Serpentine ecosystems shed light on nature of plant adaptation, speciation

Plants that live in unusual soils, such as those that are extremely low in essential nutrients, provide insight into the mechanisms of adaptation, natural selection, and endemism. A seminal paper by Arthur Kruckeberg from 1951 on serpentine plant endemism has served as a solid bedrock foundation for future research on the link between natural selection and speciation. A recent article in the American Journal of Botany focuses on how this paper has influenced subsequent research on local adaptation, evolutionary pathways, and the relationship between climate, soils, and endemism.In the latest in a series of AJB Centennial Review papers, AJB Anacker (University of California, Davis) examines the impact that Kruckeberg’s 1951 AJB paper has had on our subsequent understanding of plant evolution and ecology.Kruckeberg’s classic paper reported on reciprocal transplant experiments, in which he made several generalizations about plant competition, local adaptation, and speciation. Kruckeberg showed that the strong selective pressures of serpentine soils — characterized by low amounts of essential nutrients and water, and high in heavy metals — can lead to the formation of soil ecotypes (genetically distinct plant varieties), representing a possible first step in the evolution of serpentine endemism (e.g., plants that are only found on serpentine type soils). These important initial findings spurred subsequent research on determining plant traits (from molecular to organismal) that underlie serpentine adaptation.Anacker draws attention to a second significant contribution of Kruckeberg’s paper — researching the historic origins of endemic species, such as those found in serpentine soils. Anacker explains that endemic species are thought to originate in two ways: neoendemics are species that have formed relatively recently via nearby progenitor taxa, and paleoendemics are species that formed following habitat-specific population extirpation. Kruckeberg viewed serpentine ecotypes as representing the first step along the path of paleoendemism. While this stimulated much research in this area, Anacker points out that several serpentine endemics appear to have arisen from nearby progenitor taxa, and thus the neoendemic pathway is also likely important.Interestingly, Kruckeberg’s experiments also showed that many serpentine ecotypes actually performed better on the non-serpentine soils than on serpentine soils, which begs the question of why serpentine-adapted plants are not also found on non-serpentine soils. Anacker points out that Kruckeberg was one of the first to indicate that competition may play a key role in serpentine specialization. He also highlights recent research indicating that serpentine species are typically slow-growing stress tolerators rather than fast-growing competitive dominants, and their adaptations for being more drought-tolerant puts them at a disadvantage in soils where water and nutrients are not limiting.While serpentine ecosystems are special and unique environments, Kruckeberg and subsequent researchers have shown how important these systems are for shedding light on broader aspects of plant ecology and evolution.The 1951 paper can be accessed online at: http://www.jstor.org/discover/10.2307/2438248?uid=3739448&uid=2&uid=3737720&uid=4&sid=21103728973903Story Source:The above story is based on materials provided by American Journal of Botany. …

Read more

Delaying climate policy would triple short-term mitigation costs

Sep. 12, 2013 — Higher costs would in turn increase the threshold for decision-makers to start the transition to a low-carbon economy. Thus, to keep climate targets within reach it seems to be most relevant to not further postpone mitigation, the researchers conclude.”The transitional economic repercussions that would result if the switch towards a climate-friendly economy is delayed, are comparable to the costs of the financial crisis the world just experienced,” lead-author Gunnar Luderer says. The later climate policy implementation starts, the faster — hence the more expensive — emissions have to be reduced if states world-wide want to achieve the internationally agreed target of limiting global warming to 2 degrees above pre-industrial levels. A binding global agreement to implement the emissions reductions required to reach this target is currently still under negotiation, while global emissions have continued to rise.”For the first time, our study quantifies the short-term costs of tiptoeing when confronted with the climate challenge,” Luderer says. “Economists tend to look at how things balance out in the long-term, but decision-makers understandably worry about additional burdens for the people and businesses they are responsible for right now. So increased short-term costs due to delaying climate policy might deter decision-makers from starting the transformation. The initial costs of climate policies thus can be more relevant than the total costs.”Future energy price increases could be limitedThe researchers investigated a number of cost dimensions, including climate policy effects on energy prices. If emissions reductions are delayed beyond 2030, global energy price levels are likely to increase by 80 percent in the short term. Such price increases are of particular concern because of the burden they put on the world’s poor. …

Read more

Overweight and obese women are equally capable of the impulse control that lean women exhibit

Aug. 30, 2013 — Dieters call it willpower; social scientists call it delayed gratification.It’s the ability to delay an immediate reward in favor of a bigger future reward, for example, having a slimmer body in a few months versus the hot fudge sundae now. Previous studies have shown that overweight and obese people have a harder time delaying gratification, so they are more likely to forego the healthy body later on in favor of eating more calorie-dense foods now.But University at Buffalo research published last month in the journal Appetite now shows that behavioral interventions that improve delay of gratification can work just as well with overweight and obese women as with lean women.”This research is certainly welcome news for people who have struggled to lose weight, because it shows that when people are taught to imagine, or simulate the future, they can improve their ability to delay gratification,” says obesity expert, Leonard H. Epstein, PhD, SUNY Distinguished Professor in the UB School of Medicine and Biomedical Sciences, who was senior author on the research.The research is part of a field called prospection, the process by which people can project themselves into the future, by mentally simulating future events.Some of the most famous research done on delay of gratification includes experiments done at Stanford University in the 1960s and 1970s, where children were given an opportunity to either eat a single snack, such as a marshmallow now, or, if they waited a period of time, they could be rewarded with multiple snacks. Follow-up studies found that in general, those who were able to wait were more responsible and successful in their adult lives.Epstein notes that many people have difficulty resisting the impulse for immediate gratification. Instead, they do something called delay discounting, in which they discount future rewards in favor of smaller, immediate rewards. This tendency is associated with greater consumption of highly caloric, ready-to-eat foods. It has been speculated that if people could modify delay discounting, they would be more successful at losing weight. “Now we have developed a treatment for this,” says Epstein. “We can teach people how to reduce delay discounting, where they learn how to mentally simulate the future in order to moderate their behavior in the present.”The UB researchers evaluated how much delay discounting participants engaged in using a hypothetical test that promised different amounts of money available either now or in the future. …

Read more

Pre-war insect hunters help to save our pollinators

Aug. 22, 2013 — Maps made more than seventy years ago and records collected by amateur naturalists between the World Wars are providing new clues about declining pollinator numbers, ecologists have found. By showing which land use changes have driven pollinator declines over the past 100 years, the research reveals how we could ensure future land use benefits these vital insects.The results are presented at INTECOL, the world’s largest international ecology meeting, in London this week.Using newly-developed statistical techniques, the team from Reading, Leeds and the Centre for Hydrology & Ecology analysed two sets of historical data: pollinator data from 1921-1950 based on more than half a million records collected by the Bees, Wasps and Ants Recording Society since 1800 and now digitised; and the Dudley Stamp Land Utilisation survey from the 1930s, the earliest known land use map of Britain.By comparing this historical data for 21 sites across England with recent pollinator records and land cover maps, they found that 85% of sites had suffered declines in pollinator species richness of between 10 and 50% over the past 80-100 years.The results show urban landscapes might not be as detrimental to pollinator communities as previously thought; sites with an increased level of urbanisation around them show smaller declines in pollinator diversity. According to Dr Deepa Senapathi of the University of Reading: “This doesn’t mean that concrete jungles are good for pollinators, but urban environments may offer diverse forage resources in the shape of people’s gardens, parks, churchyards and green spaces which in turn could help support these insects.”This is the first study of its kind to look at the impact of historic land-use change on pollinator communities in Britain. It shows that the dramatic changes in land use since World War II — in particular agricultural intensification and urbanisation — have had a significant impact on pollinator communities.As well as helping explain how past land use change has driven pollinator declines, history offers important lessons about how to improve things in future. “Understanding the major step changes in land utilisation over the last 80-100 years provides a unique understanding of the drivers within changing land-use that might have the most significant impact on pollinator communities,” Dr Senapathi says.In particular, pollinators would benefit from more diverse landscapes. “Based on our results it looks increasingly like sites which were predominantly heathland but are now a combination of heathland, grassland and woodland probably provide a better landscape for pollinators than a landscape with just one habitat type,” she explains.

Read more

What can plants reveal about global climate change?

July 26, 2013 — Recently, climate change, including global warming, has been a “hot” news item as many regions of the world have experienced increasingly intense weather patterns, such as powerful hurricanes and extended floods or droughts. Often the emphasis is on how such extreme weather impacts humans, from daily heat index warnings to regulating CO2 emissions. While the media continues to present climate change as a controversial issue, many scientists are working hard to gather data, collaborate across disciplines, and use experimental and modeling techniques to track how organisms and ecosystems are responding to the current changes in our Earth’s global environment.A group of organisms that play a wide variety of crucial roles in our global ecosystems is plants. What role do plants play in helping to regulate climate change and how will they fare in future times? A new series of articles in a Special Issue on Global Biological Change in the American Journal of Botany expands our view on how global changes affect and are affected by plants and offers new ideas to stimulate and advance new collaborative research.Global change includes topics such as increasing carbon dioxide and its effect on climate, habitat fragmentation and changes in how protected and agricultural lands are used or managed, increases in alien species invasions, and increased use of resources by humans. There is increasing concern that these changes will have rapid and irreversible impacts on our climate, our resources, our ecosystems, and ultimately on life, as we know it. These concerns stimulated Stephen Weller (University of California, Irvine), Katharine Suding (University of California, Berkeley), and Ann Sakai (University of California, Irvine) to gather together a diverse series of work from botanists spanning disciplines from taxonomy and morphology to ecology and evolution, from traditional to multidisciplinary approaches, and from observations and experiments to modeling and reviews, to help synthesize our knowledge and stimulate new approaches to tackling these global biological change issues.”We have been concerned about the rapid and irreversible changes associated with a rapidly increasing human population that is already over seven billion people,” commented Weller. “Many people are familiar with the impact of rising temperatures and greater intensity of storms on humans, but have less understanding of the effects of these and other global changes on the foundation of our biological ecosystems — plants.”Focusing on a group of organisms such as plants may help provide us with insights into how such crucial organisms have responded to climate changes in the past and how they might respond to future changes. Moreover, since impacts occur from the cellular and molecular basis to the ecosystem and evolutionary scale, this Special Issue provides an excellent opportunity to synthesize the current knowledge of global change effects on a wide spectrum of aspects of plant biology, ecology, and evolution.”Plant biologists work at different levels of organization with diverse approaches and techniques to address questions about global change,” notes Suding. “What is the effect of global change on plants, and how are plants affected by global change? …

Read more

Utilizzando il sito, accetti l'utilizzo dei cookie da parte nostra. maggiori informazioni

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close