Population differences in density and resource allocation of ornamental tail feathers in the barn swallow

Many organisms show well‐defined latitudinal clines in morphology, which appear to be caused by spatially varying natural selection, resulting in different optimal phenotypes in each location. Such spatial variability raises an interesting question, with different prospects for the action of sexual selection on characters that have a dual purpose, such as locomotion and sexual attraction. The outermost tail feathers of barn swallows (Hirundo rustica) represent one such character, and their evolution has been a classic model subject to intense debate. In the present study, we examined individuals from four European populations to analyze geographical variation in the length and mass of tail feathers in relation to body size and wing size. Tail feather length differed between sexes and populations, and such variation was a result of the effects of natural selection, acting through differences in body size and wing size, as well as the effects of sexual selection that favours longer tails. The extra enlargement of the tail promoted by sexual selection (i.e. beyond the natural selection optimum) could be achieved by increasing investment in ornaments, and by modifying feather structure to produce longer feathers of lower density. These two separate processes accounting for the production of longer and more costly tail feathers and less dense feathers, respectively, are consistent with the hypothesis that both Zahavian and Fisherian mechanisms may be involved in the evolution of the long tails of male barn swallows. We hypothesize that the strength of sexual selection increases with latitude because of the need for rapid mating as a result of the short duration of the breeding season at high latitudes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 925–936.     

Adjustment of vibratory signals to ambient temperature in a host-searching parasitoid

Abstract.  Certain ichneumonid parasitoids (Hymenoptera) use self-produced vibrations transmitted on plant substrate, so-called vibrational sounding, to locate their immobile concealed pupal hosts. An ambient temperature dependency with higher frequencies and intensities at higher temperatures is postulated because signals are of myogenic origin. Here, temperature influence on vibratory signals is analysed in the temperate parasitoid Pimpla turionellae under different thermal conditions using plant-stem models to elicit host-searching behaviour. Signals are measured with laser Doppler vibrometry and analysed for time parameters and frequency components applying fast-Fourier transformations. The results reveal an unexpected effect of ambient temperature on signals produced by the female wasps. Although average values of time parameters (pulse trains, pulse train periods, inter pulse duration) are unchanged by ambient temperature, the frequency parameters show an inverse thermal effect. Within the temperature range tested (8–26 °C), decreasing temperature leads to significantly higher frequency and intensity of the self-produced vibrations in the temperate species. This inverse thermal effect may be explained by a temperature-coupled signal production in the frequency domain to compensate negative low-temperature effects on the mechanoreceptors by increased muscle activity. The option of heterothermy to produce signals reliably during vibrational sounding under low temperature is also discussed.     

The core genome of the anaerobic oral pathogenic bacterium <Emphasis Type="Italic">Porphyromonas gingivalis</Emphasis>

Background  

The Gram negative anaerobic bacterium Porphyromonas gingivalis has long been recognized as a causative agent of periodontitis. Periodontitis is a chronic infectious disease of the tooth supporting tissues eventually leading to tooth-loss. Capsular polysaccharide (CPS) of P. gingivalis has been shown to be an important virulence determinant. Seven capsular serotypes have been described. Here, we used micro-array based comparative genomic hybridization analysis (CGH) to analyze a representative of each of the capsular serotypes and a non-encapsulated strain against the highly virulent and sequenced W83 strain. We defined absent calls using Arabidopsis thaliana negative control probes, with the aim to distinguish between aberrations due to mutations and gene gain/loss.     

Phylogenetic biogeography and taxonomy of disjunctly distributed bryophytes

More than 200 research papers on the molecular phylogeny and phylogenetic biogeography ofbryophytes have been published since the beginning of this millenium. These papers corroborated assumptions of a complex genetic structure of morphologically circumscribed bryophytes, and raised reservations against many morphologically justified species concepts, especially within the mosses. However, many molecular studies allowed for corrections and modifications of morphological classification schemes. Several studies reported that the phylogenetic structure of disjunctly distributed bryophyte species reflects their geographical ranges rather than morphological disparities. Molecular data led to new appraisals of distribution ranges and allowed for the reconstruction of refugia and migration routes. Intercontinental ranges of bryophytes are often caused by dispersal rather than geographical vicariance. Many distribution patterns of disjunct bryophytes are likely formed by processes such as short distance dispersal, rare long distance dispersal events, extinction, recolonization and diversification.     

The Occurrence and Ape-to-Ape Transmission of the Entodiniomorphid Ciliate Troglodytella abrassarti in Captive Gorillas

ABSTRACT. Entodiniomorphid ciliates are often present in the colons of wild apes. In captive apes the infection tends to gradually disappear, with the exception of Troglodytella abrassarti . We used fecal examinations to screen the gorillas ( Gorilla gorilla gorilla ) in European (Czech Republic, UK) and Australian Zoos to explore the ape-to-ape transmission pattern of T. abrassarti . Gorillas from two out of three European Zoos were positive for T. abrassarti , while gorillas from the Australian Zoo were negative. We documented a horizontal transmission of T. abrassarti to a non-infected adult gorilla introduced into a Troglodytella -positive group in the Prague Zoo and traced the origin of the ciliate infection to the Paignton Zoo (UK) using serial fecal examinations. During this study, two infant gorillas born in the Prague Zoo (CZ) first became positive for T. abrassarti at the age of 9 mo. Ciliate morphology and the sequencing of the small subunit rRNA gene and the internal transcribed spacer rDNA spacer region revealed that T. abrassarti affects both captive gorillas and chimpanzees. We conclude that zoo transport plays a major role in the distribution of T. abrassarti among captive gorillas.     

An empirical demonstration of the ideal free distribution: Little Grebes Tachybaptus ruficollis breeding in intensive agricultural landscapes

The ideal free distribution (IFD) model predicts that a density‐dependent mechanism operates to regulate habitat selection and reproductive performance. We studied a Little Grebe Tachybaptus ruficollis population, which breeds on irrigation ponds in the Vega Baja Valley (southeastern Spain) to test the premises of the IFD model. These ponds are highly dynamic because they are managed according to agricultural requirements, and are subject to different levels of disturbance, which can change the quality of individual ponds across the landscape. Surveys were carried out during the breeding season from 2002 to 2006, with reproduction performance estimated during two consecutive breeding seasons, 2003 and 2004. Occupation frequency differed from random, indicating preference for some ponds over others. Habitat features such as pond construction and design, the presence of submerged vegetation, vegetation along the shore and reed beds, and pond area correlated with occupation frequency and might be considered to be indicators of pond quality. Ponds were occupied sequentially from best to worst. Thus, when the population size increased, the number of low‐quality ponds occupied also increased. High‐quality ponds held more breeding pairs than low‐quality ones, resulting in the mean reproductive success per breeding pair being independent of pond quality. Little Grebes therefore occupy ponds in a manner consistent with the expectations of the IFD model.     

Molecular cloning and characterization of an alpha1,3 fucosyltransferase, CEFT-1, from Caenorhabditis elegans

We report on the identification, molecular cloning, and characterization of an alpha1,3 fucosyltransferase (alpha1,3FT) expressed by the nematode, Caenorhabditis elegans . Although C. elegans glycoconjugates do not express the Lewis x antigen Galbeta1-- >4[Fucalpha1-->3]GlcNAcbeta-->R, detergent extracts of adult C.elegans contain an alpha1,3FT that can fucosylate both nonsialylated and sialylated acceptor glycans to generate the Lexand sialyl Lexantigens, as well as the lacdiNAc-containing acceptor GalNAcbeta1-->4GlcNAcbeta1-- >R to generate GalNAcbeta1-->4 [Fucalpha1-->3]GlcNAcbeta1-->R. A search of the C.elegans genome database revealed the existence of a gene with 20-23% overall identity to all five cloned human alpha1,3FTs. The putative cDNA for the C.elegans alpha1,3FT (CEFT-1) was amplified by PCR from a cDNA lambdaZAP library, cloned, and sequenced. COS7 cells transiently transfected with cDNA encoding CEFT-1 express the Lex, but not sLexantigen. The CEFT-1 in the transfected cell extracts can synthesize Lex, but not sialyl Lex, using exogenous acceptors. A second fucosyltransferase activity was detected in extracts of C. elegans that transfers Fuc in alpha1,2 linkage to Gal specifically on type-1 chains. The discovery of alpha-fucosyltransferases in C. elegans opens the possibility of using this well-characterized nematode as a model system for studying the role of fucosylated glycans in the development and survival of C.elegans and possibly other helminths.