West Australia Research Articles

Ecohydrological Variables Underlie Local Moisture Recycling in Mediterranean‐Type Climates

AbstractMediterranean areas are projected to face increased water scarcity due to global changes. Because a relatively large fraction of the precipitation in Mediterranean areas originates locally, changes at the land surface may further dampen local precipitation. Here, we study the contribution of evaporation to local precipitation for the first time on a scale of approximately 50 km using local evaporation recycling (ELMR) and local precipitation recycling (PLMR), and make a comparison among five Mediterranean climate regions: South West Australia, South West US, central Chile, the Mediterranean Basin, and the Cape region of South Africa. Specifically, this study aims to understand the effects of ecohydrological (dependent on vegetation or the hydrological cycle) and non‐ecohydrological variables on ELMR and PLMR. We find that (a) on average, ecohydrological variables correlate more frequently and more strongly to ELMR and PLMR than non‐ecohydrological variables; (b) ELMR is large over wet areas and PLMR is large over dry areas; and (c) there are differences in underlying factors of ELMR and PLMR among the regions due to differences in wetness, topography, and land cover. The results suggest that in Mediterranean regions, changes in vegetation cover or the hydrological cycle may strengthen the local water cycle through enhancing ELMR. Finally, ELMR and PLMR help to identify where in Mediterranean regions we might enhance the local water cycle through land cover changes.

Summer marine heatwaves in the tropical Indian Ocean associated with an unseasonable positive Indian Ocean Dipole event 2012

Marine heatwaves (MHWs) are anomalously warm events that profoundly affect climate change and local ecosystem. During the summer of 2012 (June–September), intense MHWs occurred in the tropical Indian Ocean (TIO) concurrently with an unseasonable positive Indian Ocean Dipole (pIOD) event. The MHW metrics (duration, frequency, cumulative intensity and maximum intensity) were characterized by northwestward–slanted patterns from west Australia to the Somalia coast. The analysis confirmed that these MHWs were closely associated with the unseasonable pIOD 2012. The weakening of Western North Pacific Subtropical High and strengthening of Australian High in spring induced an interhemispheric pressure gradient that drove two anticyclonic circulation patterns over the eastern TIO. The first anticyclonic circulation featured cross–equatorial wind anomalies from south of Java to the South China Sea/Philippine Sea, which led to strong upwelling off Sumatra–Java during the subsequent summer. The second anticyclonic circulation excited downwelling Rossby waves that propagated from the southeastern TIO to the western TIO. Thus, downwelling in the western pole and upwelling in the eastern pole led to a strong pIOD event peaking in summer, namely, the unseasonable pIOD 2012. These downwelling Rossby waves deepened the thermocline by more than 60 m and caused anomalous surface warming, thereby contributing to the occurrences of MHWs. With the development and peak of the unseasonable pIOD 2012, anomalous atmospheric circulation transported moisture from the TIO to the subtropical Western North Pacific (WNP), favoring a strong cyclonic anomaly that profoundly affected the summer monsoon rainfall over the subtropical WNP. This study provides some perspectives on the role of pIOD events in summer climate over the Indo–Northwest Pacific region.

Predicting suitable habitats for foraging and migration in Eastern Indian Ocean pygmy blue whales from satellite tracking data

BackgroundAccurate predictions of animal occurrence in time and space are crucial for informing and implementing science-based management strategies for threatened species.MethodsWe compiled known, available satellite tracking data for pygmy blue whales in the Eastern Indian Ocean (n = 38), applied movement models to define low (foraging and reproduction) and high (migratory) move persistence underlying location estimates and matched these with environmental data. We then used machine learning models to identify the relationship between whale occurrence and environment, and predict foraging and migration habitat suitability in Australia and Southeast Asia.ResultsOur model predictions were validated by producing spatially varying accuracy metrics. We identified the shelf off the Bonney Coast, Great Australian Bight, and southern Western Australia as well as the slope off the Western Australian coast as suitable habitat for migration, with predicted foraging/reproduction suitable habitat in Southeast Asia region occurring on slope and in deep ocean waters. Suitable foraging habitat occurred primarily on slope and shelf break throughout most of Australia, with use of the continental shelf also occurring, predominanly in South West and Southern Australia. Depth of the water column (bathymetry) was consistently a top predictor of suitable habitat for most regions, however, dynamic environmental variables (sea surface temperature, surface height anomaly) influenced the probability of whale occurrence.ConclusionsOur results indicate suitable habitat is related to dynamic, localised oceanic processes that may occur at fine temporal scales or seasonally. An increase in the sample size of tagged whales is required to move towards developing more dynamic distribution models at seasonal and monthly temporal scales. Our validation metrics also indicated areas where further data collection is needed to improve model accuracy. This is of particular importance for pygmy blue whale management, since threats (e.g., shipping, underwater noise and artificial structures) from the offshore energy and shipping industries will persist or may increase with the onset of an offshore renewable energy sector in Australia.

The Southern African Heat Low: Structure, Seasonal and Diurnal Variability, and Climatological Trends

Abstract Heat lows are key features of subtropical climates and monsoon systems. In southern Africa, they are pivotal to understanding divergent climate change projections, in particular the veracity of future rainfall decline. Compared to other heat lows, including in West Africa and Australia, the southern African heat low remains poorly documented. Here, we analyze the diurnal cycle, seasonal variability, and trends of the heat low in reanalysis data. In ERA5, 462 strong heat low days are detected between September and March from 1990 to 2019, equating to 7.3% of days sampled. These events feature ascent (exceeding −0.2 Pa s−1) at low levels (strongest between 800 and 600 hPa) and subsidence aloft, generating low-level cyclonic flow with anticyclonic flow above. This flow exhibits strong diurnal variability, with peak windspeeds between 0600 and 0900 UTC and maximum ascent at ∼2300 UTC. Heat lows form preferentially over Angola in September (∼14°S) and October (15°–20°S), and in Namibia from November to March (∼20°–26°S). Strongest ascent occurs over areas of high elevation. Finally, we show a rapidly increasing frequency of strong heat low days, with a 175% increase between 1960–89 and 1990–2019. The greatest increase (459%) has occurred in the early summer months of September and October, consistent with projections of delayed rainfall onset. Strikingly, more strong heat lows are detected in the most recent 5 years of analysis (2014–19) than in the 30-yr period from 1960 to 1989. These results suggest the heat low is an important feature in determining drying trends over southern Africa and is a vital indicator of climate model accuracy. Significance Statement This work documents the heat low that forms in southern Africa in the lowest levels of the atmosphere. The feature is present during austral summer (from September to March) and is associated with below average rainfall across much of the subcontinent. The frequency of strong heat lows has rapidly increased in line with regional amplified warming trends. The heat low is identified as an important control on circulation and precipitation patterns and changes in the frequency or intensity of the feature in the future are likely to influence the strength of declining rainfall trends across southern Africa.

Connecting Land and Sea Vertical Datums: A Data Evaluation for Developing Australia’s AUSHYDROID Model

Land and sea vertical datums have traditionally been separate reference levels, due to the different methodologies and observations used in their derivations. However, the need for a seamless connection of these datums has become important due to a wide range of applications in the coastal zone. This study evaluates existing methods, oceanographic and geodetic models and observations for the development of an operational model of coastal heights called AUSHYDROID. We use a complex study area in north west Australia to gain a new insight into how accurately the separation between the lowest astronomical tide (LAT) and a reference ellipsoid can be estimated from existing models, which could form the basis of a national AUSHYDROID model for Australia. Our results are the first attempt to use this combination of existing data in this location, suggesting that ellipsoidal heights of LAT can be estimated to an accuracy of ∼0.2 m at the coast, with the combination of DTU18MSS and FES2014b having the lowest RMS of 0.125 m. However, in some complex coastline areas such as bays and estuaries, the differences increase to >0.5 m so that additional tide gauge observations with GNSS levelling connections and improved models are needed in these regions.

Evidence that species richness begets species richness

AbstractAimThe variability in regional species richness is determined by the balance between speciation, extinction, and migration, but the underlying causes of high species richness in some regions (e.g. tropics, Mediterranean ecosystems) are challenging to explain. Species richness variability may be amplified by biotic feedbacks that promote species richness in some areas, while decreasing elsewhere. Following the example of species abundance, we speculated that species richness per area in arbitrary geographic units (e.g. quarter‐degree squares) follows a hollow‐shaped curve with the ranks of species richness to yield a species richness rank (SRR) curve. The hollowness of such an SRR curve may indicate biotic feedbacks.LocationSouth Africa, South West Australia, and global.Materials and MethodsWe used vascular plant (VP) and bird data from distinct geographic regions and global syntheses of VP, bird, mammal, and amphibian species richness. These data were subdivided into geographic grids and the deviation from normality of the species richness quantified using skewness and kurtosis and the values ranked to yield SRR curves.ResultsThese SRR curves all had a consistent hollow shape (corresponding skewness 1.08–3.4, kurtosis 0.23–18.40) distinct from a normal distribution arising if species were allocated randomly to geographic units. The SRR curves indicate that relatively species‐rich regions are rare, while species‐poor areas are common.Main ConclusionsNeutral processes, abiotic determinants, environmental heterogeneity, historical factors (e.g. climate stability), and biotic feedbacks all likely play a role in contributing to the shapes of the curves. Although these curves for diverse taxa and regions integrate these multiple drivers of species richness, they indicate an acceleration of species richness as a function of species richness as a result of speciation and/or immigration, limited by increasing extinction likelihood. Biotic feedbacks provide a parsimonious explanation for the shapes of the SRR curves across taxa and regions.

Mycobacterium ulcerans-Bordetella trematum chronic tropical cutaneous ulcer: A four-case series, Côte d’Ivoire

Background Chronic tropical cutaneous ulcers remain a neglected medical condition in West Africa, particularly Buruli ulcer, which is caused by mycolactone cytotoxin-secreting Mycobacterium ulcerans (M. ulcerans). Medical management of this highly debilitating and necrotising skin infection may be modified by colonisation and co-infection of the ulcer by opportunistic and pathogenic microorganisms, which considerably delays and increases the cost of treatment. Methodology/principal finding We diagnosed chronic tropical cutaneous ulcers in nine patients in Côte d’Ivoire using M. ulcerans-specific PCRs and culturomics. This revealed M. ulcerans in 7/9 ulcer swabs and 5/9 control swabs as well as an additional 122 bacterial species, 32 of which were specific to ulcers, 61 specifics to the controls, and 29 which were shared, adding 40 bacterial species to those previously reported. Whole genome sequencing of four Bordetella trematum (B. trematum) isolates in four Buruli ulcer swabs and no controls indicated cytolethal distending toxins, as confirmed by cytotoxic assay. Conclusions/significance In four cases of Buruli ulcer in Côte d’Ivoire, B. trematum was a co-pathogen which was resistant to rifampicin and clarithromycin, unmatching M. ulcerans antibiotic susceptibility profile and counteracting the current treatment of Buruli ulcer in West Africa and Australia. Thus, we report here chronic mixed M. ulcerans-B. trematum chronic tropical ulcer as a specific form of Buruli ulcer in West Africa.

MORPHODYNAMICS AT THE MOUTH OF A BAR-BUILT ESTUARY: CARMEL RIVER, CA, USA

Bar-built estuaries (BBEs), also known as Intermittently Closed Estuaries (ICEs), are common to coastal climates with a strong seasonal precipitation pattern and waves including the US West Coast, Australia, South Africa, and Western Europe (McSweeney et al, 2017). In California, USA, these BBEs typically go through seasonal morphological transitions from a closed state to open state as precipitation increases during the winter months. However, timing of these events is challenging owing to variable behavior for given environmental forcing conditions, and as a result often lead to intermittent flooding of the surrounding areas that is difficult to predict (Behrens et al., 2013; Orescanin and Scooler, 2018). This study uses a compilation of observations using in-situ moorings, topographic beach surveys, and remote sensing from unmanned aerial systems (UAS) to assess rates of morphological change at the Carmel River, CA, USA.

What can the development of video visitation in Australian correctional centres tell us about organisational transformation?

ABSTRACT Correctional services are closed, complex bureaucratic organisations which are historically slow to embrace change. Yet, the COVID-19 pandemic catalysed a dramatic shift to widespread video visitation across correctional services in Australia. Drawing on qualitative data with corrective services staff (n = 19) from six jurisdictions (Australian Capital Territory, New South Wales, Queensland, South Australia, Victoria and West Australia), this article charts the large-scale implementation of video visitation during the COVID-19 pandemic. It is argued that video visitation demonstrates uncharacteristic organisational agility in Australian corrective services which may provide optimism for change projects.

About this title - Tectonic Development, Thermal History and Hydrocarbon Habitat Models of Transform Margins: their Differences from Rifted Margins

Transform margins form a significant portion of Earth's continent–ocean transition and are integral to continental break-up, yet compared to other margins are poorly understood. This volume brings together new multidisciplinary research to document the structural, sedimentological and thermal evolution of transform margins, highlighting their relationship to continental structure, neighbouring oceanic segments, pull-apart basins and marginal plateaus. Special emphasis is given to the comparison of transform and rifted margins, and to the economic implications of transform margin structure and evolution. Transform case studies include the Agulhas–Falkland transform, Coromandal transform (East India), Davie margin and Limpopo transform (East Africa), Guyana transform margin, Demerara transform margin (Suriname), Romanche and St Paul transforms (equatorial Africa), Sagaing transform (Andaman Sea) and Zenith–Wallaby–Perth transform (West Australia). The broad-scale interplay between transform and rifted margin segments in the North and Central Atlantic, and Caribbean, is also examined.

Genome-wide analysis reveals distinct global populations of pink bollworm (Pectinophora gossypiella)

The pink bollworm (Pectinophora gossypiella) is one of the world’s most destructive pests of cotton. This invasive lepidopteran occurs in nearly all cotton-growing countries. Its presence in the Ord Valley of North West Australia poses a potential threat to the expanding cotton industry there. To assess this threat and better understand population structure of pink bollworm, we analysed genomic data from individuals collected in the field from North West Australia, India, and Pakistan, as well as from four laboratory colonies that originated in the United States. We identified single nucleotide polymorphisms (SNPs) using a reduced-representation, genotyping-by-sequencing technique (DArTseq). The final filtered dataset included 6355 SNPs and 88 individual genomes that clustered into five groups: Australia, India-Pakistan, and three groups from the United States. We also analysed sequences from Genbank for mitochondrial DNA (mtDNA) locus cytochrome c oxidase I (COI) for pink bollworm from six countries. We found low genetic diversity within populations and high differentiation between populations from different continents. The high genetic differentiation between Australia and the other populations and colonies sampled in this study reduces concerns about gene flow to North West Australia, particularly from populations in India and Pakistan that have evolved resistance to transgenic insecticidal cotton. We attribute the observed population structure to pink bollworm’s narrow host plant range and limited dispersal between continents.

Stability of Unsaturated Soil Slope Considering Stratigraphic Uncertainty

Stratigraphic uncertainty is widely present in nature, but it has not been well considered in the stability analysis of unsaturated soil slopes in the past. In this study, the stability of the unsaturated soil slope is evaluated based on borehole data considering stratigraphic uncertainty. Firstly, an enhanced coupled Markov chain model is used to simulate stratigraphic uncertainty. Then, a finite element algorithm for automatically calculating the safety factor (FS) and the average groundwater table (AGT) of the unsaturated soil slope is developed. At last, a hypothetical slope located in the stratum from Perth, West Australia is analyzed using the proposed algorithm under different borehole schemes. The results show that with the increase in the borehole number, the statistics of FS and AGT will not monotonically increase or decrease. But the trend is that the mean values of FS and AGT gradually approach and eventually converge to the real values, and the standard deviations of FS and AGT decrease. There is a linear relationship between the standard deviation of FS (or AGT) and the average information entropy. The FS and AGT are negatively correlated considering stratigraphic uncertainty.

Synoptic characteristics of heatwave events in Australia during austral summer of 1950/1951–2019/2020

AbstractAustralia has experienced increasing number of heatwave events (HWEs) in recent decades. This study aims to examine key synoptic features of austral summer HWEs over Australia during 1950/1951–2019/2020. Based on ERA5‐reanalysis and rotated empirical orthogonal functions, HWEs in Australia are categorized into four types according to where they often occur together: East Australia (EA), North Australia (NA), West Australia (WA) and Southeast Australia (SEA). Our results reveal that while anomalous anticyclones at 500 hPa level are the typical synoptic circulations responsible for HWEs of each subregion, their specific mechanisms differ between subregions. The atmospheric heat budget at 850 hPa level shows that anomalous diabatic heating promotes the onset of HWEs in each subregion. While anomalous vertical advection and adiabatic heating due to the anomalous subsidence play an important role in maintaining HWEs till their demise in NA, they only help trigger HWEs in EA, SEA and WA. Our results also suggest that anomalous advection of climatological mean temperature is important to both the onset and persistence of HWEs in EA and SEA, while it only helps sustain (trigger) HWEs in NA (WA). The advection of anomalous temperature also acts to trigger HWEs in EA, SEA and WA. On the surface, upward long‐wave radiation and sensible heat flux contribute to the development of HWEs, whereas both of them are reduced in SEA due to the enhanced anomalous cyclones near the surface and the decreased land–air temperature difference. These findings help improve understanding of the synoptic characteristics and distinctive mechanisms of HWEs in different subregions of Australia.

Resection of Retroperitoneal Sarcomas Involving the Inferior Vena Cava With the Use of Veno-Veno Extracorporeal Perfusion: A Review of the First 20 Cases Performed at Sir Charles Gairdner Hospital, Perth, West Australia

Prolonged inferior vena cava (IVC) clamping during retroperitoneal sarcoma resection presents specific challenges requiring a multidisciplinary approach. Veno-veno bypass (VVB) drains blood from the IVC and returns it into the right atrium, allowing excellent surgical exposure. This institution has routinely used VVB for sarcoma resections involving the IVC since 2018. This review describes outcomes of the first 20 cases.

The Adrenal Vein Sampling Outcomes Study (AVOS): success rates following adrenalectomy for unilateral primary aldosteronism

The objective was to determine the clinical and biochemical success rates and assess the nature of follow-up after adrenalectomy in patients with unilateral primary aldosteronism (PA), subtyped by adrenal vein sampling (AVS) in West Australia (WA) using the Primary Aldosteronism Surgical Outcome (PASO) criteria. Clinical and biochemical outcomes were retrospectively evaluated in patients with unilateral PA who underwent adrenalectomy according to AVS between September 2017 and September 2020. Pre- and post-surgical data were collected using a standardised questionnaire, review of clinic letters and examination of private and public pathology results and radiological reports. Follow-up data were available for 47 patients post-adrenalectomy; biochemical outcome data were available for 37 patients, clinical outcome data for 40 patients, with 30 patients having both outcomes available. Final assessment was performed between 0 to 3 months in 23/37 (62.2%) patients with biochemical outcomes, 15/40 (37.5%) with clinical outcomes, and 17/30 (56.7%) with both clinical and biochemical outcomes. Complete biochemical success was achieved in 83.8% (31/37) of patients, with 26.7% (8/30) obtaining both complete clinical and biochemical success. Complete clinical success was achieved in 35.0% (14/40) of patients, with 47.5% (19/40) obtaining partial clinical success. Overall, 93.6% (44/47) of patients derived benefit from adrenalectomy. The outcomes of adrenalectomy for unilateral PA in Western Australian using standardised PASO criteria demonstrate highly comparable clinical and biochemical success rates to international data. However, further standardisation of post-operative follow-up care needs to be implemented to ensure the recommended repeat follow-up assessment criteria are collected.

Design pedagogy in a time of change: Applying virtual flipped classroom in design higher education

This project reviewed the application of an innovative pedagogical approach, the virtual flipped classroom (VFC), in postgraduate design education. The VFC is an integration of the flipped classroom (FC) and virtual canvas. It enables teachers to proactively engage students in design thinking processes and activities to achieve active learning and better learning outcomes. To investigate the effect of VFC, the core research team implemented it to postgraduate programmes across three Australian universities, including a Master of Design Strategies course in the School of Design and the Built Environment at the Faculty of Arts and Design, University of Canberra (UC), a Master of Design course in the School of Arts and Humanities, Edith Cowan University (ECU) and a Master of Design course in the Creative Unit, University of South Australia (UniSA). The core research team observed and reflected on students’ learning achievements and motivation during their design thinking process across three Australian universities in two states (South Australia and West Australia) and the Australian Capital Territory (ACT), between 2020 and 2022. This study also explored postgraduate design students’ perceptions towards the idea of studying design online via the Interface Student Experience Questionnaire (ISEQ) and student evaluation questionnaire. It helped to identify and verify whether VFC could provide a transitional middle ground to a fully online design course. This study provides insights into student and staff reservations about online delivery and identifies the barriers and opportunities to study design within an entirely virtual environment.

Indices Development for Player’s Performance Evaluation through the Super-SBM Approach in Each Department for All Three Formats of Cricket

Player performance evaluations in all three formats of cricket have been a topic of great concern for sports analysts and research experts. This study proposed a comprehensive performance estimation tool that incorporates all the essential inputs–outputs and evaluates a cricketer’s overall performance. This research introduced three different estimation indices for player efficiency in all three formats of cricket for batting, bowling, and fielding. Further, this research employed the DEA Super-SBM model to evaluate the player’s efficiency in batting, bowling, and fielding departments of all three formats. The study estimates the most efficient batsman, bowler, and fielder in cricketing history by using the data of international cricketers (1877–2019). The results indicate that, compared to the traditional parameters, the proposed study indices are more accurate and comprehensive in nature. The most efficient batsman, bowler, and fielder in all three formats are given, respectively: (i) Sir Bradman, Sachin Tendulkar, and Virat Kohli; (ii) Muralitharan, Mitchell Starc, and Umar Gul; and (iii) Saleem Yousuf, Luke Ronchi, and Scott Edwards. For teams, England, Australia, and India were determined to be the most efficient in batting for all three formats; the West Indies, Australia, and Pakistan are the most efficient in bowling; and the Australian (Test & ODIs) and South African teams are efficient in the fielding department.

Detrital zircon U–Pb age constraints on the Meso-Tethys Ocean closure in SE Asia

Abstract The location of the Meso-Tethyan suture in SE Asia is ambiguous due to the strong overprint by the later India–Asia collisional tectonics. For the SE Asian extension of the Meso-Tethyan Bangong–Nujiang Suture (BNS) in Tibet, the two main candidates are the Longling–Ruili Suture (between the Tengchong and Baoshan blocks) and the Myitkyina ophiolite belt. Here, we present new detrital zircon U–Pb ages from high-grade metasedimentary rocks of the Gaoligong Group, which is considered to be the basement of the Tengchong Block located between the Longling–Ruili Suture and Myitkyina ophiolite belt. Our data suggest that the Gaoligong Group contains Cambrian, Triassic and Cretaceous zircons and is not a Precambrian basement, with a diagnostic age population peak at c. 1110 Ma. This peak is comparable to the c. 1170 Ma peak reported in the Australia-derived blocks (e.g. Lhasa and West Australia). Such similarities, as well as the similarities in the stratigraphy, palaeobiogeography and magmatic history of the Tengchong Block, suggest that the Tengchong Block was located adjacent to the northern Australia margin in Gondwana, and was most likely to have been linked with the Lhasa Block (southern Tibet) since the Early Paleozoic. Thus, the Longling–Ruili Suture is likely to represent a continuation of the Meso-Tethyan BNS in SE Asia.

A reappraisal of the phylogeny and historical biogeography of Sparganium (Typhaceae) using complete chloroplast genomes

BackgroundSparganium (Typhaceae) is a widespread temperate genus of ecologically important aquatic plants. Previous reconstructions of the phylogenetic relationships among Sparganium species are incompletely resolved partly because they were based on molecular markers comprising < 7,000 bp. Here, we sequenced and assembled the complete chloroplast genomes from 19 Sparganium samples representing 15 putative species and three putative subspecies in order to explore chloroplast genome evolution in this genus, clarify taxonomic lineages, estimate the divergence times of Sparganium species, and reconstruct aspects of the biogeographic history of the genus.ResultsThe 19 chloroplast genomes shared a conserved genome structure, gene content, and gene order. Our phylogenomic analysis presented a well-resolved phylogeny with robust support for most clades. Non-monophyly was revealed in three species: S. erectum, S. eurycarpum, and S. stoloniferum. Divergence time estimates suggest that the two subgenera of Sparganium split from each other ca. 30.67 Ma in the middle Oligocene. The subgenus Xanthosparganium diversified in the late Oligocene and Miocene, while the subgenus Sparganium diversified in the late Pliocene and Pleistocene. Ancestral area reconstruction suggested that the two subgenera may have originated in East Eurasia and North America.ConclusionThe non-monophyletic nature of three putative species underscores the necessity of taxonomic revision for Sparganium: S. stoloniferum subsp. choui may be more appropriately identified as S. choui, and subspecies of S. erectum may be in fact distinct species. The estimated diversification times of the two subgenera correspond to their species and nucleotide diversities. The likely ancestral area for most of subgenus Xanthosparganium was East Eurasia and North America from where it dispersed into West Eurasia and Australia. Most of subgenus Sparganium likely originated in North America and then dispersed into Eurasia. Our study demonstrates some of the ways in which complete chloroplast genome sequences can provide new insights into the evolution, phylogeny, and biogeography of the genus Sparganium.

Changes in the moisture contribution over global arid regions

Arid regions have deficient precipitation, understanding the sources and transportation of moisture for precipitation are crucial. This study examined the major moisture contributions for global six arid regions, which are classified as inland arid region (China-Mongolia) and coastal arid regions (North Africa, West Asia, West United States, South Africa, South Africa and Australia). Results indicated that, the moisture for precipitation in coastal arid regions originates mostly from the ocean, which is influenced by the general circulation, particularly by the sinking branch of the Hadley cell. For inland arid region (China–Mongolia), the surrounding mountains supply more than 150 mm of moisture in wet months due to the ablation of glacial and snow melting. In arid regions, the moisture for precipitation is mostly contributed by advection of large-scale circulation, while the contribution of local moisture recycling is secondary. The moisture available for precipitation in wet and dry months depends on the general circulation. Moisture transportation in wet months is 10 times more than that in dry months, and the moisture sources differ greatly in wet and dry months. In both wet and dry months, the external moisture transported into arid regions has significantly decreasing trend during the period 1990–2019. The decreasing trend of precipitation recycling ratio in arid regions are greater than that in the globe. The decreased precipitation and moisture in arid regions suggest a potential drying trend.