When two is better than one

Gene duplication and divergence has long been considered an important route to adaptation and phenotypic evolution. Reporting in Nature, Hittinger and Carroll (2007) provide the first clear example of adaptations in both regulatory regions and protein-coding regions after gene duplication. This combination of evolutionary changes appears to have resolved an adaptive conflict, leading to increased organismal fitness.     

When it comes to inbreeding: slower is better

The extent to which genetic diversity is lost from inbred populations is important for conservation biology, evolutionary ecology, and plant and animal breeding. This importance stems from the fact that the amount of genetic diversity a population has is expected to correlate with evolutionary potential. A population's ability to avert extinction during rapidly changing environmental conditions, or the magnitude of response to selection on a trait, depend on the ability of the genome to maintain potentially adaptive genetic variation in the face of random genetic drift. Although a few previous studies have demonstrated that the rate of inbreeding affects the amount of genetic diversity maintained, the elegant work of Demontis et al. , in this issue, clearly demonstrates that slow inbreeding maintains more genetic diversity than fast inbreeding and that the primary mechanism could be balancing selection. In their study, populations that took 19 generations, rather than one generation, to reach the same level of inbreeding maintained 10% higher levels of allelic richness and 25% higher levels of heterozygosity. The use of specifically chosen molecular markers not expected to be neutral makes this study especially noteworthy, as the study provides evidence concerning the mechanisms underlying the maintenance of genetic diversity in the face of inbreeding.     

When bigger is better: the need for Amazonian mega-reserves

The rate of forest destruction has accelerated sharply in Brazilian Amazonia, but there are also vital conservation opportunities with the ongoing designation of important new protected areas. In a timely paper, Carlos Peres argues that an extensive network of mega-reserves, operationally defined as those exceeding 1 million ha in area, is needed to ensure the long-term persistence of Amazonian species and ecological processes. Although such protected areas might seem excessively large to some, disparate lines of evidence suggest that mega-reserves are vital for the future of Amazonian biodiversity.     

ATP synthase superassemblies in animals and plants: two or more are better

ATP synthases are part of the sophisticated cellular metabolic network and therefore multiple interactions have to be considered. As discussed in this review, ATP synthases form various supramolecular structures. These include dimers and homooligomeric species. But also interactions with other proteins, particularly those involved in energy conversion exist. The supramolecular assembly of the ATP synthase affects metabolism, organellar structure, diseases, ageing and vice versa. The most common approaches to isolate supercomplexes from native membranes by use of native electrophoresis or density gradients are introduced. On the one hand, isolated ATP synthase dimers and oligomers are employed for structural studies and elucidation of specific protein-protein interactions. On the other hand, native electrophoresis and other techniques serve as tool to trace changes of the supramolecular organisation depending on metabolic alterations. Upon analysing the structure, dimer-specific subunits can be identified as well as interactions with other proteins, for example, the adenine nucleotide translocator. In the organellar context, ATP synthase dimers and oligomers are involved in the formation of mitochondrial cristae. As a consequence, changes in the amount of such supercomplexes affect mitochondrial structure and function. Alterations in the cellular power plant have a strong impact on energy metabolism and ultimately play a significant role in pathophysiology. In plant systems, dimers of the ATP synthase have been also identified in chloroplasts. Similar to mammals, a correlation between metabolic changes and the amount of the chloroplast ATP synthase dimers exists. Therefore, this review focusses on the interplay between metabolism and supramolecular organisation of ATP synthase in different organisms.     

When one is better than two: RNA with dual functions

The central dogma of biology, until not long ago, held that genetic information stored on DNA molecules was translated into the final protein products through RNA as intermediate molecules. Then, an additional level of complexity in the regulation of genome expression was added, implicating new classes of RNA molecules called non-coding RNA (ncRNA). These ncRNA are also often referred to as functional RNA in that, although they do not contain the capacity to encode proteins, do have a function as RNA molecules. They have been thus far considered as truly non-coding RNA since no ORF long enough to be considered, nor protein, have been associated with them. However, the recent identification and characterization of bifunctional RNA, i.e. RNA for which both coding capacity and activity as functional RNA have been reported, suggests that a definite categorization of some RNA molecules is far from being straightforward.Indeed, several RNA primarily classified as non-protein-coding RNA has been showed to hold coding capacities and associated peptides. Conversely, mRNA, usually regarded as strictly protein-coding, may act as functional RNA molecules. Here, we describe several examples of these bifunctional RNA that have been already characterized from bacteria to mammals. We also extend this concept to fortuitous acquisition of dual function in pathological conditions and to the recently highlighted duality between information carried by a gene and its pseudogenes counterparts.     

When less is more: accounting for overcompensation in mosquito SIT projects

Compensation and overcompensation under field conditions are confirmed in Aedes mosquitoes recently by Evans et al.: equal or increased densities of emerging adults may thus result from reduced larval densities. Here the consequences when applying the sterile insect technique and provide recommendations to avoid counterproductive effects are discussed.     

When more is more: taking advantage of species diversity to move towards sustainable aquaculture

Human population growth has increased demand for food products, which is expected to double in coming decades. Until recently, this demand has been met by expanding agricultural area and intensifying agrochemical-based monoculture of a few species. However, this development pathway has been criticised due to its negative impacts on the environment and other human activities. Therefore, new production practices are needed to meet human food requirements sustainably in the future. Herein, we assert that polyculture practices can ensure the transition of aquaculture towards sustainable development. We review traditional and recent polyculture practices (ponds, recirculated aquaculture systems, integrated multi-trophic aquaculture, aquaponics, integrated agriculture–aquaculture) to highlight how they improve aquaculture through the coexistence and interactions of species. This overview highlights the importance of species compatibility (i.e. species that can live in the same farming environment without detrimental interactions) and complementarity (i.e. complementary use of available resources and/or commensalism/mutualism) to achieve efficient and ethical aquaculture. Overall, polyculture combines aspects of productivity, environmental protection, resource sharing, and animal welfare. However, several challenges must be addressed to facilitate polyculture development across the world. We developed a four-step conceptual framework for designing innovative polyculture systems. This framework highlights the importance of (i) using prospective approaches to consider which species to combine, (ii) performing integrated assessment of rearing environments to determine in which farming system a particular combination of species is the most relevant, (iii) developing new tools and strategies to facilitate polyculture system management, and (iv) implementing polyculture innovation for relevant stakeholders involved in aquaculture transitions.     

When more is less: the fitness consequences of predators attacking more unpalatable prey when more are presented

In 1879, Fritz Müller hypothesized that mimetic resemblance in which defended prey display the same warning signal would share the costs of predator education. Although Müller argued that predators would need to ingest a fixed number of prey with a given visual signal when learning to avoid unpalatable prey, this assumption lacks empirical support. We report an experiment which shows that, as the number of unpalatable prey presented to them increased, avian predators attacked higher numbers of those prey. We calculated that, when predators increase attacks, the fitness costs incurred by unpalatable prey can be substantial. This suggests that the survival benefits of mimicry could be lower than Müller proposed. An important finding is, however, that these costs decline in importance as the total number of available prey increases.     

When feeling is more important than seeing in sensorimotor adaptation

Perception and action are based on information from multiple sensory modalities. For instance, both vision and proprioception provide information about hand position, and this information is integrated to generate a single estimate of where the hand is in space. Classically, vision has been thought to dominate this process, with the estimate of hand position relying more on vision than on proprioception. However, an optimal integration model that takes into account the precision of vision and proprioception predicts that the weighting of the two senses varies with direction and that the classical result should only hold for specific spatial directions. Using an adaptation paradigm, we show that, as predicted by this model, the visual-proprioceptive integration varies with direction. Variation with direction was so strong that, in the depth direction, the classical result was reversed: the estimate relies more on proprioception than on vision. These results provide evidence for statistically optimal integration of information from multiple modalities.