Spatial variation in the evolutionary potential and constraints of basal metabolic rate and body mass in a wild bird

An organism's energy budget is strongly related to resource consumption, performance, and fitness. Hence, understanding the evolution of key energetic traits, such as basal metabolic rate (BMR), in natural populations is central for understanding life-history evolution and ecological processes. Here we used quantitative genetic analyses to study evolutionary potential of BMR in two insular populations of the house sparrow (Passer domesticus). We obtained measurements of BMR and body mass (M_b) from 911 house sparrows on the islands of Leka and Vega along the coast of Norway. These two populations were the source populations for translocations to create an additional third, admixed ‘common garden’ population in 2012. With the use of a novel genetic group animal model concomitant with a genetically determined pedigree, we differentiate genetic and environmental sources of variation, thereby providing insight into the effects of spatial population structure on evolutionary potential. We found that the evolutionary potential of BMR was similar in the two source populations, whereas the Vega population had a somewhat higher evolutionary potential of M_b than the Leka population. BMR was genetically correlated with M_b in both populations, and the conditional evolutionary potential of BMR (independent of body mass) was 41% (Leka) and 53% (Vega) lower than unconditional estimates. Overall, our results show that there is potential for BMR to evolve independently of M_b, but that selection on BMR and/or M_b may have different evolutionary consequences in different populations of the same species.     

Current and historical factors drive variation of reproductive traits in unisexual mosses in Europe: A case study

Unisexual bryophytes provide excellent models to study the mechanisms that regulate the frequency of sexual versusasexual reproduction in plants, and their ecological and evolutionary implications. Here, we determined sex expression, phenotypic sex ratio, and individual shoot traits in 242 populations of the cosmopolitan moss Pseudoscleropodium purum spanning its whole distributional range. We tested whether niche differentiation, sex-specific differences in shoot size, and biogeographical history explained the spatial variation of reproductive traits. We observed high levels of sex expression and predominantly female-biased populations, although both traits showed high intraspecific variation among populations. Sex expression and sex ratio were partly explained by current macroscale environmental variation, with male shoots being less frequent at the higher end of the environmental gradients defined by the current distribution of the species. Female bias in population sex ratio was significantly lower in areas recolonized after the last glacial maximum (recent populations) than in glacial refugia (long-term persistent populations). We demonstrated that reproductive trait variation in perennial unisexual mosses is partially driven by macroscale and historical environmental variation. Based on our results, we hypothesize that sexual dimorphism in environmental tolerance and vegetative growth contribute to sex ratio bias over time, constraining the chances of sexual reproduction, especially in long-term persistent populations. Further studies combining genetic analyses and population monitoring should improve our understanding of the implications of the intraspecific variation in the frequency of sexual versusasexual reproduction in bryophyte population fitness and eco-evolutionary dynamics.     

Re-terrestrialization in the phylogeny of epiphytic plant lineages: Microsoroid ferns as a case study

The fern family Polypodiaceae, with over 1600 species, is not only one of the most species-rich families of ferns, but also a major contributor to the vascular epiphytic diversity throughout the tropics. Although the vast majority of species belonging to this family prefer to grow as epiphytes, several species colonize successfully rheophytic, lithophytic, and even terrestrial habitats. Here, we explore the hypothesis that non-epiphytic habitat preferences, including terrestrial growth, evolved secondarily with epiphytes being the plesiomorphic habitat preference. The results of phylogenetic analyses, based on dense taxon sampling and four chloroplast DNA regions, were integrated with divergence time estimates and ancestral character state reconstructions to test these predictions. Both fossils and secondary calibration data were incorporated to obtain divergence time estimations. The results support the prediction of multiple transitions from epiphytic/lithophytic to terrestrial/rheophytic habitats occurring mainly in the Microsoreae lineage. The change in niche preferences coincides with niche colonization opportunities created by climatic fluctuations and geographical changes during the Oligocene and Miocene periods.     

Structural proteins in the growth cone of cultured spinal cord neurons

The distribution of several structural proteins in the extending neurites and growth cones of cultured embryonic mouse spinal cord neurons was studied by indirect immunofluorescence, using affinity chromatography-purified antibodies. Fibroblastic cells in the same cultures served as internal standards for the evaluation of staining intensities. Anti-tubulin, anti-actin, and anti-clathrin stained neurons and their processes intensely, while staining with anti-α-actinin was only moderate compared with fibroblasts. Microtubules were resolved by anti-tubulin in the ‘palm’ of the growth cone but not in the neurite. Anti-actin stained even the finest lamellae and filopodia of the growth cone, and the neurite. Anti-α-actinin revealed an irregularly speckled pattern of cross-reactive material in the neurite and in the palm of the growth cone and was absent from the filopodia. Anti-clathrin stained the neurite intensely and homogeneously, and to a lesser extent the palm of the growth cone. The staining with antibodies against tubulin and clathrin differed grossly between neurons and fibroblastic cells. Within the neuron there were only gradual differences in staining intensities. The growth cone was not qualitatively different from the rest of the neurite, except for the filopodia which lacked tubulin and α-actinin, similar to the microvilli of epithelial cells.     

ESR and optical absorption studies on the copper (II) interaction with aromatic amino acids

Electron spin resonance and optical absorption studies have been done in order to investigate the interaction between Cu²⁺ and aromatic amino acids in aqueous solution at 77 K and at room temperature as well. Depending on the concentration each aromatic amino acid can form two different kinds of complexes with Cu²⁺ which can be characterized by its ESR pattern. Additional information was obtained from optical d-d and CT transitions.     

Dichtebedingter Zusammenhang zwischen Gesangstyp und ?kotyp bei der Grauammer(Emberiza calandra)?

Zusammenfassung Zwei Gesangstypen (N, S, s. Abb. 1 a, b) dürften dichteabhängig sein. Durch Tonbandreizung (Dichtesimulation?) läßt sich ein einseitiger Übergang von einem (N) zum anderen Typ (S) — beim Individuum nur in einem Halbschritt (s. Abb. 3) — provozieren. Ein dritter Gesangstyp (K, Abb. 1 c) war zu selten im Material vorhanden, um weitergehende Aussagen zu ermöglichen. Außerdem sind die Gesangstypen geographisch unterschiedlich verbreitet: N und NS (intermediär, s. Abb. 2 a) in feuchtem Steuwiesenhabitat in Mitteleuropa in kleinen, eher dispers siedelnden Population; S in trockenen teilweise kultivierten Steppenhabitaten S-Europas mit augenscheinlich sehr hoher Dichte. In Österreich und in der Schweiz gibt es auch N/S-Sänger (beide charakteristischen Elemente in einer Strophe); diese könnten von beiden Formen lernbeeinflußt sein. Diese Anhaltspunkte werden in ein Modell (Abb. 4) eingebaut.

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Density-dependent coherence of song-type and ecotype in the Corn BuntingEmberiza calandra?

Summary There are two major song-types (N, S, fig. 1 a, b) in the Corn Bunting which seem to be density-dependent. An unidirectional change to (wards characters of) type S was observed when a density-situation was simulated by playback of song (any type); fig. 3. Data of a third type (K, fig. 1 c) are too scarce to provide such significance. Without playback-experiments these types have an unequal geographic distribution (table): N and NS (intermediary type, fig. 2 a) occurring in moisty meadowland in Central Europe (small colonies of low density) S beeing most typical for dry, partly cultivated steppe-habitats in southern Europe (Evros-Delta, Greece; Camargue, southern France) where density is extremely high. In the eastern Austrian Seewinkel (lake Neusiedel) there are N/S-singers (mixed elements, see fig. 2 b) which might be cultural hybrids (Baptista 1975). These findings suggest a model which is expressed in this paper's title and fig. 4.

     

Methanococcus thermolithotrophicus,a novel thermophilic lithotrophic methanogen

An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H₂/CO₂ and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.Abbreviations G+C Guanine + Cytosine - SDS Sodium dodecylsulfate (Sodium lauryl sulfate)     

Biosystematic studies of Sorbus meinichii (Rosaceae) at Moster, S. Norway

Morphometric and cytological data were used to test the variation within the apomictic hybrid Sorbus meinichii from its type locality, in the Moster area, Bømlo in Sunnhordland, Norway. A lectotype is selected for the name. A total of 36 morphological characters were measured on leaves, stomata, flowers, pollen, fruits and seeds, from randomly selected S. meinichii individuals. In the field the material was classified into two groups, one including individuals of generally larger dimensions of leaves and fruits than the other. The preliminary classification was subsequently tested by a multivariate analysis of several characters, substantiating the existence of two morphs in the population at the type locality of S. meinichii , one corresponding to the selected lectotype. Assessment of the nature and taxonomic rank of these two morphs must await further studies. Cytological studies showed both forms of S. meinichii to be triploid, with 2n=51 chromosomes. The taxonomic separation of S. teodorii from S. meinichii on the basis of ploidy level is therefore not corroborated. Sorbus meinichii s. lat. was shown to be intermediate between its supposed parents, S. aucuparia and S. hybrida , in several leaf characters. All of the variation within the S. aucuparia × S. hybrida-complex in Fennoscandia is better included in one aggregate species Sorbus meinichii according to the present state of knowledge.     

In vivo and in vitro studies of major surface loop deletion mutants of the Escherichia coli K-12 maltoporin: contribution to maltose and maltooligosaccharide transport and binding

The trimeric protein LamB of Escherichia coli K-12 (maltoporin) specifically facilitates the diffusion of maltose and maltooligosaccharides through the outer membrane. Each monomer consists of an 18-stranded antiparallel beta-barrel with nine surface loops (L1 to L9). The effects on transport and binding of the deletion of some of the surface loops or of combinations of several of them were studied in vivo and in vitro. In vivo, single-, DeltaL4, DeltaL5, DeltaL6, and double-loop deletions, DeltaL4 + DeltaL5 and DeltaL5 + DeltaL6, abolished maltoporin functions, but not the double deletion DeltaL4 + DeltaL6 and the triple deletion DeltaL4 + DeltaL5 + DeltaL6. While deletion of the central variable portion of loop L9 (DeltaL9v) affected maltoporin function only moderately, the combination of DeltaL9v with the double deletion of loops L4 and L6 (triple deletion DeltaL4 + DeltaL6 + DeltaL9v) strongly impaired maltoporin function and resulted in sensitivity to large hydrophilic antibiotics without change in channel size as measured in vitro. In vitro, the carbohydrate-binding properties of the different loop mutants were studied in titration experiments using the asymmetric and symmetric addition of the mutant porins and of the carbohydrates to one or both sides of the lipid bilayer membranes. The deletion of loop L9v alone (LamBDeltaL9v), of two loops L4 and L6 (LamBDeltaL4 + DeltaL6), of three loops L4, L5 and L6 (LamBDeltaL4 + DeltaL5 + DeltaL6) or of L4, L6 and L9v (LamBDeltaL4 + DeltaL6 + DeltaL9v) had relatively little influence on the carbohydrate-binding properties of the mutant channels, and they had approximately similar binding properties for carbohydrate addition to both sides compared with only one side. The deletion of one of the loops L4 (LamBDeltaL4) or L6 (LamBDeltaL6) resulted in an asymmetric carbohydrate binding. The in vivo and in vitro results, together with those of the purification across the starch column, suggest that maltooligosaccharides enter the LamB channel from the cell surface side with the non-reducing end in advance. The absence of some of the loops leads to obstruction of the channel from the outside, which results in a considerable difference in the on-rate of carbohydrate binding from the extracellular side compared with that from the periplasmic side.