General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms ). Here we test the hypothesis that abiogenic H2 can be produced from rock-water reactions at 0°C in sufficient quantities to be able to support subglacial microbial activity.The ability of six silicate rock types samples from glacial catchments (gneiss, quartzite, shale, granite, nepheline-syenite, schist) to generate abiogenic H2 in water-rock reactions were tested. Calcite was used as a non-silicate control. The molar compositions of the starting materials are given in Supplementary Table S1. The rocks and mineral control were crushed to a range of different surface areas under an inert atmosphere, wetted with water, and the generation of H2 followed over time.All six silicate rock types produced H2 when crushed and wetted with water at 0°C (Figure 1). There was no detectable H2 generation in experiments with calcite (< 2.7 nmol H2 , with the free radicals formed through the shearing of surface mineral bonds during subglacial rock comminution. We note that free radicals were not detected in our crushed calcite, consistent with a lack of detectable H2 in these control experiments.Equation 1 For all three silicate rocks tested, rates of H2 generation were similar at 0°C and 10°C, but higher at 35°C (Figure 2). This temperature dependence may be due to the transformation of more stable SiO radicals to more reactive Si radicals at higher temperatures 15 .The amount of experimental H2 generated likely underestimated in situ abiogenic H2 subglacial production, for the following reasons. First, the shape of many of the H2 generation curves in Figures 2 and 3 suggest that production may continue for longer than the 120 hour experimental period. Second, it is likely that less stable surface radicals will be lost during and after dry crushing, prior to the addition of water. Third, H2 may be produced by additional water-rock interactions such as serpentinization 12,13 , although these are untested at subglacially relevant temperatures. Finally, additional H2 could have been released from fluid inclusions 18 during the initial dry crushing stage of our methods.Our experimental data suggests that the amount of H2 generated from subglacial rock comminution depends primarily on the rate of rock abrasion, the presence of liquid water, and We crudely estimated the catchment scale H2 generation by rock comminution for one of our study sites; the 600 km 2 Leverett Glacier, SW Greenland. We first used the regression equation in Figure 1c to calculate the potential H2 that could be generated from silica radicalwater reactions, using the measured mean molar silica surface area of suspended sediment from the catchment (Methods). We then scaled up our calculations using measurements of the annual suspended sediment flux from the glacier , and a diversity of methanogens 8,25 . Prior studies on subglac...
In Australia, many species have been introduced that have since undergone drastic declines in their native range. One species of note is the hog deer (Axis porcinus) which was introduced in the 1860s to Victoria, Australia, and has since become endangered in its native range throughout South‐East Asia. There is increased interest in using non‐native populations as a source for genetic rescue; however, considerations need to be made of the genetic suitability of the non‐native population. Three mitochondrial markers and two nuclear markers were sequenced to assess the genetic variation of the Victorian population of hog deer, which identified that the Victorian population has hybrid origins with the closely related chital (Axis axis), a species that is no longer present in the wild in Victoria. In addition, the mitochondrial D‐loop region within the Victorian hog deer is monomorphic, demonstrating that mitochondrial genetic diversity is very low within this population. This study is the first to report of long‐term persistence of hog deer and chital hybrids in a wild setting, and the continual survival of this population suggests that hybrids of these two species are fertile. Despite the newly discovered hybrid status in Victorian hog deer, this population may still be beneficial for future translocations within the native range. However, more in‐depth analysis of genetic diversity within the Victorian hog deer population and investigation of hybridization rates within the native range are necessary before translocations are attempted.
Hog deer were introduced to Australia in the 1860s, where they have spread across the Gippsland region of Victoria. Due to its status as an introduced species and an important game animal within Victoria, management of the species is complex. Given this complexity, genetic studies can provide important information regarding population structure and diversity which can assist in controlling problematic populations of hog deer, while also ensuring viable game stock in sites managed as game reserves. The aim of this study was to investigate the population genetic structure and diversity of the Victorian hog deer 150 years after introduction using short tandem repeats (STRs). Hog deer samples were collected across 15 sites of differing management regimes in the Gippsland region of Victoria and genotyped for 13 polymorphic STR loci. Up to four distinct genetic clusters were identified across the sites sampled, suggesting that despite low observed genetic diversity, population structure is present across their range. It was also possible to detect evidence of recent translocations among populations. This study suggests that the presence of distinct genetic clusters may enable management of separate genetic units, considering invasive species and game management objectives.
The mitochondrial genome of the hog deer (Axis porcinus) was sequenced using an Illumina MiSeq. The assembled genome consists of 16,351 bp, and shared a 99.8% similarity to the published chital deer (Axis axis) genome, suggesting that they belong to the same species. Further research is ongoing to understand why these mitochondrial genomes are highly similar.
The establishment of non-native populations of threatened and legally protected species can have many implications for the areas where these species have been introduced. Non-native populations of threatened species have the potential to be exploited and therefore the subject of legal protection, while conversely, if they have become invasive in their introduced range, there is the likelihood that population control will be carried out to reduce abundance and negative impacts associated with introduced species. From both a legal and invasive species monitoring standpoint, it is important to know how many individuals are present. Short tandem repeats (STRs) were developed for the hog deer, an endangered species that was introduced following European settlement to Victoria, Australia using Illumina MiSeq sequencing technology. These markers were combined with previous STRs characterised for hog deer to create a 29-plex identification system. A total of 224 samples were genotyped across the population in Victoria, and further analyses of null allele frequencies, deviation from Hardy-Weinberg equilibrium, and the removal of monomorphic or low amplifying markers resulted in a final marker panel of 17 loci. Despite low values for number of alleles at each locus (2-4), probability of identity showed sufficient discrimination power, with an average probability of identity at 9.46 × 10 -7 , and a probability of sibling identity of 7.67 × 10 -4 across all sites. These findings show that it is feasible to create an informative DNA profiling system that can distinguish between individuals for applications in both wildlife forensic and population control research.
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