Phylogeography of the desert scorpion illuminates a route out of Central Asia.

A comprehensive understanding of phylogeography requires the integration of knowledge across different organisms, ecosystems, and geographic regions. However, a critical knowledge gap exists in the arid biota of the vast Asian drylands. To narrow this gap, here we test an "out-of-Central Asia" hypothesis for the desert scorpion Mesobuthus mongolicus by combining Bayesian phylogeographic reconstruction and ecological niche modeling. Phylogenetic analyses of one mitochondrial and three nuclear loci and molecular dating revealed that M. mongolicus represents a coherent lineage that diverged from its most closely related lineage in Central Asia about 1.36 Ma and underwent radiation ever since. Bayesian phylogeographic reconstruction indicated that the ancestral population dispersed from Central Asia gradually eastward to the Gobi region via the Junggar Basin, suggesting that the Junggar Basin has severed as a corridor for Quaternary faunal exchange between Central Asia and East Asia. Two major dispersal events occurred probably during interglacial periods (around 0.8 and 0.4 Ma, respectively) when climatic conditions were analogous to present-day status, under which the scorpion achieved its maximum distributional range. M. mongolicus underwent demographic expansion during the Last Glacial Maximum, although the predicted distributional areas were smaller than those at present and during the Last Interglacial. Development of desert ecosystems in northwest China incurred by intensified aridification might have opened up empty habitats that sustained population expansion. Our results extend the spatiotemporal dimensions of trans-Eurasia faunal exchange and suggest that species' adaptation is an important determinant of their phylogeographic and demographic responses to climate changes.

Evolution and phylogenetic diversity of the aquaporin gene family in arachnids.

Water flux across cells predominantly occurs through the pore formed by the aquaporin channels. Since water balance is one of the most important challenges to terrestrial animals, aquaporin evolution and diversity is known to play roles in animal terrestrialisation. Arachnids (Arthropoda: Chelicerata: Arachnida) are the second most diverse group and represent the pioneer land colonists in animals; however, there remains no thorough investigation on aquaporin evolution and diversity in this evolutionarily important lineage. Here we reported a phylogenetic study of aquaporin evolution and diversity using genomic data from 116 arachnid species covering almost all (15/16) extant orders. A previously unrecognised subfamily related to aquaporin-4 (i.e. Aqp4-like subfamily) via phylogenetic analysis was identified, suggesting certain underestimate of the arachnid aquaporin diversity in earlier studies probably due to limited taxonomic sampling. Further analysis indicates that this subfamily emerged deep within the life tree of arthropods. Gene tree of another Aqp4-like subfamily (PripL) shows an unexpected basal split between acariform mites (Acariformes) and other arachnids. A closer inspection demonstrated that the PripL evolved quickly and has been under differential selection pressure in acariform mites. Evidence is provided that the evolutionarily ancient Glp subfamily (i.e. aquaglyceroporin) is significantly expanded in terrestrial arachnids compared with their marine relatives. Finally, in spite of the phylogenetic diversity, there exists conservation of some exons in size, functional domain, and intron-insertion phase: an 81-bp and a 218-bp exon, respectively, in apq4-like and glp genes across Eumetazoa lineages including arachnids and human beings. Both exons encode the carboxyl-terminal NPA motif, implying the coding and splicing pressure during hundreds of million years of animal evolution. Hypotheses were tested to explore the possible link between these findings and arachnid terrestrialisation.

Genomic insights into the secondary aquatic transition of penguins.

Penguins lost the ability to fly more than 60 million years ago, subsequently evolving a hyper-specialized marine body plan. Within the framework of a genome-scale, fossil-inclusive phylogeny, we identify key geological events that shaped penguin diversification and genomic signatures consistent with widespread refugia/recolonization during major climate oscillations. We further identify a suite of genes potentially underpinning adaptations related to thermoregulation, oxygenation, diving, vision, diet, immunity and body size, which might have facilitated their remarkable secondary transition to an aquatic ecology. Our analyses indicate that penguins and their sister group (Procellariiformes) have the lowest evolutionary rates yet detected in birds. Together, these findings help improve our understanding of how penguins have transitioned to the marine environment, successfully colonizing some of the most extreme environments on Earth.

Mapping Network Connectivity Among Symptoms of Depression and Pain in Wuhan Residents During the Late-Stage of the COVID-19 Pandemic.

Background: Symptoms of depression and pain often overlap, and they negatively influence the prognosis and treatment outcome of both conditions. However, the comorbidity of depression and pain has not been examined using network analysis, especially in the context of a pandemic. Thus, we mapped out the network connectivity among the symptoms of depression and pain in Wuhan residents in China during the late stage of the COVID-19 pandemic. Methods: This cross-sectional study was conducted from May 25, 2020 to June 18, 2020 in Wuhan, China. Participants' depressive and pain symptoms were assessed using the 9-item Patient Health Questionnaire (PHQ9) and a pain numeric rating scale (NRS), respectively. Network analyses were performed. Results: In total, 2,598 participants completed all assessments. PHQ4 (fatigue) in the depression community showed the highest strength value, followed by PHQ6 (worthlessness) and PHQ2 (depressed or sad mood). PHQ4 (fatigue) was also the most key bridge symptom liking depression and pain, followed by PHQ3 (sleep difficulties). There were no significant differences in network global strength (females: 4.36 vs. males: 4.29; S = 0.075, P = 0.427), network structure-distribution of edge weights (M = 0.12, P = 0.541), and individual edge weights between male and female participants. Conclusion: Depressive and pain symptoms showed strong cross-association with each other. "Fatigue" was the strongest central and bridge symptom in the network model, while "sleep difficulties" was the second strongest bridge symptom. Targeting treatment of both fatigue and sleep problems may help improve depressive and pain symptoms in those affected.

[In vitro screening of natural compounds with antitumor activity by trypsin].

In order to investigate the feasibility of in vitro screening the antitumor activity of natural compounds by trypsin, porcine trypsin was used to for screening test, which is marked by inhibition of enzyme activity. Four compounds, namely daidzin, genistin, matrine and oxymatrine, were selected as test subjects. The natural antitumor drug camptothecin was used as the control. The inhibitory effect was detected by two experimental methods: direct detection of trypsin activity inhibition and hydrolysis of bovine serum albumin by trypsin. The results showed the inhibitory effects of the four natural compounds on trypsin, and the inhibition rates of the four natural compounds were significantly different. The enzyme activity assay showed that the inhibitory effect of matrine was better than that of oxymatrine, indicating that trypsin had a good screening resolution. The inhibitory effect was significantly increased with the increased ratio of sample to trypsin, suggesting the structure-activity correlation and dose-effect correlation of the screening methods. Altogether, the experimental method of screening antitumor activity of natural compounds by trypsin has good application values. Since porcine trypsin is similar to human trypsin in terms of molecular structure and performance, it is more applicable for screening of antitumor efficacy of natural pharmacodynamic compounds.

High-coverage genomes to elucidate the evolution of penguins.

BACKGROUND: Penguins (Sphenisciformes) are a remarkable order of flightless wing-propelled diving seabirds distributed widely across the southern hemisphere. They share a volant common ancestor with Procellariiformes close to the Cretaceous-Paleogene boundary (66 million years ago) and subsequently lost the ability to fly but enhanced their diving capabilities. With ∼20 species among 6 genera, penguins range from the tropical Galápagos Islands to the oceanic temperate forests of New Zealand, the rocky coastlines of the sub-Antarctic islands, and the sea ice around Antarctica. To inhabit such diverse and extreme environments, penguins evolved many physiological and morphological adaptations. However, they are also highly sensitive to climate change. Therefore, penguins provide an exciting target system for understanding the evolutionary processes of speciation, adaptation, and demography. Genomic data are an emerging resource for addressing questions about such processes. RESULTS: Here we present a novel dataset of 19 high-coverage genomes that, together with 2 previously published genomes, encompass all extant penguin species. We also present a well-supported phylogeny to clarify the relationships among penguins. In contrast to recent studies, our results demonstrate that the genus Aptenodytes is basal and sister to all other extant penguin genera, providing intriguing new insights into the adaptation of penguins to Antarctica. As such, our dataset provides a novel resource for understanding the evolutionary history of penguins as a clade, as well as the fine-scale relationships of individual penguin lineages. Against this background, we introduce a major consortium of international scientists dedicated to studying these genomes. Moreover, we highlight emerging issues regarding ensuring legal and respectful indigenous consultation, particularly for genomic data originating from New Zealand Taonga species. CONCLUSIONS: We believe that our dataset and project will be important for understanding evolution, increasing cultural heritage and guiding the conservation of this iconic southern hemisphere species assemblage.

Intraspecific variation in metabolic rate and its correlation with local environment in the Chinese scorpion Mesobuthus martensii.

Scorpions are well known for their reduced resting metabolic rate (RMR) in comparison to typical arthropods. Since RMR is a key physiological trait linked with evolutionary fitness, it is expected that there may exist intraspecific RMR variation given the ecological and geographical heterogeneities across the distributional range of a species. Nevertheless, it is unclear whether RMR variation exists among scorpion populations. Here, we compared the RMR (VCO2) of 21 populations of the Chinese scorpion Mesobuthus martensii (Scorpiones: Buthidae) at 25°C after at least 3 months of laboratory acclimation. The following results were obtained. First, there was significant difference in RMR between sexes when body-weight effects were factored out. Second, significant local variation in RMR was detected by analyses of both variance and covariance, with one population showing significantly reduced RMR and another significantly increased RMR. Third, regression analysis indicated that the local mean temperature and mean annual days of rainfall were the two significant factors associated with the aforementioned inter-population difference in RMR. The implication of such an association was discussed.

Association of phthalate exposure with anthropometric indices and blood pressure in first-grade children.

We aimed to assess the relationship of urine phthalate metabolite concentrations with anthropometric indices, and blood pressure in first-grade children. We detected 11 phthalate metabolites in urine and estimated anthropometric indices, including skinfold measurements, waist circumference (WC), and body mass index (BMI) in 276 children aged 6-8 years. Multivariate linear regression models were used to assess the associations between urinary phthalate metabolite levels, and anthropometric and blood pressure indices in a gender-specific manner. In boys, a 1-ng/mL increase in monobenzyl phthalate (MBzP) concentration was associated with a 0.027-cm decrease in the skinfold measurement (95% confidence interval [CI], - 0.053 to 0.001), whereas a 1-ng/mL increase in mono-ethyl-phthalate (MEP) concentration was associated with a 0.016-mm Hg decrease in systolic blood pressure (95% CI, - 0.031 to 0.001). MBzP, mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and MEOHP concentrations were also inversely associated with WC. However, in girls, MEP concentrations were positively associated with chest measurements, but were inversely associated with WC. A 1-ng/mL increase in monomethyl phthalate concentrations was associated with a 0.039-cm increase in skinfold measurements (95% CI, 0.002 to 0.076), whereas a 1-ng/mL increase in MECPP concentrations was associated with a 0.050 cm decrease in skinfold measurements (95% CI, - 0.095 to - 0.005). In this exploratory, cross-sectional analysis, we identified various interesting associations between different phthalate metabolite levels and anthropometric indices, which suggest that some of phthalate metabolite should be considered in addition to the prevalence rates of overweight and obesity.

Assessment of heavy metal pollution and human health risks in urban soils around an electronics manufacturing facility.

Heavy metal pollution has pervaded many parts of the world, especially in developing countries. The purpose of this study was to determine the concentrations and health risks of heavy metals in urban soils around an electronics manufacturing site in the Hubei Province of China. Soils samples were collected from commercial, roadside, farmland, and residential areas around the electronics manufacturing facility. A total of 136 topsoil samples were collected, and these samples were analyzed for Cr, Cu, Zn, As, Cd, Ni, and Pb. The geoaccumulation index (Igeo), pollution index (PI), and potential ecological risk index (PER) were calculated to assess the soil pollution levels. The hazard index (HI) was used to assess the human health risks posed by the presence of heavy metals. The total concentrations of the seven congeners (∑metals) ranged from 3738.86 to 5173.25mgkg-1, and the concentrations were highest in the commercial area followed (in decreasing order) by the roadside, farmland, and residential areas. The HI for children and adults descended in the order of Cr>As>Pb>Cd>Cu>Ni>Zn. The carcinogenic risks of two metals, namely, Cr and As, for children and adults were higher than 10-4, and children faced greater health risks.

Systematic Review of Guidelines on Managing Patients with Harmful Use of Alcohol in Primary Healthcare Settings.

AIM: To appraise existing alcohol guidelines for identifying and managing harmful alcohol use in primary healthcare settings. METHODS: Seven databases and 18 health organization or medical society websites were systematically searched from inception to 31 October 2016. Guidelines in English language, developed by a national or international medical specialty society, government or health organization, and containing recommendations for identifying and managing harmful use of alcohol in primary healthcare settings, were included. The Appraisal of Guidelines Research and Evaluation II (AGREE II) instrument was used to appraise the guidelines. RESULTS: Of the 970 literature identified, 17 were included for review, with 13 guidelines developed for use in Western countries and 4 for international use. The AGREE II scores ranged from 2.0 to 5.3, out of 7. Variations in terminology of harmful alcohol use were seen, with 'harmful drinking' and 'problem drinking' being mostly used. All guidelines were in favor of screening and brief interventions due to their effectiveness and cost-effectiveness. Potential benefits and costs of applying screening and brief interventions were found, but there was a lack of evidence for long-term effects or specific populations. CONCLUSIONS: All 17 guidelines recommended screening and brief interventions due to its associated health and financial benefits. Policy makers are highly encouraged to integrate these practices into primary healthcare settings taking the drinking status, culture and resources into account. SHORT SUMMARY: Screening and brief interventions were recommended by all 17 guidelines on managing patients with harmful use of alcohol in primary healthcare settings. Policy makers and healthcare practitioners are highly encouraged to implement these recommendations.

Comparing the Effects of Mindfulness-Based Cognitive Therapy and Sleep Psycho-Education with Exercise on Chronic Insomnia: A Randomised Controlled Trial.

BACKGROUND: Mindfulness-based cognitive therapy (MBCT) is a potential treatment for chronic insomnia. We evaluated the efficacy of MBCT for insomnia (MBCT-I) by comparing it with a sleep psycho-education with exercise control (PEEC) group. METHODS: Adults with chronic primary insomnia (n = 216) were randomly allocated to the MBCT-I or PEEC group. The MBCT-I included mindfulness and psycho-education with cognitive and behavioural components under cognitive behavioural therapy for insomnia. PEEC included psycho-education of sleep hygiene and stimulus control, and exercises. Any change in insomnia severity was measured by the Insomnia Severity Index (ISI). Secondary outcomes included sleep parameters measured by a sleep diary, health service utilisation, absence from work and mindfulness measured by the Five Facet Mindfulness Questionnaire. RESULTS: The ISI score significantly decreased in the MBCT-I group compared with the PEEC group at 2 months (i.e., post-intervention) (p = 0.023, effect size [95% CI] -0.360 [-0.675, -0.046]) but not at 5 or 8 months. Treatment response rates and remission rates based on the ISI cut-off scores were not significantly different between groups. Wake time after sleep onset (WASO) was less in the MBCT-I group at 2 and 5 months. At 8 months, both groups showed a reduced ISI score, sleep onset latency and WASO, and increased sleep efficiency and total sleep time; however, no group differences were seen. Other outcome measures did not significantly improve in either group. CONCLUSIONS: Long-term benefits were not seen in MBCT-I when compared with PEEC, although short-term benefits were seen.

The effectiveness of Dietary Approaches to Stop Hypertension (DASH) counselling on estimated 10-year cardiovascular risk among patients with newly diagnosed grade 1 hypertension: A randomised clinical trial.

BACKGROUND: The Dietary Approaches to Stop Hypertension (DASH) has been shown to lower blood pressure in the West. However, the real-life impact of DASH on reducing cardiovascular (CV) risk in routine clinical setting has not been studied. METHODS: A parallel-group, open-labelled, physician-blinded, randomised controlled trial was conducted in January-June 2013 and followed up for 6- and 12-months in primary care settings in Hong Kong. Patients newly diagnosed with grade 1 hypertension (aged 40-70years) who had no concomitant medical conditions requiring dietary modifications were consecutively recruited. Subjects were randomised to standard education (usual care) (n=275), or usual care plus dietitian-delivered DASH-based dietary counselling in a single one-to-one session (intervention) (n=281). Primary outcomes were the changes in estimated 10-year CV risk. RESULTS: Outcome data were available for 504 (90.6%) and 485 (87.2%) patients at 6 and 12months, respectively. There was no difference in the reduction of 10-year CV risk between the two groups at 6months (-0.13%, 95% confidence interval [95% CI] -0.50% to 0.23%, p=0.477) and 12months (-0.08%, 95% CI -0.33% to 0.18%, p=0.568). Multivariate regression analyses showed that male subjects, younger patients, current smokers, subjects with lower educational level, and those who dined out for main meals for ≥4 times in a typical week were significantly associated with no improvements in CV risk. CONCLUSIONS: The findings may not support automatic referral of newly diagnosed grade 1 hypertensive patients for further one-to-one dietitian counselling on top of primary care physician's usual care. Patients with those risk factors identified should receive more clinical attention to reduce their CV risk. CLINICAL TRIAL REGISTRATION: ChiCTR-TRC-13003014 (http://www.chictr.org.cn/enindex.aspx).

Dietary counselling has no effect on cardiovascular risk factors among Chinese Grade 1 hypertensive patients: a randomized controlled trial.

AIMS: To evaluate the effectiveness of Dietary Approaches to Stop Hypertension (DASH) by one-off dietary counselling on reducing cardiovascular risk factors among Chinese Grade 1 hypertensive patients in primary care. METHODS AND RESULTS: A parallel-group, randomized controlled trial (ChiCTR-TRC-13003014) was conducted among patients (40-70 years old) newly diagnosed with Grade 1 hypertension in primary care settings in Hong Kong. Subjects were randomized to usual care (standard education, control) (n = 275), or usual care plus DASH-based dietary counselling (intervention) (n = 281). The study endpoints included blood pressure (BP), lipid profile, and body mass index (BMI) at 6- and 12-months. Outcome data were available for 504 (90.6%) and 485 (87.2%) patients at 6 and 12 months, respectively. Blood pressure levels reduced in both groups at follow-ups. However, the intervention group did not show a significantly greater reduction in either systolic BP (-0.7 mmHg, 95%CI -3.0-1.5 at 6-month; -0.1 mmHg, 95%CI -2.4-2.2 at 12-month) or diastolic BP (-1.0 mmHg, 95%CI -2.7-0.7 at 6-month; -1.1 mmHg, 95%CI -2.9-0.6 at 12-month), when compared with the control group. The improvements in lipid profile and BMI were observed among all subjects, yet no significant differences were detected between intervention and control groups. CONCLUSION: The DASH diet by one-off dietitian counselling which resembled the common primary care practice might confer no added long-term benefits on top of physician's usual care in optimizing cardiovascular risk factors. Physicians may still practice standard usual care, yet further explorations on different DASH delivery models are warranted to inform best clinical practice.

Rapid emergence of atherosclerosis in Asia: a systematic review of coronary atherosclerotic heart disease epidemiology and implications for prevention and control strategies.

PURPOSE OF REVIEW: There is a global epidemic of coronary heart disease (CHD) caused by atherosclerosis. We discussed its emergence, underlying reasons, and implications for prevention and control strategies in Asia. RECENT FINDINGS: Most countries in Asia are experiencing the challenges from CHD, with the mortality rate varying from 103 to 366 per 100 000 adult populations, reported by recently published studies. Raised population cholesterol levels played a pivotal role. Men, older adults, and those with dyslipidemia, hypertension, and diabetes were high-risk individuals. During the past decade, there was a marked rising trend of atherosclerosis-related burden particularly in Eastern Asia where an alarming increase of 117.2 and 115.3% of total deaths and disability adjusted life-years, respectively, were observed. The rise of CHD could be attributed to unhealthy lifestyles, clinical-risk factors, psychosocial factors, and public health transitions. Ageing, urbanization, and increase in prosperity may serve as underlying key drivers. SUMMARY: The burden of CHD is substantial, whereas contributors are multifactorial. This grand challenge should be a top priority for injecting healthcare resources. The formulation of public health measures will need to adopt an integrated and life-course approach, based on the need and risks of different population subgroups in Asia.

Suppressing limbic seizures by stimulating medial dorsal thalamic nucleus: factors for efficacy.

OBJECTIVE: The optimal sites and stimulation protocols for brain stimulation in epilepsy have not been found. Clinical trials, which have shown modest benefit in seizure reduction, have involved patients with poorly localized intractable focal epilepsy and stimulation sites without clear relations to specific underlying seizure circuits. The medial dorsal thalamic nucleus is a key node in limbic seizure circuits, and we wished to know what stimulation parameters might control seizures in a kindling model of limbic epilepsy. METHODS: In urethane-anesthetized rats, we induced limbic seizures by stimulation of the piriform cortex or CA3 of the hippocampus while recording in the entorhinal cortex or CA1 of the contralateral hippocampus to determine the effect of specific stimulation parameters on seizure duration. RESULTS: Stimulation consistently suppressed seizure duration from baseline by over 80% (p < 0.001), frequently completely preventing the seizures. Position of the thalamic electrode, stimulus intensity and frequency had a significant influence, with higher stimulus intensities (40 V vs. 20 V) and frequencies (20 Hz vs. 7 Hz) significantly suppressing seizures. The most effective position was the lateral dorsal area of the medial dorsal nucleus (MD), which corresponded to the region of axon entry. Stimulation in the MD center was not effective. An anterior-posterior relationship of the stimulating electrode pair was effective, whereas a medial lateral orientation was not. Successful stimulation suppressed the evoked responses in the entorhinal cortex or CA1. SIGNIFICANCE: Position and orientation of the stimulating electrode has to be precise, which suggests that the placement of the electrodes must be tailored to the individual's own seizure circuit. The data also indicate that successful deep brain stimulation induces a fundamental change in system physiology, which could be a marker to guide the development of stimulation parameters for each patient.

Prevention of anxiety and depression in Chinese: a randomized clinical trial testing the effectiveness of a stepped care program in primary care.

BACKGROUND: Despite empirical evidence demonstrating the effectiveness of collaborative stepped care program (SCP) in Western countries, such programs have not been evaluated in the east, which has a different services system structure and cultural nuances in seeking help for mental illness. Furthermore, only a few studies have used SCP for depression and anxiety prevention. We conducted a trial to test its effectiveness in preventing major depressive disorder and generalized anxiety disorder among primary care patients with subthreshold depression and/or anxiety in Hong Kong. METHODS: Subthreshold depression and/or anxiety patients were randomized into the SCP group (n=121) or care as usual (CAU) group (n=119). The SCP included watchful waiting, telephone counseling, problem solving therapy, and family doctor treatment within one year. The primary outcome was the onset of major depressive disorder or generalized anxiety disorder in 15 months. The secondary outcomes were depressive and anxiety symptoms, quality of life and time absent from work due to any illness. RESULTS: Survival analysis showed no differences between the SCP and CAU groups (the cumulative probability of onset at 15 month was 23.1% in the SCP group and 20.5% in the CAU group; Hazard Ratio=1.62; 95% Confidence Interval: 0.82-3.18; p=0.16). No significant differences were found in secondary outcomes. LIMITATIONS: Sample size might not have been large enough. CONCLUSIONS: SCP did not show beneficial effect on depression/anxiety prevention compared with CAU in Hong Kong primary care. As a large majority of patients improved overtime without any intervention, we are not able to exclude the possibility that the intervention might be effective. Future studies would need to have a larger sample size and conduct on patients with more severe symptoms or perform a second screening.

Impact of climate changes from Middle Miocene onwards on evolutionary diversification in Eurasia: insights from the mesobuthid scorpions.

The aridification from Middle Miocene onwards has transformed the Asian interior into an arid environment, and the Pleistocene glacial-interglacial oscillations exerted further ecological impact. Therefore, both aridification and glaciation would have considerably influenced the evolution of many mid-latitude species in temperate Asia. Here, we tested this perspective by a phylogeographic study of the mesobuthid scorpions across temperate Asia using one mitochondrial and three nuclear genes. Concordant mitochondrial and nuclear gene trees were obtained, which are consistent with species tree inferred using a Bayesian approach. The age of the most recent common ancestor (MRCA) of all the studied scorpions was estimated to be 12.49 Ma (late Middle Miocene); Mesobuthus eupeus diverged from the clade composing Mesobuthus caucasicus and Mesobuthus martensii in early Late Miocene (10.21 Ma); M. martensii diverged from M. caucasicus at 5.53 Ma in Late Miocene. The estimated MRCA ages of M. martensii and the Chinese lineage of M. eupeus were 2.37 and 0.68 Ma, respectively. Central Asia was identified as the ancestral area for the lineage leading to M. martensii and M. caucasicus and the Chinese lineage of M. eupeus. The ancestral habitat of the genus Mesobuthus is likely to have been characterized by an arid environment; a shift towards more humid habitat occurred in the MRCA of M. martensii and a lineage of M. caucasicus, finally leading to the adaptation of M. martensii to humid environment. Our data strongly support the idea that the stepwise intensified aridifications from Mid-Miocene onwards drove the diversification of mesobuthid scorpions, and suggest that M. martensii and M. eupeus observed today in China originated from an ancestral lineage distributed in Central Asia. Both the colonization and the ensuing evolution of these species in East Asia appear to have been further moulded by Quaternary glaciations.

Evaluation of a bayesian coalescent method of species delimitation.

A Bayesian coalescent-based method has recently been proposed to delimit species using multilocus genetic sequence data. Posterior probabilities of different species delimitation models are calculated using reversible-jump Markov chain Monte Carlo algorithms. The method accounts for species phylogenies and coalescent events in both extant and extinct species and accommodates lineage sorting and uncertainties in the gene trees. Although the method is theoretically appealing, its utility in practical data analysis is yet to be rigorously examined. In particular, the analysis may be sensitive to priors on ancestral population sizes and on species divergence times and to gene flow between species. Here we conduct a computer simulation to evaluate the statistical performance of the method, such as the false negatives (the error of lumping multiple species into one) and false positives (the error of splitting one species into several). We found that the correct species model was inferred with high posterior probability with only one or two loci when 5 or 10 sequences were sampled from each population, or with 50 loci when only one sequence was sampled. We also simulated data allowing migration under a two-species model, a mainland-island model and a stepping-stone model to assess the impact of gene flow (hybridization or introgression). The behavior of the method was diametrically different depending on the migration rate. Low rates at < 0.1 migrants per generation had virtually no effect, so that the method, while assuming no hybridization between species, identified distinct species despite small amounts of gene flow. This behavior appears to be consistent with biologists' practice. In contrast, higher migration rates at ≥ 10 migrants per generation caused the method to infer one species. At intermediate levels of migration, the method is indecisive. Our results suggest that Bayesian analysis under the multispecies coalescent model may provide important insights into population divergences, and may be useful for generating hypotheses of species delimitation, to be assessed with independent information from anatomical, behavioral, and ecological data.