Latitudinally structured variation in the temperature dependence of damselfly growth rates

The Metabolic Theory of Ecology predicts that the slope of the rate–temperature relationship, E, remains consistent across traits and organisms, acting as a major determinant of large‐scale ecological patterns. Although E has recently been shown to vary systematically, we have a poor understanding of its ecological significance. To address this question, we conducted a common‐garden experiment involving six damselfly species differing in distribution, estimating E at the level of full‐sib families. Each species was sampled throughout its latitudinal range, allowing us to characterise variation in E along a latitudinal gradient spanning 3600 km. We show that E differs among populations and increases with latitude. E was right‐skewness across species, but this was largely an artefact of the latitudinal trend. Increased seasonality towards higher latitude may contribute to the latitudinal trend in E. We conclude that E should be seen as a trait involved in local adaptation.     

After Last Glacial Maximum: The third migration

A critical analysis of “Real World” data concerning the genetic origins of people, archaeology and palaeoclimatic conditions, demonstrates possibilities of population migration for third time in ancient history, from East to West after Last Glacial Maximum (LGM), which gave the foundations of modern human civilization.     

Geographical zonation in the Neotropics of tree species characteristic of the Paraguay-Paraná Basin

Aim This paper uses data from the literature (monographs and taxonomic reviews) to investigate the geographical zonation in South America of 32 common tree species encountered in Paraguay. The actual spatial distribution of the species is then used to provide clues on the plant communities present in the past, and especially during the Wisconsinan age (Last major ice age: 80,000–10,000 bp ). The floristic relatedness between the Paraguayan flora and the neighbouring floras is also investigated. Methods The main vegetation patterns were highlighted using a Discriminant Analysis of the Eigenvectors of Neighbourhood Operator to emphasize the geographical zonation in South America of 32 tree species predominant in the Paraguay‐Paraná Basin. Results Three main vegetation patterns were emphasized: the Chaco, the Paraná‐São Francisco gradient and the Peri‐Amazonian gradient. The Chaco is well defined. The Peri‐Amazonian gradient is characterized by a continuous change in species from the Colombian pole towards the São Francisco pole. The São Francisco gradient shows a continuous change from the São Francisco pole towards the Paraná pole. Some of the species are monocentric (related to only one dispersal centre), whereas others are polycentric (distributed in several poles). Main conclusions The Chaquean xeromorphic forests are considered as a climax, with a stable composition resulting of the saline soil conditions. The Chaco acts as an edaphic barrier to many species, although the migration of some non‐Chaquean species is made possible by the net of gallery‐forests and low montane forests between the Río Paraguay and the Andean Piedmont. The Cerrado and the Chaco can be considered as a barrier limiting the expansion of the Paranean forest. This latter formation is a semi‐deciduous forest made of a mix of monocentric and polycentric elements. The numerous species found both in Colombia and in Paraná indicate that bridges exist, or have existed, between these two poles. The persistence in the Paraguay‐Paraná Basin of a moist forest made of the Paranean assemblages highlighted in this study confirms the hypothesis of moister and cooler phases than today.     

Development of “Plug and Play” Fiducial Marks for Structural Studies of GPCR Signaling Complexes by Single-Particle Cryo-EM

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Enzyme-Driven Speciation: Crystallizing Archaea via Lipid Capture

As the origin(s) of life on Earth remains an open question, detailed characteristics about the “last universal ancestor” (LUA) continue to be obscured. Here we provide arguments that strengthen the bacterial-like nature of the LUA. Our view attempts to recreate the evolution of archaeal lipids, the major components of the distinctive membrane that encapsulates these ancient prokaryotes. We show that (S)- 3-O-geranylgeranylglyceryl phosphate synthase (GGGPS), a TIM-barrel protein that performs the committed step in archaeal lipid synthesis, likely evolved from the duplication and fusion of a (βα)₄ half-barrel ancestor. By comparison to the well-characterized HisA and HisF TIM-barrel proteins, we propose a time line for the invention of this diagnostic archaeal biosynthetic pathway. After excluding the possibility of horizontal gene transfer, we conclude that the evolutionary history of GGGPS mirrors the emergence of Archaea from the LUA. We illustrate aspects of this “lipid capture” model that support its likelihood in recreating key evolutionary events and, as our hypothesis is built on a single initiating event, we suggest that the appearance of GGGPS represents an example of enzyme-driven speciation. Reviewing Editor: Dr. Niles Lehman     

The role of glacial cycles in promoting genetic diversity in the Neotropics: the case of cloud forests during the Last Glacial Maximum

The increasing aridity during the Last Glacial Maximum (LGM) has been proposed as a major factor affecting Neotropical species. The character and intensity of this change, however, remains the subject of ongoing debate. This review proposes an approach to test contrasting paleoecological hypotheses by way of their expected demographic and genetic effects on Neotropical cloud forest species. We reviewed 48 paleoecological records encompassing the LGM in the Neotropics. The records show contrasting evidence regarding the changes in precipitation during this period. Some regions remained fairly moist and others had a significantly reduced precipitation. Many paleoecological records within the same region show apparently conflicting evidence on precipitation and forest stability. From these data, we propose and outline two demographic/genetic scenarios for cloud forests species based on opposite precipitation regimes: the dry refugia and the moist forests hypotheses. We searched for studies dealing with the population genetic structure of cloud forest and other montane taxa and compared their results with the proposed models. To date, the few available molecular studies show insufficient genetic evidence on the predominance of glacial aridity in the Neotropics. In order to disentangle the climatic history of the Neotropics, the present study calls for a general multi‐disciplinary approach to conduct future phylogeographic studies. Given the contradictory paleoecological information, population genetic data on Neotropical cloud forest species should be used to explicitly test the genetic consequences of competing paleoecological models.     

Efficacy of loop mediated isothermal amplification (LAMP) assay for the laboratory identification of Mycobacterium tuberculosis isolates in a resource limited setting

Current methods of TB diagnosis are time consuming and less suited for developing countries. The LAMP (loop mediated isothermal amplification) is a rapid method more suitable for diagnosis in resource limited settings and has been proposed as a viable test requiring further evaluation for use as a laboratory method as well. We evaluated two LAMP assays, using culture lysates of clinical sputum samples (from Southern India) and compared it to a proprietary multiplex PCR reverse-hybridization line probe assay (‘GenoType MTBC’ from HAIN Lifescience GmbH, Germany). The LAMP procedure was modified to suit the local conditions. The Mycobacterium tuberculosis specific LAMP assay (‘MTB LAMP’) showed sensitivity and specificity, of 44.7% and 94.4% respectively in a 60 min format, 85.7% and 93.9% respectively in a 90 min format and 91.7%, and 90.9% respectively in a 120 min format. The Mycobacteria universal LAMP assay (‘Muniv LAMP’) showed a sensitivity of 99.1%. The LAMP was shown to be a rapid and accessible assay for the laboratory identification of M. tuberculosis isolates. Initial denaturation of template was shown to be essential for amplification in unpurified/dilute samples and longer incubation was shown to increase the sensitivity. The need for modification of protocols to yield better efficacy in this scenario needs to be addressed in subsequent studies.     

RECENT VERSUS RELIC: DISCERNING THE GENETIC SIGNATURE OF FUCUS VESICULOSUS (HETEROKONTOPHYTA; PHAEOPHYCEAE) IN THE NORTHWESTERN ATLANTIC1

Fucus vesiculosus L. is one of the most widespread macrophytes in the northwestern Atlantic, ranging from North Carolina (USA) to Greenland (DK). We investigated genetic diversity, population differentiation, patterns of isolation by distance, and putative glacial refugial populations across seven locations from North Carolina (USA) to Cape Breton Island, Nova Scotia (Canada), with microsatellite analyses. Distinct northern versus southern (Delaware–North Carolina) populations were revealed by microsatellite data. Five of six microsatellite loci were fixed in populations in North Carolina, suggesting a recent founder event or a bottleneck, and the same homozygous genotype was found in herbarium materials collected on the North Carolina coast from more than 60 years ago. An additional set of individuals from the northern limit in Greenland was included in our analysis of mitochondrial intergenic spacer (mt IGS) haplotypes in the northwestern Atlantic. Remarkably, 184 of 188 F. vesiculosus specimens from North Carolina to Greenland shared the same haplotype. Recent colonization of the North American shore from Europe is hypothesized based upon the ubiquity of this common haplotype, which was earlier reported from Europe.