|
Brown-led study rearranges some branches on animal tree of life
March 06, 2008A study led by Brown University biologist Casey Dunn uses new genomics tools to answer old questions about animal evolution. The study is the most comprehensive animal phylogenomic research project to date, involving 40 million base pairs of new DNA data taken from 29 animal species.
The study, which appears in Nature, settles some long-standing debates about the relationships between major groups of animals and offers up a few surprises.
The big shocker: Comb jellyfish - common and extremely fragile jellies with well-developed tissues - appear to have diverged from other animals even before the lowly sponge, which has no tissue to speak of. This finding calls into question the very root of the animal tree of life, which traditionally placed sponges at the base.
"This finding suggests either that comb jellies evolved their complexity independently from other animals, or that sponges have become greatly simplified through the course of evolution. If corroborated by other types of evidence, this would significantly change the way we think about the earliest multicellular animals," said Dunn, assistant professor of ecology and evolutionary biology at Brown. "Coming up with these surprises, and trying to better understand the relationships between living things, made this project so fascinating."
Charles Darwin introduced the idea of a "tree of life" in his seminal book Origin of Species. A sketch of the tree was the book's only illustration. Nearly 150 years after its publication, many relationships between animal groups are still unclear. While enormous strides have been made in genomics, offering up a species' entire genome for comparison, there are millions of animal species on the planet. There simply isn't the time to sequence all these genomes.
To get a better grasp of the tree of life - without sequencing the entire genomes of scores of species - Dunn and his team collected data, called expressed sequence tags, from the active genes of 29 poorly understood animals that perch on far-flung branches of the tree of life, including comb jellies, centipedes and mollusks. The scientists analyzed this data in combination with existing genomic data from 48 other animals, such as humans and fruit flies, looking for the most common genes being activated, or expressed.
The aim of this new approach is to analyze a large number of genes from a large number of animals - an improvement over comparative genomics methods which allow for a limited analysis of genes or animals. The new process is not only more comprehensive, it is also more computationally intensive. Dunn's project demanded the power of more than 120 processors housed in computer clusters located in laboratories around the globe.
Dunn and his team:
* unambiguously confirmed certain animal relationships, including the existence of a group that includes invertebrates that shed their skin, such as arthropods and nematodes;
* convincingly resolved conflicting evidence surrounding other relationships, such as the close relationship of millipedes and centipedes to spiders rather than insects;
* established new animal relationships, such as the close ties between nemerteans, or ribbon worms, and brachiopods, or two-shelled invertebrates.
"What is exciting is that this new information changes our basic understanding about the natural world - information found in basic biology books and natural history posters," Dunn said. "While the picture of the tree of life is far from complete after this study, it is clearer. And these new results show that these new genomic approaches will be able to resolve at least some problems that have been previously intractable."
Brown University
"This finding suggests either that comb jellies evolved their complexity independently from other animals, or that sponges have become greatly simplified through the course of evolution. If corroborated by other types of evidence, this would significantly change the way we think about the earliest multicellular animals," said Dunn, assistant professor of ecology and evolutionary biology at Brown. "Coming up with these surprises, and trying to better understand the relationships between living things, made this project so fascinating."
Charles Darwin introduced the idea of a "tree of life" in his seminal book Origin of Species. A sketch of the tree was the book's only illustration. Nearly 150 years after its publication, many relationships between animal groups are still unclear. While enormous strides have been made in genomics, offering up a species' entire genome for comparison, there are millions of animal species on the planet. There simply isn't the time to sequence all these genomes.
To get a better grasp of the tree of life - without sequencing the entire genomes of scores of species - Dunn and his team collected data, called expressed sequence tags, from the active genes of 29 poorly understood animals that perch on far-flung branches of the tree of life, including comb jellies, centipedes and mollusks. The scientists analyzed this data in combination with existing genomic data from 48 other animals, such as humans and fruit flies, looking for the most common genes being activated, or expressed.
The aim of this new approach is to analyze a large number of genes from a large number of animals - an improvement over comparative genomics methods which allow for a limited analysis of genes or animals. The new process is not only more comprehensive, it is also more computationally intensive. Dunn's project demanded the power of more than 120 processors housed in computer clusters located in laboratories around the globe.
Dunn and his team:
* unambiguously confirmed certain animal relationships, including the existence of a group that includes invertebrates that shed their skin, such as arthropods and nematodes;
* convincingly resolved conflicting evidence surrounding other relationships, such as the close relationship of millipedes and centipedes to spiders rather than insects;
* established new animal relationships, such as the close ties between nemerteans, or ribbon worms, and brachiopods, or two-shelled invertebrates.
"What is exciting is that this new information changes our basic understanding about the natural world - information found in basic biology books and natural history posters," Dunn said. "While the picture of the tree of life is far from complete after this study, it is clearer. And these new results show that these new genomic approaches will be able to resolve at least some problems that have been previously intractable."
Brown University
Animal Species News and Current Animal Species Events RSSPenn animal study identifies new DNA weapon against avian flu
Researchers at the University of Pennsylvania School of Medicine have identified a potential new way to vaccinate against avian flu.
Birds communicate reproductive success in song
Some migratory songbirds figure out the best place to live by eavesdropping on the singing of others that successfully have had baby birds - a communication and behavioral trait so strong that researchers playing recorded songs induced them to nest in places they otherwise would have avoided.
New study reveals large scale conservation essential
Scientists were surprised with findings of a recent study that reveals many animal species believed to persist in small contained areas actually need broad, landscape level conservation to survive.
Nitrogen retained through loss
The nitrogen cycle plays a major role in seagrass fields. Dutch researcher Arie Vonk studied the nitrogen dynamics of seagrasses in Indonesia. He discovered that the interaction between seagrasses, animals and microorganisms results in an efficient nitrogen cycle in tropical seagrass fields. Consequently the nitrogen lost from seagrasses is still retained.
NASA study links Earth impacts to human-caused climate change
A new NASA-led study shows human-caused climate change has made an impact on a wide range of Earth's natural systems, including permafrost thawing, plants blooming earlier across Europe, and lakes declining in productivity in Africa.
Human vision inadequate for research on bird vision
The most attractive male birds attract more females and as a result are most successful in terms of reproduction. This is the starting point of many studies looking for factors that influence sexual selection in birds.
Global Warming Affects World's Largest Freshwater Lake
Russian and American scientists have discovered that the rising temperature of the world's largest lake, located in frigid Siberia, shows that this region is responding strongly to global warming.
Research Team Is First to Model Photochemical Compass for Bird Navigation
A team of researchers at Arizona State University and the University of Oxford are the first to model a photochemical compass that may simulate how migrating birds use light and Earth's weak magnetic field to navigate.
Road losses add up, taxing amphibians and other animals
When frogs hit the road, many croak. Researchers found more than 65 animal species killed along a short stretch of roads in a Midwestern county. Nearly 95 percent of the total dead were frogs and other amphibians, suggesting that road-related death, or road-kill, possibly contributes to their worldwide decline, a trend that has concerned and puzzled scientists for decades.
Neurons hard wired to tell left from right
It's well known that the left and right sides of the brain differ in many animal species and this is thought to influence cognitive performance and social behaviour. For instance, in humans, the left half of the brain is concerned with language processing whereas the right side is better at comprehending musical melody.
More Animal Species News Articles
| © 2008 BrightSurf.com |