In the evolutionary mating game, brawn and stealth rule, scientists find

ScienceDaily (Dec. 27, 2010) — When prowling for a hook up, it's not always the good-looker who gets the girl. In fact, in a certain species of South American fish, brawn and stealth beat out colorful and refined almost every time.

In a series of published studies of a South American species of fish (Poecilia parae), which are closely related to guppies, Syracuse University scientists have discovered how the interplay between male mating strategies and predator behavior has helped preserve the population's distinctive color diversity over the course of time. The third study in the series was published Dec. 23 in BMC Evolutionary Biology, a publication of BioMed Central, London. The studies were supported in part by grants from the National Science Foundation (NSF).

"Poecilia parae are an ideal model for investigating how genetic diversity originates and is maintained within a species," says study author Jorge Luis Hurtado-Gonzales, a Ph.D. candidate in the Department of Biology in SU's College of Arts and Sciences. "The findings may help us better understand how to protect biodiversity in larger ecosystems." Hurtado-Gonzales' co-author is J. Albert C. Uy of the University of Miami.

Like guppies, Poecilia parae sexually reproduce and their offspring are born live. Unlike guppies, in which no two males have exactly the same color patterns, Poecilia parae males come in five, genetically determined colors -- red, yellow, blue, parae (clear with a black stripe), and immaculata (drab gray that mimics the color of immature females). When found in the wild, the abundance of each color group represented in the total population is relatively constant despite the fact that females prefer to mate with the more striking reds and yellows.

"If females prefer red and yellow males, then one would think that red and yellow would dominate and the other colors would phase out over time," Hurtado-Gonzales says. "However, red and yellow are the rarest colors found in the wild."

The most recent study in BMC Evolutionary Biology found that while females prefer reds and yellows they go for the winner of fin-to-fin combat in a significant number of cases. In the study, the larger parae almost always prevailed, thus gaining a mating advantage despite its less-than-desirable coloration. Immaculatas, which are the smallest males, generally shunned the showy displays of violence and were mostly ignored by all but yellow males. The larger yellows almost always defeated immaculatas, stopping them from approaching females.

"In the absence of male-to-male competition, we found that females will almost always choose a red male," Hurtado-Gonzales says. "However, if the red loses a fight, the female will generally seek out the winner. In most cases, that is the larger parae, which is the most dominant male."

Immaculatas compensate for their lack of physical prowess and attractiveness through a mating strategy that relies on stealth. In a 2009 study published in the journal Animal Behavior, Hurtado-Gonzales found that the immaculatas' drab color provides camouflage that enables them to stealthy mate with females while the more colorful red males were wooing them. Females are promiscuous and will mate with multiple males. Additionally, immaculatas have developed larger testes, which produce more sperm, providing a post-mating advantage in the race to fertilize female eggs.

Finally, in a study published earlier this year in the Journal of Evolutionary Biology, produced by the European Society for Evolutionary Biology, Hurtado-Gonzales found that a common predator of Poecilia parae prefers to dine on reds and yellows, most likely because their striking colors make them easier to see. This predatory disadvantage contributes to the lower numbers of reds and yellows in the overall population.

"It seems that within an evolutionary scale, the less attractive males persist in the population over their more attractive counterparts by evolving unique, but likely equally effective mating strategies," Hurtado-Gonzales says. "Therefore, the maintenance of multiple colors may result from the interaction between predator control of attractive males (reds and yellows) and the ability of less attractive males to exploit other areas of sexual selection, including male dominance, sneak behavior, and sperm competition."

A forthcoming study will focus on how blue males gain a mating advantage. Early results indicate that blues exploit habitats in which blue light waves maximize their attractiveness to females and possibly limit their vulnerability to predators.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Syracuse University, via EurekAlert!, a service of AAAS.

Journal Reference:

Jorge L. Hurtado-Gonzales, J. Albert C. Uy. Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish. BMC Evolutionary Biology, 2010; 10: 391 DOI: 10.1186/1471-2148-10-391

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Recycling and depolluting the phosphorus in livestock waste

ScienceDaily (Dec. 6, 2010) — Phosphorus is an ingredient in agricultural and household products such as fertiliser, detergents, etc. When released in excessive quantities to the environment, this mineral contributes to the development of algae and micro-organisms that pollute water, thus impacting on fishing, fish farms, swimming areas and drinking water. At Cemagref, scientists are developing a means to recycle the phosphorus present in animal effluents and limit water pollution. The new process may represent a solution for the future, given the depletion of natural phosphorus and the resulting increase in farm operating costs.

A product of mined phosphate rock  phosphorus is an indispensable element for life. In agriculture, it is used in mineral form to boost the growth of crops and animals. However, if it is incorrectly assimilated or used in excess, large quantities are subsequently released to the environment through erosion and run-off. In areas with intensive crop farming and/or animal production, over 50% of the phosphorus in rivers is the result of such diffuse pollution. A further source is the phosphorus used in detergents that is released in household wastewater. The excessive quantities of this mineral cause eutrophication in rivers and the development of certain bacteria that impact on water quality, thus affecting fishing, fish farms, swimming areas and drinking water.

Recycling in addition to good agricultural practices

To limit these risks, the regulations on spreading of phosphorus-based products now encourage farmers to reduce quantities of fertiliser. But in intensive animal-production zones such as Brittany, the quantities of phosphorus (and nitrogen) produced via animal effluents and available as fertiliser exceed the amounts needed for crops. How can the manure be treated to recover the phosphorus so as to be transportable to other regions, thus limiting pollution levels?

At Cemagref, scientists are developing processes to recycle phosphorus, whether from wastewater-treatment plants or agricultural effluents, so that it can then be used as a direct substitute for phosphate-based mineral fertilisers. A team is paying particular attention to the various types of phosphorus contained in livestock effluents and how they are modified during treatment. Between 60 and 80% of the phosphorus is in the form of mineral particles that settle with the organic matter.

A four-step process

The team has designed a process to separate the phosphorus from the organic matter in the effluents. It comprises four steps, i.e.

1) dissolve the phosphorus using formic acid, thus making it recoverable in the liquid phase,

2) separate the solids from the solution containing the phosphorus,

3) precipitate the solution chemically by adding magnesia to crystallise the phosphorus, and

4) filter the solution to recover the phosphorus in mineral form for use as a fertiliser. The goal is to obtain large crystals which are easier to filter and dry. Process optimisation depends on improving the separation step, prior to precipitation. If the solids are simply decanted, only 50% of the phosphorus can be recycled, but the crystals are large enough to be filtered. Another technique involves adding a polymer and then straining the solution before precipitation, which results in 80% recovery of the phosphorus, but the crystals are small and difficult to filter. The researchers are continuing their efforts to optimise this essential crystallisation step in order to devise the best conditions to produce large crystals and improve recycling efficiency).

Take action prior to the depletion of natural phosphate supplies

On the basis of current knowledge, phosphorus recycling necessarily includes the acid-dissolution step, whose high cost constitutes the main economic obstacle to wider use of this recycling process. The work carried out at Cemagref on these economic aspects, in conjunction with the European university of Brittany, has revealed that recycled fertiliser is not competitive with imported, chemical fertilisers. However, that should change over the coming decades due to the increase in fertiliser prices caused by the progressive depletion of phosphate reserves and the resulting increase in extraction costs. Though estimations diverge on when phosphorus supplies will be depleted, currently exploitable reserves may be gone within the next century.

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Pterygotid sea scorpions: No terror of the ancient seas?

ScienceDaily (Dec. 24, 2010) — Experiments by a team of researchers in New York and New Jersey have generated evidence that questions the common belief that the pterygotid eurypterids ("sea scorpions") were high-level predators in the Paleozoic oceans. This group, which ranged the seas from about 470 to 370 million years ago (long before the dinosaurs appeared), included the largest and, arguably, scariest-looking arthropods known to have evolved on planet Earth.

Reaching lengths of 2 ½ meters with a body supported by well-developed legs, and armed with a pair of forward-facing claws laden with sharp projecting spines, they seem like the Tyrannosaurus rex among the invertebrates.

But in a new study, published in volume 39 of the Bulletin of the Buffalo Society of Natural Sciences, Richard Laub (Buffalo Museum of Science) and his colleagues Victor Tollerton (Research Associate, New York State Museum) and Richard Berkof (Stevens Institute of Technology) show that the mechanical constraints on the claw of the pterygotid sea scorpion Acutiramus made it incapable of penetrating the external shell of a medium-sized horseshoe crab without danger of rupturing.

They suggest that these imposing sea scorpions, and by extension others of their family who lived in the seas about 470 to 370 million years ago, were not necessarily the voracious predators they are commonly believed to have been. The practical operational force that could be safely applied by the claw of Acutiramus without causing damage to it was no more than about 5 Newtons, whereas a force of 8-17 Newtons was required to penetrate the horseshoe crab's armor.

Laub's team also noted that the absence of an 'elbow joint' between the claws and the body of Acutiramus limited claw movement, making them more effective in grasping prey on the sea floor than capturing actively fleeing fish or other swimming animals. Armed with serrated spines, the claws may have been used together to both capture and shred the prey, but the predatory capabilities of Acutiramus would appear to lack the force necessary for this animal to operate as a major predator.

"I have long been suspicious of prevailing popular interpretations" said Dr. Roy Plotnick, Department of Earth and Environmental Sciences at the University of Illinois at Chicago, who was not involved in the study. "This is a welcome contribution that strongly supports an alternative interpretation of claw function" he said.

"Our results derail the image of these imposing-looking animals, the largest arthropods yet known to have existed, as fearsome predators, or at least as predators of other eurypterids and of the armored fishes of the time" said team leader Richard Laub, who noted that "it opens the possibility that they were scavengers or even vegetarians."

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Journal Reference:

Laub, R.S., Tollerton, Jr. V.P. and Berkof, R.S. The cheliceral claw of Acutiramus (Arthropoda: Eurypterida): Functional analysis based on morphology and engineering principles. Bulletin of the Buffalo Society of Natural Sciences, 2010; 39: 29

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New evidence for eye-protective effects of omega-3-rich fish, shellfish

ScienceDaily (Dec. 1, 2010) — Researchers at Wilmer Eye Institute, Johns Hopkins School of Medicine, wanted to know how the risk of age-related macular degeneration (AMD) would be affected in a population of older people who regularly ate fish and seafood, since some varieties are good sources of omega-3 fatty acids. A diet rich in omega-3s probably protects against advanced AMD, the leading cause of blindness in whites in the United States, according to the Age-Related Eye Disease Study (AREDS) and other recent studies. High concentrations of omega-3s have been found in the eye's retina, and evidence is mounting that the nutrient may be essential to eye health.

The new research, led by Sheila K. West, PhD, was part of the Salisbury Eye Evaluation (SEE) study.

Food intake information with details on fish and shellfish consumed was collected over one year using a validated questionnaire for 2,391 participants aged 65 to 84 years who lived along Maryland's Eastern Shore. After dietary assessment was complete, participants were evaluated for AMD. Those with no AMD were classified as controls (1,942 persons), 227 had early AMD, 153 had intermediate-stage disease, and 68 had advanced AMD. In the advanced AMD group, the macular area of the retina exhibited either neovascularization (abnormal blood vessel growth and bleeding) or a condition called geographic atrophy. Both conditions can result in blindness or severe vision loss.

"Our study corroborates earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD." Dr. West said. "While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD were significantly less likely to consume high omega-3 fish and seafood," she said.

The study also looked at whether dietary zinc from crab and oyster consumption impacted advanced AMD risk, but no significant relationship was found. Zinc is also considered protective against AMD and is included in an AMD-vitamin/nutrient supplement developed from the AREDS study. Dr. West speculated that her study found no effect because the levels of zinc obtained from seafood/fish were low compared to supplement levels.

A side note: fish and shellfish were part of the normal diet of the study population, rather than added with the intention of improving health. The links between fish consumption, omega-3s and healthy lifestyles were not widely known in the early 1990s when the dietary survey was conducted. In fact, some of the study participants who consumed the most seafood were also smokers and/or overweight, two factors usually associated with AMD and other health risks.

The research is published in the December issue of Ophthalmology, the journal of the American Academy of Ophthalmology.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Academy of Ophthalmology, via EurekAlert!, a service of AAAS.

Journal Reference:

Bonnielin K. Swenor, Susan Bressler, Laura Caulfield, Sheila K. West. The Impact of Fish and Shellfish Consumption on Age-Related Macular Degeneration. Ophthalmology, 2010; DOI: 10.1016/j.ophtha.2010.03.058

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'No fish left behind' approach leaves Earth with nowhere left to fish, study finds

ScienceDaily (Dec. 3, 2010) — Earth has run out of room to expand fisheries, according to a new study led by University of British Columbia researchers that charts the systematic expansion of industrialized fisheries.

In collaboration with the National Geographic Society and published in the online journal PLoS ONE, the study is the first to measure the spatial expansion of global fisheries. It reveals that fisheries expanded at a rate of one million sq. kilometres per year from the 1950s to the end of the 1970s. The rate of expansion more than tripled in the 1980s and early 1990s -- to roughly the size of Brazil's Amazon rain forest every year.

Between 1950 and 2005, the spatial expansion of fisheries started from the coastal waters off the North Atlantic and Northwest Pacific, reached into the high seas and southward into the Southern Hemisphere at a rate of almost one degree latitude per year. It was accompanied by a nearly five-fold increase in catch, from 19 million tonnes in 1950, to a peak of 90 million tonnes in the late 1980s, and dropping to 87 million tonnes in 2005, according to the study.

"The decline of spatial expansion since the mid-1990s is not a reflection of successful conservation efforts but rather an indication that we've simply run out of room to expand fisheries," says Wilf Swartz, a PhD student at UBC Fisheries Centre and lead author of the study.

Meanwhile, less than 0.1 per cent of the world's oceans are designated as marine reserves that are closed to fishing.

"If people in Japan, Europe, and North America find themselves wondering how the markets are still filled with seafood, it's in part because spatial expansion and trade makes up for overfishing and 'fishing down the food chain' in local waters," says Swartz.

"While many people still view fisheries as a romantic, localized activity pursued by rugged individuals, the reality is that for decades now, numerous fisheries are corporate operations that take a mostly no-fish-left-behind approach to our oceans until there's nowhere left to go," says Daniel Pauly, co-author and principal investigator of the Sea Around Us Project at UBC Fisheries Centre.

The researchers used a newly created measurement for the ecological footprint of fisheries that allows them to determine the combined impact of all marine fisheries and their rate of expansion. Known as SeafoodPrint, it quantifies the amount of "primary production" -- the microscopic organisms and plants at the bottom of the marine food chain -- required to produce any given amount of fish.

"This method allows us to truly gauge the impact of catching all types of fish, from large predators such as bluefin tuna to small fish such as sardines and anchovies," says Pauly. "Because not all fish are created equal and neither is their impact on the sustainability of our ocean."

"The era of great expansion has come to an end, and maintaining the current supply of wild fish sustainably is not possible," says co-author and National Geographic Ocean Fellow Enric Sala. "The sooner we come to grips with it -- similar to how society has recognized the effects of climate change -- the sooner we can stop the downward spiral by creating stricter fisheries regulations and more marine reserves."

The University of British Columbia Fisheries Centre, in the College for Interdisciplinary Studies, undertakes research to restore fisheries, conserve aquatic life and rebuild ecosystems. It promotes multidisciplinary study of aquatic ecosystems and broad-based collaboration with maritime communities, government, NGOs and other partners. The UBC Fisheries Centre is recognized globally for its innovative and enterprising research, with its academics winning many accolades and awards. The Sea Around Us Project is funded in part by the Pew Environment Group. For more information, visit www.fisheries.ubc.ca and www.cfis.ubc.ca.

The National Geographic Society, the Waitt Foundation, the SEAlliance along with strategic government, private, academic and conservation partners including the TEDPrize, Google and IUCN, are beginning an action-oriented marine conservation initiative under the banner of "Mission Blue" that will increase global awareness of the urgent ocean crisis and help to reverse the decline in ocean health by inspiring people to care and act; reducing the impact of fishing; and promoting the creation of marine protected areas. For more information, go to www.iamtheocean.org.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of British Columbia, via EurekAlert!, a service of AAAS.

Journal Reference:

Wilf Swartz, Enric Sala, Sean Tracey, Reg Watson, Daniel Pauly. The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present). PLoS ONE, 2010; 5 (12): e15143 DOI: 10.1371/journal.pone.0015143

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Link between ancient lizard fossil in Africa and today's Komodo dragon in Indonesia

ScienceDaily (Dec. 30, 2010) — University of Alberta researchers have unearthed a mysterious link between bones of an ancient lizard found in Africa and the biggest, baddest modern-day lizard of them all, the Komodo dragon, half a world away in Indonesia.

Biologists Alison Murray and Rob Holmes say the unique shape of the vertebrae links the 33-million-year-old African lizard fossil with its cousin the Komodo, which has only been around for some 700,000 years.

"The African fossil was found on the surface of a windswept desert," said Holmes. "It's definitely from the lizard genus Varanus and there are more than 50 species alive today, including Komodos and other large lizards."

Holmes says the telltale African vertebrae fossils belonged to a lizard that was about a metre- and-a-half long whose ability to swim may be key to figuring out how more than 30 million years later its ancestors turned up on the other side of the world.

Holmes says the ancient African Varanus specimen was found on land that was once the bottom of a river or small lake. "Whether the animals lived in the water or surrounding land, we don't know, but we do know that some modern day species of Varanus are comfortable swimming in fresh water."

The researchers agree that fresh-water swimming wouldn't get the African lizard all the way to Indonesia. Murray says the mystery of how the animals spread deepens when you consider ancient world geography. "From about 100 million years ago until 12 million years ago, Africa was completely isolated, surrounded by ocean, but somehow they got out of Africa during that period," said Murray. "That's why this paper is important because there was no known land connection."

Murray says one unproven theory of how Varanus moved out of Africa is that over millions of years, small land masses or micro-plates may have moved from one place to another, carrying their fauna with them.

The work of the U of A researchers and various co-authors runs counter to some prevailing theories about the origins of some ancient fossil types found in Africa including Varanus lizards and some fresh-water fish. "The assumption for several types of ancient African fossils is that the animals didn't originate in Africa but came there from Asia," says Holmes. "But the fossil record of Varanus shows exactly the opposite path of migration."

The work of Murray and Holmes and various co-authors was published in the journal Palaeontology.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Alberta, via EurekAlert!, a service of AAAS.

Journal Reference:

Robert B. Holmes, Alison M. Murray, Yousry S. Attia, Elwyn L. Simons, Prithijit Chatrath. Oldest known Varanus (Squamata: Varanidae) from the Upper Eocene and Lower Oligocene of Egypt: support for an African origin of the genus. Palaeontology, 2010; 53 (5): 1099 DOI: 10.1111/j.1475-4983.2010.00994.x

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Pancreas disease transmits horizontally during the seawater phase

ScienceDaily (Dec. 29, 2010) — Researchers and the salmon industry have been debating whether fingerling (young fish) from freshwater farms can be a source of the virus that causes pancreas disease (PD): salmonid alfavirus (SAV). The results of a new doctoral study show that this is not the case: pancreas disease transmits horizontally in the seawater phase and infection in fresh water has little bearing on how the disease spreads.

During her doctoral research, Mona Dverdal Jansen has followed the progression of pancreas disease (PD) in Norwegian farmed salmon from the fresh water phase and throughout the entire seawater phase. The research involved testing 46 different fish populations of farmed salmon from 6 counties for SAV in the fresh water phase, before the fish were released into seawater. SAV was not found to occur in any of these populations.

The 46 salmon populations were transferred to 51 seawater locations, where they were tested for SAV three times during the production phase, including when they were slaughtered. 36 of the 51 locations were situated within the infected zone and 23 (64%) of these 36 were shown to be affected by the SAV virus during the seawater phase. The fish populations were infected during the entire seawater phase, and the risk of infection increased, the longer the fish were in the seawater.

With the exception of three populations, where SAV was detected when the salmon were slaughtered, all the infected populations developed PD. In contrast, no SAV was detected during the production phase amongst the populations released into the 15 uncontaminated seawater locations.

Jansen investigated a number of potential risk factors for infection, but the only factor shown to have any significance was the location within the infected zone. These findings confirm earlier discoveries: that PD infects horizontally from population to population in the seawater phase and that the fresh water phase is insignificant as a source of SAV.

Furthermore, Jansen's thesis describes how, once a population is infected, it remains infected until the time of slaughter. She observed a very varying time lapse between the detection of the SAV virus and the outbreak of PD in some populations. In addition, she found that mortality rates resulting from PD also varied greatly from population to population. She found no signs that the SAV virus was reactivated when the fish were stripped in the one broodstock population she examined.

Dying and thin fish had a higher risk of testing positive in one or more of the diagnostic trials, compared to apparently healthy fish from the same population. This indicates that current routines for taking samples and studying the disease, where dying and clinically abnormal fish are given priority, ought to be continued. The degree of observed conformity between the diagnostic tests employed varied according to which stage of the disease the fish were in.

Jansen carried out genetic analyses of SAV sequences. All belonged to SAV subtype 3 -- the only subtype identified in Norway so far. The sequence variation was found to be somewhat larger than previously reported in the case of one of the genetic fragments studied.

A model based on a stochastic scenario tree indicated that there was an extremely high probability that SAV infection would be absent within the uncontaminated area in the model year of 2007, and this tallied with the results of the field studies.

Jansen carried out her research at the Centre for Epidemiology and Biostatistics at The Norwegian School of Veterinary Science (NVH) and at The National Veterinary Institute from 2006-2010.

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