Directional selection effects on patterns of phenotypic (co)variation in wild populations.

Phenotypic (co)variation is a prerequisite for evolutionary change, and understanding how (co)variation evolves is of crucial importance to the biological sciences. Theoretical models predict that under directional selection, phenotypic (co)variation should evolve in step with the underlying adaptive landscape, increasing the degree of correlation among co-selected traits as well as the amount of genetic variance in the direction of selection. Whether either of these outcomes occurs in natural populations is an open question and thus an important gap in evolutionary theory. Here, we documented changes in the phenotypic (co)variation structure in two separate natural populations in each of two chipmunk species (Tamias alpinus and T. speciosus) undergoing directional selection. In populations where selection was strongest (those of T. alpinus), we observed changes, at least for one population, in phenotypic (co)variation that matched theoretical expectations, namely an increase of both phenotypic integration and (co)variance in the direction of selection and a re-alignment of the major axis of variation with the selection gradient

Incinerate, recycle, or wash and reuse

What is the best way to minimize the environmental impact of using a product such as paper? Three debating teams were formed within a university class. One team advocated increased recycling of paper. Another team pointed to evidence showing reduced environmental impact and lower net CO2 emissions if the paper is incinerated rather than recycled. A third team advocated the replacement of paper by items such as porcelain plates and video screens, cutting costs and reducing waste by multiple reuse

“RETRO-,” AN EMERGING PREFIX FOR FUTURE TECHNOLOGICAL DEVELOPMENT?

It is proposed that the prefix “retro” can serve as an irreverent, but timely buzzword for the development of new technology to meet human needs. Society has carried out experiments at a very large scale for the last century or so to meet our collective needs though the use of fossil-based fuels and synthetic materials. Those experiments have seemed successful in the short term, feeding more of us and supplying a lot of us with rising standards of living. But the experiments often have failed us in terms of sustainability. A health crisis, global warming, and resource depletion are urgent problems caused by careless use of fossil fuels and related synthetic organic chemicals. The prefix “retro,” as in “retrotechology,” signals a disciplined return to a reliance on nature-based products, as well as a respect for the beauty, but also the fragile character of our natural environment

From here to sustainability

Many readers and contributors to BioResources are working to develop sustainable technology. Such research attempts to use products of photosynthesis to meet long-term human needs with a minimum of environmental impact. Archeological and historical studies have concluded that the long-term success or failure of various past civilizations has depended, at least in part, on people’s ability to maintain the quality of the resources upon which they depended. Though it is possible for modern societies to learn from such examples, modern societies are interconnected to an unprecedented degree. It is no longer realistic to expect one region to be immune from the effects of environmental mistakes that may happen elsewhere in the world. Research related to renewable, lignocellulosic resources is urgently needed. But in addition to the research, there also needs to be discussion of hard-hitting questions, helping to minimize the chances of technological failure. The next failed civilization may be our own

Sensing the electrokinetic potential of cellulosic fiber surfaces

The charged nature of a cellulosic fiber surface is expected to play major roles in such phenomena as fiber dispersion, flocculation, adhesion, and adsorption of polyelectrolytes. This review focuses on the evaluation of such charges by means of electrokinetic measurements, with emphasis on the fiber-pad streaming potential technique. Results of recent experiments suggest that a continuous network or networks of pores below the outer surface of a kraft fiber can significantly contribute to observed streaming potential data. At present it is not clear whether the main subsurface contributions to the observed electrokinetic effects come from fibrillar layers on the fiber surfaces or from systems of nanopores within the cell walls of fibers. Based on the literature it is possible to suggest two conceptual models to account for the fact that the streaming potential of polymer-treated fibers can change in sign, dependent on the concentration of salt. Additional research is needed to clarify various theoretical and practical points. There may be opportunities to make more effective use of streaming potential tests in the future by carrying out such tests at reduced salt levels

Diversidad de la morfología craneofacial en América del Norte, Central y del Sur: implicaciones para las discusiones sobre biología y salud oral

Craniofacial morphology plays an important role in many aspects of the masticatory function and the oral health of individuals, and as such should be considered a baseline for studies that aim to integrate anthropological and dentistry practices that can improve oral health, dental hygiene, and care practices in populations from different biological and cultural backgrounds. This article presents a synthesis of our current understanding of the craniofacial and dental variation among native populations of North, Central, and South America, as part of the special volume on “Anthropology meets Dentistry in Central America: Research and education in oral biology”. The article presents an overview of the history of the human occupation of the American continents, with special focus on how early and recent past events have contributed to the craniofacial morphological diversity observed in these continents. However, there is limited information about native Central American populations, and current inferences about them depend largely on extrapolating from what is known about North and South America. Given the current state of knowledge, this article argues that modern Central Americans share a facial morphological pattern distinct from other populations worldwide, which means that applying models developed for other groups may not be appropriate in this context. Therefore, understanding regional variation in craniofacial morphological patterns is an important priority of study, which must consider the different cumulative factors (genetics, developmental, cultural, and historical) that have differently influenced the biological and cultural history of the populations in the region.La morfología craneofacial tiene un importante rol en varios aspectos de las funciones masticatorias y de la salud oral de individuos y, por lo tanto, debe ser considerada un aspecto básico de investigaciones dedicadas a la integración de prácticas antropológicas y ortodónticas, dirigidas a mejorar las condiciones de salud oral e higiene bucal en poblaciones de distintos contextos bioculturales. Este artículo presenta una síntesis del conocimiento actual sobre la diversidad craneofacial en poblaciones nativas de las Américas del Norte, Central, y del Sur, sumándose al volumen especial sobre “La antropología se une a la odontología en América Central: Investigación y educación en biología oral”. El artículo resume la historia de ocupación humana de los continentes americanos, con especial énfasis en cómo eventos tempranos y recientes contribuyeron a la diversidad morfológica observada en los continentes. Sin embargo, existe poca información sobre poblaciones nativas de la América Central, e inferencias sobre la región dependen en gran parte de extrapolaciones de lo que se conoce desde las Américas del Norte y del Sur. Considerándose el estado de conocimiento actual, este artículo propone que grupos actuales de América Central presentan características morfológicas únicas a la región, lo que significa que la aplicación de modelos construidos usando como referencia otras poblaciones del planeta pueden ser de poca validez. Por lo tanto, comprender la variación regional en la morfología craneofacial es una prioridad, y debe ser abordada considerando los distintos factores cumulativos (genéticos, de desarrollo, culturales, e históricos) que han influenciado la historia biológica y cultural de las poblaciones de América Central

Fracturing ranked surfaces

Discretized landscapes can be mapped onto ranked surfaces, where every element (site or bond) has a unique rank associated with its corresponding relative height. By sequentially allocating these elements according to their ranks and systematically preventing the occupation of bridges, namely elements that, if occupied, would provide global connectivity, we disclose that bridges hide a new tricritical point at an occupation fraction $p=p_{c}$, where $p_{c}$ is the percolation threshold of random percolation. For any value of $p$ in the interval $p_{c}< p \leq 1$, our results show that the set of bridges has a fractal dimension $d_{BB} \approx 1.22$ in two dimensions. In the limit $p \rightarrow 1$, a self-similar fracture is revealed as a singly connected line that divides the system in two domains. We then unveil how several seemingly unrelated physical models tumble into the same universality class and also present results for higher dimensions

The time evolution of aerosol composition over the Mexico City plateau

International audienceThe time evolution of aerosol concentration and chemical composition in a megacity urban plume was determined based on 8 flights of the DOE G-1 aircraft in and downwind of Mexico City during the March 2006 MILAGRO field campaign. A series of selection criteria are imposed to eliminate data points with non-urban emission influences. Biomass burning has urban and non-urban sources that are distinguished on the basis of CH3CN and CO. In order to account for dilution in the urban plume, aerosol concentrations are normalized to CO which is taken as an inert tracer of urban emission, proportional to the emissions of aerosol precursors. Time evolution is determined with respect to photochemical age defined as ?Log10 (NOx/NOy). The geographic distribution of photochemical age and CO is examined, confirming the picture that Mexico City is a source region and that pollutants become more dilute and aged as they are advected towards T1 and T2, surface sites that are located at the fringe of the City and 35 km to the NE, respectively. Organic aerosol (OA) per ppm CO is found to increase 7 fold over the range of photochemical ages studied, corresponding to a change in NOx/NOy from nearly 100% to 10%. In the older samples the nitrate/CO ratio has leveled off suggesting that evaporation and formation of aerosol nitrate are in balance. In contrast, OA/CO increases with age in older samples, indicating that OA is still being formed. The amount of carbon equivalent to the deduced change in OA/CO with age is 56 ppbC per ppm CO. At an aerosol yield of 5% and 8% for low and high yield aromatic compounds, it is estimated from surface hydrocarbon observations that only ~9% of the OA formation can be accounted for. A comparison of OA/CO in Mexico City and the eastern U.S. gives no evidence that aerosol yields are higher in a more polluted environment

Growth and metal bioconcentration by conspecific freshwater macroalgae cultured in industrial waste water

The bioremediation of industrial waste water by macroalgae is a sustainable and renewable approach to the treatment of waste water produced by multiple industries. However, few studies have tested the bioremediation of complex multi-element waste streams from coal-fired power stations by live algae. This study compares the ability of three species of green freshwater macroalgae from the genus Oedogonium, isolated from different geographic regions, to grow in waste water for the bioremediation of metals. The experiments used Ash Dam water from Tarong power station in Queensland, which is contaminated by multiple metals (Al, Cd, Ni and Zn) and metalloids (As and Se) in excess of Australian water quality guidelines. All species had consistent growth rates in Ash Dam water, despite significant differences in their growth rates in “clean” water. A species isolated from the Ash Dam water itself was not better suited to the bioremediation of that waste water. While there were differences in the temporal pattern of the bioconcentration of metals by the three species, over the course of the experiment, all three species bioconcentrated the same elements preferentially and to a similar extent. All species bioconcentrated metals (Cu, Mn, Ni, Cd and Zn) more rapidly than metalloids (As, Mo and Se). Therefore, bioremediation in situ will be most rapid and complete for metals. Overall, all three species of freshwater macroalgae had the ability to grow in waste water and bioconcentrate elements, with a consistent affinity for the key metals that are regulated by Australian and international water quality guidelines. Together, these characteristics make Oedogonium a clear target for scaled bioremediation programs across a range of geographic regions