stature. Pups don’t develop complete diving skills for a long time. This could be why they aren’t wean until much later than other pinnipeds. They have extended period to develop the diving skills needed to go to the benthic depths their mothers exhibit. The pups use this time to become good hunters because of their environment which doesn't have a season like the other species of pinnipeds where their prey volume fluctuates in their environment.

Dives of 6-month-old pups, 15-month-old pups, 23-month-old pups, and mothers were recorded using an electronic time/depth recorder. Data shows that 6-month-old pups spent most of their time on shore and exhibit shallow, short dives. As the pups grew older they were diving deeper, diving for longer, and taking more trips. However, these dives were no where near the depth or time of an adult female.

For these reasons, the Australian sea lion population is leveling off or declining. It takes them longer to be independent and mature enough to be reproducing. Other species of pinnipeds wean their pups earlier and acquire the diving skills sooner. But this is also due to their richer environment. Also human-induced disturbances may alter the Australian sea lions’ environment to the point where it holds the pups back. The advantage of deep dives is the larger prey. Fishery trawls that disrupt the habitat and take the bigger prey on the benthic level affect the sea lions. With the fishery trawls, the prey are scarcer and so it affects the pups and also the adults that can hunt in the benthic level. Environmental modifications impact juveniles hunting in the deeper water depths. These things should all be taken into concern when treading in the Australian sea lion’s major colony.

Posted by Karisma (8)

Radioactive scorpion venom may be used to fight cancer

Health physicists have established a safe procedure which is for brain cancer therapy using radio active versions of a certain protein that is found in scorpion venom. This development is being done to help cultivate a new therapy for brain cancer. This venom which is produced by the yellow Israeli scorpion attaches to the cells of a specific incurable brain cancer known as gliomas. Scientists have created a radioactive version of this venom which they have named TM-601.

The venom contains an artificial version of the venom protein which is attached to a radio active substance called iodine 131. When this venom enters the bloodstream, it attaches to the gliomas cells. Upon attaching to the cells the iodine 131 then releases radiation which kills the cancerous cells.

This compound made by the physicists have enabled treatment for high-grade gliomas that are found in about 17,000 people a year. These gliomas cause death in most patients within the first year of diagnosis. In order to receive the treatment, patients are usually injected with the compound and don't usually have to receive chemotherapy or radiation afterwards. The first earliest trials using this venom on cancer patients have showed potential signs for treating the cancer as well as extending the survival rate of the patient.

posted by cmt ( 8 )

Overprotective Mice Mothers

At some point in our lives we have all thought our mothers were overprotective, but have you ever wondered if there was a reason for this behavior other than the common explanation that it is for your own good and because they care? Many species of animals give parental care and protection to their young in the early stages in life so as to increase the survival rate of those offspring, but different animals exhibit this behaviour in different ways. In mice, females have been observed to become more anxious and aggressive as their pregnancies progress with the most aggressive behavior exhibited just prior to giving birth and during lactation.

Research into the causes of aggression in prospective mice mothers by F.R. D'Amato, R. Rizzi, and A. Moles was published in the October 2006 issue of Animal Behaviour. These scientists hypothesized that the overall number of pups and the male to female ratio in the litter would determine female agressive behavior. Scientists believed that as the number of pups in a litter increased the level of aggression of the mother would also increase, and that a mother mouse about to have more male than female babies would also show higher levels of agression than a mouse about to have a litter with more female than male pups. The experimental results showed that aggression does indeed increase with the number of pups in a litter, but does not show a relation to the male to female ratio of the litter.

To explain this behavior D'Amato, Rizzi, and Moles point out that maternal aggression is key in the survival of the pups because the behavior of the mother provides some protection for the young from both predators and fratricidal male mice. Scientists suggest that certain internal and external stimulii that the femal recieves from her litter give her an idea as to the reproductive value of that particular litter. A larger litter means that a mother's genes will be passed on to the next generation in higher frequency so it maks sense that the female will have more to gain in an evolutionary sense if a larger litter survives.

So in the end it comes down to a matter of weighing benefits against losses. When confronted with a predator or intruding male a female must decide to run or try to chace it off. If she runs her pups are likely to die, but she will live to breed another day, whereas if the mother stays she may die her pups have a greater chance of survival. This explains why female mice show less fear and more agression when confronted with a predator or male while she is carrying and nursing a large litter of pups. If a female has a litter of 10 or 12 pups her genes better represented in the next generation than if she has a litter of 6 or 7 pups. When we consider this it makes sense that the mother will be less likely to run and more likely to stay and try to chase off an intruding predator or male mouse when she has more babies on the line, because she has more to gain from an evolutionary stand point if a litter of 12 survives than she does from the survival of a litter of 6.

posted by MFP

Humpback Whales Speak a Language all Their Own

When you think of a whale jumping out of the water or making noises, which is the first one that comes to mind? Humpback whales have long been known for their majestic aerobatic maneuvers, and their deep singing voices. These whales do in fact, have the largest vocal range of baleen whales and their ‘song’ is being called the most complex of the animal kingdom. Besides the actual make-up of the songs, another interesting part is the evolution of the songs of a whale population over time. So why are these songs so complex and important?

According to a study this year out of MIT, headed by Ryuji Suzuki, due to the varying conditions underwater the humpbacks depend more on sound than any other sense. Sound travels four times faster than it does in air, which makes their communication much more efficient over long distances. Suzuki used the tools of information theory – a mathematical study of data used to analyze the complex patterns of moans, cries, and chirps in the whales’ songs for clues to the information being sent. He designed a computer program that enabled scientists to classify the structure of the whales’ songs and gather better conclusions. Their songs are repetitive and rigid and made up of little ‘units’ like a human’s speech.

Scientists are still unclear on many aspects of humpback’s calls. They are unsure of how the sounds are even produced, since they have a larynx but no vocal chords. It is assumed that since they don’t exhale to produce sounds like a human would either, they recycle the air in the body to make such a sound. They know that it is usually males singing only during the six-month period around breeding grounds, but they aren’t really sure whether the behavior is to flirt with females about reproductive availability or simply a fighting call to warn other males to stay away.

An interesting point however is that the songs, like some species of birds, are very strict to population and change once a year within the same population, but different non-overlapping populations have completely different songs unique to themselves. Much more study is needed to being to understand this complex communication behavior that these whales possess.

Posted by MPC (7)

To Bee or Not to Bee?

We all know that many animals have the ability to mimic the environment or a less tasty animal in order to hide from predators. But what about animals that mimic other species, not in order to hide from predators, but to take advantage of a species resources? An example of this behavior was recently exhibited in blister beetle larvae.

According to a recent study at Kelso Dunes in San Francisco, researchers Saul-Gershenz and Jocelyn Millar observed clusters of blister beetle larvae are able to mimic the physical shape and smell of female bees. The beetle larvae are able to demonstrate this behavior so well that male bees try to mate with them. Then the beetle larvae make their way back to the nest where they receive free food and shelter from the bees. But how do they trick male bees and make this journey to the bee's nest?

Researchers observed the beetle larvae hatch on plants, where they bunch into a ball and release a chemical similar to a female bee pheromone that attracts male bees. Then when a male bee comes near by, the beetle larvae extend their front legs, latching onto the back of the male bee, while it is tricked into a fake copulation. But when this male bee mates with an actual female bee, the beetle larvae on the male bee latch on to the female bee. She flies back to the nest, unaware that she brought the beetle larvae with her. Then the beetle larvae feed on the bee's eggs and nectar to grow and start the cycle again.

Researchers concluded that this is a survival tool that the blister beetles developed through evolution to survive in its harsh desert habitat in California. Now researchers are currently trying to uncover this behavior in depth by discovering how the beetle larvae communicate and collaborate with each other. They suggest that some of the larvae may act as leaders for the group. It will be interesting to learn more new information about this as it comes up.

Posted by Chamel413 (6)

Dolphins May Use Tools

Bottlenose dolphins may now be capable of using tools to protect their most sensitive of body parts. A study performed by Michael Krützen of the University of Zurich in Switzerland has found that dolphins may cover their beaks with sponges to protect them from damage while foraging. The sponge-using dolphins reside off the coast of Australia in Shark Bay, and are believed to descend from a single maternal lineage.

The researchers believe that this is a passing along of a learned behavior from mother to offspring. The first sighting of this behavior was in 1986 when a passerby boat caught a glimpse of a dolphin, which appeared to have a “tumor” on its beak. In 1997, it was then that researchers took action and found a population of dolphins that exhibit this practice which is now known as sponging. This behavior is the first recorded instance of tool use among dolphins.

The study of these dolphins has been difficult according to the researchers for the reason of large shark populations also residing within the bay. However, DNA was studied from this dolphin population of one-hundred and eighty-five, with 12 female spongers and only one male. The rest of the dolphins were non-carriers. The dolphins in ten scenarios of inheritance produced unsuccessful results in a genetic explanation to the female-bias of sponging. The exact cause how certain dolphins exhibit this behavior is unknown because of failed genetic trials and spongers and non-spongers coexsiting together.

Because a genetic solution is doubtful, these researchers believe that cultural transmission, or the learning of a taught behavior, is the best possible explanation. Further observation will be needed to determine the exact methods on how bottlenose dolphins obtain this behavior.

Posted by BRW (6)

And You Thought Your Family Had Issues

Have you ever thought your parent(s) favor you brother/ sister over you? It may surprise many to find out that human families are not the only families with issues. Just like humans, birds fight over parental duties and even favor certain offspring over others. A study done by Tudor Draganoi, a post doctoral researcher at Leiden University in the Netherlands, shows some bird pairs split up and even divide offspring between the mother and father.

This study observed black redstarts, Phoenicurus ochruros, in the small mountain village of La Valla sur Rochefort, France. The study found that these birds would sometimes split up because of conflicts; many times one of the birds would abandon some of the young. The divorced birds would split up, and take with them the favorable offspring.

The study also concluded that parents responded more to the calls of the babies which they doted on. The parents prefer certain offspring over others. The factors are not known as to why the parents prefer certain young over others. Size and sex do not seem to be a factor.

The division of the two parents may result from conflicts over parental investment. Draganoi believes each parent may try to do the least amount of work and push the other parent to work harder. This will maximize current reproductive success, and also save energy for future reproduction. This theory makes sense because it would maximize reproductive success, but more studies need to be done to confirm it. The splitting up of offspring between parents also occurs in a number of other species including: blackbirds, robins, bluethroats, dunnocks, prairie warblers, song sparrows, white-throated sparrows, great crested grebe, and the coot.

Posted by Brian Salem (6)

And You Thought Your Family Had Issues

Have you ever thought your parent(s) favor you brother/ sister over you? It may surprise many to find out that human families are not the only families with issues. Just like humans, birds fight over parental duties and even favor certain offspring over others. A study done by Tudor Draganoi, a post doctoral researcher at Leiden University in the Netherlands, shows some bird pairs split up and even divide offspring between the mother and father.

This study observed black redstarts, Phoenicurus ochruros, in the small mountain village of La Valla sur Rochefort, France. The study found that these birds would sometimes split up because of conflicts; many times one of the birds would abandon some of the young. The divorced birds would split up, and take with them the favorable offspring.

The study also concluded that parents responded more to the calls of the babies which they doted on. The parents prefer certain offspring over others. The factors are not known as to why the parents prefer certain young over others. Size and sex do not seem to be a factor.

The division of the two parents may result from conflicts over parental investment. Draganoi believes each parent may try to do the least amount of work and push the other parent to work harder. This will maximize current reproductive success, and also save energy for future reproduction. This theory makes sense because it would maximize reproductive success, but more studies need to be done to confirm it. The splitting up of offspring between parents also occurs in a number of other species including: blackbirds, robins, bluethroats, dunnocks, prairie warblers, song sparrows, white-throated sparrows, great crested grebe, and the coot.

Posted by Brian Salem (6)

The Power of Sex: Making Males Change for Their Mates

Animals are incredibly sensitive to the world around them. Animals can get nervous when a large storm is coming or if a stranger enters their territory. When the seasons change, some migrate to distant lands while others hunker down and prepare for whatever is coming. But what if animals are even more connected to their world than we think? And what if this connection is the key to the animals’ progress in evolution? In a recent study, researchers have put this connection to the test by observing the effects of global warming on the migration patterns of birds. According to the results many birds are beginning to migrate earlier than in previous years, especially in species that depend greatly on sexual selection.

This basic principle behind this theory is that the males of a species will need to stake their claim on territories for nesting and mating before the females arrive. The females are equally sensitive to the climate changes, but males of a very sexually selective species will be inclined to migrate earlier so as to get the best territory to optimize the mating process. Evolutionary ecologist Claire Spottiswoode and her team analyzed the migratory patterns of nine different species on two islands off the coast of Germany. They correlated data from published works about the species’ sexual tendencies with the time-shifts in the migratory patterns. By doing so, they were able to determine which species were more selective in choosing their mates.

All of the species that were examined had experienced shifts in migrations to an earlier timetable, especially in those that proved to be more sexually selective. These results demonstrate another aspect of natural selection. All animals are sensitive to their own environment; even the slightest of changes can upset their way of life. Those that respond and adapt to these disturbances, however, are perhaps the ones that have the greatest chance of surviving, flourishing, and evolving to fit the changing world around them.

Posted by BC (5)

Home…Sweet Home?

Wherever we go, there’s always a home for us to come back to. We return because it’s what we’re use to and where we feel most comfortable within our surroundings. We’re less likely to encounter danger or starvation. But is this the case for animals as well? According to a recent article, researchers have been conducting experiments in terms of understanding how animals move about in their habitats. Although animals are free to roam as they wish in the wild, they still stay close to a certain area. This area is known as their “home range.”

Luca Börger and several of his colleagues has spent four years tracking the movement of one particular species: the roe deer (Capreolus capreolus). The monitoring took place in Maremma Regional Park in southern Tuscany. They found that an animal’s home range stems from the complexity of interactions between the animal’s behavior and it’s environment. An animal’s response to certain changes plays an important role in survival. The climate and day length also plays a part in the movement of the animals. During the summer, the deer will tend to have a smaller home range than that of it if it was during the fall or winter. More than one deer in general can share a home range, yet they may also be occupied individually as well depending on where it is. During the winter, more ground is covered in order for the deer to forage for food since everything is covered by snow. They must move constantly to a variety of places to obtain necessary amounts of food to survive. Thus their home range is broadened. Their home range narrows during the summer since food is more available due to the growth of many plants and vegetation. However, if at a particular time in a season there is less rain or more substantial heat than usual, animals will vary from wider ranges to even smaller ones. If the home range is well suited, then there would no need for the deer to venture elsewhere. If the area they occupied becomes uninhabitable, meaning there is a shortage of food or a high profusion of predators, it will then find an alternative range to settle in. The area of the home range is determined by the scarcity of food in that particular area and how far the deer is willing to travel to search for it.

In order to keep track of the behavior and movements of the roe deer, a selected amount were marked with colored collars containing a radio tap and whipped antenna. This method can be helpful in testing future populations and species while also comparing the distinctions amongst how different animals may react to climate change in their given home ranges. In a sense, animals are just like us. All they want is to be able to feel comfortable in the own home ranges while living comfortably with what’s around them.

Posted by HC (5)

Primates vs. Sea Lions: Who Has Better Self-Control?

Primates and sea lions are very different species living in totally different environments, but when it comes to their mental and physical abilities, both areclosely related. A lot has been studied on primate behavior and their cognitive abilities, but not much has been done on the sea lions’. In this study conducted, researchers were curious of which of the two mammalian species would have better self-control and used better judgment when it came to making decisions about choosing food.

In the first experiments, they wanted to test if each were capable of assessing the ability to learn continuous reverse-reward tasks. This meaning that they would have to choose from two options presented in front of them. There would be the lower quantity food of 1 fish with in return of being chosen, received a higher quantity of 5 fish. If they first chose the higher quantity of 5 fish first, then they received the lower amount of 1. All of the sea lion subjects learned to conduct the correct responses. The previous primate tests that were conducted much before the sea lions, consisted of primates including, orang-utans, chimpanzees, and cottontop tamarins, who all also succeeded in the choosing of more quantity food options. The tests were repeated many times over a long period of time in order to test that they were actually learning it as a generalization and not just from the recent training.

The results in both the primates and sea lions were very similar showing that they were each successful in making the right choices most of the time for receiving more food as a reward. To answer the question to this experiment, the species with the better ability for self-control would be the sea lion according to the testing results. Suggestions to their performance in these reverse-reward tasks may be due to their food searching strategies in natural habitats. They hunt alone therefore have little competition and less need to go with the impulsive decision of choosing more food first. Most primates do live in highly socialized groups but still have the capability of self-control and cognitive skills. Overall, they are both truly amazing animals.

Posted by KDB (5).

The Risk of Sibling Competition in Nestlings

Many individuals can relate to sibling competition. Sibling competition can result form wanting attention, more privileges, or even for more selfish reasons like wanting your personal needs met before your other siblings. However, sibling competition does not only occur in humans but it also occurs in other animals. For example, young birds have been observed competing with their siblings within their colonies resulting in many nestlings falling out of their nest. This has been observed to happen quite frequently, with over 350 living findings a year. Falling out of the nest is usually fatal for most nestlings. Several experiments are being conducted that analyze these behaviors and to discover what is exactly causing such fatal catastrophes for the little nestlings.

A lack of space within the nest is the primary cause for sibling competition and disappearance between nestlings. In the June 2006 journal of Animal Behaviour, scientist Bize and Roulin researched this behavior in greater detail to see if they can figure out why space causes such a competition between the nestlings. They discovered that the nestlings engage in jostling for position which is directly related to where the parents deliver the food. This act of jostling can cause the nestlings to either fall out of the nest or to be pushed out of the way by an eager sibling. This results in a lack of motivation in some needy nestlings to go after food in order to protect themselves from the plunge from the nest.

Experiments are being conducted around the word to further understand sibling competition in birds. In a journal from Science , a study of brown-headed cowbirds that parasitized sparrow nest was done. Far more males survive the nest competition when both sexes are grouped together in a colony. It is also less common for a parasitized nestling to fall out of the nest because of their tendency to switch nest rather than compete for food.

Overall, the birds are looking for provisions from their parents. Nestlings tend to stay as close as possible to their parents’ in competition for their full attention, so that they will become a priority during feeling. Siblings can get pushed out of the nest very easily in an attempt to make brood size as small as possible.

posted by TNS (5)

UMASS Faculty Wins Noble Prize in Medicine

Craig C. Mello from the UMASS Medical School in Worcester and Andrew Z. Fire of Stanford University have won this year's Noble Prize in medicine. Their work concerns the use of double-stranded RNA (dsRNA) for blocking the production of specific proteins. In addition, by blocking whole sets of genes these dsRNA's may also function in keeping mature cells in a specific developmental state.

The New York Times has an article on the award. Pure Pedantry has a clear and concise explanation of RNA interference and why this work is so important. For an evolutionary perspective on dsRNA check out the Looms post.

Posted by PWH.