(Press-News.org) New species evolve whenever a lineage splits off into several. Because of this, the kinship between species is often described in terms of a 'tree of life', where every branch constitutes a species. Now, researchers at Uppsala University have found that evolution is more complex than this model would have it, and that the tree is actually more akin to a bush.
Less than a year ago, a consortium of some hundred researchers reported that the relationship between all major bird clades had been mapped out by analysing the complete genome of around 50 bird species. This included the exact order in which the various lineages had diverged.
Since then, two of the members of the consortium, Alexander Suh and Hans Ellegren at the Uppsala University Evolutionary Biology Centre, have expanded upon this model by analysing the avian genome through a new method, which hinges on so-called 'jumping genes'. Their results paint a partially contrasting picture of the kinship between the various species.
'We can see that the very rapid rate at which various bird species started evolving once the dinosaurs went extinct, i.e. around 65 million years ago, meant that the genome failed to split into separate lineages during the process of speciation', Hans Ellegren says.
This is because evolution moved quickly, and many species arose in quick succession. When this happens, different parts of the genome can tell disparate tales of the kinship between the new species. The phenomenon has previously been explained theoretically and is a result of the genetic variation passing from one species to another. If new species then continue to evolve quickly, random chance can end up determining which original genetic variants end up in each lineage. The phenomenon is called incomplete lineage sorting.
'Previously, the difficulty resided in finding instances of incomplete lineage sorting far back in time', Hans Ellegren says. 'Therefore, it's been unknown if this phenomenon has affected evolution to any appreciable extent'.
By using the jumping genes, or so-called retrotransposed elements, the Uppsala researchers have found that, for instance, a cuckoo can be more closely related to a hummingbird than a pigeon in a certain part of its genome, while the opposite holds true in another part. The study found numerous examples to corroborate the existence of the phenomenon.
This is one of the first cases in evolutionary research where researchers have been able to document and quantify incomplete lineage sorting far back in time. It is likely a far more common occurrence than previously thought.
'The more complex kinship patterns that result from this phenomenon mean that the Tree of Life should often be understood as a Bush of Life', Alexander Suh and Hans Ellegren say.
The results will be published in the leading research journal PLoS Biology. The authors and their study are also featured in the leading editorial.
INFORMATION:
Read the article in PLoS Biology: http://dx.doi.org/10.1371/journal.pbio.1002224
August 18, 2015 - For children with aggressive brain cancers called high-grade gliomas (HGG), the chances of survival are improved when surgery is successful in eliminating all visible cancer, reports a study in the September issue of Neurosurgery, official journal of the Congress of Neurological Surgeons. The journal is published by Wolters Kluwer.
In addition to showing better survival with gross total resection (GTR) for children with HGG, the results suggest that this survival benefit is greater in girls compared to boys with HGG. The study provides "compelling evidence ...
Women's contraceptive choices are more often driven by current relationships and sexual activity than by long-term pregnancy intentions, according to Penn State College of Medicine researchers.
Cynthia H. Chuang, associate professor of medicine and public health sciences and Carol S. Weisman, Distinguished Professor of Public Health Sciences and Obstetrics and Gynecology and colleagues surveyed nearly 1,000 women in Pennsylvania, all with private health insurance covering prescription contraception, on their contraception use -- including prescription and over-the-counter ...
DURHAM, N.C. -- New methods for analyzing personal health and lifestyle data captured through wearable devices or smartphone apps can help identify college students at risk of catching the flu, say researchers at Duke University and the University of North Carolina-Chapel Hill.
With help from a mobile app that monitors who students interact with and when, epidemiologist Allison Aiello of UNC and statistician Katherine Heller of Duke have developed a model that enables them to predict the spread of influenza from one person to the next over time.
Unlike most infection ...
Imagine staying dry underwater for months. Now Northwestern University engineers have examined a wide variety of surfaces that can do just that -- and, better yet, they know why.
The research team is the first to identify the ideal "roughness" needed in the texture of a surface to keep it dry for a long period of time when submerged in water. The valleys in the surface roughness typically need to be less than one micron in width, the researchers found. That's really small -- less than one millionth of a meter -- but these nanoscopic valleys have macroscopic impact.
Understanding ...
(SACRAMENTO, Calif.) -- In a discovery that is likely to rewrite immunology text books, researchers at UC Davis have found that early exposure to inflammatory cytokines, such as interleukin 2, can "paralyze" CD4 T cells, immune components that help orchestrate the body's response to pathogens and other invaders.
This mechanism may act as a firewall, shutting down the immune response before it gets out of hand. However, from a clinical standpoint, this discovery could lead to more effective cancer immunotherapies, better drugs for autoimmune conditions and new ways to ...
Scientists are planning for a future in which superbugs gain the upper hand against our current arsenal of antibiotics. One emerging class of drug candidates, called AMLPs (antimicrobial lipopeptides), shows promise, and an August 18 study in the Biophysical Journal explains why: they selectively kill bacterial cells, while sparing mammalian host cells, by clumping together into microscopic balls that stick to the bacterial membrane--a complex structure that will be slower to mutate and thus resist drugs.
"The pressing need for novel antibiotics against resistant strains ...
SAN FRANCISCO--Early data coming in from a massive, four-year deployment of seismometers onshore and offshore in the Pacific Northwest are giving scientists a clearer picture of the Cascadia subduction zone, a region with a past and potential future of devastating "megathrust" earthquakes.
The preliminary results from the Cascadia Initiative include a report of previously undetected, small earthquakes offshore, and seismic imaging that reveals new offshore structures at the subduction zone. The reports, published as a focus section in the September-October 2015 issue ...
Research indicates that the use of condoms may cause some men to experience erection difficulties. However, in a study of 479 heterosexual men who used condoms and were 18 to 24 years old, those who reported condom-associated erection problems were also more likely to experience more generalized erection difficulties.
Investigators also found that more than one-third of participants had never been taught how to use a condom correctly. Clinicians should assess whether men using condoms experience condom-associated erection problems and where appropriate, make referrals ...
Liver diseases affect hundreds of millions of people and cause significant illness and death. A new study indicates that liver scarring (or fibrosis), which can ultimately lead to liver failure, is fairly common. It was present in 5.6% of adults in the Rotterdam Study, a population-based study among individuals in a suburb of Rotterdam, the Netherlands, who were ?45 years old. It was especially prevalent in individuals with diabetes or steatosis, the latter of which occurs when fat cells infiltrate the liver.
"In the context of an aging population and an increasing prevalence ...
New research indicates that use of oral contraceptives may provide benefits for women with inflammatory arthritis.
Among 273 women with early inflammatory arthritis, women who had used oral contraceptives in the past and those who were currently using them reported fewer problems related to how well they can function, their mood, and how active their disease is.
The findings are published in Arthritis Care & Research.
INFORMATION: ...
