Population genetic analysis of the recently rediscovered Hula painted frog (Latonia nigriventer) reveals high genetic diversity and low inbreeding

After its recent rediscovery, the Hula painted frog (Latonia nigriventer) has remained one of the world’s rarest and least understood amphibian species. Together with its apparently low dispersal capability and highly disturbed niche, the low abundance of this living fossil calls for urgent conservation measures. We used 18 newly developed microsatellite loci and four different models to calculate the effective population size (Ne) of a total of 125 Hula painted frog individuals sampled at a single location. We compare the Ne estimates to the estimates of potentially reproducing adults in this population (Nad) determined through a capture-recapture study on 118 adult Hula painted frogs captured at the same site. Surprisingly, our data suggests that, despite Nad estimates of only ~234–244 and Ne estimates of ~16.6–35.8, the species appears to maintain a very high genetic diversity (HO = 0.771) and low inbreeding coefficient (FIS = −0.018). This puzzling outcome could perhaps be explained by the hypotheses of either genetic rescue from one or more unknown Hula painted frog populations nearby or by recent admixture of genetically divergent subpopulations. Independent of which scenario is correct, the original locations of these populations still remain to be determined

Fine-Scale Temporal Dynamics of a Fragmented Lotic Microbial Ecosystem

Microbial ecosystems are often assumed to be relatively stable over short periods of time, but this assumption is seldom tested. An urban stream influenced by both flow and varying levels of anthropogenic influences is expected to have high temporal variability in microbial composition, and short-term ecological instability. Thus, we analyzed the bacterioplankton composition of a weir-fragmented urban stream using Automated rRNA Intergenic Spacer Analysis (ARISA). A total of 46 sequential samples were collected in July 2009 for 7 days, every 7 hours, from both the up-stream side of the weir (stream water) and the downstream side of the weir (estuarine) water. Bray-Curtis similarity based analysis showed a clear division between upstream and downstream communities. A sudden pH drop induced change in both communities, but composition stability partially recovered within less than a day. Thus, our results show that microbial ecosystems can change rapidly, but re-establish a new equilibrium relatively quickly

Sediment respiration pulses in intermittent rivers and ephemeral streams

Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32–66‐fold upon sediment rewetting. Structural equation modelling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2–0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting‐drying cycles on respiration and CO2 emissions in stream networks

A global analysis of terrestrial plant litter dynamics in non-perennial waterways

Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments

Extensive variation of sequence within isolates of Grapevine Virus B

© Springer. Part of Springer Science+Business Media The original publication can be found at www.springerlink.comFour regions covering 1247 nucleotides of the RNA genome of 20 isolates of a Vitivirus, Grapevine virus B (GVB), from three countries were analyzed. All the regions in these isolates varied in sequence as compared to the published GVB sequence. Of these, the intergenic region varied the most, with 73.2% nucleotide sequence homology, while ORF4 encoding coat protein varied the least when compared both at nucleotide sequence (80.3% homology) and at amino acid sequence levels (90.6% homology). The variations were scattered along each region length and were higher at the nucleotide level than at the amino acid level, but none resulted in a frame shift or stop codon. These results indicate that GVB may exist as a heterogeneous population, possibly resulting from mixing different strains by grafting practices or by RNA-RNA recombination in the grapevine, the only known natural host of this virus. Although it has been reported that GVB is associated with corky bark disease, no corky bark symptoms were observed in any of the GVB positive grapevine sample collected from Australia.Bu-jun Shi, Nuredin Habili, Roni Gafny and Robert H. Symon

A modified method for purification of biological samples collected on FTA cards for STR analysis

FTA cards are regarded as a method of choice for the preservation and storage of blood and saliva prior to genetic testing. In this study, we compared the recommended protocol of DNA purification and amplification from FTA cards to a method we developed in the laboratory. Our simplified method was tailored for amplification using the AmpFLSTR SGM Plus kit. The modified method proved to decrease artifacts in DNA profiles and was more time- and cost-effective than the manufacturer's protocol