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Arachis hypogaea L., commonly known as the peanut or groundnut, is an important and widespread food legume. Because the crop has a narrow genetic base, genetic diversity in A. hypogaea is low and it lacks sources of resistance to many pests and diseases. In contrast, wild diploid Arachis species are genetically diverse and are rich sources of disease resistance genes. The majority of known plant disease resistance genes encode proteins with a nucleotide binding site domain (NBS). In this study, degenerate PCR primers designed to bind to DNA regions encoding conserved motifs within this domain were used to amplify NBS-encoding regions from Arachis spp. The Arachis spp. used were A. hypogaea var. Tatu and wild species that are known to be sources of disease resistance: A. cardenasii, A. duranensis, A. stenosperma and A. simpsonii. A total of 78 complete NBS-encoding regions were isolated, of which 63 had uninterrupted ORFs. Phylogenetic analysis of the Arachis NBS sequences derived in this study and other NBS sequences from Arabidopsis thaliana, Medicago trunculata, Glycine max, Lotus japonicus and Phaseolus vulgaris that are available in public databases This analysis indicates that most Arachis NBS sequences fall within legume-specific clades, some of which appear to have undergone extensive copy number expansions in the legumes. In addition, NBS motifs from A. thaliana and legumes were characterized. Differences in the TIR and non-TIR motifs were identified. The likely effect of these differences on the amplification of NBS-encoding sequences by PCR is discussed.

Although species assignment of scats is important to study carnivore biology, there is still no standardized assay for the identification of carnivores worldwide, which would allow large-scale routine assessments and reliable cross-comparison of results. Here, we evaluate the potential of two short mtDNA fragments [ATP6 (126 bp) and cytochrome oxidase I gene (COI) (187 bp)] to serve as standard markers for the Carnivora. Samples of 66 species were sequenced for one or both of these segments. Alignments were complemented with archival sequences and analysed with three approaches (tree-based, distance-based and character-based). Intraspecific genetic distances were generally lower than between-species distances, resulting in diagnosable clusters for 86% (ATP6) and 85% (COI) of the species. Notable exceptions were recently diverged species, most of which could still be identified using diagnostic characters and uniqueness of haplotypes or by reducing the geographic scope of the comparison. In silico analyses were also performed for a 110-bp cytochrome b (cytb) segment, whose identification success was lower (70%), possibly due to the smaller number of informative sites and/or the influence of misidentified sequences obtained from GenBank. Finally, we performed case studies with faecal samples, which supported the suitability of our two focal markers for poor-quality DNA and allowed an assessment of prey DNA co-amplification. No evidence of prey DNA contamination was found for ATP6, while some cases were observed for COI and subsequently eliminated by the design of more specific primers. Overall, our results indicate that these segments hold good potential as standard markers for accurate species-level identification in the Carnivora.

Aim Amphibians exhibit two basic reproductive modes, terrestrial and aquatic, each with different ecophysiological constraints related to evaporative water loss. We hypothesize that these fundamental niche differences will generate strong geographical patterns at the global scale in response to spatial heterogeneity in temperature and water availability. Location Global. Time period Present. Major taxa studied Amphibians. Methods We used global distribution maps of 5,434 amphibian species, classified into terrestrial or aquatic breeders, to estimate the occurrence and proportion of terrestrial breeding species per 1° cell. We used multiple regression models to test the relative importance of seven abiotic variables: annual precipitation, annual mean temperature, annual mean relative air humidity, annual mean actual evapotranspiration, availability of lotic and lentic environments and slope. We used residuals autocovariate (RAC) generalized multiple regression models to control for spatial autocorrelation and a spatial vector based on amphibian phylogeny to account for phylogenetic dependencies among cells. Model generality was evaluated by contrasting results between 11 widely recognized world zoogeographical realms. Results Globally, the occurrence of terrestrial breeding species was better explained by temperature followed by total annual rainfall, relative air humidity and terrain slope. In contrast, the proportion of terrestrial breeders was better explained by terrain slope, followed by total rainfall, temperature and relative air humidity. Actual evapotranspiration and the extension of large lotic and lentic water bodies played a minor role. However, the relative importance and even the sign of the regression coefficients varied among realms, revealing different evolutionary pressures. Main conclusions Niche differences among terrestrial and aquatic breeding amphibian species are reflected in their distinct geographical distribution across the globe. Adequate conditions for terrestrial reproduction to evolve and thrive are reached in distinct ways in different realms. Temperature constraints and slope suggest that reproductive modes will be impacted differently by climate change.

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