Blog Archives

Reshaping the horse through millennia: Sequencing reveals genes selected by humans in domestication

Whole genome sequencing of modern and ancient horses unveils the genes that have been selected by humans in the process of domestication through the latest 5,500 years, but also reveals the cost of this domestication. A new study led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from 11 international universities, reports that a significant part of the genetic variation in modern domesticated horses could be attributed to interbreeding with the descendants of a now extinct population of wild horses. This population was distinct from the only surviving wild horse population, that of the Przewalski’s horses. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

The domestication of the horse some 5,500 years ago ultimately revolutionized human civilization and societies. Horses facilitated transportation as well as the circulation of ideas, languages and religions. Horses also revolutionized warfare with the advent of chariotry and mounted cavalry and beyond the battlefield horses greatly stimulated agriculture. However, the domestication of the horse and the subsequent encroachment of human civilization also resulted in the near extinction of wild horses.

The only surviving wild horse population, the Przewalski’s horses from Mongolia, descends from mere 13 individuals, preserved only through a massive conservation effort. As a consequence of this massive loss of genetic diversity, the effects of horse domestication through times have been difficult to unravel on a molecular level. Says Dr. Ludovic Orlando, Associate Professor at the Centre for GeoGenetics, who led this work

“The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates. This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically.”

Recent advances in ancient DNA research have opened the door for reconstructing the genomes of ancient individuals. In 2013, Ludovic Orlando and his team succeeded in decoding the genome of a ~700,000 year-old horse, which represents the oldest genome sequenced to date. This time, the researchers focused on much more recent horse specimens, dating from ~16,000 and ~43,000 years ago. These were carefully selected to unambiguously predate the beginning of domestication, some 5,500 years ago. The bone fossils were excavated in the Taymyr Peninsula, Russia, where arctic conditions favor the preservation of DNA.

The human reshaping of the horse

While the horse contributed to reshaping human civilization, humans in turn reshaped the horse to fit their diverse needs and the diverse environments they lived in. This transformation left specific signatures in the genomes of modern horses, which the ancient genomes helped reveal. The scientists were able to detect a set of 125 candidate genes involved in a wide range of physical and behavioral traits, by comparing the genomes of the two ancient horses with those of the Przewalski’s horse and five breeds of domesticated horses. Says Dr. Dan Chang, post-doctoral researcher at the UCSC Paleogenomics Lab and co-leading author of the study:

“Our selection scans identified genes that were already known to evolve under strong selection in horses. This provided a nice validation of our approach.”

Dr. Beth Shapiro, head of the UCSC Paleogenomics Lab continues: “We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses. This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation.”

And Dr. Ludovic Orlando from the Centre for GeoGenetics at the University of Copenhagen concludes: “Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms.”

The ‘cost of domestication’ in horses

However, the reshaping of the horse genome during their domestication also had significant negative impacts. This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses. This finding supports an earlier theory coined ‘the cost of domestication’, which predicted increasing genetic loads in domesticates compared to their wild ancestors. Says Professor Laurent Excoffier, University of Bern and group leader at the Swiss Institute for Bioinformatics:

“Domestication is generally associated with repeated demographic crashes. Yet, mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small. Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. This had already been shown for rice and dogs. Horses now provide another example of this phenomenon.”

This is something that was only detectable in the horse in comparison to the ancient genomes, as Przewalski’s horses were found to show a proportion of deleterious mutations similar to domesticated horses. Says Hákon Jónsson, PhD-student at the Centre for GeoGenetics, co-leading author of the study: “The recent near extinction of the Przewalski’s horse population resulted in the persistence of deleterious mutations in the population, following the same mechanism that once led to the accumulation of deleterious mutations in the genomes of domesticated horses. What is striking is that a similar order of magnitude was reached even though this occurred in a much shorter time scale than domestication.”

An ancient contribution to the present

In addition, comparison of the ancient and modern genomes revealed that the ancient individuals contributed a significant amount of genetic variation to the modern population of domesticated horses, but not to the Przewalski’s horses. This suggests that restocking from a wild population descendant from the ancient horses occurred during the domestication processes that ultimately led to the modern domesticated horses. Mikkel Schubert, PhD- student at the Centre for GeoGenetics, co-leading author of the study concludes:

“This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process. However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population. That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses.”

Agriculture and Food News — ScienceDaily

Reshaping the horse through millennia: Sequencing reveals genes selected by humans in domestication

Whole genome sequencing of modern and ancient horses unveils the genes that have been selected by humans in the process of domestication through the latest 5,500 years, but also reveals the cost of this domestication. A new study led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from 11 international universities, reports that a significant part of the genetic variation in modern domesticated horses could be attributed to interbreeding with the descendants of a now extinct population of wild horses. This population was distinct from the only surviving wild horse population, that of the Przewalski’s horses. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

The domestication of the horse some 5,500 years ago ultimately revolutionized human civilization and societies. Horses facilitated transportation as well as the circulation of ideas, languages and religions. Horses also revolutionized warfare with the advent of chariotry and mounted cavalry and beyond the battlefield horses greatly stimulated agriculture. However, the domestication of the horse and the subsequent encroachment of human civilization also resulted in the near extinction of wild horses.

The only surviving wild horse population, the Przewalski’s horses from Mongolia, descends from mere 13 individuals, preserved only through a massive conservation effort. As a consequence of this massive loss of genetic diversity, the effects of horse domestication through times have been difficult to unravel on a molecular level. Says Dr. Ludovic Orlando, Associate Professor at the Centre for GeoGenetics, who led this work

“The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates. This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically.”

Recent advances in ancient DNA research have opened the door for reconstructing the genomes of ancient individuals. In 2013, Ludovic Orlando and his team succeeded in decoding the genome of a ~700,000 year-old horse, which represents the oldest genome sequenced to date. This time, the researchers focused on much more recent horse specimens, dating from ~16,000 and ~43,000 years ago. These were carefully selected to unambiguously predate the beginning of domestication, some 5,500 years ago. The bone fossils were excavated in the Taymyr Peninsula, Russia, where arctic conditions favor the preservation of DNA.

The human reshaping of the horse

While the horse contributed to reshaping human civilization, humans in turn reshaped the horse to fit their diverse needs and the diverse environments they lived in. This transformation left specific signatures in the genomes of modern horses, which the ancient genomes helped reveal. The scientists were able to detect a set of 125 candidate genes involved in a wide range of physical and behavioral traits, by comparing the genomes of the two ancient horses with those of the Przewalski’s horse and five breeds of domesticated horses. Says Dr. Dan Chang, post-doctoral researcher at the UCSC Paleogenomics Lab and co-leading author of the study:

“Our selection scans identified genes that were already known to evolve under strong selection in horses. This provided a nice validation of our approach.”

Dr. Beth Shapiro, head of the UCSC Paleogenomics Lab continues: “We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses. This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation.”

And Dr. Ludovic Orlando from the Centre for GeoGenetics at the University of Copenhagen concludes: “Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms.”

The ‘cost of domestication’ in horses

However, the reshaping of the horse genome during their domestication also had significant negative impacts. This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses. This finding supports an earlier theory coined ‘the cost of domestication’, which predicted increasing genetic loads in domesticates compared to their wild ancestors. Says Professor Laurent Excoffier, University of Bern and group leader at the Swiss Institute for Bioinformatics:

“Domestication is generally associated with repeated demographic crashes. Yet, mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small. Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. This had already been shown for rice and dogs. Horses now provide another example of this phenomenon.”

This is something that was only detectable in the horse in comparison to the ancient genomes, as Przewalski’s horses were found to show a proportion of deleterious mutations similar to domesticated horses. Says Hákon Jónsson, PhD-student at the Centre for GeoGenetics, co-leading author of the study: “The recent near extinction of the Przewalski’s horse population resulted in the persistence of deleterious mutations in the population, following the same mechanism that once led to the accumulation of deleterious mutations in the genomes of domesticated horses. What is striking is that a similar order of magnitude was reached even though this occurred in a much shorter time scale than domestication.”

An ancient contribution to the present

In addition, comparison of the ancient and modern genomes revealed that the ancient individuals contributed a significant amount of genetic variation to the modern population of domesticated horses, but not to the Przewalski’s horses. This suggests that restocking from a wild population descendant from the ancient horses occurred during the domestication processes that ultimately led to the modern domesticated horses. Mikkel Schubert, PhD- student at the Centre for GeoGenetics, co-leading author of the study concludes:

“This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process. However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population. That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses.”

Agriculture and Food News — ScienceDaily

Reshaping the horse through millennia: Sequencing reveals genes selected by humans in domestication

Whole genome sequencing of modern and ancient horses unveils the genes that have been selected by humans in the process of domestication through the latest 5,500 years, but also reveals the cost of this domestication. A new study led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from 11 international universities, reports that a significant part of the genetic variation in modern domesticated horses could be attributed to interbreeding with the descendants of a now extinct population of wild horses. This population was distinct from the only surviving wild horse population, that of the Przewalski’s horses. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

The domestication of the horse some 5,500 years ago ultimately revolutionized human civilization and societies. Horses facilitated transportation as well as the circulation of ideas, languages and religions. Horses also revolutionized warfare with the advent of chariotry and mounted cavalry and beyond the battlefield horses greatly stimulated agriculture. However, the domestication of the horse and the subsequent encroachment of human civilization also resulted in the near extinction of wild horses.

The only surviving wild horse population, the Przewalski’s horses from Mongolia, descends from mere 13 individuals, preserved only through a massive conservation effort. As a consequence of this massive loss of genetic diversity, the effects of horse domestication through times have been difficult to unravel on a molecular level. Says Dr. Ludovic Orlando, Associate Professor at the Centre for GeoGenetics, who led this work

“The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates. This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically.”

Recent advances in ancient DNA research have opened the door for reconstructing the genomes of ancient individuals. In 2013, Ludovic Orlando and his team succeeded in decoding the genome of a ~700,000 year-old horse, which represents the oldest genome sequenced to date. This time, the researchers focused on much more recent horse specimens, dating from ~16,000 and ~43,000 years ago. These were carefully selected to unambiguously predate the beginning of domestication, some 5,500 years ago. The bone fossils were excavated in the Taymyr Peninsula, Russia, where arctic conditions favor the preservation of DNA.

The human reshaping of the horse

While the horse contributed to reshaping human civilization, humans in turn reshaped the horse to fit their diverse needs and the diverse environments they lived in. This transformation left specific signatures in the genomes of modern horses, which the ancient genomes helped reveal. The scientists were able to detect a set of 125 candidate genes involved in a wide range of physical and behavioral traits, by comparing the genomes of the two ancient horses with those of the Przewalski’s horse and five breeds of domesticated horses. Says Dr. Dan Chang, post-doctoral researcher at the UCSC Paleogenomics Lab and co-leading author of the study:

“Our selection scans identified genes that were already known to evolve under strong selection in horses. This provided a nice validation of our approach.”

Dr. Beth Shapiro, head of the UCSC Paleogenomics Lab continues: “We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses. This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation.”

And Dr. Ludovic Orlando from the Centre for GeoGenetics at the University of Copenhagen concludes: “Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms.”

The ‘cost of domestication’ in horses

However, the reshaping of the horse genome during their domestication also had significant negative impacts. This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses. This finding supports an earlier theory coined ‘the cost of domestication’, which predicted increasing genetic loads in domesticates compared to their wild ancestors. Says Professor Laurent Excoffier, University of Bern and group leader at the Swiss Institute for Bioinformatics:

“Domestication is generally associated with repeated demographic crashes. Yet, mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small. Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. This had already been shown for rice and dogs. Horses now provide another example of this phenomenon.”

This is something that was only detectable in the horse in comparison to the ancient genomes, as Przewalski’s horses were found to show a proportion of deleterious mutations similar to domesticated horses. Says Hákon Jónsson, PhD-student at the Centre for GeoGenetics, co-leading author of the study: “The recent near extinction of the Przewalski’s horse population resulted in the persistence of deleterious mutations in the population, following the same mechanism that once led to the accumulation of deleterious mutations in the genomes of domesticated horses. What is striking is that a similar order of magnitude was reached even though this occurred in a much shorter time scale than domestication.”

An ancient contribution to the present

In addition, comparison of the ancient and modern genomes revealed that the ancient individuals contributed a significant amount of genetic variation to the modern population of domesticated horses, but not to the Przewalski’s horses. This suggests that restocking from a wild population descendant from the ancient horses occurred during the domestication processes that ultimately led to the modern domesticated horses. Mikkel Schubert, PhD- student at the Centre for GeoGenetics, co-leading author of the study concludes:

“This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process. However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population. That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses.”

Agriculture and Food News — ScienceDaily

Reshaping the horse through millennia: Sequencing reveals genes selected by humans in domestication

Whole genome sequencing of modern and ancient horses unveils the genes that have been selected by humans in the process of domestication through the latest 5,500 years, but also reveals the cost of this domestication. A new study led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from 11 international universities, reports that a significant part of the genetic variation in modern domesticated horses could be attributed to interbreeding with the descendants of a now extinct population of wild horses. This population was distinct from the only surviving wild horse population, that of the Przewalski’s horses. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

The domestication of the horse some 5,500 years ago ultimately revolutionized human civilization and societies. Horses facilitated transportation as well as the circulation of ideas, languages and religions. Horses also revolutionized warfare with the advent of chariotry and mounted cavalry and beyond the battlefield horses greatly stimulated agriculture. However, the domestication of the horse and the subsequent encroachment of human civilization also resulted in the near extinction of wild horses.

The only surviving wild horse population, the Przewalski’s horses from Mongolia, descends from mere 13 individuals, preserved only through a massive conservation effort. As a consequence of this massive loss of genetic diversity, the effects of horse domestication through times have been difficult to unravel on a molecular level. Says Dr. Ludovic Orlando, Associate Professor at the Centre for GeoGenetics, who led this work

“The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates. This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically.”

Recent advances in ancient DNA research have opened the door for reconstructing the genomes of ancient individuals. In 2013, Ludovic Orlando and his team succeeded in decoding the genome of a ~700,000 year-old horse, which represents the oldest genome sequenced to date. This time, the researchers focused on much more recent horse specimens, dating from ~16,000 and ~43,000 years ago. These were carefully selected to unambiguously predate the beginning of domestication, some 5,500 years ago. The bone fossils were excavated in the Taymyr Peninsula, Russia, where arctic conditions favor the preservation of DNA.

The human reshaping of the horse

While the horse contributed to reshaping human civilization, humans in turn reshaped the horse to fit their diverse needs and the diverse environments they lived in. This transformation left specific signatures in the genomes of modern horses, which the ancient genomes helped reveal. The scientists were able to detect a set of 125 candidate genes involved in a wide range of physical and behavioral traits, by comparing the genomes of the two ancient horses with those of the Przewalski’s horse and five breeds of domesticated horses. Says Dr. Dan Chang, post-doctoral researcher at the UCSC Paleogenomics Lab and co-leading author of the study:

“Our selection scans identified genes that were already known to evolve under strong selection in horses. This provided a nice validation of our approach.”

Dr. Beth Shapiro, head of the UCSC Paleogenomics Lab continues: “We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses. This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation.”

And Dr. Ludovic Orlando from the Centre for GeoGenetics at the University of Copenhagen concludes: “Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms.”

The ‘cost of domestication’ in horses

However, the reshaping of the horse genome during their domestication also had significant negative impacts. This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses. This finding supports an earlier theory coined ‘the cost of domestication’, which predicted increasing genetic loads in domesticates compared to their wild ancestors. Says Professor Laurent Excoffier, University of Bern and group leader at the Swiss Institute for Bioinformatics:

“Domestication is generally associated with repeated demographic crashes. Yet, mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small. Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. This had already been shown for rice and dogs. Horses now provide another example of this phenomenon.”

This is something that was only detectable in the horse in comparison to the ancient genomes, as Przewalski’s horses were found to show a proportion of deleterious mutations similar to domesticated horses. Says Hákon Jónsson, PhD-student at the Centre for GeoGenetics, co-leading author of the study: “The recent near extinction of the Przewalski’s horse population resulted in the persistence of deleterious mutations in the population, following the same mechanism that once led to the accumulation of deleterious mutations in the genomes of domesticated horses. What is striking is that a similar order of magnitude was reached even though this occurred in a much shorter time scale than domestication.”

An ancient contribution to the present

In addition, comparison of the ancient and modern genomes revealed that the ancient individuals contributed a significant amount of genetic variation to the modern population of domesticated horses, but not to the Przewalski’s horses. This suggests that restocking from a wild population descendant from the ancient horses occurred during the domestication processes that ultimately led to the modern domesticated horses. Mikkel Schubert, PhD- student at the Centre for GeoGenetics, co-leading author of the study concludes:

“This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process. However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population. That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses.”

Agriculture and Food News — ScienceDaily

In grasslands remade by humans, animals may protect biodiversity: Grazers let in the light, rescue imperiled plants

A comparative study of grasslands on six continents suggests there may be a way to counteract the human-made overdose of fertilizer that threatens to permanently alter the biodiversity of the world’s native prairies.

The solution is one that nature devised: let grazing animals crop the excess growth of fast growing grasses that can out-compete native plants in an over-fertilized world. And grazing works in a way that is also natural and simple. The herbivores, or grazing and browsing animals, feed on tall grasses that block sunlight from reaching the ground, making the light available to other plants.

That’s the key finding of a five-year study carried out at 40 different sites around the world and scheduled for online publication March 9, 2014 in the journal Nature. More than 50 scientists belonging to the Nutrient Network, a team of scientists studying grasslands worldwide, co-authored the study.

“This study has tremendous significance because human activities are changing grasslands everywhere,” said study co-author Daniel S. Gruner, associate professor of entomology at the University of Maryland. “We’re over-fertilizing them, and we’re adding and subtracting herbivores. We have a worldwide experiment going on, but it’s completely uncontrolled.”

Gruner, a member of the Nutrient Network (which participants have nicknamed NutNet) since its founding in 2006, helped plan the worldwide study and analyze its results. Elizabeth Borer of the University of Minnesota was the study’s lead author.

The U.N. Food and Agricultural Organization estimates that grasslands cover between one-fifth and two-fifths of the planet’s land area and are home to more than one-tenth of humankind. But like all plant communities, grasslands are suffering from too much fertilizer.

As humans burn fossil fuels, dose crops with chemical fertilizers, and dispose of manure from livestock, they introduce extra nitrogen and other nutrients into the soil, air and water. The excess is a special problem for grasslands, where many plants, like annual wildflowers and others, have adapted to low nutrient levels. They often struggle to compete against grasses that use the extra nutrients to grow faster and bigger.

At the same time, grasslands worldwide are being converted to pastures for domestic animals, with native grazers like elk and antelope giving way to cattle and sheep.

Ecological theory asserts that grazers can counteract the effects of over-fertilizing in most cases, but the theory has never been broadly tested, Gruner said. To do that, the NutNet scientists ran essentially the same experiment worldwide, marking off test plots in groups of four at each of 40 sites. In each group, one plot was fenced to keep grazing animals out. One was treated with a set dose of fertilizers, to mimic the effect of excess nutrients from human sources, but was not fenced so the animals could graze. One was both fenced and fertilized. And one was left alone.

The researchers did not try to alter the test sites’ animal populations. In some places native animals were abundant. At others they’d been mostly replaced by domestic animals like cattle, goats and sheep. And still others were former pastures where livestock had browsed in the past, but were no longer there.

In general, where fertilizer was added and grazing animals were kept out, the variety of plants in the experimental plots decreased. Where animals were allowed to graze in the fertilized plots, plant diversity generally increased. The researchers’ data analysis concluded that the grazers improved biodiversity by increasing the amount of light reaching ground level.

Grassland plants have evolved a variety of strategies to take advantage of a setting where nutrients are in short supply and inconsistently available. They may be ground-hugging, or ephemeral, or shoot up when they capture a nutrient pulse, Gruner explained. These differing strategies create a diverse grassland ecosystem.

In the human-altered world where nutrients are always plentiful, plants that put their effort into growing tall to capture sunlight have an advantage. They block the sunlight from reaching most other plant species, which cannot grow or reproduce. But grazing animals cut down the light-blocking plants and give the others a chance to bloom.

“Where we see a change in light, we see a change in diversity,” said Borer, the lead author. “Our work suggests that two factors which humans have changed globally, grazing and fertilization, can control ground-level light. Light appears to be very important in maintaining or losing biodiversity in grasslands.”

The effect was greatest where large animals, wild and domesticated, grazed on the test plots: cattle, pronghorn and elk on North America’s Great Plains; wildebeests and impala on Africa’s Serengeti; and horses, sheep and ibex in rural India. In places where the only grazers were small animals like rabbits, voles and gophers, the grazers’ effect was weak and variable.

Agriculture and Food News — ScienceDaily

Horse gaits controlled by genetic mutation spread by humans

From the Faroe Pony to the Spanish Mustang, fewer animals have played such a central role in human history as the horse. New research in Animal Genetics reveals that a horse’s gait, an attribute central to its importance to humans, is influenced by a genetic mutation, spread by humans across the world.

The team, led by Dr. Leif Andersson from the Swedish University of Agricultural Sciences, explored the distribution of a mutation in the DMRT3 gene which affects the gait of horses, known as the ‘gait keeper.’

“All over the world, horses have been used for everyday transportation, in military settings, cattle herding and agricultural power, pulling carriages and carts, pleasure riding or racing,” said Dr. Andersson. “Over the centuries, horse populations and breeds have been shaped by humans based on the different purposes for which the animals were used.”

The DMRT3 gene is central to the utility of horses to humans, as it controls a range of gaits as well as pace. From racing to pleasure riding, many species have been bred to encourage smoothness of gait.

“For example, the Paso Fino is a breed from Latin America in which the frequency of the ‘gait keeper’ mutation is nearly 100%. It is claimed that the Paso Fino gait is so smooth that you can have a glass of wine in your hand without letting it spill,” said Dr. Andersson.

The team analyzed 4,396 horses from 141 breeds around the world and found that the ‘gait keeper’ mutation is spread across Eurasia from Japan in the East, to the British Isles in West, on Iceland, in both South and North America, and also in breeds from South Africa.

“Humans have spread this mutation across the world primarily because horses carrying this mutation are able to provide a very smooth ride, in some breeds referred to as a running walk,” said Dr. Andersson. “During such ambling gaits the horse has at least one foot on the ground that means that the vertical movement of the rider is minimal.”

Story Source:

The above story is based on materials provided by Wiley. Note: Materials may be edited for content and length.

Agriculture and Food News — ScienceDaily

Pet Food Safety: When Pet Food Makes Pets and Humans Sick

Between late 2011 and spring 2012, dozens of people across 20 U.S. states and Canada were falling ill with apparent Salmonella infections all coming from the same source. For nearly six months, the illnesses slowly cropped up around North America, with health investigators unable to connect the dots with how they were being caused.

It wasn’t until April 2012 that the puzzle finally came together, when the Michigan Department of Agriculture and Rural Development performed a routine test on a retail product that came up positive for Salmonella. When they checked the exact strain against a federal disease database, they realized the food had been sickening people for half a year.

But the food in question was not something like raw chicken or leafy greens — it was dry dog food. More specifically, Diamond Naturals Lamb Meal & Rice, produced at a Diamond Pet Foods plant in South Carolina.

Soon after, the Ohio Department of Agriculture found another contaminated bag of a different formula. And then the U.S. Food and Drug Administration found more when inspecting the South Carolina facilities.

The plant-wide contamination resulted in one of the largest pet food recalls in recent history and actually encompassed nine brands names, including Canidae and Natural Balance. The company expanded the recall eight times — eventually including cat food — and FDA inspectors found additional contamination at another Diamond plant in Missouri.

Ultimately, 49 humans tested positive for Salmonella from the pet food. But the actual number ill could have been closer to 1,500. (For every person who actually tests positive for Salmonella, another 30 are estimated to have been infected, according the U.S. Centers for Disease Control and Prevention.)

That outbreak was a reminder that contaminated pet food poses a threat to not just dogs and cats, but their owners as well. A few years earlier, in 2007, at least 62 people fell ill in a Salmonella outbreak linked to pet food manufactured by Mars Petcare, which owns brand names such as Pedigree and Whiskas.

When a new pet food outbreak makes headlines, readers often ask how humans end up getting sick. Pet owners don’t need to eat kibbles to get sickened by contaminated food.

Most people who fall ill from pet food do so by handling contaminated food or having contact with infected animals. Thorough hand washing after serving pet food or touching pets is always recommended to avoid potential pathogen transmission.

Of course, foodborne illness outbreaks can work both ways. Among the patients testing positive for Salmonella in the 2008-2009 peanut butter outbreak was one dog.

Because dogs and cats are almost never tested for foodborne pathogens such as Salmonella or E. coli, it’s impossible to know how many get sickened when big outbreaks strike a pet food product. Only two dogs were tested positive for Salmonella in the Diamond outbreak, for instance.

When dogs or cats do become infected with a foodborne illness, they typically suffer the familiar symptoms, such as diarrhea (sometimes including blood or mucus), vomiting, dehydration and lethargy. But some pets may serve as carriers without showing any symptoms, shedding the pathogen in their stools or harboring it on their fur or saliva.

Parents are often advised to take extra precaution with pets around young children for this reason, due to children having developing immune systems that are especially susceptible to pathogenic transmission. Of the patients in the Mars Petcare outbreak, 39 percent were less than one year old.

It’s possible that children could crawl on floors where pets have been eating contaminated food or treats, or simply come into contact with a pet that has fecal contamination in its fur.

These pet-to-human contamination scenarios are one of the many reasons the FDA is proposing to overhaul safety rules on pet food manufacturing as part of the Food Safety Modernization Act. Read more on Food Safety News about the changes FDA is proposing, the reactions FDA has received, and 10 changes that have been recommended by experts.

The pet food safety series on Food Safety News is sponsored by ABC Research, a company that conducts testing on pet food products. Read more about ABC Research pet food testing on the company blog.

Food Safety News

US (WA): Humans and robots team up for high-tech fruit harvest

US (WA): Humans and robots team up for high-tech fruit harvest

With a bumper crop of apples expected this season, many Washington tree fruit growers dream of a day when automated technology helps bring in the harvest. Manoj Karkee, assistant professor with the Center for Precision and Automated Agricultural Systems at Washington State University, believes that day will soon be here.

Karkee and his team of WSU scientists recently won a $ 548,000 US Department of Agriculture grant to develop tree fruit harvesting technology where robots and humans work side by side.

The cost of seasonal labor is increasing and the availability of a semi-skilled labor force continues to become more uncertain. But will growers embrace robotic fruit harvesting? “Growers are very, very interested in this technology and enthusiastically waiting for it,” Karkee said. “In three to five years we hope to have a prototype to demo in the field, and in another five years be able to point to where growers can adopt the technology.”

Funding for the research was awarded through the National Robotics Initiative, a joint program of the National Science Foundation, USDA National Institute for Food and Agriculture, National Institutes of Health and National Aeronautics and Space Administration.

Source: scienceblog.com

Publication date: 8/29/2013


FreshPlaza.com