Edaphic Habitats Research Articles

Specific leaf area is lower on ultramafic than on neighbouring non-ultramafic soils

ABSTRACT Background Specific leaf area (SLA) is a core trait within the leaf economic spectrum that describes differences in plant performance and productivity. Research on the sources of variation in the leaf economic spectrum and SLA has primarily focused on climate. Much less is known about SLA variation across unusual edaphic environments, such as on ultramafic soils. Aims To determine the role of ultramafic soils as a driver of SLA variation. Methods We measured SLA for dominant species on paired ultramafic and non-ultramafic soils in five biogeographically distinct regions around the globe and compared mean SLA values to globally reported values. Results SLA was lower on ultramafic than on non-ultramafic soils in all regions, except Puerto Rico, and both climate and soil were important drivers of SLA. For three of the five regions, SLA values on ultramafic soils were lower than the global average. Conclusions Soils can be a major driver of SLA along with climate. Low SLA on ultramafic soil points to selection for stress resistance strategies. Furthermore, in some bioregions, SLA values on ultramafic soils were among the lowest on the planet and thus represent globally rare phenotypes that should be conserved within these unique edaphic habitats.

Testing the concept of edaphism for the quartz island flora of the Knersvlakte, South Africa

• Plant-functional traits are useful to study floras on unusual soils. • Quartz island flora, traits and environment differ from the surrounding. • Taxonomic, functional and edaphic diversity are high on quartz islands. • The flora of unusual edaphic habitats is worthy of particular protection. Edaphically unusual sites harbor a flora that is often unique in its taxonomic as well as functional composition and contain many endemic species. While this edaphic endemism, edaphism, has been discussed previously on various special soils, in this study we relate it for the first time to the floristic characteristics of so called “quartz islands”, edaphically driven special habitats in South Africa, and their surroundings (matrix habitat). We sampled the vegetation and soil for 245 vegetation plots in the Knersvlakte Nature Reserve and examined 336 plant species with respect to their evolutionary (plant family, habitat specificity), biogeographical (distributional range) as well as functional traits (life form, leaf succulence, flowering onset, dispersal mode). Based on the floristic uniqueness of the quartz islands, we expect them to host a highly specialized and locally endemic flora with smaller life forms, pronounced leaf succulence (both indicative of resource-conservative economics) and distinct reproductive traits than their surroundings. We find that, compared to the matrix habitat, quartz islands have significantly higher salinity and lower soil pH, and show higher proportion of leaf-succulent species of smaller life forms – some of which are restricted to quartz islands and have different timing of flowering onset, while dispersal via zoochory is less important. Like other special soils, quartz islands harbor unique plant species, which are distinguished by distinct trait patterns. We conclude that the concept of edaphism can be applied to quartz islands.

A new species of the genus Gaeolaelaps Evans & Till (Acari: Mesostigmata: Laelapidae) from China

As members of the family Laelapidae, Gaeolaelaps species are generally acknowledged from litter and edaphic habitats (Joharchi 2019; 2022). The taxonomic history of Gaeolaelaps is complicated and long-term (Halliday & Lindquist 2007). Gaeolaelaps was first defined by Evans and Till (1966) and used to be a subgenus of Hypoaspis (Halliday & Lindquist 2007; Beaulieu 2009). Prior to this paper, the genus Gaeolaelaps consisted of more than 120 described species (Nemati & Mohseni 2013; Kazemi 2020), with 20 species reported from China (Yan et al. 2018). Herein, a new species of Gaeolaelaps Evans & Till, 1966, Gaeolaelaps sp. nov. is described from adult females collected in soil under the Osmanthus trees in Jiangxi Province, China. 

Are Iron-Rich Calcareous Mine Sites Easily Invaded by Invasive Plant Species?

Plant diversity in relatively harsh environments, such as metal-polluted areas tends to be relatively low. Invasive plants may invade harsh environments more easily than native plants. However, studies often find fewer invasive species in stressful edaphic habitats (such as serpentine soils). Those examples may represent relatively extreme conditions. Moderately stressful habitats may be more invaded given the advantages of invasive plants. We surveyed the plant diversity in four site pairs across three seasons. Sites consist of abandoned mines and reference sites. The mine sites have calcareous soils with relatively high iron, basic pH, and lower nutrients than reference sites. Results: There were 153 plant species among the four site pairs. Around 80 and 66% of species in calcareous and reference sites were introduced species respectively. Diversity varied across seasons but tended to be lower in the mine sites. One of the mines was significantly more invaded. Across sites, the number of invasive species and their abundances was not different from that of native species. Invasive plants are as capable of invading moderately stressful calcareous sites as native species, with some sites tending to be even more invaded.

Anatomical and physiological systematics of Capparis decidua (Forsskal.) Edgew from different habitats of Cholistan Desert, Pakistan

Capparis decidua a medicinal shrub belonging to the family Capparaceae, grows abundantly in wild regions of Asia, Africa, and Saudi Arabia. Due to its medicinal and nutritional value, a study on anatomical and physiological adaptations under various desert habitats was conducted. Results revealed that plants in saline areas showed significant anatomical and physiological modifications particularly in stem and roots show better survival under the harsh saline conditions of the desert. It was noted that the root epidermis thickness was not affected in a slightly saline environment as it showed no significant increasing or decreasing trend in the cross-section of the plant population from non-saline to slightly saline (p > 0.05) while it increased significantly in plants growing at highly saline (p < 0.05). Whereas endodermis cell area differs significantly between plants growing at all selected study sites it increased continuously with a rise in the salinity level of the soil (p < 0.05). Meanwhile, water storage capacity and reduction of water loss in the stem area, epidermis, and sclerenchyma were also recorded. In a highly saline environment, results intimate the deduction of photosynthetic pigments, an increase in total soluble proteins, total free amino acids, total soluble sugars, and proline, and a rise in stem and root tissue Na+, K+, Ca2+, and Cl− contents and meanwhile, accumulation of secondary metabolites (Phenolics and flavonoids). These anatomical and physiological adaptations in natural populations appear to be very important for their better survival in a harsh saline desert environment. It was concluded that C. decidua was found in all different edaphic habitats of the Cholistan Desert, due to its adaptive features, which were very obvious in this plant and highly saline site.

Water Uptake Pattern by Coniferous Forests in Two Habitats Linked to Precipitation Changes in Subtropical Monsoon Climate Region, China

Variations in precipitation patterns under climate changes influence water availability, which has important implications for plants’ water use and the sustainability of vegetation. However, the water uptake patterns of the main forest species under different temporal spatial conditions of water availability remain poorly understood, especially in areas of high temporal spatial heterogeneity, such as the subtropical monsoon climate region of China. We investigated the water uptake patterns and physiological factors of the most widespread and coniferous forest species, Cunninghamia lanceolata L. and Pinus massoniana L., in the early wet season with short drought (NP), high antecedent precipitation (HP), and low antecedent precipitation (LP), as well as in the early dry season (DP), in edaphic and rocky habitats. The results showed that the two species mainly absorbed soil water from shallow layers, even in the short drought period in the wet season and switched to deeper layers in the early dry season in both habitats. It was noted that the trees utilized deep layers water in edaphic habitats when the antecedent rainfall was high. The two species showed no significant differences in water uptake depth, but exhibited notably distinct leaf water potential behavior. C. lanceolata maintained less negative predawn and midday water potential, whereas P. massoniana showed higher diurnal water potential ranges. Moreover, the water potential of P. massoniana was negatively associated with the antecedent precipitation amount. These results indicate that for co-existing species in these communities, there is significant eco-physiological niche segregation but no eco-hydrological segregation. For tree species in two habitats, the water uptake depth was influenced by the available soil water but the physiological factors were unchanged, and were determined by the species’ genes. Furthermore, during the long drought in the growing season, we observed probable divergent responses of C. lanceolata and P. massoniana, such as growth restriction for the former and hydraulic failure for the latter. However, when the precipitation was heavy and long, these natural species were able to increase the ecohydrological linkages between the ecosystem and the deep-layer system in this edaphic habitat.

Campodeidae (Hexapoda: Diplura) from Kyrgyzstan, Central Asia, with the description of a remarkable new genus and species

Samples collected in Central Asia, Kyrgyzstan, have revealed a hitherto unknown diversity of Campodeidae (Diplura) in soil and cave habitats, including a new genus and species, Kyrgyzstancampa sanare Sendra &amp; Ferreira gen. et sp. nov., Turkmenocampa edaphica Sendra &amp; Sánchez-García sp. nov. and a previously recognized soil-dwelling species, Campodea (Dicampa) catalana Denis, 1930. Kyrgyzstancampa sanare Sendra &amp; Ferreira gen. et sp. nov. was collected in the deep zone of an interesting geological and cultural cave, Ak-Turpak Cave, located near the western margin of Kadamjay District, Batken Province. This genus belongs to the subfamily Campodeinae, sharing the morphology of the pretarsus with Eutrichocampa and other related genera, but differing from them in the shape of the claws and the laminar lateral processes, in addition to its unique cupuliform organ and the macrosetal pattern on the thorax and abdomen. Turkmenocampa edaphica Sendra &amp; Sánchez-García sp. nov. was found in humid edaphic habitats, under stones or near roots, and is morphologically and geographically very similar to the cave-dwelling species Turkmenicampa mirabilis Sendra #38; Stoev, 2017, which occurs in an isolated cave in the nearby country of Turkmenistan.

How do soil resources affect herbivory in tropical plants along environmental gradients? A test using contrasting congeneric species

Plants adapted to different habitats exhibit differences in functional traits and these characteristics are influenced by soil properties. We tested the hypothesis that soil resource availability influences the functional traits of plants, affecting therefore herbivory levels. We examined three Byrsonima plant species with different life forms that occurred across a distinct edaphic habitat along the Doce River Basin, South-eastern Brazil. We characterized habitats according to soil nutrient concentration and measured functional characteristics of crown architecture, leaf nutrients, sclerophylly, leaf area and leaf density. In addition, we evaluated how these variables influenced herbivory levels of congeneric plants. Our data show that species along a gradient of soil nutrients have functional characteristics influenced by habitat, which in turn affect herbivory levels. By comparing congeners with different life forms found along a stress-gradient of continuous habitats, we describe a corresponding gradient of plant functional traits and tissue consumption by herbivorous insects.

Effect of Long-Term Soil Management Practices on Tree Growth, Yield and Soil Biodiversity in a High-Density Olive Agro-Ecosystem

Edaphic arthropod communities provide valuable information about the prevailing status of soil quality to improve the functionality and long-term sustainability of soil management. The study aimed at evaluating the effect of plant and grass cover on the functional biodiversity and soil characteristics in a mature olive orchard (Olea europaea L.) managed for ten years by two conservation soil managements: natural grass cover (NC) and conservation tillage (CT). The trees under CT grew and yielded more than those under NC during the period of increasing yields (years 4–7) but not when they reached full production. Soil management did not affect the tree root density. Collecting samples underneath the canopy (UC) and in the inter-row space (IR), the edaphic environment was characterized by soil structure, hydrological properties, the concentration and storage of soil organic carbon pools and the distribution of microarthropod communities. The soil organic carbon pools (total and humified) were negatively affected by minimum tillage in IR, but not UC, without a loss in fruit and oil yield. The assemblages of microarthropods benefited, firstly, from the grass cover, secondly, from the canopy effect, and thirdly, from a soil structure ensuring a high air capacity and water storage. Feeding functional groups—hemiedaphic macrosaprophages, polyphages and predators—resulted in selecting the ecotonal microenvironment between the surface and edaphic habitat.

Genetic conservation strategies of endemic plants from edaphic habitat islands: The case of Jacobaea auricula (Asteraceae)

Conservation genetics is a well‐established and essential scientific field in the toolkit of conservation planning, management, and decision‐making. Within its framework, phylogeography allows the definition of conservation strategies, especially in threatened endemic plants. Gypsum and salt-rich outcrops constitute a model example of an edaphic island-like habitat and contain rare and endemic species, many of them threatened. This is the case of Jacobaea auricula, an Iberian gypsohalophytic species with biological, ecological, and conservation interest. Genetic-based criteria were used to preserve the highest possible percentage of the species' genetic pool as well as to dispose of a set of genotypes for translocation and/or reinforcement planning of degraded populations. Relevant Genetics Units for Conservation (RGUCs) were selected as in situ conservation planning. As a complementary ex situ measure, the optimal contribution for the populations to maximize the genetic pool within each genetic cluster was calculated. To preserve the maximum genetic diversity and the highest percentage of rare AFLP bands possible, eight RGUCs were selected; the ex situ conservation design included twenty-one populations, gathering all haplotypes and ribotypes. Our genetic conservation proposal of J. auricula would improve the implementation of future genetic conservation measures, as a species model of endemic plants from edaphic habitat islands.

Contrasting phosphorus sensitivity of two Australian native monocots adapted to different habitats

Contrasting nutrient-acquisition strategies would explain why species differ in their distribution in relation to soil phosphorus (P) availability, promoting diversity. However, what drives the differential distribution of plant species with the same P-acquisition strategy remains poorly understood. We selected two Haemodoraceae species, Anigozanthos flavidus and Macropidia fuliginosa, to investigate physiological responses in non-mycorrhizal monocots adapted to different edaphic habitats that vary in P availability. Plants were grown in nutrient solution in large tanks at a range of P concentrations (0, 0.1, 1, 10 µM P). After seven months, we measured growth, photosynthetic rate, net P-uptake capacity, and leaf [P]. Fresh weights of A. flavidus plants were highest at 1 µM P and lowest at 0 µM P. Fresh weights of M. fuliginosa plants were lowest at 10 µM P compared with those at other P levels. Rates of P uptake by A. flavidus showed a steady decline with increasing P level during growth from 0 to 1 µM P, and then a sharp decline from 1 to 10 µM P. Rates of P uptake in M. fuliginosa did not differ among growth P levels, except between 0 and 1 µM P. Both species showed a drastic increase in the concentration of both total P and inorganic P at 10 µM P. The results support our hypothesis that A. flavidus is efficient in down-regulating its P-uptake capacity, while M. fuliginosa is not. Thus, partly explaining the narrower and wider distribution of these species.

Whole Plastome Sequencing Within Silene Section Psammophilae Reveals Mainland Hybridization and Divergence With the Balearic Island Populations.

Reconstructing the phylogenetic relationships within Caryophyllaceae tribe Sileneae has been obscured by hybridization and incomplete lineage sorting. Silene is the largest genus in the Caryophyllaceae, and unraveling its evolutionary history has been particularly challenging. In order to infer the phylogenetic relationships among the five species in Silene section Psammophilae, we have performed a genome skimming approach to acquire the complete plastid genome (cpDNA), nuclear ribosomal cistron (nrDNA), and partial mitochondrial genome (mtDNA). We have included 26 populations, representing the range of each species' distribution. This section includes five morphologically similar species endemic to the Iberian Peninsula and Balearic Islands (Ibiza and Formentera), yet some of them occupy distinct edaphic habitats (e.g. maritime sands, calcareous sandstones). In addition to phylogeographic analyses, genetic structuring using the chloroplast data set was inferred with Discriminant Analysis of Principal Components (DAPC), analyses of molecular variance (AMOVA), and a partial Mantel test. Reference-guided assembly of 50 bp single-end and 250 bp paired-end Illumina reads produced the nearly complete cpDNA genome (154 kbp), partial mtDNA genome (from 81 to 114 kbp), and the nrDNA cistron (6.4 kbp). Selected variable regions of the cpDNA and mtDNA assemblies were confirmed by Sanger sequencing. Phylogenetic analyses of the mainland populations reveal incongruence among the three genomes. None of the three data sets produced relationships consistent with taxonomy or geography. In contrast, Silene cambessedesii, present in the Balearic Islands, is the only species that forms a strongly supported monophyletic clade in the cpDNA genome and is strongly differentiated with respect to the remaining taxa of the Iberian Peninsula. These results contrast with those obtained for mainland populations. Across the entire analysis, only one well-supported mainland clade of Silene littorea and Silene stockenii emerges from the southern region of the Iberian Peninsula. DAPC and AMOVA results suggest the absence of genetic structure among mainland populations of Silene section Psammophilae, whereas partial Mantel test discarded spatial correlation of genetic differentiation. The widespread incongruence between morphology-based taxonomic boundaries and phylogeography suggests a history of interspecific hybridization, in which only a substantial geographic barrier, like isolation by the Mediterranean Sea, was sufficient to create and maintain species boundaries in Silene section Psammophilae.

Achyranthemum N.G.Bergh, a new genus segregated from Syncarpha DC. (Asteraceae, Gnaphalieae)

The genus Syncarpha from the Cape region of South Africa has been shown to comprise two separate lineages based on phylogenetic analysis of plastid and nuclear DNA sequence data. The lineage that does not house the type of Syncarpha corresponds to the ‘Helichrysum paniculatum group’ of species. Here we erect a new genus, Achyranthemum, to house these species, make the necessary nomenclatural changes, and present a taxonomic revision with key, descriptions and distribution maps based on verified records. Achyranthemum comprises seven species confined to the Cape Floristic Region and with the highest concentration of species in the Port Elizabeth region. Species are distinguished by leaf shape and orientation, leaf and peduncle indumentum, colour of the involucral bracts, and capitulum arrangement, as well as other features including differences in edaphic habitat. Nomenclatural and taxonomic investigations indicate that Syncarpha chlorochrysum is a synonym of Syncarpha mucronatum, and that there are two species present in the taxon currently known as Syncarpha argentea.

Plant ecology of tropical and subtropical karst ecosystems

AbstractSubstantial areas of tropical forests, including those within nine tropical biodiversity hotspots, contain karst landscapes that have developed on soluble carbonate rocks. Here, we review how the ecology of karst forest trees is influenced by hydrological, edaphic, and topographic factors that exhibit fine spatial heterogeneity. Comparative analysis of drought tolerance traits including wood density contributes to the assessment of whether karst tree species are more drought‐tolerant compared to non‐karst trees. Although karst ecosystems are generally considered to have low phosphorus availability, foliar nitrogen‐to‐phosphorus ratios exhibit wide variation across karst regions without a clear difference from non‐karst ecosystems. According to the analyses of leaf phenology, stem water storage, and isotopic signatures from xylem sap, water use strategies of karst trees can be classified into five types: (a) soil water dependent, (b) epikarst water dependent (mainly use water stored in fine pores and gaps within the epikarst rock during the dry season), (c) groundwater dependent, (d) fog water dependent, and (e) drought‐deciduous (shed leaves during the dry season). Overall, published data suggest that only a subset of karst tree species are exclusively distributed within karst hilltops where water availability is limited. The diverse resource acquisition and utilization strategies of karst plants across edaphic habitats must be considered when developing effective strategies to conserve and restore biodiversity in karst landscapes, which are under increasing anthropogenic pressure.

Low Level of Genetic Variation and Signs of Isolation in the Native Hungarian Sea Buckthorn Population Compared to Cultivated Specimens

Sea Buckthorn population from Újpest Nature Reserve, the only one assumed to be native in Hungary sustains at the periphery of Budapest city on the sandy substrate deposited by the Danube river. The study aims to characterize the gene stock preserved on this small edaphic habitat by comparing with the genetic material of planted specimens of known origin used in horticultural and gardening practice. Fragment length variations of seven nuclear microsatellite markers were evaluated and a phylogenetic tree was constructed based on sequence variation of an intron from nuclear gene encoding the chalcone synthase enzyme. Gender rate was evaluated by female specific SCAR marker. Microsatellite analysis pointed out the extremely low variation of the natural sea buckthorn population from Újpest Nature Reserve compared to the cultivated specimens, while the phylogenetic tree revealed that the natural population belongs to the genetic lineage distributed mostly in Western and Middle-Europe, and in Romania, region, which has strong links to the Balkan and the Black Sea. The analysis clearly separated the genetic material of the native Újpest population from the planted individuals from the vicinity that proved to be of allochthonous origin. The HrX2 SCAR marker revealed the dominance of the males (1:1.42). The study provides support for the autochthonous origin of the Hungarian remnant population being in reproductive isolation that suggest for its long persistence and relict status. Ex situ conservation and nature protection measures are highly recommended to maintain one of the last native sea buckthorn populations of the Pannonian region.&#x0D; &#x0D; *********&#x0D; In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.&#x0D; *********

Natural disturbance and soils drive diversity and dynamics of seasonal dipterocarp forest in Southern Thailand

AbstractIn 2000, we established a 24-ha plot in Peninsular Thailand to investigate how forest composition, structure and dynamics vary with spatial heterogeneity in resource availability. Detailed soil and topographic surveys were used to describe four edaphic habitats in the plot. Disturbance history was inferred from historical records and floristic analysis. The plot included &amp;gt;119 000 trees ≥1 cm dbh in 578 species, and was recensused in 2010. Species distributions, floristic turnover, stand structure, demographic rates and biomass dynamics were strongly influenced by heterogeneity in soils, topography and disturbance history. Over 75% of species were aggregated on specific edaphic habitats leading to strong compositional turnover across the plot. Soil chemistry more strongly affected species turnover than topography. Forest with high biomass and slow dynamics occurred on well-drained, low fertility ridges. The distribution and size structure of pioneer species reflected habitat-specific differences in disturbance history. Overall, above-ground biomass (AGB) increased by 0.64 Mg ha−1 y−1, from 385 to 392 Mg ha−1, an increase that was entirely attributable to recovery after natural disturbance. Forest composition and stand structure, by reflecting local disturbance history, provide insights into the likely drivers of AGB change in forests. Predicting future changes in tropical forests requires improved understanding of how soils and disturbance regulate forest dynamics.

Microhabitat characteristics and impacts of invasive species for the triple-ribbed milkvetch (Astragalus tricarinatus [Fabaceae]) in the San Bernardino Mountains, California.

Astragalus tricarinatus A.Gray is a federally-listed short lived perennial herb endemic to southern California. Its primary habitat is along the ecotone of the Mojave and Colorado Deserts in the San Bernardino and Little San Bernardino Mountains between 390 and 1525 m. Discovery of this species' upland habitat has prompted research into the ecology of populations across its range, as the life history and threats may be different from those of the previously-known wash populations. Our study sought to further document A. tricarinatus distribution and abundance within its range, as well as quantify impacts to its growth and reproductive efforts associated with co-occurring native and invasive plant species. We mapped all known localities in our study area on aerial imagery then used this to visually recognize its typical edaphic habitat and identify new potential sites. Where A. tricarinatus was found, we established plots in which plant size, the number of reproductive structures, and microhabitat characteristics were recorded. Two new occurrences (defined here as >1 km away from known localities) were recorded within its existing range as well as a previously undocumented locality between two known occurrences containing an estimated 2600 plants. Most plants were found on south and east aspects, and on slopes ranging from 30–45°. We found that increases in invasive cover correlated with a decrease in production of reproductive structures. As a federally-listed species occurring in steep, remote habitats with few threats, these findings suggesting an association between invasive species presence and reduced reproductive structures should be further investigated experimentally, as they affect population dynamics and conservation of this species.

Genomic Signature of Adaptive Divergence despite Strong Nonadaptive Forces on Edaphic Islands: A Case Study of Primulina juliae.

Both genetic drift and divergent selection are expected to be strong evolutionary forces driving population differentiation on edaphic habitat islands. However, the relative contribution of genetic drift and divergent selection to population divergence has rarely been tested simultaneously. In this study, restriction-site associated DNA-based population genomic analyses were applied to assess the relative importance of drift and divergent selection on population divergence of Primulina juliae, an edaphic specialist from southern China. All populations were found with low standing genetic variation, small effective population size (NE), and signatures of bottlenecks. Populations with the lowest genetic variation were most genetically differentiated from other populations and the extent of genetic drift increased with geographic distance from other populations. Together with evidence of isolation by distance, these results support neutral drift as a critical evolutionary driver. Nonetheless, redundancy analysis revealed that genomic variation is significantly associated with both edaphic habitats and climatic factors independently of spatial effects. Moreover, more genomic variation was explained by environmental factors than by geographic variables, suggesting that local adaptation might have played an important role in driving population divergence. Finally, outlier tests and environment association analyses identified 31 single-nucleotide polymorphisms as candidates for adaptive divergence. Among these candidates, 26 single-nucleotide polymorphisms occur in/near genes that potentially play a role in adaptation to edaphic specialization. This study has important implications that improve our understanding of the joint roles of genetic drift and adaptation in generating population divergence and diversity of edaphic specialists.

Evidence of microbial rhodopsins in Antarctic Dry Valley edaphic systems.

Microorganisms able to synthesize rhodopsins have the capacity to translocate ions through their membranes, using solar energy to generate a proton motive force. Rhodopsins are the most abundant phototrophic proteins in oceanic surface waters and are key constituents in marine bacterial ecology. However, it remains unclear how rhodopsins are used in most microorganisms. Despite their abundance in marine and fresh-water systems, the presence of functional rhodopsin systems in edaphic habitats has never been reported. Here, we show the presence of several new putative H+ , Na+ and Cl+ pumping rhodopsins identified by metagenomic analysis of Antarctic desert hypolithic communities. Reconstruction of two Proteobacteria genomes harboring xanthorhodopsin-like proteins and one Bacteroidetes genome with a Na-pumping-like rhodopsin indicated that these bacteria were aerobic heterotrophs possessing the apparent capacity for the functional expression of rhodopsins. The existence of these protein systems in hypolithic bacteria expands the known role of rhodopsins to include terrestrial environments and suggests a possible predominant function as heterotrophic energy supply proteins, a feasible microbial adaptation to the harsh conditions prevalent in Antarctic edaphic systems.

Mesovoid shallow substratum as a biodiversity hotspot for conservation priorities: analysis of oribatid mite (Acari: Oribatida) fauna

The mesovoid shallow substratum (MSS) is a unique habitat that shelters and serves as a microrefuge for epigean, endogean and hypogean invertebrate species. Understanding the MSS community′s spatio-temporal structure and species diversity patterns in relation to the environmental parameters plays a crucial role in conservation. In this study we investigated: i) the diversity and community structure of oribatid mites from edaphic habitat, superficial MSS (i.e., the upper layer of MSS) and deep MSS (i.e., lower layer of MSS) in an alpine region of Southern Carpathians, Romania, and ii) the relationships between the oribatid mite communities and the environmental variables, such as temperature and humidity. The composition and the structure of oribatid communities differed along the three habitats indicating possible habitat specialization. The structure of the oribatid community was influenced by temperature and humidity. The rich and mixed oribatid communities in the MSS and the oribatid communities' response to surface and subsurface environmental variables suggest that the MSS may offer a micro-refuge for edaphic species when the conditions in the surface habitats become too harsh. Thus, we suggest that MSS should be prioritized for conservation because it may be the key component in maintaining biodiversity.