Boy Or Girl? In Lizards, Egg Size Matters

SOURCE

ScienceDaily (June 22, 2009) — Whether baby lizards will turn out to be male or female is a more complicated question than scientists would have ever guessed, according to a new report published online on June 4th in Current Biology. The study shows that for at least one lizard species, egg size matters.

"We were astonished," said Richard Shine of the University of Sydney. "Our studies on small alpine lizards have revealed another influence on lizard sex: the size of the egg. Big eggs tend to give girls, and small eggs tend to give boys. And if you remove some of the yolk just after the egg is laid, it's likely to switch to being a boy, even if it has female sex chromosomes; and if you inject a bit of extra yolk, the egg will produce a girl, even if it has male sex chromosomes."
In many animals, the sex of offspring depends on specialized sex chromosomes. In mammals and many reptiles, for instance, males carry one X and one Y chromosome, while females have a pair of X chromosomes. In contrast, animals such as alligators depend on environmental cues like temperature to set the sex of future generations.
The new findings add to evidence that when it comes to genetic versus environmental factors influencing sex determination, it doesn't have to be an either/or proposition. In fact, Shine and his colleagues earlier found in hatchlings of the alpine-dwelling Bassiana duperreyi that extreme nest temperatures can override the genetically determined sex, in some cases producing XX boys and XY girls. His group had also noticed something else: large lizard eggs were more likely to produce daughters and small eggs to produce sons.
Despite the correlation, Shine said he had assumed that the association was indirect. In fact, his colleague Rajkumar Radder conducted studies in which he removed some yolk from larger eggs, more likely to produce daughters, to confirm that assumption.
"We were confident that there would be no effect on hatchling sex whatsoever," Shine said. "When those baby boy lizards started hatching out, we were gob-smacked."
Shine thinks there will be much more to discover when it comes to lizard sex determination.
"I suspect that the ecology of a species will determine how it makes boys versus girls, and that our yolk-allocation effect is just the tip of a very large iceberg," he said.
The authors include Rajkumar S. Radder, University of Sydney, Australia; David A. Pike, University of Sydney, Australia; Alexander E. Quinn, University of Canberra, Australia; and Richard Shine, University of Sydney, Australia.
Journal reference:
Rajkumar S. Radder, David A. Pike, Alexander E. Quinn, and Richard Shine. Offspring Sex in a Lizard Depends on Egg Size. Current Biology, 2009; DOI: 10.1016/j.cub.2009.05.027
Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Biologist Discovers Pink-winged Moth In Chiracahua Mountains

SOURCE

ScienceDaily (June 12, 2009) — University of Arizona biologist Bruce Walsh has identified a new species of moth in southern Arizona. Normally, this is not a big deal. The region is one of the most biologically rich areas in the country and collectors have been finding hundreds of new species for decades. This one, however, is different.

Walsh is a professor of ecology and evolutionary biology and a member of the UA's BIO5 Institute. He is best known in the science community as an authority on plant and animal breeding, having written one of the leading textbooks on the subject.
His work also spans several departments and programs, including statistics, applied math, insect science and genetics. He also teaching biostatistics in the UA Zuckerman College of Public Health and has worked with trial attorneys on interpreting DNA evidence. Collecting moths is a hobby.
His new discovery is Lithophane leeae. Walsh found it in the Chiracahua mountains east of Tucson, and reported it in the journal Zoo Keys.
Lithophane moths are members of the noctuid family, which often are dull colored. Walsh's moth, in contrast, is bright pink. He also named it after his wife, Lee, who has an affinity for the color.
Walsh discovered L. leeae while collecting one evening at Onion Saddle, at about 7,700 feet in the Chiracahuas. Collecting involves illuminating a sheet with mercury vapor lamps. Moths are attracted by the lights and will land on the sheet.
"This large moth flew in and we didn't think much of it because there is a silk moth very much like it, a Doris silk moth that feeds on pines that has dark wings with pink on the hind wings. It's fairly common there."
On closer inspection, though, the moth, a female, appeared to be an entirely different species from an entirely different family. Walsh said it currently is the only known individual.
Scientists are generally reluctant to identify a new species based on one individual, but L. leeae appears so distinct from others that Walsh said it is highly unlikely that it is an aberration of an existing species. A DNA barcode later confirmed it as a distinct species.
Walsh said he is confident there are bound to be more. "If this thing is flying at the top of the Chiracahuas, it's probably pretty common," he said.
Finding it is another matter because moths like Lithophane tend to over-winter at higher elevations, hibernating when there is snow on the ground and flying off at the first signs of spring. Walsh said bats are the primary predators of moths, and so if the insects can make it through the winter, when bats hibernate, they will likely do well as the weather gets warmer.
As to why L. leeae hasn't been found before, Walsh theorized that his specimen simply emerged late from hibernation when it was caught. Another theory is that it could be a stray from another mountain range in the region. He said there are a number of species that fly early in the summer and are rare in collections and not often seen in most years.
"We can now add L. leeae to this group of large, but quite elusive, species," he said.
Adapted from materials provided by University of Arizona.

Close Social Ties Make Baboons Better Mothers, Study Finds

SOURCE

ScienceDaily (June 11, 2009) — Baboons whose mothers have strong relationships with other females are much more likely to survive to adulthood than baboons reared by less social mothers, according to a new study by researchers at UCLA, the University of Pennsylvania and other institutions.

"If you're a baboon, the strength of your mother's relationship with other females is the best predictor of whether you'll live to have children yourself," said Joan Silk, the study's lead author and a UCLA professor of anthropology. "The study adds to mounting evidence of the biological benefits of close relationships among females."
The findings are significant because "survivorship to reproduction is the gold standard in evolutionary biology," said co-author Dorothy Cheney, a professor of biology at the University of Pennsylvania. "Females who raise offspring to a reproductive age are more likely see their genes pass along, so these findings demonstrate an evolutionary advantage to strong relationships with other females. In evolutionary terms, social moms are the fittest moms — at least when it comes to baboons."
The study appears online in the Proceedings of the Royal Society B, a peer-reviewed journal published by the national academy of science of the United Kingdom and the Commonwealth.
Silk, Cheney and seven other researchers from the University of Pennsylvania, the University of Michigan and the University of St. Andrews in Kenya analyzed 17 years worth of records on more than 66 adult female baboons in the Moremi Game Reserve, a 2,000-square-mile national park in Botswana that teems with wildlife.
Collected on the ground by primatologists who tracked the baboons six days a week, 12 months a year, the records reflected the sex and survival rates of baboon offspring, as well as telling details of the mothers' social lives, including their ranking within the group, as measured by the direction of approach/retreat interactions, and the amount of social interactions they had with each of the group's other females.
In addition to showing how often one animal approached another, the records of social interactions included details of grooming, which is known to be the primary form of social interaction in Old World monkeys. The researchers noted how much time — frequency and duration — the females spent grooming each other and how often they solicited grooming from other females.
Of all the factors studied, the strength of a mother's social bonds with another female had the most significant effect on the survival rates of offspring. A mother's dominance rank proved to have no affect on the survival rate of her offspring.
"We really expected dominance status to be more influential than it proved to be," Silk said.
Offspring from the most social mothers turned out to be about one-and-a-half times more likely to survive to adulthood than offspring from the least social mothers.
The strongest social bonds were measured between mothers and adult daughters, followed by sisters and all other potential relationships, including aunts, nieces, cousins and baboons with no familial ties. Bonds between mothers and adult daughters proved to be three times stronger than those between sisters and 10 times stronger than relationships with other females.
"What really matter to these girls are mother-daughter bonds," Silk said. "They're really strong, and they last forever. If your mom is alive, she's one of your top partners, always. But more importantly, it's the strength of these bonds, because females whose bonds with their mothers and daughters were strong had higher offspring survival than females whose bonds with these relatives were weak."
Silk's past research with Jeanne Altmann, the Eugene Higgins Professor of Ecology and Evolutionary Biology at Princeton University, and Susan C. Alberts, a professor of biology at Duke University, on baboons in the Amboseli Basin of Kenya had found a higher survival rate for baboons with social mothers, but the research only tracked offspring through the first year of life.
For the new study, researchers followed offspring from 1 year of age through sexual maturity — roughly 5 years of age. The new study also differs from past baboon research by focusing on the strength and duration of relationships between pairs of females rather than on the amount of social interactions in general.
"The benefit comes not from being wildly social — it's about having close social bonds," said Cheney, who runs the Moremi baboon-tracking project with University of Pennsylvania psychology professor Robert M. Seyfarth.
"These females form strong relationships with particular partners," Silk said. "They don't treat everyone the same. They spend a lot more time with — and a lot more time grooming — some females than others, and these relationships tend to be very long-lasting."
Additional research is needed to determine how the female bonds improve infant survival, but it may have to do with such stress hormones as cortisol, Silk said. Research has shown that prolonged elevations of stress hormones in primates can lead to cardiovascular disease and other serious health problems. Research has also shown that grooming tends to lower these stress hormones in baboons.
"Our research suggests that somehow there is a link between the kind of social relationships you form and the natural, normal stresses that occur in everyday life, and that seems to have — at least in baboons — a long-term effect on reproductive success," Silk said.
Said to share 92 percent of their DNA with humans, baboons are close relatives of humans. Baboons and humans last shared a common ancestor about 18 million years ago. The new findings on social interactions among mothers parallel recent research that has shown health benefits for humans who enjoy particularly close social networks.
"Our findings suggest benefits from forming close relationships are built into us from a long way back," Silk said.
The research received funding from the National Geographic Foundation, the Research Foundation of the University of Pennsylvania, the Institute for Research in Cognitive Science at the University of Pennsylvania, the National Institute of Health and the National Science Foundation.
Adapted from materials provided by University of California - Los Angeles.

Female Water Striders Expose Their Genitalia Only After Males 'Sing'

SOURCE

ScienceDaily (June 11, 2009) — Chang Seok Han and Piotr Jablonski at Seoul National University, Korea have found that by evolving a morphological shield to protect their genitalia from males' forceful copulatory attempts, females of an Asian species of water strider seem to "win" the evolutionary arms race between the sexes. Instead, females only expose their genitalia for copulation after males produce a courtship "song" by tapping the water surface.

150 years after the publication of Charles Darwin's On the Origin of Species, Han and Jablonski used common insects, water striders, to study the intricacies of evolutionary conflict between males and females. The mechanisms for the way Darwinian natural selection, acting separately on males and females, result in different traits in males than in females (for example, different body sizes to guarantee the highest number of offspring during an individual's lifetime) are already quite well understood.
Sometimes, however, a behavioral trait, such as mating frequency, depends on both the male and the female characteristics. Natural selection favors higher mating frequency in males than in females in many animals, including humans. This leads to an evolutionary "arms race" where males evolve adaptations that force females to mate, while females evolve defenses against males' attempts.
As in the arms races between countries and political powers, it is rare for one sex to "win" in this evolutionary race.
However, in the study by Han and Jablonski, carried out at the Laboratory of Behavioral Ecology and Evolution at Seoul National University, females of an Asian species of water striders, Gerris gracilicornis, do seem to win this race as they have evolved a morphological shield behind which their genitalia are hidden from males, protecting them against the males' forceful attempts to mate.
In an apparent response to the female adaptation, after the violent mounting onto the female's back (typical in water striders), males of this species produce courtship signals by tapping the water surface with their middle legs. It is only after receiving the male's "song" that females expose their genitalia for copulation
Journal reference:
Han et al. Female Genitalia Concealment Promotes Intimate Male Courtship in a Water Strider. PLoS ONE, 2009; 4 (6): e5793 DOI: 10.1371/journal.pone.0005793
Adapted from materials provided by Public Library of Science, via EurekAlert!, a service of AAAS.

New Animal And Plant Species Found In Vietnam

Source:

http://www.sciencedaily.com/releases/2007/09/070925204929.htm

Science Daily — World Wildlife Fund scientists have just announced the discovery of 11 new animal and plant species in a remote area in central Vietnam. They say this underscores the importance of conservation efforts in the ancient tropical forests of the region.

Within the ancient tropical forests of a region known as Vietnam's "Green Corridor," scientists found a snake, five orchids, and two butterflies as well as three other plants new to science and exclusive to the Annamites Mountain Range. Ten other plant species, including four orchids, are still under examination but also appear to be new species.
"Discoveries of so many new species are rare and occur only in very special places like the Green Corridor," said Dr. Chris Dickinson, WWF's chief conservation scientist in the Green Corridor. "Several large mammal species were discovered in the 1990s in the same forests so these latest discoveries may be just the tip of the iceberg."
The rainforests of the Central Annamites likely existed as continuous undisturbed forest cover for thousands of years, and, as a result, offer unique habitats for many species, said WWF experts.
The new snake species, called the white-lipped keelback, prefers living by streams where it catches frogs and other small animals. With a beautiful yellow-white stripe sweeping along its head and red dots covering its body, the white-lipped keelback can reach 31 inches--almost a yard in length.
Three of the new orchid species are entirely leafless, a rarity even among orchids. Containing none of the chlorophyll or green pigment commonly found in plants, these orchids live on decaying matter like many fungal species. The other new plants include an aspidistra which produces a nearly black flower and a newly-discovered species of arum with beautiful yellow flowers. Arum plants have funnel-shaped leaves surrounding the flowers.
The two new butterfly species are among eight discovered in the province since 1996. One is a skipper -- a butterfly with quick, darting flight habits--from the genus Zela and the other is a new genus in the subfamily of Satyrinae.
According to WWF experts, all of these species are at risk from illegal logging, hunting, unsustainable extraction of natural resources and conflicting development interests. However, local authorities -- in particular the Thua Thien Hue Provincial Forest Protection Department -- have committed to conserve and sustainably manage these valuable forests.
"The area is extremely important for conservation and the province wants to protect the forests and their environmental services, as well as contribute to sustainable development," said Hoang Ngoc Khanh, director of Thua Thien Hue Provincial Forest Protection Department.
Stretching from the mountainous forests of the Annamites to one of the last remaining lowland wet evergreen forests, the Green Corridor supports significant populations of threatened species and includes some of the longest remaining stretches of lowland river with intact forest habitat in Vietnam feeding into the Perfume River.
Recent surveys found 15 reptiles and amphibians and six bird species among the threatened species living there. It is also home to one of the world's most endangered primates--white-cheeked crested gibbons--and the best location in Vietnam to save the saola--a unique type of wild cattle just discovered by scientists in 1992.
According to WWF experts, the forests of the Annamites are important water catchments, supplying water for thousands of people who depend on the region's rivers. Local ethnic minority groups earn more than half of their income from the non-timber resources of these same forests. Note: This story has been adapted from a news release issued by World Wildlife Fund.

Fausto Intilla

www.oloscience.com

Birch Trees To Edge Out Aspens In Warming World

Source:

http://www.sciencedaily.com/releases/2007/09/070905151422.htm

Science Daily — Birches will likely drive out many aspens in northern forests as mounting levels of carbon dioxide force the trees to compete more fiercely for soil nutrients in the coming decades, a University of Michigan researcher and his colleagues have concluded.

Carbon dioxide is emitted when fossil fuels are burned, and it's a heat-trapping gas blamed for global warming. But rising carbon dioxide levels also have a fertilizing effect on trees and other plants, making them grow faster than they normally would.
At a 38-acre experimental forest in northeastern Wisconsin, U-M microbial ecologist Donald Zak and his colleagues have been pumping extra carbon dioxide into the tree canopies since 1997 to simulate atmospheric conditions expected in the latter half of this century. The forest contains several thousand trembling aspen, paper birch and sugar maple trees.
Mixed aspen-and-birch stands bathed in extra carbon dioxide grow about 45 percent faster than their untreated neighbors. To sustain that speedy growth, the experimental trees had to find a way to extract more of the essential nutrient nitrogen from the soil.
It appears that the extra carbon dioxide (CO2) helps the trees do just that, by allowing them to grow more roots and "forage" more successfully for nitrogen, said Zak, a professor at the U-M School of Natural Resources and Environment and the Department of Ecology and Evolutionary Biology.
The birch trees seem better at nitrogen foraging than aspens, said Zak, one of the lead scientists at the federally funded experiment in Rhinelander, Wis. In mixed stands of aspen and birch subjected to elevated carbon dioxide levels, birch trees increased recent nitrogen acquisition by 68 percent, compared to a 19 percent increase among the aspens.
"The implication from that experiment is that it could alter the abundance of birch and aspen—in places like Michigan—by favoring birch," Zak said.
In another study being published online in the Proceedings of the National Academy of Sciences, Zak and colleagues at three other experimental forests say current models about how ecosystems will respond to mounting carbon dioxide fail to include their critical recent findings about nitrogen foraging.
Climate researchers and ecosystem modelers assume that in the coming decades, CO2's fertilizing effect will boost the growth rate of northern temperate forests for some unknown period of time. But eventually, current models say, the growth spurt will grind to a halt because the plants won't be able to get the soil nitrogen needed to sustain it.
But in the PNAS paper, Zak and his colleagues say enhanced nitrogen-foraging abilities should allow trees to keep the fast-growth train chugging right along.
And that's significant because forests are important carbon "sinks." They pull carbon dioxide gas out of the air during photosynthesis and lock the carbon away, for a time, in tree tissues.
In doing so, forests could help dampen the heat-trapping effects of rising carbon dioxide -- if they sustain this greater growth and nutrient uptake as they mature. If the period of CO2-enhanced tree growth persists longer than scientists previously believed, then the climate-buffering effects of northern temperate forests could be greater than they'd assumed.
"Some of our initial assumptions about ecosystem response are not correct," Zak said. "Elevated CO2 increases the ability of these forest trees to get limiting nutrients out of the soil. And that's a mechanism that's not in our current conception of how CO2 will affect the way forests work."
The journal of Global Change Biology article was published online August 6. Zak and former U-M researcher William Holmes are authors of both the PNAS and Global Change Biology papers. Other authors of the PNAS article are from Boston University, Oak Ridge National Laboratory, Duke University, the University of Tennessee, the U.S. Forest Service, the College of Charleston, and several European institutions. Other authors of the Global Change Biology paper are from Michigan Technological University, North Carolina State University, and the U.S. Forest Service. Note: This story has been adapted from a news release issued by University Of Michigan.

Fausto Intilla

www.oloscience.com