Brown University, Providence, Rhode Island

A conservation biologist considers the role of nature reserves in a warming world.

Over the next 100 years, climate change is expected to extirpate many species from their current locations. As a scientist who studies these effects, I was surprised by the magnitude of a recent projection. Of the nearly 500 protected reserves in the San Francisco Bay area of California, more than 98% are expected to have entirely different summer temperatures going forwards, with no overlap between the warmest conditions found within these areas now and the coolest conditions in the future.

David Ackerly at the University of California, Berkeley, and his team studied the pace of climate change in the western United States (D. D. Ackerly et al. Divers. Distrib. 16, 476–487; 2010). By mapping current temperatures and those projected by a moderate warming scenario, they found that the geographical locations of specific temperatures will move by as much as 4.9 kilometres per year. This means that conditions currently experienced at a particular location could shift by hundreds of kilometres in just 50 years.

These findings have important implications for the design and management of protected areas. With climate change, most reserves will not maintain conditions that are suitable for the set of species that exists there at present. To survive, many species will need to move, either on their own or with human assistance. Accommodating this will require a major change in the perceived role of nature reserves. Traditionally, these have been managed as ‘museums’ that maintain historically accurate compositions of species and ecosystems. In the future, we may need some reserves to function as ‘way stations’, with transient compositions of species. This may be the only way to promote the long-term conservation of species that can no longer survive in their present locales.

Okinawa Institute of Science and Technology, Japan

A neuroscientist explores what brain imaging can reveal about deliberative and intuitive decision-making.

When you pick a dish from a menu, do you select it for its taste or its calculated nutritional benefits? The decision-making processes of intuition and deliberation can be considered as, respectively, model-free learning, which involves trial and error, and model-based learning — evaluating future outcomes using a pre-learned model of the results of choices. A big question is how these complementary processes are realized in the brain.

Using functional magnetic resonance imaging (fMRI) in humans, Jan Gläscher at the California Institute of Technology in Pasadena and his co-authors found neural signatures for these two modes of learning (J. Gläscher et al. Neuron 66, 585–595; 2010). The team scanned the brains of volunteers as they learned a two-step choice task. During the first part of the study, volunteers were presented with an abstract image and had to choose a left- or right-button press. Depending on which button they chose, they were then presented with another image and asked to make a second left-or-right choice to see a third image.

Over many trials, the volunteers learned the probability of a certain image resulting from a particular choice. During the half-time break, they were told that each final image would have a specific monetary reward (0, 10 or 25 cents). During the second half of the study, volunteers could use what they had learned in the first half to make profitable choices.

Analysis of the fMRI data revealed involvement of the brain’s intraparietal and lateral prefrontal cortices in model-based learning, and the ventral striatum in model-free learning. The study paints a new picture of the neuroscience of deliberation versus intuition. We should now be able to ask not only where in the brain but also by what algorithms we make decisions.

Free University of Brussels

A cancer biologist marvels at how key gene regulators are still revealing hidden talents.

What a difference time makes! It does not seem long since I learned, as a university student and as if it was a closed topic, that the regulation of fruitflies’ ‘homeotic’ genes — which control developmental patterns — is carried out by the Polycomb group of proteins. However, over the past couple of years, thanks to the booming field of epigenetics, these proteins have been given a new lease of life in research labs. They are proving to be multifaceted and dynamic in a range of cellular activities, including cancer progression.

In this light, work by Danny Reinberg at the New York University School of Medicine and his team captured my attention (G. Li et al. Genes Dev. 24, 368–380; 2010). The group addressed one of the burning questions in the field: how exactly does the Polycomb-repressive complex 2 (PRC2), which comprises these Polycomb proteins, recognize and home in on the genes that it regulates? The authors show that the protein encoded by the gene Jarid2, which is also important for development, forms a key component of the PRC2 complex and is involved in its recruitment to target DNA sequences. A slew of recent studies from other groups report similar observations.

The jury is still out on the precise mechanism by which JARID2 aids in the recruitment of PRC2 to its target genes. It is already evident that Jarid2 is only one piece of an elaborate puzzle, and we can expect many exciting discoveries of the remaining pieces. Clearly, Polycomb proteins, which have been well studied since they were discovered more than 50 years ago, are still yielding new insight into gene regulation and other cell activities — and are thus a formidable force to be reckoned with, in both biology and medicine.

Joseph Fourier University, Grenoble, France

A geoscientist ponders possible links between erosion and Earth’s climate.

Mountain ranges have been eroding at an increasing rate over the past 60 million years — seemingly in response to a cooling climate. Some researchers have proposed that this higher rate of erosion has increased the rate at which tectonic plates move at Earth’s surface, suggesting that there is a link between Earth’s climate and its tectonics.

As a member of the Earth science community who studies the relationship between these factors, I was interested in findings by Anthony Dosseto of Macquarie University in Sydney, Australia, and his co-authors. They measured the change in the sediment erosion rate over the past 100,000 years, a period that includes the last glacial cycle (A. Dosseto et al. Geology 38, 395–398; 2010). By dating sediments from several locations in the Murrumbidgee River catchment of southeastern Australia, they discovered that the residence time — the length of time for which sediments remain on the landscape before they are eroded away — varied over geological time. The residence time was longer during warmer periods (such as around 100,000 years ago and today) and shorter during colder periods (such as around 15,000 years ago).

The authors interpret this change in residence time as a consequence of variations in vegetation type. The absence of trees in the higher parts of the catchment during cold periods resulted in an increased erosion rate, whereas the eucalyptus forest that was present during the warm periods slowed the erosion rate.

These results provide a rare quantitative estimate of the influence of vegetation and climate on erosion. This link might also be relevant to estimating how the current anthropogenic changes to Earth’s climate and vegetation affect soil erosion.

University of Vienna

A cognitive biologist foresees breakthroughs in understanding vocal learning.

Vocal learning — the capacity to reproduce sounds heard in the environment — is key to human speech. Humans are alone among primates in having vocal-learning abilities, but a surprising variety of non-primates, such as songbirds and parrots, are also excellent vocal learners. The list of mammals with the ability is comparatively short, comprising humans, some whales and seals, and probably elephants. Now research on tropical bats has added another creature to the list.

Mirjam Knörnschild at the University of Erlangen-Nuremberg in Germany and her colleagues studied sac-winged bats (Saccopteryx bilineata) in Costa Rica (M. Knörnschild et al. Biol. Lett. 6, 156–159; 2010). Male Saccopteryx produce elaborate courtship displays that include complex songs. Surprisingly, young bats also produce songs, and acoustic analysis showed that as the bats grew older, their songs became more like those of the local territorial male. For about half the pups, the local male was not their father, ruling out simple genetic effects. Moreover, pups’ songs often became less species-typical over time, ruling out simple maturation. This research thus provides the first clear evidence for complex vocal learning in bats.

The finding is exciting for several reasons. First, the species is the only mammalian vocal learner that could conveniently be kept and eventually bred in the lab, opening the door to detailed scientific investigation. Second, previous work suggests that the FOXP2 gene, which is known to be involved in vocal learning in humans and birds, has also been under strong selection in bats, although we don’t yet know why. Echolocation is probably part of the answer, but this study suggests that social communication could be another. I believe that research on Saccopteryx will usher in an era of increased understanding of mammalian vocal learning.