Geoscientists shed a light on life's evolution 800 million years ago

Is nitrate responsible for algae, flowers, and even your neighbors?

A team of Virginia Tech geoscientists have unearthed evidence that may indicate yes.

The team's findings, recently published in Science Advances, reveal an increase in biologically available nitrogen during the time that marine eukaryotes -- organisms whose cells have a nucleus -- became dominate. Complex eukaryotic cells evolved into multicellular organisms and are credited for ushering in a whole new era for life on Earth, including animals, plants, and fungi.

"Where we sit today, with life as it is on the planet, is the sum total of all the events that happened in the past," said Ben Gill, an associate professor of sedimentary geochemistry and co-author on the paper. "And this is a key event where we shift from dominantly prokaryotic ecosystems -- cells that are much simpler than the ones in our bodies -- to eukaryotes. If that did not happen, we would not be here today."

Previous research focused on phosphorus' role in the rise of eukaryotes, but Junyao Kang, a doctoral student in the Department of Geosciences and lead author of the paper, was curious about the part nitrogen played in this event.

"This data is unique because nitrogen isotope data are virtually nonexistent from the early Neoproterozoic time period, or between a billion and 800 million years ago," said Kang.

Collaborating with the Nanjing University in Najing, China, Kang has spent two years working to understand what drove the rise of eukaryotes through nitrogen isotope analysis of rock samples from the North China Craton. Home to rocks dating back 3.8 billion years ago, the region was once covered by an ocean.

"We had some rough ideas of when eukaryotes became ecologically successful," said Shuhai Xiao, professor of geobiology and a paper co-author. "They had been there for a long time in a low-key status until about 820 million years ago, when they became abundant."

Kang decided he wanted to learn why. He took the data from the rock samples, entered it into a larger database, and analyzed it across a longer time scale that spanned different geographic locations.

"Once we did this kind of integration and put it into a big picture, we saw the rise of nitrates through time, which happened around 800 million years ago," said Kang.

Solid collaboration

A collaborative, international approach was key to connecting this new data with biological events, mostly notably, the rise of eukaryotes.

Gill and Rachel Reid, also a College of Science geochemist and co-author of the paper, provided critical analyses through resources, including the mass spectrometer in the Geoscience Stable Isotope Lab at Virginia Tech. An elemental analyzer coupled to the mass spectrometer allowed the researchers to extract pure nitrogen gas from the samples for analysis.

Gill specializes in reconstructing present and past chemical cycles on our planet. He collaborates with paleontologists to study the record of life preserved in the geological record and examines what potential environmental drivers might have enabled changes in life through history.

Reid, who generally focuses her research on Earth's more recent events, had a special opportunity to offer her nitrogen isotope expertise to these ancient fossils.

Feifei Zhang, a geochemist at Nanjing University, was the paper's fourth co-author. Zhang provided insights on how much oxygen would have been available in the oceans during the time when nitrate increased in abundance.

All of the Virginia Tech authors are affiliated members of the Fralin Life Sciences Institute's Global Change Center, with Kang serving as a Ph.D. fellow in the Interfaces of Global Change graduate program. The center brings together experts from diverse disciplines to solve these complex global challenges and train the next generation of leaders.

Past, present, and future

Xiao, who has helped excavate and study some of the most ancient fossils from around the world, said this type of study gives him hope for future discoveries. The team members look forward to collaborating with NASA on future grants, such as the exobiology program supporting their current research.

He also credits University Libraries at Virginia Tech for its support of open-access publications, such as Science Advances, to provide a vetted selection of research, freely available to readers.

"We can link the dots from the nitrogen isotopic compositions in the ancient past and then go to the next step and infer how much nitrate was available for organisms," said Xiao. "And then we tie that with the fossil data to show that there's a relationship."

While ancient oceans are long gone, what happened in ancient oceans are recorded in rocks, and studying these rocks provides a link from our Earth's history to the present and to the future.

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Bigger flowers, greater rewards: Plants adapt to climate disruptions to lure pollinators

There's been a well-documented shift toward earlier springtime flowering in many plants as the world warms. The trend alarms biologists because it has the potential to disrupt carefully choreographed interactions between plants and the creatures -- butterflies, bees, birds, bats and others -- that pollinate them.

But much less attention has been paid to changes in other floral traits, such as flower size, that can also affect plant-pollinator interactions, at a time when many insect pollinators are in global decline.

In a study published online in the journal Evolution Letters, two University of Michigan biologists and a University of Georgia colleague show that wild populations of the common morning glory in the southeastern United States increased the size of their flowers between 2003 and 2012.

Increased flower size suggests a greater investment by the plants in pollinator attraction, according to the researchers. The changes were most pronounced at more northern latitudes, in line with a broad range of previous work showing that northern plant populations tend to show more dramatic evolutionary responses to climate change.

A shift to earlier flowering was also observed among those morning glory populations. In addition, there were tantalizing indications that the plants have increased their investment in floral rewards -- the nectar and pollen obtained by the bees, syrphid flies and wasps that pollinate the white, pink and blue morning glory flowers.

"There is a major gap in our understanding of how traits that are crucial for plant-pollinator interactions may be evolving over time as a response to a changing climate," said study lead author Sasha Bishop, a doctoral student in the U-M Department of Ecology and Evolutionary Biology.

"We show that -- in addition to well-documented shifts to earlier flowering -- floral architecture and rewards can also play significant roles in the evolutionary response to contemporary environmental change."

The common morning glory is an annual weedy vine found across the eastern, midwestern and southern United States. It is frequently seen along roadsides and crop fields.

The U-M-led study used a "resurrection" approach that involved germinating morning glory seeds collected from the edges of agricultural soy and corn fields in Tennessee, North Carolina and South Carolina in two years: 2003 and 2012.

During that nine-year span, the region experienced rising temperatures -- particularly rising minimum and nighttime temperatures -- and an increase in the number of extreme rainfall events interspersed with more extreme drought.

To look for changes in floral morphology, the researchers planted field-collected seeds from both years in a greenhouse at U-M's Matthaei Botanical Gardens. When the flowers bloomed, various floral traits were measured with digital calipers.

Measurements showed that morning glory corollas became significantly wider during the nine-year interval -- 4.5 centimeters (1.8 inches) in diameter in 2003 and 4.8 centimeters (1.9 inches) in 2012, and the change in corolla width was greatest in populations at more northern latitudes. The petals of a flower are collectively known as the corolla.

The study also revealed a shift to earlier flowering times between 2003 and 2012, driven primarily by populations at more northern latitudes. The start of flowering occurred an average of four days earlier for the plants grown from seeds collected in 2012.

Interestingly, the researchers also observed a latitude-influenced trend toward greater investment in floral rewards (pollen and nectar) over time. On average, morning glory flowers grown from 2012-collected seeds produced more pollen grains and more nectar sucrose than the flowers from the 2003-collected seeds.

However, the pollen and nectar analyses involved only four populations of morning glory plants. Due to the low number of populations examined, the floral rewards findings were not included in a statistical test to look for evidence that adaptation through natural selection is occurring in the plants.

"Nonetheless, it appears likely that there is a temporal increase in investment in pollinator attraction and that this result is driven by populations at northern latitudes," said study senior author Regina Baucom, an associate professor in the U-M Department of Ecology and Evolutionary Biology.

The study found no evidence that morning glories are increasing the rate at which they self-pollinate. Evidence from some previous studies pointed to increased "selfing" as a possible response to climate change and/or pollinator declines associated with land-use change.

"This is the first article to use the resurrection approach to examine the potential that traits responsible for plant-pollinator interactions may be evolving over time, concomitant to decreases in pollinator abundance and dramatic environmental changes due to changing climate and land-use regimes," Bishop said.

Fifteen morning glory populations were included in the resurrection experiment looking at changes in floral morphology. Twenty-three populations were included in the study of earlier springtime flowering. In total, 2,836 flowers were measured from 456 plants.

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Whiskers help nectar-eating 'acro bats' hover like hummingbirds

From dragonflies to hummingbirds, hovering flight is among the most complex and captivating forms of animal movement -- a physiological feat of size, musculature and wing development.

For nectar-feeding bats that hover as they feed from flowers, this aerial maneuver also depends on extra-long whiskers unlike those of most other bat species, according to a Dartmouth College-led study in the journal Proceedings of the Royal Society B. The researchers used high-speed cameras to capture how the stiff hairs jutting forward from the face of nectar-eating bats provide enhanced spatial information that guides the animals as they swoop in to quickly feed -- within a second or less -- on succulent flowers without landing.

"The whiskers of nectar-feeding bats are critical sensory organs that provide high-quality input the brain works with to optimize hovering. It's a cool junction between sensory biology and bio-kinematics, between form and function," said lead author Eran Amichai, a postdoctoral researcher in biological sciences at Dartmouth who studies echolocation in bats. Co-authors are postdoctoral fellow David Boerma from the American Museum of Natural history, animal behavioralist Rachel Page at the Smithsonian Tropical Research Institute in Panama, Sharon Swartz, a professor of biology and engineering at Brown University, and Hannah ter Hofstede, a past assistant professor of biological sciences at Dartmouth now at the University of Windsor in Canada.

The researchers worked at the Smithsonian Tropical Research Institute recording Pallas's long-tongued bats -- a South and Central American bat that has the fastest metabolism of any mammal -- as they drank from hand-blown glass flowers designed for the study to replicate the plants the animals feed from. High-speed infrared cameras captured photos and video of the bats as they descended upon the glass flowers and navigated their muzzles and tongues into the "bloom" to eat the nectar. Feedings typically lasted between a half- to one second.

The researchers found that bats with clipped whiskers were less agile and accurate during feeding and flight than animals with untouched whiskers. The animals with clipped whiskers were held for a few days until the hairs regrew, then released back into the jungle. "Clipping the whiskers doesn't reduce the bats' ability to feed, they just do it a little less gracefully," Amichai said. "If it were gymnastics, they'd get an 8.5 instead of a 9.8."

The role of long whiskers in nectar-feeding bats' flight control provides new insight into the coevolution of the bats with the flowers they feed on, Amichai said. The majority of bats possess short whiskers not arranged in any particular pattern or direction. But the researchers found that whisker length in nectar-eating bats evolved at least twice to -- along with long tongues and faces -- potentially help them better navigate the deep chambers of the flowers they prefer. In turn, the long reach these flowers require results in more pollen sticking to their pollinators and thus the broader proliferation of their kind.

The researchers plan to continue their work using higher-resolution images, flowers that move, interactions with predators and other expansions on the experimental model, Amichai said.

In the meantime, the latest study offers a fascinating glimpse into how nectar-feeding bats combine various forms of sensory information to navigate the world around them, Amichai said. Their world is a combination of scent, echolocation, spatial memory, knowledge of the seasons and the physical sensation and equilibrium provided by their whiskers.

"I find thinking in these terms of switching back and forth between completely different ways to perceive the world -- and seamlessly integrating their input -- to be a mind-blowing concept," Amichai said. Understanding how animals perceive and interact with their surroundings helps scientists develop better conservation strategies, he said.

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Magma and ice

Let's pretend it's the Late Cretaceous, roughly 66 to 100 million years ago. We've got dinosaurs roaming the land and odd-looking early species of birds, although the shark as we know it is already swimming in the prehistoric oceans -- which cover 82% of Earth. Redwood trees and other conifers are making their debut, as are roses and flowering plants, and with them come bees, termites and ants. Most of all, it's warm, volcanically active and humid all over the place with nary an ice sheet in sight.

Except, according to a group of scientists from UC Santa Barbara, University of Oregon and University of Manitoba, icy conditions did exist in the region of the South Pole.

"And it wasn't just a single-valley glacier," said UCSB geologist John Cottle, "it was probably multiple glaciers or a large ice sheet." Contrary to our widely held picture of the Late Cretaceous as "hot everywhere," he said, there's evidence that polar ice existed during that period, even at the height of global greenhouse conditions. The geologists' study is published in the journal Nature Communications.

A Prehistoric Puzzle

Fast-forward to today. Let's pretend we're in Antarctica. It's chilly, it's barren, and we're standing near a large grouping of exposed glassy rock along the Transantarctic Mountains, adjacent to the Ross Ice Shelf, called the Butcher Ridge Igneous Complex (BRIC).

"I actually heard about these rocks when I was a grad student 20 or so years ago, and they're just really weird," Cottle said. Remote, even by today's Antarctic exploration standards, the BRIC is unusual because the rocks' composition and formation are uncharacteristic of nearby rock formations, with, among other things, large amounts of glass and layered alteration that indicates significant physical, chemical or environmental events that changed their mineral composition.

Cottle got the chance to finally sample the BRIC on a recent expedition, and in the process of analyzing how it was formed, he and his team encountered an "unusually large amount of water."

"So you have a really hot rock that interacts with water, and as it cools, incorporates it into the glass," he said. "If you look at the composition, then you can tell something about where that water came from. It can exist as hydroxyl, which tells you that it probably came from the magma, or it could be molecular, which means it is probably external."

What they were expecting to see was that the alteration in the rock was caused by the water already in the magma as it cooled. What they found instead was a record of a climate process that was thought not to have existed at the time.

In their spectroscopic analysis of the samples, the researchers determined that while some of the water indeed originated with magma as it plumed upward from Earth's interior, as the molten rock cooled into glass just beneath the Earth's surface, it also incorporated groundwater.

"We determined that most of the water in these rocks is externally derived," Cottle said. "We then measured the oxygen and hydrogen isotopic composition of the water and it matches very well to the composition of Antarctic snow and ice."

To lock in their result, Cottle and team also conducted argon-argon geochronology to date the rock and its alteration.

"The problem is, these rocks are Jurassic, so about 183 million years old," he said. "So when you measure the alteration, what you don't know is when that happened." They were able to recover the age of the rock (Jurassic), but also found a younger age (Cretaceous). "So when these rocks cooled and were altered," he continued, "it also reset the argon isotope as well, and you can match the age of the alteration to the composition of the alteration."

There are other, similar volcanic rocks roughly 700 km north of the BRIC that also have a Cretaceous alteration age, indicating that polar glaciation might have been regionally extensive in Antarctica during that time. "What we'd like to do is go to other places in Antarctica and see if we can determine the scale of the glaciation, if we recover the same results that we've already found," he said.

Finding evidence of large ice sheets dating back to the Cretaceous might not alter our general picture of a hot and humid Earth at that time, Cottle said, "but we would have to think about the Cretaceous and Antarctica quite differently than we do now."

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Bees use patterns -- not just colors -- to find flowers

Honeybees rely heavily on flower patterns -- not just colours -- when searching for food, new research shows.

A team led by the University of Exeter tested bee behaviour and built bee's-eye-view simulations to work out how they see flowers.

Honeybees have low-resolution vision (about 100 times lower than human vision), so they can only see a flower's pattern clearly when they are within few centimetres.

However, the new study shows bees can very effectively distinguish between different flowers by using a combination of colour and pattern.

In a series of tests, bees rarely ignored pattern -- suggesting colour alone does not lead them to flowers.

This may help to explain why some colours that are visible to bees are rarely produced by flowers in nature.

"We analysed a large amount of data on plants and bee behaviour," said Professor Natalie Hempel de Ibarra, from Exeter's Centre for Research in Animal Behaviour.

"By training and testing bees using artificial patterns of shape and colour, we found they relied flexibly on their ability to see both of these elements.

"Showing how insects see colour and learn colour patterns is important to understand how pollinators may, or may not, create evolutionary 'pressures' on the colours and patterns that flowers have evolved.

"Our findings suggest that flowers don't need to evolve too many different petal colours, because they can use patterns to diversify their displays so bees can tell them apart from other flowers."

One consistent feature identified in the study is that the outside edges of flowers usually contrast strongly with the plant's foliage -- while the centre of the flower does not have such a strong contrast with the foliage colour.

This could help bees quickly identify colour differences and navigate to flowers.

While flowers may be beautiful to humans, Professor Hempel de Ibarra stressed that understanding more about bees -- and the threats they face -- meant we need to see the world "through the eyes of a bee and the mind of a bee."

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Flowers' unseen colors can help ensure pollination, survival

You can't see it, but different substances in the petals of flowers create a "bulls-eye" for pollinating insects, according to a Clemson University scientist whose research sheds light on chemical changes in flowers which helps them respond to environmental changes, including climate change, that might threaten their survival.

Matthew H. Koski, an assistant professor of biological sciences in the Clemson College of Science, led a research team that studied the bright, yellow flowers of Argentina anserina -- a member of the rose family commonly known as silverweed -- to learn how pigments in the petals that are visible only in the ultraviolet spectrum play an integral part in the plant's plasticity; that is, its ability to quickly respond to a changing environment. The team also included Clemson researchers Lindsay M. Finnell, Elizabeth Leonard and Nishanth Tharayil.

The journal Evolution featured the findings on the cover of its March edition.

The researchers studied silverweed growing at different elevations in southwestern Colorado to better understand the roles of the various UV-absorbing chemicals in the plants' petals and how these chemicals work to aid in pollination and, thus, reproduction.

Koski explained that although humans cannot see the UV patterns on the flower's petals, many of its pollinators can.

"I've always been fascinated with how [color variation of flowers] arises and how it evolves and what factors drive the evolution of color variation," Koski said, "so I got interested in thinking about how we perceive color versus how the organisms that interact more frequently with flowers perceive color."

"Insects -- pollinators, for example -- see in the ultraviolet spectrum," he continued. "So, flowers that reflect or absorb ultraviolet wavelengths give (to pollinators) the perception of different colors that we can't see. I've been fascinated with uncovering what these UV signals might be doing functionally with respect to pollination. When I thought about the trait of interest in ultraviolet absorption, it is biochemistry. It's a biochemical trait that leads to different perceptions of UV absorption and reflectance."

Koski said a wide range of plants have concentrations of UV-absorbing chemicals at the base of the flower's petals, while the tips of the petals have more UV-reflecting chemicals. He said this creates an overall "bulls-eye" effect that guides insects in their search for pollen.

The team wanted to uncover more about how the plants adapt to thrive in different environments -- in this case, a difference in altitude of 1,000 meters. They found that flowers at different altitudes adapt to their environments by producing differing amounts of UV-blocking or UV-absorbing chemicals.

"At higher elevations, there are always more UV-absorbing compounds or larger spatial area of UV absorption on the petals, compared to the low-elevation populations," Koski said.

The researchers said this demonstrates the plant's plasticity, which Koski defined as how differing traits arise in the same organisms under different environmental conditions. This is a critical step in understanding how organisms adapt to survive change.

"What's important about plasticity is, when we think about climate change and global change, plasticity is one mechanism by which natural populations can respond really rapidly to changing climates and persist under those climates," he said. "The process of evolution, where you're getting changes in the genetic code over time, is thought to proceed more slowly than just responding plastically to environmental change."

Koski said that one question raised by the research is whether plastic responses to environmental situations are adaptive. Do they offer any advantage to an organism, or are they changes in how a trait develops because of the environment without impacting plant fitness?

"One thing this study found is that the plastic change in UV pigmentation benefited the plant, especially the ones at high elevations because increases in ultraviolet absorption on the petals resulted in increased pollen viability," he explained.

Koski went on to say the research will help scientists better understand how organisms respond to environmental changes and even predict if or how well some organisms would be able to survive rapid environmental change, such as from global climate change. The research could also be important for agriculture, he said, because some of the same UV-sensitive pigments at work in silverweed are also present in commercial crops such as mustard and sunflowers.

"It's interesting to think about if abiotic factors like UV or temperature are shifting the expression of these traits, how is that going to impact how pollinators view the flowers, and how's that going to affect things like yield and seed production in crops, for example," Koski said.

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Sudden evolutionary change in flowers

When Charles Darwin first codified the theory of evolution by means of natural selection, he thought of it as a gradual process. "We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages," he wrote in his seminal work, "On the Origin of Species."

But Darwin didn't have the full picture. "Evolution doesn't necessarily take all these small changes like Darwin proposed," said Scott Hodges, a professor in UC Santa Barbara's Department of Ecology, Evolution, and Marine Biology.

Hodges, doctoral student Zachary Cabin and their colleagues just have identified a case of a sudden evolutionary change. In the journal Current Biology, the scientists describe a population of columbines that have lost their petals, including the characteristic nectar spurs. A drastic change caused by a mutation in a single gene. The finding adds weight to the idea that adaptation can occur in large jumps, rather than merely plodding along over extended timespans.

Ever since the theory of evolution was put forward, biologists have debated whether it always occurs in small, gradual steps over long timespans or sometimes as an equilibrium punctuated by abrupt changes. Often, large morphological changes appear within short geologic timescales where intermediate forms may not have fossilized. The question then remains whether many small changes occurred in a short period of time, or perhaps whether single large-scale mutation might be responsible. So, researchers really have to catch the development in action if they hope to build a case that sudden changes can drive evolution.

Enter the Colorado blue columbine. In one population, a mutation has caused many of the plants to lose their petals with the iconic nectar spurs. While not an uncommon occurrence in columbines, spurlessness seems to have stuck around in this area: About a quarter of the plants lack the distinctive feature.

A single gene

The team plumbed the plant's genome to find the source of the unusual morphology. They considered a gene, APETALA3-3, known to affect spur development. They found that this single gene controlled the entire development of the flower's spurs and nectaries.

"The gene is either on or off, so it's about as simple of a change you can get," said lead author Zachary Cabin. "But that simple difference causes a radical change in morphology."

A single broken gene causes mutant plants to develop flowers with no petals or nectar spurs.

If these flowers were preserved in the fossil record, scientist could well sort them into two wholly different genera. And there would also be a puzzling gap: no intermediate form documenting a transition from one morphology to the other.

"This finding shows that evolution can occur in a big jump if the right kind of gene is involved," Hodges said. APETALA3-3 tells the developing organ to become a petal. "When it's broken, those instructions aren't there anymore, and that causes it to develop into a completely different organ, a sepal," he explained.

APETALA3-3 is a type of homeotic gene, one that specifies the development of an entire organ. A mutation in one of these genes can have a drastic effect on an organism's morphology. For instance, one homeotic mutation causes a fly to develop legs where it should have antennae. "Most of the mutations of this nature are going to be like that, just awful," Hodges continued. "The animal won't have any chance of surviving. Biologist Richard Goldschmidt called them 'hopeless monsters.'"

But once in a very long while, one of these radical changes might provide a beneficial trait in a particular environment, creating a "hopeful monster." And a hopeful monster would show that evolution can proceed in single, large jumps, supporting the punctuated equilibrium hypothesis.

"We did not have a good example of a hopeful monster due to a single genetic change," said Hodges, "until now." Researchers have to catch these abrupt changes as they're happening, otherwise they disappear into an organism's genome. For example, other relatives of columbines have lost their petals and nectaries in the past, but it's now impossible to tell if these events occurred in one fell swoop. The fact that it is actively happening in the Colorado blue columbine enabled the team to confirm their status as a hopeful monster.

"There's definitely some luck involved with us being around at the right time to capture this," Cabin said.

Surprising selection

Catching the change in action offers another benefit as well: the opportunity to study the genetics and selective pressures at work.

The team discovered five versions, or alleles, of APETALA3-3, only one of which codes for a petal with a functional nectar spur. The other four were broken, as Hodges put it. They also determined that spurlessness is a recessive trait. The flower will develop normally as long as the plant has one copy of the functional allele. But any two of the mutant alleles together will prevent this. "You can mix and match them," Cabin explained.

About a quarter of Colorado blue columbines in this area display the recessive trait of spurlesness, more than can be attributed to mere chance.

Across all species of columbines it's possible to find rare individuals that develop flowers without nectar spurs. But with a quarter of the Colorado population missing the feature, Cabin and Hodges knew this was more than a chance occurrence. "To get that many of this mutant type really suggests that there's selection favoring it somehow," Hodges said, which he finds odd, since the spur produces nectar that attracts the plant's pollinators.

Hodges is deeply familiar with columbines, and all of his previous research suggests that nectar spurs are important to the group. Even slight changes to the structure have driven speciation and diversification in the genus. "So, how the heck can you lose your spurs and still be favored?" he asked.

Attracting pollinators is only one factor contributing to reproductive success. It turned out the mutant plants actually produced more seeds than their counterparts, much to the team's surprise. They began combing through their observations, searching for an explanation.

"The first time we really realized the pattern was at the airport on the way home," Cabin recalled. He was reading off data as Hodges entered it into the computer. "Scott could see the pattern developing, because he had all the data in front of him, and was getting more and more excited."

The team had recorded herbivory from caterpillars, aphids and deer on the different morphs. Damage from caterpillars and aphids can hamper seed production, Cabin explained, while deer can devastate an entire plant. And as the data built up, a clear trend emerged: Deer and aphids preferred flowers with nectar spurs.

Shifts in floral morphology are usually driven by pollinators, but spurlessness seems to be driven by herbivory. "Natural selection can come from very surprising sources," Hodges said. "It's not always what you'd expect it to be."

Timing it right

Now that they've identified their hopeful monster, Cabin and Hodges plan to investigate the DNA around APETALA3-3 to build a timeline of when the mutations may have occurred. When the gene first mutated, only one of the plant's chromosomes was affected. That means that every descendant with that mutation would have the same genetic code around APETALA3-3 for many generations, Hodges explained.

However, chromosomes do swap alleles occasionally in a process called recombination. By tracking the amount of recombination that has accumulated around the different versions of APETALA3-3, the scientists can estimate how long ago each mutation occurred. More variation requires more time to accumulate. And the closer this variation is to APETALA3-3 itself, the more recombination events there have been since a mutation first appeared.

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Scientists identify new genus and species of legume, now mysteriously extinct

Oregon State University researchers have described a new legume tree from flowers embedded in several lumps of amber recovered from deep within an amber mine in the mountains of the Dominican Republic.

OSU's George Poinar Jr. and Kenton Chambers placed the 20- to 30-million-year-old flowers in a novel genus and species, Salpinganthium hispaniolanum, in the family Fabaceae.

"The flowers are quite striking with their spreading sepals and petals, along with the 10 extended stamens," said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past. "While now darkened with age, the petals were probably white, yellow or even pink, which are the petal colors of the closely related purpleheart tree, whose strong, durable, purplish wood is prized by artists, ship builders, furniture makers and other crafts people."

Groves of purpleheart trees continue to grow along rivers in tropical rain forests in Central and South America, particularly in the Amazon basin, said Poinar, professor emeritus in the Oregon State College of Science.

Poinar and Chambers, professor emeritus in the OSU College of Agricultural Sciences, derived the name of the genus from the Greek words for tube, trumpet and flower. The species name is based on the Caribbean island, Hispaniola, where the fossil originated.

"While purpleheart trees are still with us, Salpinganthium trees have disappeared," said Poinar. "We can only speculate about why these fossil trees have become extinct."

They could have succumbed to some unique biological and/or physical events, such as the loss of a pollinator, presence of a pathogen or climatic change that ravaged populations throughout their entire range, Poinar said. Finding their flowers in five separate pieces of amber shows that they were well established in the Dominican amber forest, he added.

Poinar and Chambers placed Salpinganthium hispaniolanum, the latest in a number of flowers described by the authors from Dominican amber mines, in the resin-producing tribe Detarieae; the tribe's members have sepals and petals dotted with glands.

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Big bumblebees learn locations of best flowers

 Big bumblebees take time to learn the locations of the best flowers, new research shows.

Meanwhile smaller bumblebees -- which have a shorter flight range and less carrying capacity -- don't pay special attention to flowers with the richest nectar.

University of Exeter scientists examined the "learning flights" which most bees perform after leaving flowers.

Honeybees are known to perform such flights -- and the study shows bumblebees do the same, repeatedly looking back to memorise a flower's location.

"It might not be widely known that pollinating insects learn and develop individual flower preferences, but in fact bumblebees are selective," said Natalie Hempel de Ibarra, Associate Professor at Exeter's Centre for Research in Animal Behaviour.

"On leaving a flower, they can actively decide how much effort to put into remembering its location.

"The surprising finding of our study is that a bee's size determines this decision making and the learning behaviour."

In the study, captive bees visited artificial flowers containing sucrose (sugar) solution of varying concentrations.

The larger the bee, the more its learning behaviour varied depending on the richness of the sucrose solution.

Smaller bees invested the same amount of effort in learning the locations of the artificial flowers, regardless of whether sucrose concentration was high or low.

"The differences we found reflect the different roles of bees in their colonies," said Professor Hempel de Ibarra.

"Large bumblebees can carry larger loads and explore further from the nest than smaller ones.

"Small ones with a smaller flight range and carrying capacity cannot afford to be as selective, so they accept a wider range of flowers.

"These small bees tend to be involved more with tasks inside the nest -- only going out to forage if food supplies in the colony are running low."

The study was conducted in collaboration with scientists from the University of Sussex.

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