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Environmental change drove macroevolution in cupuladriid bryozoans

Smithsonian Libraries
Most macroevolutionary events are correlated with changes in the environment, but more rigorous evidence of cause and effect has been elusive. We compiled a 10 Myr record of origination and extinction, changes in mode of reproduction, morphologies and abundances of cupuladriid bryozoan species, spanning the time when primary productivity collapsed in the southwestern Caribbean as the Isthmus of Panama closed. The dominant mode of reproduction shifted dramatically from clonal to aclonal, due in part to a pulse of origination followed by extinction that was strongly selective in favour of aclonal species. Modern-day studies predict reduced clonality in increasingly oligotrophic conditions, thereby providing a mechanistic explanation supporting the hypothesis that the collapse in primary productivity was the cause of turnover. However, whereas originations were synchronous with changing environments, extinctions lagged 1â€"2 Myr. Extinct species failed to become more robust and reduce their rate of cloning when the new environmental conditions arose, and subsequently saw progressive reductions in abundance towards their delayed demise. Environmental change is therefore established as the root cause of macroevolutionary turnover despite the lag between origination and extinction.

Environmental change preceded Caribbean extinction by 2 million years

Smithsonian Libraries
Communicated by W. A. Berggren, Woods Hole Oceanographic Institution, Woods Hole, MA, December 10, 2006 (received for review May 1, 2006)Paleontologists typically treat major episodes of extinction as single and distinct events in which a major environmental perturbation results in a synchronous evolutionary response. Alternatively, the causes of biotic change may be multifaceted and extinction may lag behind the changes ultimately responsible because of nonlinear ecological dynamics. We examined these alternatives for the major episode of Caribbean extinction 2 million years ago (Ma). Isolation of the Caribbean from the Eastern Pacific by uplift of the Panamanian Isthmus was associated with synchronous changes in Caribbean near shore environments and community composition between 4.25 and 3.45 Ma. Seasonal fluctuations in Caribbean seawater temperature decreased 3-fold, carbonate deposition increased, and there was a striking, albeit patchy, shift in dominance of benthic ecosystems from heterotrophic mollusks to mixotrophic reef corals and calcareous algae. All of these changes correspond well with a simple model of decreased upwelling and collapse in planktonic productivity associated with the final stages of the closure of the isthmian barrier. However, extinction rates of mollusks and corals did not increase until 3-2 Ma and sharply peaked between 2 and 1 Ma, even though extinction overwhelmingly affected taxa commonly associated with high productivity. This time lag suggests that something other than environmental change per se was involved in extinction that does not occur as a single event. Understanding cause and effect will require more taxonomically refined analysis of the changing abundance and distribution patterns of different ecological guilds in the 2 million years leading up to the relatively sudden peak in extinction.

New Hall of Human Origins points to environmental change as major force in evolution of hominins

Smithsonian Insider

Based on decades of cutting-edge research, the 15,000-square-foot Hall of Human Origins offers visitors an immersive, interactive journey through 6 million years of human evolution spelling out how defining characteristics of the human species have evolved during millions of years in response to a changing world.

The post New Hall of Human Origins points to environmental change as major force in evolution of hominins appeared first on Smithsonian Insider.

Environmental change prior to the K-T boundary inferred from temporal variation in the morphology of cheilostome bryozoans

Smithsonian Libraries
Fluctuations in the marine environment just prior to the K-T extinction event have been inferred from several geological sections around the world. Most previous studies have employed isotope or trace element proxies. This study uses morphological changes in erect and free-living cheilostome bryozoans as a proxy to investigate environmental change through the final stages of the Maastrichtian at the Nye Kiev section in Denmark. The metrics used are: (1) mean zooid size as a proxy for temperature; (2) intracolony variation in zooid size as a proxy for degree of seasonality; (3) density of defensive avicularia as a proxy for palaeoproductivity; and (4) colony size and asymmetry as proxies for unfavourable environmental conditions. Three semi-distinct phases in the benthic environment are evident: The lowest 3.5 m of the roughly 4.5 m section experienced apparently normal marine conditions. Next, low estimates of benthic seasonality, and highly symmetrical and large colonies with many avicularia indicate a time of increased environmental stability. Subsequent to this quiescence, the uppermost similar to 20 cm of the section witnessed environmental volatility and deterioration with mean zooid sizes in all species falling dramatically suggesting a rapid warming or dysoxic event, sharply increasing seasonality estimates implying unusual oceanographical states, and the growth of small, asymmetrical colonies with few avicularia all suggesting unfavourable conditions. These data therefore indicate that strong environmental perturbations occurred just prior to the K-T boundary in the Danish Basin. Such events may have contributed to biotic turnover at the K-T boundary because cause and effect in macroevolution can be delayed. However, potential mechanisms of turnover need to be robustly tested within a detailed palaeoenvironmental framework construct from a suite of independent proxies. (C) 2011 Elsevier B.V. All rights reserved.

Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea

Smithsonian Libraries
Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian–Permian transition in North–Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific habitats, during both short-term cyclic environmental change and a long-term trend of increasing aridity. The deposits examined principally comprise the terrestrial Markley and its approximate marine equivalent, the Harpersville Formation and parts of lower Archer City Formation. Fossiliferous deposits are lens-like, likely representing fill sequences of channels formed during abandonment phases. Palaeosols, represented by blocky mudstones, comprise a large fraction of the deposits. They suggest progressive climate change from minimally seasonal humid to seasonal subhumid to seasonal dry subhumid. Five lithofacies yielded plants: kaolinite-dominated siltstone, organic shale, mudstone beds within organic shale, coarsening upward mudstone–sandstone interbeds and channel sandstone. Both macro- and microflora were examined. Lithofacies proved compositionally distinct, with different patterns of dominance diversity. Organic shales (swamp deposits), mudstone partings (swamp drainages) and coarsening upward mudstone–sandstone interbeds (floodplains) typically contain Pennsylvanian wetland vegetation. Kaolinite-dominated siltstones and (to the extent known) sandstones contain taxa indicative of seasonally dry substrates. Some kaolinite-dominated siltstones and organic shales/coals yielded palynomorphs. Microfloras are more diverse, with greater wetland–dryland overlap than macrofloras. It appears that these two floras were coexistent at times on the regional landscape.

Environmental Button

National Museum of American History
Some environmental campaigns sought to change the behavior of government agencies. As the world’s largest public engineering, design, and construction agency, the U.S. Army Corps of Engineers attracted broad-based criticism in the 1960s and thereafter for its aggressive program of dams and channel building. River advocates in particular were urged to “Keep Busy Fighting the Corps.”

Annotating Change in Satellite Images

SI Center for Learning and Digital Access
Lesson plan where students observe and analyze land use change over time, using before and after satellite images to create an animated view. Identifying, outlining, and marking areas of change in the images results in a color-coded map that shows the location and geographical extent of change. This technique can be used with deforestation, urbanization, changes in the shoreline, and flooding.

Environmental Button

National Museum of American History
This button depicts the polar bear, one of the most beloved species on the planet. It, along with the whale, gorilla, and elephant, is sometimes referred to as “charismatic megafauna” because of its popularity with humans.

Environmental groups have often used charismatic megafauna in campaigns to increase public awareness about conservation efforts. By employing people’s inherent interest in these animals, they are able to attract attention towards needs which might otherwise have been disregarded. For example the polar bear has been used to highlight issues ranging from wilderness preservation to climate change.

Environmental Button

National Museum of American History
The National Association of Audubon Societies was founded in 1905 to protect birds whose populations were being decimated by hunters for the plume (feather) trade. The organization was named after John James Audubon, a 19th century naturalist and artist who produced the book series Birds of America, published between 1827 and 1838. In 1940 the Association changed its name to the National Audubon Society, and since that time it has become engaged with a broad array of environmental concerns.

Environmental Button

National Museum of American History
Several types of renewable energy sources are available as alternatives to non-renewable, carbon-based fuels. This button advocates the use of solar energy to generate electricity. It was distributed in 1978 by Solar Action, the Washington, D.C.-based organization that helped to organize Sun Day (3 May 1978.) For many people, the 1970s energy crisis was a call to action to change how electricity was generated and used. Making the choice to “go solar”—and encouraging others to do the same—reflected growing optimism about the potential of clean, accessible solar energy.

Change No Chainsaws

National Museum of American History

Smithsonian Environmental Research Center Video Conferences

SI Center for Learning and Digital Access
Interactive videoconferences, 30 to 60 minutes, on topics related to SERC research including animals, plants, and ecology. Students participate in hands-on science demonstrations and interact with SERC staff.

Music as Environmental Advocacy

SI Center for Learning and Digital Access
Smithsonian archivist Jeff Place looks at the lives and works of musicians who have spread a message of appreciation and personal responsibility for our rivers, lakes, and oceans.

How Legos Could Change What We Know About Plants

Smithsonian Magazine

More than a half century after it hit shelves, the humble Lego brick remains a wildly successful toy, thanks to the building block’s versatility as well as multiple licensing deals over the last decade (which, most recently, catapulted the company over Mattel to make it the top toy maker in the world).

But Lego bricks have also occasionally found their way into laboratories as tools for scientific research.  A team at The University of Cambridge, for instance, used the bricks to build synthetic bones.

Now, researchers at Iowa State University have turned to transparent Lego bricks as a novel, low-cost way to study plant growth. The work, recently published in the journal PLOS One, argues that the bricks can be used to create highly precise, centimeter-scale systems with chemical gradients to study how chemical changes affect root growth.

Understanding how chemical and environmental changes affect plant root growth could increase crop yields and give us a better understanding of how certain crops will react to climate change.

Ludovico Cademartiri, an assistant professor of materials science and engineering at Iowa State University and a co-author of the paper, told that the idea of using Legos came out of a brainstorming session sparked by how surprisingly little is known about the way plants respond to environmental changes.

“There is a growing consensus that it is one of the most important areas that needs development for plant science and Agronomy,” Cademartiri says. “If we want to improve our crop yields, we need to learn how plants respond to very complex environmental cues.”

He says the reason we don’t yet know more about the subject is, in part, because of a lack of tools available for these precise kinds of experiments.  High-level techniques have long existed to study small single- or multi-celled organisms, but plants present a problem in that they start out tiny and grow much larger throughout the time of study. Greenhouses work well for large studies that require all plants to have a homogeneous external environ­­ment (the same level of heat and humidity, for instance, among other factors). But imagine a plant experiment in which scientists might need to set up 100 plants in 100 different controlled environments, both above and below the soil level, with each setup allowing enough room for the plant to grow, and you start to get a sense of the problem.

Existing microfluidic technologies allow scientists like molecular biologists to control test environments with the precision of a millionth of a meter, but those systems can be very difficult and expensive to scale up for plant research.

Transparent Lego bricks present a happy medium, in that they are affordable but create environments precise enough for serious study, as Cademartiri and his team learned when they began to investigate the idea.

The researchers chose off-the-shelf transparent Lego pieces, which can be purchased individually directly from Lego's Website, put them in an autoclave for sterilization, then used the pieces to build rectangular containers to hold the gel or other soil substitute. The containers can be built to varying sizes to accommodate different plant sizes or root types. When an experiment is over, the pieces can be broken down, cleaned and used again.

Doctoral student Kara Lind, another author of the study, worked on ways to ensure Lego bricks could hold the transparent gels that are used as soil substitutes to allow researchers to easily see root changes, the Iowa State News Service reported. She also worked out ways to create specific chemical gradients within the structures, to see how plants react to different chemicals, be they toxins or nutrients. 

The result: “It turned out that Lego performed a lot better than we thought, for a couple of reasons,” Cademartiri says. 

For one, a “transparent Lego is made of polycarbonate, so that means it can be sterilized, which makes it ideally suitable for biological work," he says. The bricks are also chemically inert, so they won’t react with surrounding materials and potentially spoil experiments.

The team aims to continue to develop Legos as a platform and tool set for serious plant study, in the hopes that other scientist will find the iconic bricks useful in their own research.   

Cademartiri says it’s too soon to tell to what extent scientists will or won’t take up Legos for plant study, but he is optimistic. Educators have long been using Legos in classrooms, and the company's Mindstorms robotics line, aside from being used to help build artificial bones, have also been used by researchers at the University of Vermont to create robots that change their shape to "learn" how to walk. So it's at least likely that Lego bricks will continue to find an occasional home in research laboratories as well as the toy box.

“What we did was to force ourselves to create the simplest, cheapest, most convenient, and capable tools that we could devise,” Cademartiri says. “So, we’re hoping that other scientists will find them useful, and we think they will.”

Idealabs: Prehistoric Climate Change (and Why It Matters Today)

SI Center for Learning and Digital Access
Online interactive in which students compare leaf fossils to learn about the climate millions of years ago. They also meet a Smithsonian paleontologist in a video.

Five Conflicts and Collapses That May Have Been Spurred by Climate Change

Smithsonian Magazine

Is climate change a matter of national security? In a warming world, sea-level rise, drought and soil degradation are putting basic human needs such as food and shelter at risk. In March, the U.S. Department of Defense called climate change a "threat multiplier," saying that competition for resources "will aggravate stressors abroad such as poverty, environmental degradation, political instability and social tensions—conditions that can enable terrorist activity and other forms of violence."

Connecting climate change to a global increase in violence is tricky, and attempts to make such a link receive a fair amount of criticism. A hotter planet doesn't automatically become a more conflict-ridden one. The 2000s, for instance, saw some of the highest global temperatures in recorded history—and some of the lowest rates of civil conflict since the 1970s.

But there are historical examples of civilizations that did not fare well when faced with drastic environmental change, and those examples may offer a window into the future—and even help prevent catastrophe. "We can never know with 100-percent certainty that the climate was the decisive factor [in a conflict]," says Solomon Hsiang, assistant professor of public policy at the University of California, Berkeley. "But there's a lot of cases where things look pretty conspicuous."

Environmental Dilemma Part I

SI Center for Learning and Digital Access
Teacher-created lesson in which students devise a plan or create an invention to combat global warming.

Climate Change Cuts Climate Change Study Short

Smithsonian Magazine

Doing environmental research isn't easy. From wild animals to foul weather, researchers have to jump lots of unexpected hurdles while collecting data. But as The Guardian’s Ashifa Kassam reports, for one group of Canadian climate scientists, the obstacle standing in their way was their research subject itself: climate change.

A huge study called BAYSYS launched earlier this year with the goal of understanding how climate change affects the Hudson Bay. BAYSYS is a massive undertaking. The project is composed of five research teams of scientists from seven Canadian universities and Manitoba Hydro, and costs over $11 million U.S. dollars. But in May, the first leg of the trip went horribly wrong and scientists were forced to turn back. 

Blame a bevy of icebergs for the abandoned trip. As Kassam reports, an icebreaker the researchers were using got diverted off the coast of Newfoundland when huge chunks of ice trapped boats in the area. When the team studied the ice that was holding up their boat, notes Kassam, they realized it was Arctic ice that had made its way south due to—you guessed it—climate change.

The Canadian Coast Guard tells CBC News’ Laura Glowacki that they had never seen those kinds of conditions in the area. Glowacki reports that the ice was multi-year ice, not the thinner varieties that can be found on the North American coast. It usually forms in the Arctic due to the landlocked geography of the region. But because it forms over many years instead of a single season, explains the National Snow & Ice Data Center, it’s much tougher than other ice and can be hard for icebreakers like the one used by the Canadian scientists to sail around and clear away.

According to NASA, over 13 percent of all Arctic sea ice is melting every decade. This ice melt serves as a kind of bellwether of the severity and pace of climate change. The melt is driven by a warming atmosphere, which in turn heats the oceans. As warmer water circulates, multiyear ice thins. Chunks of this ice break off and are carried along on the ocean’s currents. Thinning also reduces the insulating properties of the ice, which protects the freezing arctic atmosphere from the relatively warm ocean waters. But without this barrier, the atmosphere has no insulation from the ocean heat, further warming the planet.

In the future, that melt could do much more than cut scientific missions short. As ocean physicist Peter Wadhams notes for Yale Environment 360, scientists expect a barrage of cascading effects from Arctic ice melt. The Arctic ice that does remain is expected to absorb less heat, warming global temperatures. As permafrost melts, it spews warming methane in to the atmosphere. And all that escaping water means more atmospheric water vapor, which in turn warms the air even more.

As for the expedition, all is not lost. Kassam reports that its second leg will continue in July. If anything, it shows how important climate change research will be as long as scientists can make it to the areas they need to explore to learn more.

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