Roadside connectivity does not increase reptile abundance or richness in a fragmented mallee landscape

The effect of isolation and the importance of dispersal in establishing and maintaining populations in fragments of remnant habitat remain poorly understood. Nevertheless, environmental connectivity is likely to be important for ensuring the long‐term preservation of biodiversity in extensively cleared landscapes. In this study, we compared reptile communities in large conservation parks with those in small woodland remnants 6.5–12 km from the parks, on the Eyre Peninsula, South Australia, Australia. We assessed the impact of fragmentation on the abundance, richness and habitat preferences of reptiles, and examined whether connection to linear roadside vegetation altered reptile communities in small woodland remnants. Of the 31 reptile species, 12 were restricted to conservation parks and six to habitat fragments in farmland. There was a substantial reduction in reptile species richness and abundance in farmland fragments. Direct connection of remnant vegetation to roadside corridors did not affect abundance of common species in the farmland fragments, although species richness was lower in isolated remnants in one of our two study regions. The habitat preference of the scincid lizard Menetia greyii differed between farmland fragments, where they were regularly found on dunes and roadsides, and conservation parks, where they were rare and not detected on dunes. We suggest that habitat fragmentation may have altered interspecific interactions, enabling an expansion of habitat use in the farming landscape. Significantly lower abundance of four common species in farmland settings compared with reserves indicated that existing corridors and small fragments provide inadequate connectivity over larger distances. To counter this effect, large reserves may need to be less than 10 km apart.     

Phylogenetic diversity of stress signalling pathways in fungi

Background  

Microbes must sense environmental stresses, transduce these signals and mount protective responses to survive in hostile environments. In this study we have tested the hypothesis that fungal stress signalling pathways have evolved rapidly in a niche-specific fashion that is independent of phylogeny. To test this hypothesis we have compared the conservation of stress signalling molecules in diverse fungal species with their stress resistance. These fungi, which include ascomycetes, basidiomycetes and microsporidia, occupy highly divergent niches from saline environments to plant or mammalian hosts.     

An updated 18S rRNA phylogeny of tunicates based on mixture and secondary structure models

Background  

Tunicates have been recently revealed to be the closest living relatives of vertebrates. Yet, with more than 2500 described species, details of their evolutionary history are still obscure. From a molecular point of view, tunicate phylogenetic relationships have been mostly studied based on analyses of 18S rRNA sequences, which indicate several major clades at odds with the traditional class-level arrangements. Nonetheless, substantial uncertainty remains about the phylogenetic relationships and taxonomic status of key groups such as the Aplousobranchia, Appendicularia, and Thaliacea.     

GMDD: a database of GMO detection methods

Background  

Since more than one hundred events of genetically modified organisms (GMOs) have been developed and approved for commercialization in global area, the GMO analysis methods are essential for the enforcement of GMO labelling regulations. Protein and nucleic acid-based detection techniques have been developed and utilized for GMOs identification and quantification. However, the information for harmonization and standardization of GMO analysis methods at global level is needed.     

Molecular and morphological evidence for a new grass genus,Dupontiopsis (Poaceae tribe Poeae subtribe Poinae s.l.), endemic to alpine Japan,and implications for the reticulate origin of Dupontia and Arctophila within Poinae s.l.

Phylogenetic analyses within Poaceae tribe Poeae subtribes Puccinellinae (=Coleanthinae), Phleinae, Poinae s.l. (including Alopecurinae), and Miliinae (PPAM clade), revealed that one species formerly placed in Poa represents a new monotypic genus belonging to subtribe Poinae s.l., Dupontiopsis gen. nov., D. hayachinensis comb. nov. (based on Poa hayachinensis), endemic to wet, gravelly, serpentine, alpine habitats in northern Japan. This genus forms a strongly supported clade (DAD) with two circumarctic Poinae genera, Arctophila and Dupontia, in phylogenetic analyses of plastid and nuclear ribosomal DNA sequence data. Both morphology and DNA sequence analyses provide support for D. hayachinensis as a lineage distinct from either Arctophila or Dupontia, with moderate DNA support for a position as sister to these two genera. Dupontiopsis resembles these other monotypic genera in its several-flowered spikelets, lemmas usually 3-nerved, with frequently awned attenuate scarious apices (as in Dupontia) and calluses with a crown of hairs around the base of the lemma, but differs in its keeled lemmas, scabrous palea keels, glumes shorter than the first lemma. Our investigation suggests that the most recent shared ancestor of the DAD clade evolved from a single hybridization event, as a hexaploid, probably in western Beringia. The probable parentage of the ancestor is considered to be within the Poinae–Alopecurinae clade excluding Poa. We provide evidence for possible secondary hybridization and introgression of duodecaploid Dupontia fisheri with Puccinellia. A key to perennial genera of PPAM with hairy calluses, and a supplemental table of morphological characters in the genera accepted in PPAM are provided.     

Influence of Tertiary paleoenvironmental changes on the diversification of South American mammals: a relaxed molecular clock study within xenarthrans

Background  

Comparative genomic data among organisms allow the reconstruction of their phylogenies and evolutionary time scales. Molecular timings have been recently used to suggest that environmental global change have shaped the evolutionary history of diverse terrestrial organisms. Living xenarthrans (armadillos, anteaters and sloths) constitute an ideal model for studying the influence of past environmental changes on species diversification. Indeed, extant xenarthran species are relicts from an evolutionary radiation enhanced by their isolation in South America during the Tertiary era, a period for which major climate variations and tectonic events are relatively well documented.     

Proliferative activity in the cerebellar external granular layer evaluated by bromodeoxyuridine labeling

We have optimised an indirect immunoperoxidase technique demonstrating bromodeoxyuridine (BrdU) incorporation into dividing cells for cerebellar tissue sections of four-day-old rats injected with this marker. This permits confident identification of granule-cell precursors engaged in DNA synthesis in the external granular layer of the developing cerebellum. Preservation of BrdU immunoreactivity is attained using methanol/acetic acid fixation and different pretreatments before immunostaining, while unlabeled nuclei can be recognized clearly after Feulgen or hematoxylin counterstaining. We established conditions to ensure satisfactory BrdU uptake without affecting cell-cycle progression during the postlabeling time period. The dose of BrdU employed provides saturation S-phase labeling from at least 1 h after BrdU delivery. Various kinetic parameters and phase durations have been determined in experiments involving a single injection or cumulative labeling sequences, and the cycle time was calculated based on two models of generative behavior: steady-state and exponential growth. The working hypothesis of steadystate kinetics can be adopted successfully if the existence of neuroblasts with different proliferation rates is taken into account.     

A new AluI satellite DNA in the root-knot nematode Meloidogyne fallax: relationships with satellites from the sympatric species M. hapla and M. chitwoodi

A highly abundant satellite DNA comprising 20% of the Meloidogyne fallax (Nematoda, Tylenchida) genome was cloned and sequenced. The satellite monomer is 173 bp long and has a high A + T content of 72.3%, with frequent runs of A's and T's. The sequence variability of the monomers is 2.7%, mainly due to random distribution of single-point mutations. A search for evidence of internal repeated subunits in the monomer sequence revealed a 6-bp motif (AAATTT) for which five degenerated repeats, differing by just a single base pair, could be identified. Pairwise comparison of the M. fallax satellite with those from the sympatric species Meloidogyne chitwoodi and Meloidogyne hapla revealed a high sequence similarity (68.39%) with one satellite DNA subfamily in M. chitwoodi, which indicated an unexpected close relationship between them. Given the high copy number and the extreme sequence homogeneity among monomeric units, it may be assumed that the satellite DNA of M. fallax could have evolved through some recent and extensive amplification burst in the nematode genome. In this case, its relatively short life would not yet have allowed the accumulation of random mutations in independent amplified repeats. Considering the morphological resemblance between the two species and their ability to produce interspecific fertile hybrids under controlled conditions, these results indicate that M. fallax may share a common ancestor with M. chitwoodi, from which it could have diverged recently. All these data suggest that M. fallax could be the result of a recent speciation process and show that Meloidogyne satellite DNAs may be of interest to resolve phylogenetic relationships among closely related species from this genus.