Parasitic wasps lay eggs in caterpillars using toxins to paralyze their hosts. The wasp young then eat their way out. A study in Science magazine confirms the genetics of wasp toxins rely heavily of the DNA of viruses that infected the insects millions of years ago.
By James Morgan Science reporter, BBC News, Chicago
It is the ultimate "gentleman's agreement". Rather than compete for females, male long-tailed manakins co-operate with their friends.
The tropical birds pair up to perform a courtship song and dance, but the alpha male gets the girl every time.
Meanwhile his "wingman" spends five years playing second fiddle. But he eventually inherits the mating site.
The dance, dubbed "backwards leapfrog", was filmed in Costa Rica by zoologists from the University of Wyoming.
At first glance, it appears like a competitive "dance-off".
But in fact it is a co-operative pact between buddies, says Dr David McDonald, of Wyoming University.
"As far as I know it is the only example of male-male [mating] co-operation in the animal kingdom," he told delegates at the American Association for the Advancement of Science (AAAS) meeting in Chicago.
"The male birds' partnership lasts up to five years. During that time, the beta male does not copulate.
"He has to wait until alpha male dies - he doesn't kick him out. So he may be waiting until he's 10, 15 or even older."
The wingman may be equally as good at dancing as the alpha. Nevertheless, he agrees to forego sex and let his buddy take the spoils.
In return, he will eventually inherit the mating site and become the alpha himself.
The deal could be compared to Gordon Brown and Tony Blair's infamous "Granita pact".
At the London restaurant, Brown allegedly agreed to support Blair in his bid for Prime Minister, on condition that he would eventually inherit the reins.
"It's a rough life for a beta male manakin," concedes Dr McDonald.
"But if he hits the jackpot he is one of the most successful vertebrates on the planet earth."
The courtship duet is also highly unusual in evolutionary terms.
Most examples of co-operation in the animal kingdom involve either relatedness or kin selection, but neither is working here, says Dr McDonald.
"The way it works is he is helping establish a reputation for the dance site.
"The females don't know the males individually. They map the sites where males are doing really hot performances.
"Once a dance site has a strong reputation, females will keep coming back, even when it has a different alpha male.
"You don't go to a restaurant because you know the chef - you go because you know the meal is good.
"In the same way, the female manakins are happy as long as the singing and dancing is good. They let the males sort it all out."
But how do the males decide which of them is the alpha?
It is not a case of who is a better dancer, says Dr McDonald.
"Was Michelangelo's master a better artist than he was? Not necessarily," says Dr McDonald.
What it comes down to is how "well connected" he is among his buddies.
"As males grow up, they go through a complex network of social interactions," says Dr McDonald.
"How well connected a young male is will predict how he will do - whether he becomes an alpha or a beta.
Baboons And Pigeons Are Capable Of Higher-level Cognition, Behavioral Studies Show
General testing apparatus for pigeons. (Credit: Ed Wasserman, University of Iowa)
ScienceDaily (Feb. 16, 2009) — It's safe to say that humans are smarter than animals, but a University of Iowa researcher is investigating the extent of that disparity in intelligence.
And, it may not be as great a gap as you suspect, according to UI psychologist Ed Wasserman, who presents his findings at the American Association for the Advancement of Science (AAAS) meeting February 12 in Chicago.
One cognitive capacity that is vital to human intelligence is the ability to determine whether two or more items are the same or different - a skill the famous American psychologist William James called the very "backbone" of our thinking. If you have two pennies in your left hand and a nickel and a dime in your right hand, then you can correctly report that the two coins in your left hand are the "same" and that the two coins in your right hand are "different." You can also make similar judgments with any collection of items.
Wasserman's research shows that baboons and pigeons can do that, too. A recent study by Wasserman and UI graduate student Dan Brooks found that both pigeons and people can learn same-different discriminations with visual stimuli that never repeat from trial to trial, thus proving that simple memorization cannot explain this cognitive feat.
In other studies, Wasserman and his colleagues at other research centers took the matter a step further, posing the question: Can animals learn the relations between relations? The answer appears to be "yes."
Wasserman and his associates discovered that both baboons and pigeons also understand the relations between relations - something that only humans were believed to appreciate. For example, the relation between A and A and the relation between B and B is the same: same equals same. So, too, is the relation between A and B and the relation between C and D: different equals different. But, the relation between A and A and the relation between C and D is different: same does not equal different.
Using joysticks and computerized visual images, Wasserman and colleagues Joel Fagot of the French CNRS (National Center for Scientific Research) and Mike Young of Southern Illinois University at Carbondale found that baboons also exhibit this level of cognition by solving the so-called relational matching-to-sample problem. Here, the baboons indicated which of two testing arrays of pictures involved the same relationship as the sample array that they had recently been shown. In a follow-up study, Wasserman and colleague Bob Cook of Tufts University repeated the experiment with pigeons; the pigeons learned to peck a computerized touchscreen to accomplish the same feat as the baboons.
"The newsworthiness of our baboon experiment was to show that nonhuman primates are capable of higher-order relational learning. Understanding the relation between relations was previously believed to be a kind of cognition that sets humans apart from all other animals," Wasserman said. "The follow-up discovery - that pigeons too are capable of such higher-order relational learning - affirmed our suspicion that we've really established a finding of broad evolutionary significance."
Despite obvious anatomical differences, this behavioral evidence confirms Charles Darwin's proposal that "the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind."
The notion that there might only be a quantitative - not a qualitative - disparity between human and animal intelligence may make people uneasy, Wasserman said.
"What we're really trying to understand is the extent to which cognition is general throughout the animal kingdom. The evidence that we collect constantly surprises us, suggesting that we're not alone in many of these cognitive abilities," Wasserman said. "Why we would believe that humans alone have such capabilities is a peculiar and unfortunate arrogance. That's one reason why I enjoy studying animals; the smarter we discover them to be, the more humble we should be."
In addition to keeping human egos in check by proving we're not the only smart creatures on earth, this research may have practical applications, Wasserman said.
Some of the methods he uses to study baboons and pigeons can be deployed to study human cognition. Currently, Wasserman and colleague Leyre Castro in the UI Department of Psychology are collaborating with Amanda Owen of the UI Communication Sciences and Disorders Department to apply these animal-testing methods to studying the cognitive performance of children with language impairments.
"Because we must invent entirely nonverbal methods to study cognition in animals, these same methods may have particular promise for studying children with communicative disorders, like Specific Language Impairment and Autism," Wasserman said. "These methods may prove to have unique diagnostic and therapeutic significance."
Presenters discussed how scrub-jays can exhibit episodic-like memory and future planning; how chimpanzees can hold in memory extremely detailed environmental information; how monkeys can count and perform arithmetic operations; how pigeons and baboons can learn abstract concepts like same and different; how crows can fabricate and use tools; and, how monkeys and other animals may be aware of what they know and remember.
Parasite Wasps Have Practiced Gene Therapy For A Hundred Million Years
A braconid parasite wasp on a caterpillar. (Credit: Copyright IRBI-CNRS, Annie Bézier)
ScienceDaily (Feb. 16, 2009) — Braconid parasite wasps and their caterpillar hosts form a unique host-parasite model: the wasps lay their eggs inside the caterpillars and simultaneously inject some viral particles to get around the host's defenses and control its physiology. The genes from these viral particles have now been identified in the wasp's own genome by a team at the Institut de recherche sur la biologie de l'insecte (CNRS/Université François-Rabelais Tours), in collaboration with a laboratory at University of Berne and Genoscope d'Evry.
These genes came from a virus captured by a common ancestor of these wasps 100 million years ago. These results, published in Science 13 February 2009, could provide new means of designing transfer vectors for gene therapy.
Wasps of the family Braconidae reproduce by laying their eggs in caterpillars, which then serve as food for the developing wasp larvae (1). However, the body of a caterpillar is a hostile environment, with an efficient defense system that forms a capsule of immune cells around foreign objects. To get around these defenses, when the wasp lays her eggs in the caterpillar, she also injects some special particles made in her ovaries. These particles enter the caterpillar's cells where they induce immunosuppression and control development, allowing the wasp larvae to survive.
Although many examples of symbiotic bacteria are known, the present case of a parasitic species using a virus to control its host's physiology is unique. To improve our understanding of the phenomenon, researchers at the Institut de recherche sur la biologie de l'insecte (CNRS/Université François-Rabelais Tours) are studying these viral particles in detail. In previous work, they had questioned whether the particles were truly viral, as they found that the particle genome lacked the necessary machinery for replication usually found in viruses.
Their most recent findings, published in Science, show that the particles are indeed viral in nature, but that their components lie within the wasp's own genome. More that twenty different genes coding for characteristic components of nudiviruses – insect viruses often used in biological pest control – are expressed in the wasps' ovaries. Furthermore, these genes are conserved in the different kinds of wasp that make these particles.
The results indicate that the ancestor of the braconid wasps integrated the genome of a nudivirus into its own genome. Although these genes continue to produce viral particles, the particles now deliver the wasp's own virulence genes into the parasitized host.
The wasps have therefore “domesticated” a virus to turn it into a vector for transferring their genes. Study of this phenomenon is particularly interesting for the development of new vectors for gene therapy, a therapeutic technique that consists of inserting genes into an individual's cells or tissues to treat an illness. Genes are delivered using a deactivated virus as a vector. The particles from parasite wasps are in fact true “natural” vectors, selected over 100 million years to perform this function and capable of transferring large quantities of genetic material (more than 150 genes). Understanding how they work could therefore be very useful for the design of new therapeutic vectors.
(1) The wasp pierces the caterpillar's skin with a sort of stylet, called an auger. It then lays its eggs inside the body , and the wasp larvae then develop in the caterpillar's blood, on which they feed. Journal reference:
1. Bezier et al. Polydnaviruses of Braconid Wasps Derive from an Ancestral Nudivirus. Science, 2009; 323 (5916): 926 DOI: 10.1126/science.1166788
Ker Than for National Geographic News February 11, 2009
Animals don't need to be fast or strong to lead their flocks, herds, or swarms, only willing—or desperate enough—to break from their neighbors and go their own way, a February 2009 study suggests.
Photograph by Bianca Lavies
They might not win many presidential elections, but mavericks are often leaders among flocks of birds, herds of beasts, and other creatures, a new swarm theory says.
A new computer model suggests animals don't need to be fast or strong to lead their swarms, only willing—or desperate enough—to break from their neighbors and go their own way.
Swarm "leaders are not necessarily the weakest and most vulnerable, but they can be," said study team member Larissa Conradt of University of Sussex in the United Kingdom.
The model suggests that a few very hungry birds in a well-fed flock of thousands can alter the flight path of their entire group simply by veering off to search for food.
Creatures that fly, swim, and run together are hardwired to stay together, Conradt explained.
Swarm living provides protection against predators and a convenient supply of potential mates, so members rarely perform actions that could tear the group apart.
"If some group members are desperate to reach their optimal destination, while others care relatively less whether they reach theirs or not, the desperate ones will lead," said Conradt, whose new research will be detailed in an upcoming issue of the journal American Naturalist.
Biologist David Sumpter studies collective animal behavior at Uppsala University in Sweden and did not participate in the research.
The new study is interesting, Sumpter said, because it shows how "a small number of highly motivated leaders can manipulate the group dynamics significantly for their own purposes but without destroying the cohesive motion of the flock."
Pubic Hair Provides Evolutionary Home For Gorilla Lice
ScienceDaily (Feb. 12, 2009) — There are two species of lice that infest humans: pubic lice, Pthirus pubis, and human head and body lice, Pediculus humanus. A new article suggests one explanation for the separation of the two species.
In the article, Robert Weiss from University College London describes how he was struck by inspiration while pondering the question of why lice would separate into two groups when our ancestors are quite uniformly hairy, "I was having difficulty envisioning a clear separation of habitats between the groin and other parts of our ancient common ancestor. My 'eureka moment' came, appropriately enough, in the shower: although naked apes have pubic hair, surely our hairy cousins don't?"
Pthirus pubis, popularly known as crabs, evolved from the structurally similar gorilla louse, Pthirus gorillae. Interestingly however, while genetic analysis carried out by David Reed at the University of Florida indicates that this split occurred around 3.3 million years ago, humans are believed to have diverged from gorillas much earlier - at least 7 million years ago - suggesting that early humans somehow caught pubic lice from their gorilla cousins. Happily, this may not be as sordid as it sounds.
According to Weiss, "Before one conjures up a King Kong scenario, it should be noted that predators can pick up parasites from their prey. The close contact involved in human ancestors butchering gorillas could have enabled Pthirus to jump hosts, rather as bushmeat slaughter practices allowed HIV to invade humans from chimpanzees in modern times."
So, while head lice may be viewed as a 'family heirloom', inherited down the generations as humans have evolved, pubic lice may well be a recent and slightly unwelcome gift from the more hirsute branch of our evolutionary family.
1. Weiss et al. Apes, lice and prehistory. Journal of Biology, 2009; 8 (2): 20 DOI: 10.1186/jbiol114
New Questions About Evolution Of Hormones In Mammals
ScienceDaily (Feb. 13, 2009) — New techniques used to examine hormones in feces and urine of mammals in the wild are yielding surprising results about hormones and evolution. The new techniques allow scientists to examine the social structure of a broader range of mammals.
San Francisco State Biology Professor Jan Randall will present findings at the AAAS meeting that examine social stress and how they correlate to survival and reproduction in mammals. The recent developments of noninvasive techniques such as tracking mammals to gather feces, and sensitive assays for fecal hormone metabolites, have allowed Randall to formulate a more complete picture of the relationships among behavior, social systems and hormone function in mammals in the wild. "Previously, much of the information we have on hormones came from limited sets of models like lab rats and mice," Randall said. "This non-invasive method is allowing us to ask evolutionary, physiological questions about animals in the wild in completely new ways."
While most of the recent field research has been conducted on rodents, researchers are beginning to conduct field work with whales, predatory animals and other mammals. Randall said it's important to challenge findings discovered in a lab setting. "We see species specific adaptation of control systems so we must rethink our evolutionary models of hormones," she said. "As we discover more in the field, we may discover many more unusual adaptations important for reproduction and survival."
When Randall began post-doc work in the late 1970s, research was confined to drawing hormones from blood or from trapping animals in the wild. Often, those methods yielded hormone samples that were tainted by heightened stress hormones when the animals were handled by researchers. If researchers can identify which specific animal produced the feces, it's possible to gain a better understanding of the effects of social stress and survival. "We need a specific sample and a social context to know what's going on hormonally," Randall said.
To study stress in natural populations, Randall collected feces from the great gerbil, Rhombomys opimus, in Uzbekistan over the course of six years, and the giant kangaroo rat, Dipodomys ingens, in California. The great gerbils are highly social rodents who live in high density communities. Some male gerbils would live with up to six females and their offspring. Randall wanted to know whether the social stress was affecting the male's ability to survive. For six years, Randall and her collaborators collected feces from specific males at various times throughout the year and found that males were stressed in large family groups but that outside factors like drought had a greater influence on survival than stress.
Randall and her graduate student, Julia Barfield, collected fecal samples during the breeding and non-breeding cycles of the giant kangaroo rat. They found significantly higher levels of testosterone in the summer non-breeding season than in the breeding season in both male and female kangaroo rats, which counters previous research conducted in a laboratory setting. Randall said the finding illustrates the flexibility of hormonal control systems and the importance of exploring them in wild populations.
Survival Of The Weakest? Cyclical Competition Of 3 Species Favors Weakest As Victor
ScienceDaily (Feb. 13, 2009) — The extinction of species is a consequence of their inability to adapt to new environmental conditions, and also of their competition with other species. Besides selection and the appearance of new species, the possibility of adaptation is also one of the driving forces behind evolution. According to the interpretation that has been familiar since Darwin, these processes increase the “fitness” of the species overall, since, of two competing species, only the fittest would survive.
LMU researchers have now simulated the progression of a cyclic competition of three species. It means that each participant is superior to one other species, but will be beaten by a third interaction partner. “In this kind of cyclical concurrence, the weakest species proves the winner almost without exception,” reports Professor Erwin Frey, who headed the study. “The two stronger species, on the other hand, die out, as experiments with bacteria have already shown. Our results are not only a big surprise, they are important to our understanding of evolution of ecosystems and the development of new strategies for the protection of species.”
Ecosystems are composed of a large number of different species, which interact and compete with one another for scarce resources. This competition between species in turn affects the probability with which the individual can reproduce and survive – a matter of life and death, as it were. All of these processes are also largely probabilistic and lead to fluctuations that ultimately lead to the extinction of species. We know that up to 50 species become extinct every day on Earth, which at this high rate can be attributed to the influence of man.
Yet, the phenomenon of extinction of species itself cannot be avoided altogether – and is still only barely understood. Theoretical ecologists and biophysicists are therefore intensively researching conditions and mechanisms that affect the biodiversity of Earth. Cyclic dominance is a particularly interesting constellation of species competing with each other. It means that each participant is superior to one other interaction partner, but will be beaten by a third. In ecosystems, this would be three subpopulations – in the simplified model – which dominate in turn. In fact, communities of subpopulations following such rules have been identified in numerous ecosystems, ranging from coral reef invertebrates to lizards in the inner Coast Range of California.
Such cyclical interaction is also familiarly termed “rock-paper-scissors” interaction. This is where the rock blunts the scissors, which cut the paper, which in turn wraps around the rock. Together, these non-hierarchical relationships form a cyclical motion. “The game can help describe the diversity of species,” explains Frey. “The background is a branch of mathematics called game theory, and in this case evolutionary game theory. It helps analyze systems that involve multiple actors whose interactions are similar to those in parlor games.”
Using game theory, one can also study the collective development of populations. In their study, the scientists working with Frey developed elaborate computer simulations in order to calculate the probabilities with which species in cyclical competition will survive. The games started off with three species coexisting in the systems, and ran until two species became extinct – with the third being the only remaining survivors. “What we saw was that in large populations, the weakest species would – with very high probability – come out as the victor,” says Frey.
This “law of the weakest” even held true when the difference between the competing species was slight. “This result was just as unexpected for us,” reports Frey. “But it shows once more that chance plays a big part in the dynamics of an ecosystem. Incidentally, in experiments that were conducted a couple of years ago on bacterial colonies, in order to study cyclical competition, there was one clear result: The weakest of the three species emerged victorious from the competition.”
The project was supported by the cluster of excellence “Nanoinitiative Munich (NIM)”, of which Professor Erwin Frey is a principal investigator.
1. Berr et al. Zero-One Survival Behavior of Cyclically Competing Species. Physical Review Letters, 2009; 102 (4): 048102 DOI: 10.1103/PhysRevLett.102.048102
Grizzlies reveal 'fancy footwork' By Rebecca Morelle Science reporter, BBC News
They may look slow and clumsy, but underwater cameras have revealed that grizzly bears can perform some fancy footwork when a meal is on the cards.
A BBC team followed the bears as the annual salmon migration got underway.
They filmed them using their huge feet to deftly kick dead fish from deep pools into shallower water.
This behaviour, caught on camera for the first time, meant that the grizzlies could grab the fish without the bother of getting their ears wet.
Wildlife cameraman Jeff Turner said: "Most bears will do anything to avoid getting their ears wet - they hate it."
The footage forms part of the new BBC Natural History Unit series Nature's Great Events.
Mr Turner has been filming grizzly bears ( Ursus arctos horribilis ) for the past 20 years in Alaska and Canada.
And the annual salmon migration, where millions of Pacific salmon swim thousands of kilometres to return to the exact patch of river where they were born, provided an opportunity to uncover more about the way the bears hunt.
The cameraman first tried to use remotely operated cameras to capture underwater footage of the grizzlies fishing.
But this proved problematic - the hungry bears kept on biting on the cable.
The team then replaced the thick cable with fine optical fibres, but the difficulties prevailed.
"The water was low and the salmon weren't spending as much time in the shallow parts of the river - they were concentrating on the deeper pools," Mr Turner explained.
"So we moved the equipment there, but the next problem was that the bears were using the camera as a platform - their feet were hanging over the end of the lens and they were knocking the camera over.
"But we were getting these tantalising glimpses of what they were doing in there." “ It is the first time that anyone has really seen what they are doing underwater ” Jeff Turner
Eventually, Mr Turner decided to try a different approach.
He said: "At the end of the day, I just thought rather than rely on this remote technology, the bears seemed to be tolerating us pretty well, so I just stayed in the water and hand-held the camera on the end of the pole and followed them around with it."
Standing just 2m (6ft) away from the bears, Mr Turner was able to record the grizzlies' clever footwork.
Mr Turner said: "The older, more experienced bears would look down and see where the fish was, and then they would kick it along the bottom with their feet until they got it into the shallows.
"And then they could just reach down and pick it up.
"I've seen this before from above the water, and you have a sense of what they are doing, but it is the first time that anyone has really seen what they are doing underwater."
The team also managed to capture another rare sight - baby grizzlies emerging with their mother from their den high up in the Alaskan mountains.
Mr Turner said: "It is something I've been trying to do for over 10 years. It was a real treat to crack it."
Fruit fly (Drosophila melanogaster). (Credit: Image courtesy of Wiley - Blackwell)
ScienceDaily (Feb. 20, 2009) — Mating can be exhausting. When fruit flies mate, the females' genes are activated to roughly the same extent as when an immune reaction starts. This is shown in a study at Uppsala University that is now appearing in the scientific publication Journal of Evolutionary Biology.
Using a combination of behavioral studies and genomic technology, so-called microarrays, researchers at Uppsala University can show how fruit fly females are affected by mating.
"We monitor how genetic expression is impacted by mating and show that the most common process that is affected is the immune defense system," says Ted Morrow at the Department of Ecology and Evolution, Uppsala University.
What's more, the cost of mating turns out to be rather high.
"Previous research findings show that if this cost were not a factor, females would produce 20 percent more offspring,” says Ted Morrow.
It is costly for females to mate because competition among males has led to behaviours and adaptations in males that are injurious to females, such as harassment during mating rituals and toxic proteins in their sperm fluid.
"Our results are the strongest evidence that the cost to females is probably tied to the cost of starting an immune reaction. In other words, the males are like a ‘sickness' to females," says Ted Morrow.
We can thus conclude the following from the study: the immune defence has developed to combat not only pathogens but also substances produced by males. This lends new meaning to the term ‘lovesick.'
1. Innocenti et al. Immunogenic males: a genome-wide analysis of reproduction and the cost of mating in Drosophila melanogaster females. Journal of Evolutionary Biology, 2009; DOI: 10.1111/j.1420-9101.2009.01708.x
Female C. echinata coral, expelling its eggs into the water around it. (Credit: Image courtesy of Tel Aviv University)
ScienceDaily (Feb. 20, 2009) — Trees do it. Bees do it. Even environmentally stressed fish do it. But Prof. Yossi Loya from Tel Aviv University’s Department of Zoology is the first in the world to discover that Japanese sea corals engage in “sex switching” too.
His research may provide the key to the survival of fragile sea corals -- essential to all life in the ocean -- currently threatened by global warming.
In times of stress like extreme hot spells, the female mushroom coral (known as a fungiid coral) switches its sex so that most of the population becomes male. The advantage of doing so, says the world-renowned coral reef researcher, is that male corals can more readily cope with stress when resources are limited. Apparently, when times get tough, nature sends in the boys.
“We believe, as with orchids and some trees, sex change in corals increases their overall fitness, reinforcing the important role of reproductive plasticity in determining their evolutionary success,” says Prof. Loya, whose findings recently appeared in the Proceedings of the Royal Society B.
The Will to Fight and Survive
“One of the evolutionary strategies that some corals use to survive seems to be their ability to change from female to male,” says Prof. Loya. “As males, they can pass through the bad years, then, when circumstances become more favorable, change back to overt females. Being a female takes more energy. And having the ability to change gender periodically enables a species to maximize its reproductive effort.”
Corals, though a part of the animal kingdom, can act like plants. Both are sedentary life forms, unable to move when times get tough.
In stressful environmental conditions, male corals can “ride out the storm,” so to speak, says Prof. Loya. “Males are less expensive -- in the evolutionary sense -- to maintain. They are cheaper in terms of their gonads and the energy needed to maintain their bodies,” he adds.
He also notes that this theory probably doesn’t apply to humans, even those who have opted for a sex change.
While admired for their beauty by divers, coral reefs provide an essential habitat for thousands of species of underwater creatures. Without the reefs, much of the underwater wildlife in reef habitats would perish. And for millions of people in the tropical regions, coral reef sea life is a major source of daily protein. Keeping the Food Chain and Natural Wonders Alive
Coral reef destruction, however, is expected to continue as an effect of global warming. About one-quarter of coral reefs around the world have already been lost. Prof. Loya’s finding may give new insight to scientists into developing coral breeding strategies for the time when the massive climate changes predicted by scientists set in.
“This knowledge can help coral breeders. Fungiid corals are a hardy coral variety which can be grown in captivity. Once you know its mode of reproduction, we can grow hundreds of thousands of them,” says Prof. Loya, currently involved in coral rehabilitation projects in the Red Sea.
Prof. Yossi Loya has been studying coral reefs for over 35 years. He has also won the prestigious Darwin Medal, awarded once every four years by the International Society for Coral Reefs, for a lifetime contribution to the study of coral reefs.
Animals Successfully Relearn Smell Of Kin After Hibernation
Ground squirrels are able to relearn their ability to recognize the smell of their siblings after hibernation, which gives an additional advantage in forming groups for protection. (Credit: Jill Mateo, University of Chicago)
ScienceDaily (Feb. 21, 2009) — Animals can re-establish their use of smell to detect siblings, even following an interruption such as prolonged hibernation, research at the University of Chicago on ground squirrels shows.
Smell is an important animal survival tool. Female ground squirrel sisters, for instance, bond in groups for protection and use smell to recognize each other. Animals also need to recognize siblings to avoid inbreeding, which would have a negative effect on their genetic fitness, said Jill Mateo, Assistant Professor in Comparative Human Development at the University.
The research on how animals recognize kin is vital to helping plan conservation programs for endangered species, Mateo said in the presentation, "Sex and Smells: Kin Recognition, the Armpit Effect and Mate Choice," Friday, Feb. 13 at the annual meeting of the American Association for the Advancement of Science.
"Understanding kin recognition memory systems, or templates, is important to studying habitat selection, food choice, social bonds and mate preferences. It also is important to understand the degree of plasticity in these templates," she explained.
"Knowledge of how long individuals maintain memories of familiar kin and non-kin is important for the design of captive-breeding programs and for the release of endangered species into the wild," she said. The information can help scientists organize groups of animals who would more successfully adapt to a natural environment after they were reintroduced from captivity.
For her study, Mateo live-trapped pregnant Belding's ground squirrels at a research laboratory in California near Yosemite National Park. The squirrels are native to alpine and sub-alpine habitats. After birth, she mixed litters so that pups were raised with their siblings as well as foster pups.
In the spring, at about 25 days of age, 32 juveniles and their mothers were transferred to large outdoor enclosures, where unrelated litters were introduced to serve as potential social partners. Unfamiliar littermates were placed in separate enclosures.
In the fall, the juveniles were taken to a laboratory, where they were placed in cages and began a hibernation period from November to April. Mateo then collected samples of the animals' odors on plastic cubes and tested the animals to determine their interest in smells from their siblings as well as their foster siblings.
"Yearlings investigated odors of their littermates significantly longer than odors of their foster mates, both of which they were reared with as pups," said Mateo, which showed that they had lost the memory of the smell of the foster pups with whom they had been raised. During the previous summer, they had learned and responded to the smells of both their birth and foster siblings.
The findings show that pups lost memories of both smells, but were able to reconnect with the littermates because they compared their smells to their own, a process colloquially called the 'armpit effect.'
The re-established recognition helps siblings successfully compete for survival in their environment, she said.
Mateo received funding for the AAAS presentation from the Animal Behavior Society and University of Chicago's Institute for Mind and Biology.
Cannibalism Among Rattlesnakes Helps Females To Recover After Birth
Rattlesnake in Mexico (Crotalus polystictus). (Credit: Estrella Mociño / SINC)
ScienceDaily (Feb. 22, 2009) — Spanish, American and Mexican researchers have produced the first quantitative description of cannibalism among female rattlesnakes (Crotalus polystictus) after monitoring 190 reptiles. The study has shown that these animals ingest on average 11% of their postpartum mass (in particular eggs and dead offspring) in order to recover energy for subsequent reproduction.
The lack of information about cannibalism in rattlesnakes (Crotalus polystictus) led researchers to start a study in 2004, which they continued for three years in central Mexico, where this species is endemic. They measured "cannibalistic behaviour" among 190 females, which had 239 clutches of eggs, and determined that this phenomenon is justified by "enabling the mother to recover and regain strength".
"A cannibal rattlesnake female can recover lost energy for reproduction without having to hunt for food, a dangerous activity that requires time and expends a great deal of energy," Estrella Mociño and Kirk Setser, lead authors of the study and researchers at the University of Granada, along with Juan Manuel Pleguezuelos, tell SINC.
The study, published in the latest issue of the journal Animal Behaviour, shows that cannibalism in this species is an evolutionary result of its feeding behaviour, since its prey is dead for some time before being eaten by the snake. "Viperids in general are prepared to eat carrion, and for this reason it is not so strange that they consume the non-viable sections of their clutches after going through the great energy expenditure caused by reproduction," says Mociño.
The research team say this behaviour can be explained by four biological factors - the day of the birth (females that give birth at the end of July are more likely to be cannibals, since they have less time to feed and prepare themselves to reproduce again), the proportion of dead babies per clutch, the level of maternal investment (the larger the brood, the greater the chance that it will contain non-viable elements, which she will eat), and stress caused by being in captivity (the researchers maintained the females in captivity for an average of 21 days).
Of all the females, 68% consumed part or all of their dead offspring, and 83% of these ate them all, and waited little time to do so (around 16 hours), although some ate them "immediately after giving birth", adds Mociño. The rest (40%) of the females "did not display cannibalistic behaviour".
According to the scientists, cannibalism is "not an aberrant behaviour, and is not an attack on the progeny", since it is not the same as parricide or infanticide as it does not involve live elements. It simply recovers some of what the snake invested in the reproduction process, and prepares it to reproduce once again.
Snakes can distinguish between dead and live offspring
The scientists showed there was a low risk of the snakes eating healthy offspring, which look very similar to dead ones for the first two hours after emerging from their membranes. During the study, only one female ate live babies.
"In comparison with mammals or birds, snakes are not as maternal, but the study shows that they also display behaviour that has evolved, and that helps the female and her offspring to reproduce and grow successfully," say Mociño and Setser.
Crotalus polystictus is categorised as a "threatened species" according to the Official Mexican Regulations on protection of native species of wild flora and fauna in Mexico. Limited habitat, urban expansion and the growth of agriculture are the main threats to the snake.
To date, the scientists have marked more than 2,000 individuals of this species, which range in length on average from 50cm to 90 cm, and which display different survival strategies from many other rattlesnakes in the north of Mexico and the United States.
This reptile has a very rapid reproduction rate, suggesting that it is experiencing a high death rate caused by external factors. As well as contributing to scientific knowledge about animal cannibalism from an evolutionary perspective, the scientists hope that publicising these results will "lead to human beings being less aggressive towards these snakes".
1. Mocinodeloya et al. Cannibalism of nonviable offspring by postparturient Mexican lance-headed rattlesnakes, Crotalus polystictus. Animal Behaviour, 2009; 77 (1): 145 DOI: 10.1016/j.anbehav.2008.09.020
Tree Lizard’s Quick Release Escape System Makes Jumpers Turn Somersaults
When the green anole drops its tail to escape a predator, it loses agility and mobility. (Credit: Mount Holyoke College)
ScienceDaily (Feb. 23, 2009) — If you've ever tried capturing a lizard, you'll know how difficult it is. But if you do manage to corner one, many have the ultimate emergency quick release system for escape. They simply drop their tails, leaving the twitching body part to distract the predator as they scamper to safety. According to Gary Gillis from Mount Holyoke College, USA, up to 50% of some lizard populations seem to have traded some part of their tails in exchange for escape.
This made Gillis wonder how this loss may impact on a lizard's mobility and ability to survive. Specifically how do branch hopping, tree dwelling lizards cope with their loss. Teaming up with undergraduate student Lauren Bonvini, the pair began encouraging lizard leaps to see how well the reptiles coped without their tails.
Constructing a jumping arena from boxes and fine sandpaper, the duo gently encouraged arboreal Anolis carolinensis (anole) lizards to launch themselves from a 11cm high platform as they filmed the animals' jumps. The animals performed well, launching themselves by pushing off with their back feet and landing gracefully, covering distances ranging from 14.9-29.9 cm.
But how well would the animals perform without their tails? Encouraging the lizards to drop their tails by holding them, just like a hungry predator would, Bonvini then persuaded the tailless reptiles to jump while Gillis filmed them. As soon as the first animal took to the air, Gillis knew something was different. 'It looked weird' says Gillis, 'the animals became blurred as they jumped. I called Lauren over and said "you're not going to believe this"'. Replaying the animal's jump in slow motion, the team could see that the animals were tumbling backwards uncontrollably as their tail stump flailed around. Filming other tailless anoles, three more backflipped out of control, although two others seemed to manage their trajectories better.
Teaming up with Duncan Irschick to analyse the reptiles' leaps, the team could see that everything about the tailless lizards' take off was exactly the same as it had been before they lost the appendage. Things only started to go wrong as they left the jump stage. The lizards began flipping back by more than 30deg; some tumbled so far that they landed on their backs. The team also realised that as the animals took off, they raised the base of their tails as the rest of the appendage trailed along the ground, as if it was somehow stabilising the take off.
'If jumping and landing are important for lizards, they are really compromised,' says Gillis. 'Coordinated landing on a branch is out of the question when spinning backwards,' he adds. Escaping lizards probably pay a significant ecological cost for their life saving quick release system.
So how do the animals use their tails to ensure a safe touch down? Gillis isn't sure whether the lizards push down with their tails at take off to prevent themselves from spinning, or whether the trailing tail passively stabilises the animal's departure. He is also keen to find out more about how the animals adjust to life without their tails, and after they have grown back.
1. Gillis, G.B., Bonvini, L.A. and Irschick, D.J. Losing stability: tail loss and jumping in the arboreal lizard Anolis carolinensis. Journal of Experimental Biology, 2009; 212 (5): 604 DOI: 10.1242/jeb.024349