European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Involvement of auxin pathways in modulating root architecture during beneficial plant–microorganism interactions

A wide variety of microorganisms known to produce auxin and auxin precursors form beneficial relationships with plants and alter host root development. Moreover, other signals produced by microorganisms affect auxin pathways in host plants. However, the precise role of auxin and auxin‐signalling pathways in modulating plant–microbe interactions is unknown. Dissecting out the auxin synthesis, transport and signalling pathways resulting in the characteristic molecular, physiological and developmental response in plants will further illuminate upon how these intriguing inter‐species interactions of environmental, ecological and economic significance occur. The present review seeks to survey and summarize the scattered evidence in support of known host root modifications brought about by beneficial microorganisms and implicate the role of auxin synthesis, transport and signal transduction in modulating beneficial effects in plants. Finally, through a synthesis of the current body of work, we present outstanding challenges and potential future research directions on studies related to auxin signalling in plant–microbe interactions.     

Climate‐induced changes in the distribution of freshwater fish: observed and predicted trends

1. Climate change could be one of the main threats faced by aquatic ecosystems and freshwater biodiversity. Improved understanding, monitoring and forecasting of its effects are thus crucial for researchers, policy makers and biodiversity managers. 2. Here, we provide a review and some meta‐analyses of the literature reporting both observed and predicted climate‐induced effects on the distribution of freshwater fish. After reviewing three decades of research, we summarise how methods in assessing the effects of climate change have evolved, and whether current knowledge is geographically or taxonomically biased. We conducted multispecies qualitative and quantitative analyses to find out whether the observed responses of freshwater fish to recent changes in climate are consistent with those predicted under future climate scenarios. 3. We highlight the fact that, in recent years, freshwater fish distributions have already been affected by contemporary climate change in ways consistent with anticipated responses under future climate change scenarios: the range of most cold‐water species could be reduced or shift to higher altitude or latitude, whereas that of cool‐ and warm‐water species could expand or contract. 4. Most evidence about the effects of climate change is underpinned by the large number of studies devoted to cold‐water fish species (mainly salmonids). Our knowledge is still incomplete, however, particularly due to taxonomic and geographic biases. 5. Observed and expected responses are well correlated among families, suggesting that model predictions are supported by empirical evidence. The observed effects are of greater magnitude and show higher variability than the predicted effects, however, indicating that other drivers of changes may be interacting with climate and seriously affecting freshwater fish. 6. Finally, we suggest avenues of research required to address current gaps in what we know about the climate‐induced effects on freshwater fish distribution, including (i) the need for more long‐term data analyses, (ii) the assessment of climate‐induced effects at higher levels of organisation (e.g. assemblages), (iii) methodological improvements (e.g. accounting for uncertainty among projections and species’ dispersal abilities, combining both distributional and empirical approaches and including multiple non‐climatic stressors) and (iv) systematic confrontation of observed versus predicted effects across multi‐species assemblages and at several levels of biological organisation (i.e. populations and assemblages).     

Characterization of tetranucleotide microsatellites for Rio Grande cutthroat trout and rainbow trout,and their cross‐amplification in other cutthroat trout subspecies

We describe the isolation and characterization of 12 tetranucleotide microsatellites for Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis) and rainbow trout (Oncorhynchus mykiss), and subsequently investigate their performance in Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus), greenback cutthroat trout (Oncorhynchus clarkii stomias) and Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri). All 12 loci are polymorphic in all subspecies of O. clarkii examined.     

A multiplex set of microsatellite markers for the scarlet rosefinch (Carpodacus erythrinus)

Cardueline finches have become important models in studies of sexual selection and evolution of carotenoid‐based ornamentation. Here, we describe eight new polymorphic microsatellites isolated from the Scarlet rosefinch (Carpodacus erythrinus) and four from the House finch (Carpodacus mexicanus). Together with the cross‐species amplification of additional loci, originally published for two species of songbirds, we optimized a multiplex panel for C. erythrinus allowing genotyping of 22 polymorphic loci. Number of alleles and heterozygosity per locus in a sample of 34 individuals ranged from three to 38 and from 0.27 to 0.94, respectively.     

Changes in Sapwood of Roots of Norway Spruce, Attacked by Fomes annosus. Part I

Chemical and physiological changes occurring in root sapwood of Norway spruce (Picea abies [L.] Karst.), when attacked by Fomes annosus (Fr.) Cke, were studied. The transformation of sapwood to reaction zone, induced by the fungal attack, implies a very sharp increase of carbonate content, correlated with higher amounts of potassium, calcium and magnesium. The buffer capacity of the reaction zone is strong, especially in the pH range 6–9. The high peroxidase activity in the rays of the sapwood is almost totally absent in the reaction zone, probably due to inactivating phenolic compounds. o-Diphenol oxidase was detectable only in the presence of microorganisms. p-Diphenol oxidase was active in connection with decaying wood but not in the reaction zone.     

Behavioural and chemical mechanisms behind a Mediterranean ant–ant association

1. Interspecific competition among ants is common, and so is competitive exclusion among dominant ant species. In contrast, specific associations between non‐parasitic ant species are rare, especially in the temperate zones. As an exception, the subordinate ant Camponotus lateralis frequently co‐occurs with the dominant Crematogaster scutellaris but rarely with other dominant ants. 2. This association is one of various associations between Camponotus and Crematogaster species across the world. However, the mechanisms behind these co‐occurences are largely unknown. 3. In the present study, we therefore investigated the association of Ca. lateralis and Cr. scutellaris. We studied the spatial association of the nests, interspecific aggression, both species' cuticular hydrocarbon profiles, and their propensity to follow the other species' pheromone trails. 4. Crematogaster scutellaris usually attacked and displaced the generally submissive Ca. lateralis, but was significantly less aggressive at jointly used trails. Camponotus nests were always in close proximity to Crematogaster nests. 5. The cuticular hydrocarbons of both species consisted of alkanes with chain lengths between C21 and C35. The two species had 25 hydrocarbons in common, including mono‐, di‐, and tetramethyl alkanes. Despite this qualitative similarity, however, the quantitative hydrocarbon composition differed between the two species. 6. Camponotus lateralis followed artificial trails containing trail pheromones of Cr. scutellaris, but the latter did not follow Ca. lateralis trail pheromones. Interspecific trail‐following by Camponotus, but not vice versa, has been observed in another Camponotus–Crematogaster association and may be a more general mechanism that facilitates associations between the two ant genera.     

Asymmetric impacts of two herbivore ecotypes on similar host plants

1. Ecotypes may arise following allopatric separation from source populations. The simultaneous transfer of an exotic plant to a novel environment, along with its stenophagous herbivore, may complicate more traditional patterns of divergence from the plant and insect source populations. 2. The present study evaluated herbivory effects by two Cyrtobagous salviniae ecotypes on two species of Salvinia: the larger S. molesta and the smaller S. minima. Evaluations were based on relative growth rates, biomass production, coverage, and nutrient cycling in a series of complementary and comparative laboratory and outdoor tank experiments. 3. In general, the experiment results indicated that the smaller Florida ecotype of C. salviniae impacted both Salvinia species more than the larger Brazil ecotype. Herbivory, especially by the Florida ecotype, also improved water quality and accelerated nutrient cycling by increasing the rates of litterfall from the standing crops of salvinia. 4. The smaller size of the Florida ecotype may be adaptive by allowing maximal exploitation of host plants via internal larval feeding, which presumably reduces predation risk while increasing damage to the plant. These findings provide support for relying on the suppressive effects of the Florida ecotype in Florida, rather than introducing the Brazil ecotype to counter new infestations of S. molesta.     

Estimating population structure from AFLP amplification intensity

In the last decade, amplified fragment length polymorphisms (AFLPs) have become one of the most widely used molecular markers to study the genetic structure of natural populations. Most of the statistical methods available to study the genetic structure of populations using AFLPs consider these markers as dominant and are thus unable to distinguish between individuals being heterozygous or homozygous for the dominant allele. Some attempts have been made to treat AFLPs as codominant markers by using AFLP band intensities to infer the most likely genotype of each individual. These two approaches have some drawbacks, the former discarding potentially valuable information and the latter being sometimes unable to correctly assign genotypes to individuals. In this study, we propose an alternative likelihood‐based approach, which does not attempt at inferring the genotype of each individual, but rather incorporate the uncertainty about genotypes into a Bayesian framework leading to the estimation of population‐specific F_IS and F_ST coefficients. We show with simulations that the accuracy of our method is much higher than one using AFLP as dominant markers and is generally close to what would be obtained by using the same number of Single‐Nucleotide Polymorphism (SNP) markers. The method is applied to a data set of four populations of the common vole (Microtus arvalis) from Grisons in Switzerland, for which we obtained 562 polymorphic AFLP markers. Our approach is very general and has the potential to make AFLP markers as useful as SNP data for nonmodel species.     

Vertebrate Axial and Appendicular Patterning: The Early Development of Paired Appendages

Determination of paired fin or limb number, identity and positionare key issues in vertebrate development and evolution. Phylogeniesincluding fossil data show that paired appendages are uniqueto jawed vertebrates and their immediate ancestry; that suchfins evolved first as a single pair in an anterior location;that appendicular endoskeletons are primitively AP asymmetric;and that pectoral and pelvic fins primitively differ. It isconjectured that Hox gene expression patterns along the lateralplate mesoderm establish boundaries that contribute to localisationof AP levels at which signals initiate outgrowth from the bodywall. Such regionalisation may be regulated independently ofthat in the paraxial mesoderm and axial skeleton. When combinedwith current hypotheses of Hox gene phylogenetic and functionaldiversity, these data suggest a new model of fin/limb developmentalevolution. This coordinates body wall outgrowth regions withprimitive boundaries established in the gut, and the fundamentalnon-equivalence of pectoral and pelvic structures.