27
Dec/11

Fish fossil records near extinction events contradicts previous models

by under Ecology, Evolution

The history of evolution is periodically marked by explosions in biodiversity, as groups of species try out a wide range of shapes and sizes. With a new analysis of two such adaptive radiations in the fossil record, researchers have discovered that these diversifications proceeded head-first.

By analyzing the physical features of fossil fish that diversified around the time of two separate extinction events, scientists from the University of Chicago and the University of Oxford found that head features diversified before body shapes and types. The discovery disputes previous models of adaptive radiations and suggests that feeding-related evolutionary pressures are the initial drivers of diversification.

“It seems like resources, feeding and diet are the most important factors at the initial stage,” said lead author Lauren Sallan, graduate student in the Department of Organismal Biology and Anatomy at the University of Chicago. “Strange heads show up first – crushing jaws, animals with big teeth, with long jaws – but they’re all pretty much attached to the same body.”

Two radiations of ray-finned fishes (Actinopterygii), Carboniferous forms (facing left) and acanthomorph teleosts (facing right) underwent distinct cranial (feeding) and later postcranial (habitat) stages in trait diversification. Credit: (Photographs by Lauren Sallan and Matt Friedman).

Adaptive radiations underlie the evolution of dominant and diverse groups. After a major disruption, such as an extinction event, surviving species diversify into a myriad variety of forms. Modern examples of this diversity are the fish family of cichlids, with more than 1,000 documented species, or “Darwin’s finches” of the Galapagos Islands, which exhibit many different beak types.

Evolutionary biologists have used these living species to propose at least two models of how adaptive radiations work. One model proposes a single “burst” of divergence followed by a long period of relative stability. Another, sometimes known as the “general vertebrate model,” introduced the idea of staged divergences, with habitat-driven changes in body type preceding diversification of head types.

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27
Dec/11

Over 65 million years North American mammal evolution

by under Biology, Ecology, Evolution

History often seems to happen in waves – fashion and musical tastes turn over every decade and empires give way to new ones over centuries. A similar pattern characterizes the last 65 million years of natural history in North America, where a novel quantitative analysis has identified six distinct, consecutive waves of mammal species diversity, or “evolutionary faunas.” What force of history determined the destiny of these groupings? The numbers say it was typically climate change.

“Although we’ve always known in a general way that mammals respond to climatic change over time, there has been controversy as to whether this can be demonstrated in a quantitative fashion,” said Brown University evolutionary biology Professor Christine Janis. “We show that the rise and fall of these faunas is indeed correlated with climatic change – the rise or fall of global paleotemperatures – and also influenced by other more local perturbations such as immigration events.”

This painting by artist Carl Buell depcits a scene from the late Eocene of North America. The rhino‑like animals in the background are brontotheres. The pony‑sized Hyracodon, a closer relative of living rhinos, in the foreground. Credit: Courtesy of Carl Buell

Specifically, of the six waves of species diversity that Janis and her Spanish collaborators describe online this week in the Proceedings of the National Academy of Sciences, four show statistically significant correlations with major changes in temperature. The two transitions that show a weaker but still apparent correlation with the pattern correspond to periods when mammals from other continents happened to invade in large numbers, said Janis, who is the paper’s senior and second author.

Previous studies of the potential connection between climate change and mammal species evolution have counted total species diversity in the fossil record over similar time periods. But in this analysis, led by postdoctoral scholar Borja Figueirido, the scientists asked whether there were any patterns within the species diversity that might be significant. They were guided by a similar methodology pioneered in a study of “evolutionary faunas” in (continue reading…)

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27
Dec/11

The first map of protein interactions within neurons, in a live organism

by under Biology, Evolution, Research

Via 7d News, A dive into its inner brain network

University of Miami biology professor Akira Chiba is leading a multidisciplinary team to develop the first systematic survey of protein interactions within brain cells. The team is aiming to reconstruct genome-wide in situ protein-protein interaction networks (isPIN) within the neurons of a multicellular organism. Preliminary data were presented at the American Society for Cell Biology annual meeting, December 3 through 7, 2011, in Denver, Colorado.

At the core of the new imaging technology is the phenomenon known as FRET that occurs only when two fluorescently tagged molecules come within the distance of eight nanometer or less. Detecting the FRET serves as a proxy for the two proteins X and Y associating with each other within a living cell. Credit: Credit: A. Chiba, University of Miami

“This work brings us closer to understanding the mechanics of molecules that keep us functioning,” says Chiba, principal investigator of this project. “Knowing how our cells work will improve medicine. Most importantly, we will gain a better understanding of what life is at the molecular level.”

Neurons are the cells that are mainly responsible for signaling in the brain. Like all other cells, each neuron produces millions of individual proteins that associate with one another and form a complex communication network. Until recently, observing these protein-protein interactions had not been possible due to technical difficulties. Individual proteins are small and typically less than 10 nm (nanometer) in diameter. Yet, this nano-scale distance was considered to be off-limits even with super-resolution microscopy.

Now, Chiba and his collaborators have developed a novel methodology to examine interaction of individual proteins in the fruit fly – the model organism of choice for this project. The researchers are creating genetically engineered insects that are capable of expressing over 500 fluorescently-tagged assorted proteins, two at a time. The fluorescent tags make it possible to visualize the exact spot where a given pair of proteins associates with each other.

The team utilizes a custom- built 3D FLIM (fluorescent lifetime imaging microscopy) system to quantify this association event within the cells of a live animal. FLIM shows the location and time of such protein interaction, (continue reading…)

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27
Dec/11

A fatal combination for Pacific herring

by under Ecology, Oceanology

The 2007 Cosco Busan disaster, which spilled 54,000 gallons of oil into the San Francisco Bay, had an unexpectedly lethal impact on embryonic fish, devastating a commercially and ecologically important species for nearly two years.

The study, to be published the week of Dec. 26 in the early edition of the journal Proceedings of the National Academy of Sciences, suggests that even small oil spills can have a large impact on marine life, and that common chemical analyses of oil spills may be inadequate.

“Our research represents a change in the paradigm for oil spill research and detecting oil spill effects in an urbanized estuary,” said Gary Cherr, director of the UC Davis Bodega Marine Laboratory and a study co-author.

On the foggy morning of Nov. 7, 2007, when the container ship collided with the San Francisco-Oakland Bay Bridge, bunker oil contaminated spawning habitats for the largest U.S. coastal population of Pacific herring—a month before spawning season.

The new study, which analyzed Pacific herring embryos following the spill, highlights the effects of bunker oil on fish embryos in shallow water, the potential significance of sunlight interacting with oil compounds, and the extreme vulnerability of fish in early life stages to spilled oil.

Specifically, the study found that components of Cosco Busan bunker oil accumulated in naturally spawned herring embryos, then interacted with sunlight during low tides to kill the embryos. Laboratory fertilized eggs, caged in deeper waters, were protected from the lethal combination of sunlight and oil, but still showed less severe abnormalities associated with oil exposure.

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25
Dec/11

Parasitic wasps released for the first time in California to protect citrus industry

by under Biology, Ecology

Scientists released a natural enemy of the Asian citrus psyllid (ACP) yesterday on campus to help control the spread of the psyllid, an invasive pest that could devastate the state’s $1.1 billion citrus industry and citrus trees in home landscapes. This is the first time the psyllid’s natural enemy has been released in California.

UC Riverside Executive Vice Chancellor Dallas Rabenstein and Mark Hoddle, the director of the Center for Invasive Species Research, released Tamarixia radiata – tiny, stingless parasitic wasps that lay eggs in ACP nymphs – in a citrus grove near the UCR Botanic Gardens. A total of 281 wasps (95 males and 186 females) were released.

Over the next several years, UCR and California Department of Agriculture Food and Agriculture (CDFA) scientists will raise thousands of Tamarixia for release throughout California. The Tamarixia larvae will eat the ACP nymphs, killing them, and emerge as adults about 12 days later. Adult female Tamarixia also eat other ACP nymphs, killing many in the process.

This is a female Tamarixia radiata, highly magnified. The tiny parasitic wasp lays eggs in Asian citrus psyllid nymphs, eventually killing them. Credit: Mike Lewis, CISR, UC Riverside.

“This release of 281 Tamarixia is the first salvo against ACP in California,” Hoddle said. “We anticipate that over the next year or so thousands of these parasitoids from Pakistan will be released throughout Los Angeles, Riverside and San Bernardino counties and other areas as the pest continues to spread. Once Tamarixia establishes, it will move and find new populations of ACP to attack and kill.”

Hoddle, a biological control specialist in the Department of Entomology, collected colonies of Tamarixia radiata during four trips to the Punjab region of Pakistan during the past 18 months. Christina Hoddle, his wife and an assistant specialist in the department, was an integral part of the field work in Pakistan.

In total, about 1,500 parasitic wasps were brought to Riverside from Pakistan under permit from USDA-Animal and Plant Health Inspection Service. Twelve colonies were quarantined on campus. On Dec. 7, 2011, state and federal authorities cleared Tamarixia from quarantine with the issuance of a permit to release this natural enemy for establishment in California. The parasitic wasps do not bite or sting people or animals. Safety testing in quarantine demonstrated that the parasites are (continue reading…)

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25
Dec/11

Millipede border control

by under Biology, Evolution

Via: 7d News, Millipedes border control

A mysterious line where two millipede species meet has been mapped in northwest Tasmania, Australia. Both species are common in their respective ranges, but the two millipedes cross very little into each other’s territory. The ‘mixing zone’ where they meet is about 230 km long and less than 100 m wide where carefully studied.

The mapping was done over a two-year period by Dr Bob Mesibov, who is a millipede specialist and a research associate at the Queen Victoria Museum and Art Gallery in Launceston, Tasmania. His results have been published in the open access journal ZooKeys.

‘I have no idea why the line is so sharp’, said Dr Mesibov. ‘The boundary runs up and down hills, crosses rivers and different bedrocks and soils, and ignores vegetation type and climate differences. Its position and its sharpness seem to be the result of an unexplained biological arrangement between the two millipede species.’

Tasmaniosoma hickmanorum and Tasmaniosoma compitale, preserved in alchohol. Credit: Bob Mesibov

Biogeographers use the term ‘parapatry’ for the case where two species ranges meet but do not overlap, or overlap very little. Dr Mesibov said that parapatry has been reported before in other species of millipedes and in other terrestrial invertebrate animals, in Tasmania and elsewhere in the world. However, parapatric boundaries often parallel a geographical feature, such as a ridgeline, or a steep rainfall gradient.

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25
Dec/11

UK’s wrapping paper and festive cards could provide energy to send a bus to the moon more than 20 times

by under Ecology, Research

If all the UK’s discarded wrapping paper and Christmas cards were collected and fermented, they could make enough biofuel to run a double-decker bus to the moon and back more than 20 times, according to the researchers behind a new scientific study.

The study, by scientists at Imperial College London, demonstrates that industrial quantities of waste paper could be turned into high grade biofuel, to power motor vehicles, by fermenting the paper using microorganisms. The researchers hope that biofuels made from waste paper could ultimately provide one alternative to fossil fuels like diesel and petrol, in turn reducing the impact of fossil fuels on the environment.

According to some estimates 1.5 billion cards and 83 square kilometres of wrapping paper are thrown away by UK residents over the Christmas period. They currently go to landfill or are recycled in local schemes. This amount of paper could provide 5-12 million litres of biofuel, say the researchers, enough to run a bus for up to 18 million km.

“If one card is assumed to weigh 20g and one square metre of wrapping paper is 10g, then around 38,300 tonnes of extra paper waste will be generated at Christmas (continue reading…)

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17
Dec/11

Ecologists show for the first time threshold values for natural wildfires

by under Ecology, Research

Large forest regions in Canada are apparently about to experience rapid change. Based on models, scientists can now show that there are threshold values for wildfires just like there are for epidemics. Large areas of Canada are apparently approaching this threshold value and may in future exceed it due to climate change. As a result both the area burnt down annually and the average size of the fires would increase, write the researchers of the Helmholtz Centre for Environmental Research (UFZ) and the University of Michigan in the December issue of the journal the American Naturalist. The strategies for combating wildfires in large parts of Canada should therefore be reconsidered.

a forest fire in Canada. Large areas of Canada are apparently approaching this threshold value and may in future exceed it due to climate change. As a result both the area burnt down annually and the average size of the fires would increase, write the researchers of the Helmholtz Centre for Environmental Research (UFZ) and the University of Michigan in the December issue of the journal the American Naturalist. Credit: Photo: skylight/Fotolia

According to media reports, after weeks of drought around 1,000 hectares of forest and scrubland were burnt down in the West Canadian province British Columbia in the summer of 2009 alone. 11,000 people had to be evacuated. Are such events on the rise as a result of climate change? This question is being hotly debated by ecologists all over the world. In July a group of US researchers led by Anthony Westerling of the University of California forecasted similar changes in the journal PNAS. They believe that climate change might result in a dramatic increase in the threat of wildfires in Yellowstone National Park and that the forests might disappear here in the 21st century.

Fires are an important factor in many terrestrial ecosystems. They are a result of the interaction of the weather, vegetation and land use, which makes them very sensitive to global change. “Changes in the wildfire regime have a significant impact on a local and global scale and therefore on the climate as well. It is therefore important to understand how the mechanisms which (continue reading…)

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17
Dec/11

The great barracuda (Sphyraena barracuda)

by under Biology, Evolution, Oceanology

For anglers and boaters who regularly travel the coasts of Florida the great barracuda (Sphyraena barracuda) is a common sight. Surprisingly, however, very little is known about the early life stage of this ecologically and socio-economically important coastal fish.

In the journal Marine Biology, lead author Dr. Evan D’Alessandro and University of Miami Rosenstiel School of Marine & Atmospheric Science colleagues Drs. Su Sponaugle, Joel Llopiz and Robert Cowen shed light on the larval stage of this ocean predator, as well as several other closely related species.

In the journal Marine Biology, lead author Dr. Evan D’Alessandro and University of Miami Rosenstiel School of Marine & Atmospheric Science colleagues Drs. Su Sponaugle, Joel Llopiz and Robert Cowen shed light on the larval stage of barracuda, as well as several other closely related species for the first time. Credit: Evan D'Alessandro

“Due in large part to the expense and difficulty of collecting fish larvae from the open ocean, the larval ecology of barracuda were a mystery until now,” said D’Alessandro. “A research study led by Dr. Robert Cowen, which sampled the Straits of Florida regularly for two years, provided a unique opportunity to catch a glimpse of the larval life of many fishes.”

The study samples included great barracuda (92.8%) and their relatives Sphyraena borealis and Sphyraena picudilla (6.6%), commonly known as sennets.

In their larval stage, which generally lasts several weeks, barracuda and sennets remain in the upper 25 m of the ocean and live on a similar diet. They start out consuming copepods, or (continue reading…)

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12
Dec/11

An unusually hot melting season in 2010 accelerated ice loss in southern Greenland

by under Ecology, Research

That’s the finding from a network of nearly 50 GPS stations planted along the Greenland coast to measure the bedrock’s natural response to the ever-diminishing weight of ice above it.

Every year as the Greenland Ice Sheet melts, the rocky coast rises, explained Michael Bevis, Ohio Eminent Scholar in Geodynamics and professor in the School of Earth Sciences at Ohio State University. Some GPS stations around Greenland routinely detect uplift of 15 mm (0.59 inches) or more, year after year. But a temperature spike in 2010 lifted the bedrock a detectably higher amount over a short five-month period – as high as 20 mm (0.79 inches) in some locations.

In a presentation Friday at the American Geophysical Union meeting in San Francisco, Bevis described the study’s implications for climate change. “Pulses of extra melting and uplift imply that we’ll experience pulses of extra sea level rise,” he said. “The process is not really a steady process.” Because the solid earth is elastic, Bevis and his team can use the natural flexure of the Greenland bedrock to measure the weight of the ice sheet, just like the compression of a spring in a bathroom scale measures the weight of the person standing on it.

Bevis is the principal investigator for the Greenland GPS Network (GNET), and he’s confident that the anomalous 2010 uplift that GNET detected is due to anomalous ice loss during 2010: “Really, there is no other explanation. The uplift anomaly correlates with maps of the 2010 melting day anomaly. In locations where there were many extra days of melting in 2010, the uplift anomaly is highest.” In scientific parlance, a melting day “anomaly” refers to the number of extra melting days – that is, days that were warm enough to melt ice – relative to the average number of melting days per year over several decades.

The 2010 Uplift Anomaly (green arrows), superimposed on a map shows the 2010 Melting Day Anomaly (shaded in red). Credit: Produced by R. Simmon of the NASA Earth Observatory using data provided by M. Tedesco. Courtesy of Ohio State University

In 2010, the southern half of Greenland lost an extra 100 billion tons of ice under conditions that scientists would consider anomalously warm. GNET measurements indicate that as that ice melted away, the bedrock beneath it rose. The amount of uplift differed from station to station, depending on how close the station was to regions where ice loss was greatest.

Southern Greenland stations that were very close to zones of heavy ice loss rose as much as 20 mm (about 0.79 inches) over the five months. Even stations that were located far away (continue reading…)

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