December 31, 2006, 7:51 PM CT

Ground Spider Diversity

None of Takesha Henderson's discoveries are named Charlotte, but they are weaving a new chapter in Texas entomology. Her graduate studies at Texas A&M University have led to the discovery of 25 new spiders in Brazos County and one species found for the first time in Texas.

In research sponsored by the National Science Foundation, Henderson, who is earning a master's degree, has been studying ground spider diversity, distribution and abundance in the 515-acre Lick Creek Park south of College Station.

She has caught 1,000 specimens in 111 species over two years. The most common were several species of wolf spiders, she said.

A total of 989 species of spiders have been identified in Texas; 280 of these are found in Brazos County.

Henderson set out pitfall traps - made of plastic cups, funnels and animal-safe antifreeze - to collect the spiders. A variety of sites - including upland woods, post oak woodlands and an area disturbed by a high level of human activity - were chosen.

The collected samples are being identified and placed in the Texas A&M Insect Collection, department of entomology.

Dr. Marvin Harris, Texas Agricultural Experiment Station entomologist and chair of Henderson's master's committee, began working with her when she was an undergraduate.........

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December 28, 2006, 8:44 PM CT

Sex Ends As Seasons Shift

A hormone implicated in the onset of human puberty also appears to control reproductive activity in seasonally breeding rodents, report Indiana University Bloomington and University of California at Berkeley researchers in the March 2007 issue of Endocrinology. The paper is now accessible online via the journal's rapid electronic publication service.

The scientists present evidence that kisspeptin, a recently discovered neuropeptide encoded by the KiSS-1 gene, mediates the decline of male Siberian hamsters' libido and reproduction as winter approaches and daylight hours wane.

"Ours isn't the first study to link the peptide to reproduction, but it is the first to connect kisspeptin to how animals interpret seasonal cues, including day length," said IUB biologist Gregory Demas. "Kisspeptin likely plays an integral role in coordinating seasonal reproduction in a wide range of animals."

Kisspeptin joins a select few proteins believed to act as switches that connect environmental changes to a physiological response.

"This peptide is poised to act as an integrator of environmental information to allow for the optimal neuroendocrine control of reproduction in vertebrates, including humans," said UC Berkeley neuroscientist Lance Kriegsfeld. "In humans and other species, if the environment is not satisfactory, sex drive will decline; kisspeptin is likely part of the pathway responsible for this regulation."........

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December 26, 2006, 6:04 PM CT

Biggest Fish Catch In 24 Years

Five tons of marbled Antarctic cod (Notothenia rossii), now that was surely a big surprise to researchers and crew on board of Polarstern, alike considering that prior and subsequent hauls barely ever reaped such plentiful harvests.

Their shimmering silver and dark blue bodies, which can grow up to 70 cm, were piled on the aft deck of the research vessel maintained by the Alfred Wegener Institute for Polar and Marine Research.

In combination with prior stock assessments, fisheries biologists onboard interpreted the catch as a sampling of a discrete, small-scale aggregation of this fish species.

There are two hypotheses to explain the observed dense aggregation: 1. krill, the main prey of marbled Antarctic cod, aggregate to form a band of dense shoals in close vicinity to its preferred habitat; and 2. certain seafloor topographies, such as canyons or cliffs may be conducive to its aggregation. The tendency to shoal made them an easy target for commercial fisheries in the past. After depletion of marbled Antarctic cod stocks the "Convention on the Conservation of Antarctic Marine Living Resources" (CCAMLR) decided to ban fishing activities. Resuming commercial fisheries could easily lead to stocks being overfished. Gera number of, represented by the Federal Research Centre for Fisheries, is constantly providing results to the responsible CCAMLR working group to prevent overexploitation of Antarctica's fish stocks.........

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December 26, 2006, 5:56 PM CT

How Does A Zebrafish Grow A New Tail?

This interesting article I was reading today illustrates how amazingly zebra fish regains its tail after losing one. Apparently a zebrafish tail grows back within a matter of one week. It not only can replace the tail, but also can replace a number of other body parts. Amazing!

A tail fin, for example, has a number of different types of cells and is a very intricate structure. It is the fish version of an arm or leg.

The question of how cold-blooded animals re-grow missing tails and other appendages has fascinated veterinary and medical scientists. They also wonder if people, and other warm-blooded animals that evolved from these simpler creatures, might still have untapped regenerative powers hidden in their genes.

People are constantly renewing blood components, skeletal muscles and skin. We can regenerate liver tissue and repair minor injuries to bone, muscle, the tips of our toes and fingers, and the corneas of our eyes. Finding out more about the remarkable ability of amphibians and fish to re-grow complex parts might provide the information necessary to create therapys for people whose hearts, spinal cords, eyes or arms and legs have been badly hurt.

Researchers have discovered some of the genes and cell-to-cell communication pathways that enable zebrafish to restore their tail fins.........

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December 23, 2006, 10:56 AM CT

Beaked Whales Observed

On the 17th of December, Meike Scheidat & Linn Lehnert, the whale watchers on board of Polarstern, made a remarkable cetaceans sighting: Four Arnoux's Beaked Whales (Berardius arnuxii), observed from the helicopter.

The Arnoux's Beaked Whales is one of the least known species of the Beaked Whales family (Ziphidae), itself poorly known in general. Arnoux's is one of the biggest species amongst beaked whales. The ones observed were probably 9 metre long. These deep-sea feeding whales are especially sensitive to underwater acoustic disturbances. The pictures showed a whole array of scars on their skin, which are already under investigation. Some of these scars could have been inflicted by orcas, their potential predators, or by squids, their most common preys, as proposed by Elaina Jorgensen one of our cephalopod specialist onboard. Other scars could be caused by cookie-cutter sharks, which would imply big migration between the subtropical waters where these sharks are found and the ice-edge (64 degree 06 S) where they were observed.

Supply of German Neumayer station

After crossing the Atlantic and the sea ice of the Atka Bay Polarstern supplied the German research station Neumayer on the Ekstrom Ice Shelf with food and fuel. Helicopters brought up hoses to refill eight 20,000-liter tanks with diesel fuel. The tanks were sitting on sledges ready for later transportation to the station by Caterpillars. The cargo had to be loaded on a secure area on the sea ice as ice conditions did not allow Polarstern to enter the "ice port" right next to the shelf edge.........

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December 23, 2006, 9:00 AM CT

Giraffe: Winning by a neck

Whenever I go to a zoo, I stand in front of the giraffes and watch with awe and respect at these wonderful creatures. I always consider them to be an extreme example of natural selection. I read this article and thought it would be worth mentioning in our blog.

The giraffe's elongated neck has long been used in textbooks as an illustration of evolution by natural selection, but this common example has received very little experimental attention. In the recent issue of the American Naturalist, scientists at the Mammal Research Institute in the Department of Zoology and Entomology at the University of Pretoria tested whether foraging competition with shorter herbivores could explain why giraffes feed mostly on leaves high in trees, despite being able to feed at lower levels as well.

"This [study] provides the first real experimental evidence that the long neck of the giraffe might have evolved as a consequence of competition, which provides support for a previously untested textbook example of natural selection," says Elissa Cameron (University of Pretoria), who coauthored the study with Johan du Toit (University of Pretoria and Utah State University).

Giraffes are well known for their unusual height, and they generally feed high in the tree canopy, above the height other herbivores can reach. Giraffes receive more leaves per bite by foraging high in the tree, but it's unclear whether this is caused by competition -- smaller browsers eating some of the leaves at lower heights -- or if more leaves grow at higher levels.........

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December 20, 2006, 7:01 PM CT

Tadpoles Fly To Puerto Rico

While a number of of New York's snow birds head south to Puerto Rico for time in the sun, a recent batch of first-time fliers--born and raised in the city--are heading down for a different reason: to save their own species. And tadpoles generally do not fly, unless they are part of a reintroduction program to save the Puerto Rican crested toad, as per the Wildlife Conservation Society (WCS), which has joined an ongoing effort to save the island's only native toad.

Specifically, animal husbandry experts from WCS have successfully reared nearly 500 tadpoles at the Central Park Zoo and recently released them in Puerto Rico's Guanica State Forest.

"The release went well, and we're hoping that this new generation of toads can help secure a future for this species" said Bruce Foster, Collections Manager for WCS' Central Park Zoo, where he and other curatorial staff successfully reared some 475 healthy tadpoles for the reintroduction effort. "Puerto Rico is an island of great natural beauty, and protecting the natural inhabitants of the island is an important part of preserving that beauty".

Foster flew down to Puerto Rico with his precious cargo and made the rendezvous with other participants at the release site: a manmade pond in Guanica State Forest. Combined with contributions from the Fort Worth Zoo, the Buffalo Zoo, and the Sedgwick County Zoo, a total of 2,700 tadpoles were released into the pond. The project is also supported by the U.S. Fish and Wildlife Service, and the Puerto Rican Department of Natural Resources.........

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December 20, 2006, 5:09 AM CT

Climate Change And Endangered Naked Carp

Forthcoming in the January/February 2007 issue of Physiological and Biochemical Zoology, a groundbreaking study reveals an unanticipated way freshwater fish may respond to water diversion and climate change. Endangered naked carp migrate annually between freshwater rivers, where they spawn, and a lake in Western China, where they feed and grow. However, Lake Qinghai is drying up and becoming increasingly more saline--leading to surprising adjustments to the carps' metabolic rate.

Naked carp take seven to ten years to reach reproductive size. Eventhough historically abundant, overfishing and destruction of spawning habitat through dam-building caused the species to become endangered during the 1990s. Diversion of water for agriculture from the lake has been compounded by climate change, leading to a decline in water level in the lake of 1012 cm per year during the past fifty years (see accompanying image).

However, Chris M. Wood (McMaster University) and coauthors observed that naked carp respond to the increased salinity of the lake water in a surprising way--by taking a "metabolic holiday." In the first forty-eight hours after transitioning from the freshwater river system to lake water, the carps' oxygen consumption falls --eventually reaching just 60 percent of that in river fish.........

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December 18, 2006, 9:30 PM CT

How To Avoid A Bat

Current understanding of the co-evolution of bats and moths has been thrown into question following new research reported today in Current Biology.

Dr James Windmill from the University of Bristol, UK, has shown how the Yellow Underwing moth changes its sensitivity to a bat's calls when the moth is being chased. And in case there is another attack, the moth's ear remain tuned in for several minutes after the calls stop.

Dr Windmill said: "Because the moth cleverly tunes its ear to enhance its detection of bats, we must now question whether the bat in turn modifies its calls to avoid detection by the moth. In view of the vast diversity of bat calls, this is only to be expected.

"To date, this phenomenon has not been reported for insects or, in fact, for any other hearing system in the animal kingdom. These findings change our understanding of the co-evolution of bats and moths and have implications for the hearing of a number of other animals".

It has been known for over 50 years that moths can hear the ultrasonic hunting calls of their nocturnal predator, the bat. Previously it was thought that these ears were only partially sensitive to the sound frequencies usually used by bats and that bats would make their hunting calls inaudible to moths.........

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December 18, 2006, 9:26 PM CT

Flexibility In Flight Behaviour In Marine Iguanas

Who of us has not dreamt of living on an island? Apparently, island life has certain advantages. This is also true for the marine iguanas. For millions of years they have lived without natural predators. In the course of evolution they have become excessively tame. Hundreds of reptiles doze, spread-eagled, on black lava rocks, soaking up the sun - behaviour that would be unthinkable in an environment with predators, where reptiles are persistently exposed to the threat of being devoured by others.

The absence of predators may lead to adaptations in the behaviour of insular animals. Over a longer evolutionary period, birds for example can lose their ability to fly. This would greatly reduce their ability to escape should new predators appear. In contrast to such "hard wired" traits, however, behavioural patterns should be significantly more flexible. In programmes introducing tame species into the wild, animals are trained to recognise and cope with predators. But in most cases it is very difficult to predict the flexibility in behaviour because little is known about the underlying physiological mechanisms that control behaviour such as flight.

The scientist around Thomas Rodl from the Max Planck Institute for Ornithology visited the Galápagos Islands for field studies from December 2003 until January 2004 and again in March 2005, using the research platform of the Max Planck Society. The islands in the Pacific Ocean continue to be a magnet for evolutionary biologists. Nowhere else is it possible to observe such a variety of different adaptation strategies in such a relatively small number of species. However, it is not only researchers who are drawn to the island; increasingly tourists have also discovered this unique archipelago. In 2005, approx. 126,000 people descended on the island, and the trend is rising. And this causes problems. Not only do tourists disturb the a number of animals living on the Galápagos Islands; they also introduce alien animal and plant species which are causing great damage to local flora and fauna.........

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