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Several species of dryland cyanobacteria are known to occur as hypoliths under semi-translucent rocks. In the Mojave Desert, these organisms find refuge from intense solar radiation under milky quartz where moisture persists for a longer period of time than in adjacent soil surface habitat. Desert mosses, which are extremely desiccation-tolerant, can also occur in these hypolithic spaces, though little is known about this unique moss microhabitat and how species composition compares to that of adjacent soil surface communities. To address this question, we deployed microclimate dataloggers and collected moss samples from under and adjacent to 18 milky quartz rocks (quartz mean center thickness 26 ± 15 mm) in a western high elevation Mojave Desert site. Light transmission through Mojave quartz rocks may be as low as 1.2%, and data from microclimate loggers deployed for five months support the hypothesis that quartz provides thermal buffering and higher relative humidity compared to the soil surface. Of the 53 samples collected from hypolith and surface microhabitats, 68% were Syntrichia caninervis, the dominant bryophyte of the Mojave Desert biological soil crust. Tortula inermis accounted for 28% of the samples and 4% were Bryum argenteum. In a comparison of moss community composition, we found that S. caninervis was more likely to be on the soil surface, though it was abundant in both microhabitats, while T. inermis was more restricted to hypoliths, perhaps due to protection from temperature extremes. In our study site, the differences between hypolithic and surface microhabitats enable niche partitioning between T. inermis and S. caninervis, enhancing alpha diversity. This work points to the need to thoroughly consider microhabitats when assessing bryophyte species diversity and modelling species distributions. This focus is particularly important in extreme environments, where mosses may find refuge from the prevailing macroclimatic conditions in microhabitats such as hypoliths.

Given the history of the International Criminal Court in Africa, the relationship between African states and the Court is particularly significant to its legitimacy. If the power of the Court is grounded in international political support and the perception that it transcends international and national politics to deny impunity for ‘atrocity’ crimes, the Court's perceived legitimacy and normative legitimacy are so intertwined that charges of illegitimacy from significant regional stakeholders hold particular weight. More importantly, criticisms voiced by African actors point to a valid challenge to the Court's legitimate moral standing as an arbiter of global justice: the international power imbalance that seems to be becoming more entrenched and apparent in the Court's work. Tactics adopted by some African leaders of prioritising the issue of heads-of-state immunity, however, minimise the broader issue of power differentials and reduce the chance that African states will find allies in their cause to challenge the Court's operations.

PREMISE OF RESEARCH: Natural populations of many mosses appear highly female‐biased based on the presence of reproductive structures. This bias could be caused by increased male mortality, lower male growth rate, or a higher threshold for achieving sexual maturity in males. Here we test these hypotheses using samples from two populations of the Mojave Desert moss Syntrichia caninervis. METHODS: We used double‐digest restriction‐site associated DNA (RAD) sequencing to identify candidate sex‐associated loci in a panel of sex‐expressing plants. Next, we used putative sex‐associated markers to identify the sex of individuals without sex structures. KEY RESULTS: We found a 17:1 patch‐level phenotypic female to male sex ratio in the higher elevation site (Wrightwood) and no sex expression at the low elevation site (Phelan). In contrast, on the basis of genetic data, we found a 2:1 female bias at the Wrightwood site and only females at the Phelan site. The relative area occupied by male and female genets was indistinguishable, but males were less genetically diverse. CONCLUSIONS: Our data suggest that both male‐biased mortality and sexual dimorphism in thresholds for sex expression could explain genetic and phenotypic sex ratio biases and that phenotypic sex expression alone over‐estimates the extent of actual sex ratio bias present in these two populations of S. caninervis.

Biological soil crusts (biocrusts) are widespread in drylands and deserts. At the microhabitat scale, they also host hypolithic communities that live under semitranslucent stones. Both environmental niches experience exposure to extreme conditions such as high UV radiation, desiccation, temperature fluctuations, and resource limitation. However, hypolithic communities are somewhat protected from extremes relative to biocrust communities. Conditions are otherwise similar, so comparing them can answer outstanding questions regarding adaptations to environmental extremes. Using metagenomic sequencing, we assessed the functional potential of dryland soil communities and identified the functional underpinnings of ecological niche differentiation in biocrusts versus hypoliths. We also determined the effect of the anchoring photoautotroph (moss or cyanobacteria). Genes and pathways differing in abundance between biocrusts and hypoliths indicate that biocrust communities adapt to the higher levels of UV radiation, desiccation, and temperature extremes through an increased ability to repair damaged DNA, sense and respond to environmental stimuli, and interact with other community members and the environment. Intracellular competition appears to be crucial to both communities, with biocrust communities using the Type VI Secretion System (T6SS) and hypoliths favoring a diversity of antibiotics. The dominant primary producer had a reduced effect on community functional potential compared with niche, but an abundance of genes related to monosaccharide, amino acid, and osmoprotectant uptake in moss-dominated communities indicates reliance on resources provided to heterotrophs by mosses. Our findings indicate that functional traits in dryland communities are driven by adaptations to extremes and we identify strategies that likely enable survival in dryland ecosystems. Biocrusts serve as a keystone element of desert and dryland ecosystems, stabilizing soils, retaining moisture, and serving as a carbon and nitrogen source in oligotrophic environments. Biocrusts cover approximately 12% of the Earth's terrestrial surface but are threatened by climate change and anthropogenic disturbance. Given their keystone role in ecosystem functioning, loss will have wide-spread consequences. Biocrust microbial constituents must withstand polyextreme environmental conditions including high UV exposure, desiccation, oligotrophic conditions, and temperature fluctuations over short time scales. By comparing biocrust communities with co-occurring hypolithic communities (which inhabit the ventral sides of semitranslucent stones and are buffered from environmental extremes), we identified traits that are likely key adaptations to extreme conditions. These include DNA damage repair, environmental sensing and response, and intracellular competition. Comparison of the two niches, which differ primarily in exposure levels to extreme conditions, makes this system ideal for understanding how functional traits are structured by the environment.

In 2018, Prime Minister Trudeau made two announcements regarding the International Criminal Court, both, it seems, aimed at reinforcing Canada’s claim of human rights promotion and multilateralism: Canada declared Myanmar’s actions against the Rohingya people genocide and urged the United Nations Security Council to refer the situation to the International Criminal Court, and it joined a collective referral of the Venezuela situation to the Court. As public measures of support, these are positive developments for the International Criminal Court, which has been suffering poor public relations and challenges to its legitimacy. However, Canada could do more by better supporting the financial viability of the Court. Currently, it aims to increase the Court’s workload without supporting an increased budget, as reflected in Canada’s involvement at the December 2018 Assembly of States Parties meeting. A seemingly sure way to undermine the International Criminal Court would be to add to its workload without ensuring it has the financial resources to do the work.

Premise In dioicous mosses, sex is determined by a single U (female, ♀) or V (male, ♂) chromosome. Although a 1 : 1 sex ratio is expected following meiosis, phenotypic sex ratios based on the production of gametangia are often female‐biased. The dryland moss Syntrichia caninervis (Pottiaceae) is notable for its low frequency of sex expression and strong phenotypic female bias. Here we present a technique to determine genotypic sex in a single shoot of S. caninervis, and report results of a case study examining genotypic and phenotypic sex ratios. Methods We reanalyzed 271 non‐expressing gametophyte shoots from a previous study on S. caninervis sex expression across microhabitats using a restriction fragment length polymorphism (RFLP) method. Results We recovered a genotypic sex ratio in non‐expressing shoots of 18.4♀ : 1♂, which exceeds the female bias of the phenotypic ratio (5.3♀ : 1♂; P = 0.013). We also found that the distribution of male and female genotypes across microsites with different levels of sun exposure was not predicted by patterns of sex expression in these microsites. Discussion These findings contribute to our understanding of how the environment may modulate sex ratios in S. caninervis, either through its direct influence on sex expression or through selection on genotypes with particular sex expression phenotypes.

Three genes encoding dehydrins have been previously described from peach. In the course of searching the peach genome, three additional members of this stress-associated family were recognized, PpDhn4 - 6. PpDhn1 and 6 have no introns, whereas the remaining four genes have a single intron located near the 3′ end of the serine (S) tract. PpDHN2 was the only dehydrin with a predicted basic pI; pI predictions for the other dehydrins ranged from about 5.3 to about 6.3. None of the peach dehydrins have tryptophan residues, but, in contrast to most dehydrins, three (PpDHN1, 3, and 4) have one or more cysteine residues. Phylogenetic analysis indicated a close relationship between PpDhn1 and 6 and PpDhn3 and 4 . Expression analysis under low temperature and dehydration confirmed that PpDhn2 is the major responder to drought, while both PpDhn1 and 6 respond exclusively to cold. Comparison of the first 500 base pairs upstream of the translation start site revealed the presence of cis -elements associated with low temperature and drought/osmotic/salt and hormone response regulation.

Premise of research. If sexual reproduction is necessary for maintaining genotypic diversity, then plant populations lacking sex might be expected to exhibit less genotypic diversity than sexually reproducing populations. This pattern could be particularly pronounced in mosses of harsh environments, where haploid gametophytes persist in the apparent absence of sex, presumably through vegetative cloning. Here we compare genetic diversity in four Mojave Desert populations of the moss Syntrichia caninervis to assess the degree to which sexual reproduction is associated with genotypic diversity. This study helps define the role of reproductive modes in producing and maintaining genetic diversity. Methodology. Eight microsatellite loci were used to genotype four Mojave Desert populations of S. caninervis, which consisted of two sites with lower environmental stress and sexual reproduction and two sites with higher stress and no apparent sexual reproduction. Pivotal results. Of 341 ramets that amplified successfully across at least seven of the eight loci, 191 unique genotypes were identified; of these, 87 and 131 differed by one and two stepwise mutations, respectively. Genetic diversity was high and did not differ significantly between sexual and asexual populations. Estimates of mutation-scaled migration rates between sites ranged from four to 48 individuals per generation. Conclusions. Despite different levels of sex expression and sporophyte production, genetic and clonal diversity did not differ significantly between higher- and lower-stress populations. The relatively low population structure among sites, high number of clonal lineages, and predominance of genotypes differing by only one or two mutation steps suggests that migration and somatic mutation are responsible for the observed genotypic diversity. These results support the idea that established populations can persist through cloning and that migration can occur over large physical distances. However, retention of genotypic diversity from a time when the environment was more permissive to sexual reproduction cannot be ruled out as an influence on population structure.

In seed plants, populations located at the margins of species distributions are often characterized by reduced sexual reproduction and an increased reliance asexual reproduction. The degree to which this pattern applies to reproductive traits in haploid–dominant, non–seed plants was assessed in the Syrrhopodon involutus Schwaeg complex, a group of closely related tropical mosses with unisexual gametophytes. The second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA was sequenced for samples from throughout the range of the Syrrhopodon involutus Schwaeg complex and a maximum likelihood analysis was performed on the sequence data to infer phylogenetic history. Reproductive data were collected from 270 herbarium vouchers representing at least 337 individuals, and analyzed to test for geographic or phylogenetic differences in sex expression and sexual reproduction. Female sex expression was significantly lower among marginally distributed individuals compared to individuals collected from areas central to the distribution of the complex, and the marginal group contained a higher proportion of non–expressing individuals. The proportion of male–expressing gametophytes was not significantly different between marginal and central areas. Despite the lower proportion of female–expressing gametophytes in marginally distributed individuals, the percentage of female–expressing gametophytes undergoing successful fertilization and producing sporophytes was not significantly different in marginal and central distributional areas. These results suggest that the availability of males constrains the production of sporophytes, not only at the margins of species distributions, but in central areas as well, and that geography exerts a disproportionate effect on male and female sex expression.