This alien-looking creature is known as Nematostella vectensis, or the starlet sea anemone. Like other anemones, starlets start life as free-swimming larvae. They then settle into an appropriately mucky spot on the seafloor and metamorphose into their adult polyp form, seen here.
Anemones lack brains, but the section of the larvae containing the sensory organs actually becomes the bulbous root end of the adult, while the other side sprouts delicate tentacles and transforms into a filter-feeding mouth.
Researchers have now found that the “head genes” of N. vectensis, though held in what eventually becomes the animal’s “foot,” correspond to the head genes found in the actual heads of higher animals. Humans and other brainy beasts share a common, brainless, ancestor with sea anemones that lived 600 million to 700 million years ago. The findings were released Feb. 20, 2013 in the journal PLOS Biology.
The bladderwort, named for its water-filled bladders (shown left) that suck in unsuspecting prey, is a relative of the tomato. Since their evolutionary split 87 million years ago, both plants have experienced episodes of genetic duplication where the plants’ DNA doubled in size…
Ant Family Tree Constructed: Confirms Date of Evolutionary Origin, Underscores Importance of Neotropics
by Science Daily staff
Apr. 22, 2013 — Anyone who has spent time in the tropics knows that the diversity of species found there is astounding and the abundance and diversity of ants, in particular, is unparalleled. Scientists have grappled for centuries to understand why the tropics are home to more species of all kinds than the cooler temperate latitudes on both sides of the equator. Several hypotheses have been proposed to explain the higher species numbers in the tropics, but these hypotheses have never been tested for the ants, which are one of the most ecologically and numerically dominant groups of animals on the planet.
New research by evolutionary biologists Dr. Corrie Moreau of Chicago’s Field Museum and Dr. Charles Bell of the University of New Orleans is helping answer these questions. Their findings are presented this week in the journal Evolution.The scientists used DNA sequence data to build the largest ant tree-of-life to date. This tree-of-life, or family tree of ants, not only allowed them to better understand which ant species are related, but also made it possible to infer the age for modern ants because information from the fossil record in the form of geologic time was included in the research…
The coelacanth isn’t called a “living fossil” for nothing. The 2-meter-long, 90 kg fish was thought to have gone extinct 70 million years ago—until a fisherman caught one in 1938—and the animal looks a lot like its fossil ancestors dating back 300 million years. Now, the first analysis of the coelacanth’s genome reveals why the fish may have changed so little over the ages. It also may help explain how fish like it moved onto land long ago.
“I’m very excited about this paper because coelacanths are animals that we really want to know more about,” says Per Ahlberg, a paleontologist at Uppsala University in Sweden who was not involved with the study.
In order to sequence a coelacanth’s (Latimeria chalumnae) genome, scientists required fresh tissue and blood. That’s no easy task: These fish dwell in deep-sea caves and are exceedingly rare. Only 309 have been spotted in the past 75 years, off the east coast of sub-Saharan Africa and Indonesia. Moreover, caught coelacanths die immediately because of the change in pressure and temperature, and under the hot tropical sun, their DNA quickly degrades…
First Migration from Africa Less Than 95,000 Years Ago: Ancient Hunter-Gatherer DNA Challenges Theory of Early Out-Of-Africa Migrations
by Science Daily staff
Mar. 22, 2013 — Recent measurements of the rate at which children show DNA changes not seen in their parents — the “mutation rate” — have challenged views about major dates in human evolution.
In particular these measurements have made geneticists think again about key dates in human evolution, like when modern non-Africans split from modern Africans. The recent measurements push back the best estimates of these dates by up to a factor of two. Now, however an international team led by researchers at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology in Leipzig, present results that point again to the more recent dates. The new study is published in Current Biology…
Scientists at the University of Alaska Museum of the North are using ancient DNA from museum specimens housed at several U.S. museums to find out whether one particular species of treeshrew (Tupaia glis) is actually several different species.
Thanks to a grant from the National Science Foundation, Mammals Curator Link Olson and his colleagues are using both DNA and skeletal evidence. Their work is featured on the cover of the current issue of the Journal of Mammalogy.
“We tested our own previous hypothesis based solely on DNA extracted from historic museum specimens up to 120 years old in the museum’s Ancient DNA Laboratory,” Olson said.
The scientists obtained skeletal data by X-raying the specimens to accurately measure the foot bones. “We found congruence between the two types of data and were consequently able to resurrect three species from synonymy, including the one gracing the cover. This served as a test case, and we anticipate many more treeshrew species will be rescued from taxonomic oblivion in the near future.”
The scientists hope their work will aid conservation and management decisions in Southeast Asia, one of the world’s hottest biodiversity hotspots that is undergoing rapid and accelerating rates of habitat destruction.
Each Tetrahymena has a gene for its own sex—or mating type—in its regular nucleus, but it also carries a second nucleus used only for reproduction. This “germline nucleus” contains incomplete versions of all seven mating type genes, which are cut and pasted together until one complete gene remains and the other six have been deleted…
Salamander DNA reveals evidence of older land connection between Central and South America
by Smithsonian staff
The two continents are generally believed to have been joined together around three million years ago by the formation of a land bridge–what is now Panama–that sealed up the sea channel between them.
However, a new study of salamanders in South America by a research team lead by Kathryn Elmer of the University of Glasgow, has found evidence that challenges these assumptions and supports a controversial claim by Carlos Jaramillo, a paleontologist at the Smithsonian Tropical Research Institute in Panama, that most of the Isthmus of Panama was formed around 23 million years ago.
The fusion of both land masses led to a two-way migration of animals called the ‘Great American Biotic Interchange’, where animals that had previously evolved separately moved between the two continents, increasing the biodiversity in both regions.
The relative dearth of species of salamander in South America–around 30–compared to Central America, where there are more than 300 species, is usually attributed to the relatively short time the tiny amphibians have had to make their way south down the Isthmus of Panama–a thin strip of land only 30 miles wide at its narrowest point.
However, using DNA analysis, Elmer found that salamanders in South America had much greater genetic divergence from their Central American cousins than should be expected if salamanders migrated across a three- million-year-old land bridge…
The bdelloid rotifer – a tiny, all-female creature – has endured the past 80 million years without sex. Now, researchers discover the asexual animal’s secret lies in gobbling up foreign DNA from other simple life-forms.
First Large-Scale DNA Barcoding Assessment of Reptiles in the Biodiversity Hotspot of Madagascar, Based on Newly Designed COI Primers 
DNA barcoding of non-avian reptiles based on the cytochrome oxidase subunit I (COI) gene is still in a very early stage, mainly due to technical problems. Using a newly developed set of reptile-specific primers for COI we present the first comprehensive study targeting the entire reptile fauna of the fourth-largest island in the world, the biodiversity hotspot of Madagascar…
An international team led by an infectious disease expert, Professor Lin-Fa Wang, at the Duke-NUS Graduate Medical School (Duke-NUS) in Singapore has found that the evolution of flight in bats may have contributed to the development of a highly effective immune system, allowing bats to harbour some of the world’s deadliest viruses such as Ebola and SARS.
In their study, published in the prestigious international journal Science, Professor Wang and colleagues used a state-of-the-art whole-genome sequencing technique to analyse the genomes of two distantly-related bat species, the fruit bat Pteropus alecto (Black flying fox, a species native to Australia, Papua New Guinea, and Indonesia) and the insect-eating bat Myotis davidii (David’s mouse-eared bat, a species endemic in China).
Although bats are the second largest group of mammals, with over 1,000 species of bats documented so far, they are distinctive because they are the only mammals capable of sustained flight; other mammals such as flying squirrels glide but do not fly. Previous research has shown that this ability to fly may be linked to high metabolic rates in bats. However, increased metabolism also elevates the amount of free radicals in living cells, resulting in DNA damage that is harmful to the bats…
Until 2010, boas were thought to only reproduce sexually. But when a female boa produced several all-female litters that carried a rare genetic mutation, scientists from North Carolina State University in Raleigh performed a DNA fingerprint analysis. Although the genetic studies indicated that the female offspring were the result of parthenogenesis, researchers have yet to untangle the cellular factors that explain how and why this happened.
Like the New Mexico whiptail, bdelloid rotifers are all female and reproduce entirely by parthenogenesis. Despite tens of millions of years of celibacy, these rotifers are an amazingly diverse group with more than 300 species. The animalsappear to offset a loss of genetic diversity by eating any DNA floating in their environment and incorporating it into their genome.
(via: Science NOW) (photo: Wim van Egmond/Visuals Ulmtd.)
Genomes of limpet, leech, and worm put spotlight on lophotrochozoans.
by JADE BOYD
A new report in the journal Nature unveils three of the first genomes from a vast, understudied swath of the animal kingdom that includes as many as one-quarter of Earth’s marine species. By publishing the genomes of a leech, an ocean-dwelling worm and a kind of sea snail creature called a limpet, scientists from Rice University, the University of California-Berkeley and the Department of Energy’s Joint Genome Institute (JGI) have more than doubled the number of genomes from a diverse group of animals called lophotrochozoans (pronounced: LOH-foh-troh-coh-zoh-uhns).
Lophotrochozoans are a diverse group of animals that includes mollusks – such as snails, clams and octopuses — and annelids — such as leeches and earthworms. Like humans and all other animals, lophotrochozoans can trace their evolutionary history to the earliest multicellular creatures. But the lophotrochozoan branch of the evolutionary tree diverged more than 500 million years ago from the branch that produced humans.
Almost all published genomes are from the animal kingdom’s most-studied clades: deuterostomes, which includes humans and other vertebrates, and ecdysozoans, which includes insects. Only two lophotrochozoan genomes have been previously mapped, and both are for parasitic worms, which aren’t representative of most species in the clade…