Proximate Reason Research Articles

Delay in diagnosis is the most important proximate reason for mortality in hereditary angio-oedema: our experience at Chandigarh, India.

Hereditary angio-oedema (HAE) is a rare autosomal dominant disorder characterized clinically by recurrent episodes of nonpruritic subcutaneous and/or submucosal oedema. Laryngeal oedema is the commonest cause of mortality in patients with HAE. Prior to the availability of first-line treatment options for the management of HAE, mortality was as high as 30%. Mortality has significantly declined in countries where first-line treatment options are available and patients can access these therapies. There is a paucity of literature on the outcomes of patients with HAE in developing countries where availability of and access to first-line treatment options are still a challenge. To report our experience on mortality in patients with HAE and to report factors associated with the death of these patients. We carried out a record review of all patients diagnosed with HAE between January 1996 and August 2022. Families with HAE who had reported the death of at least one family member/relative from laryngeal oedema were studied in detail. Of the 65 families (170 patients) registered in the clinic, 16 families reported the death of at least one family member/relative from laryngeal oedema (total of 36 deaths). Of these 16 families, 14 reported that 1 or more family members had experienced at least 1 attack of laryngeal oedema. One patient died during follow-up when she was taking long-term prophylaxis with stanozolol and tranexamic acid, while the remaining 35 patients were not diagnosed with HAE at the time of their death. At the time of death of all 36 patients, at least 1 other family member had symptoms suggestive of HAE, but the diagnosis was not established for the family. To our knowledge, this is the largest single-centre cohort of patients with HAE in India reporting mortality data and factors associated with death in these families. The delay in diagnosis is the most important reason for mortality.

Group Formation and the Evolution of Human Social Organization

Humans operate in groups that are oftentimes nested in multilayered collectives such as work units within departments and companies, neighborhoods within cities, and regions within nation states. With psychological science mostly focusing on proximate reasons for individuals to join existing groups and how existing groups function, we still poorly understand why groups form ex nihilo, how groups evolve into complex multilayered social structures, and what explains fission–fusion dynamics. Here we address group formation and the evolution of social organization at both the proximate and ultimate level of analysis. Building on models of fitness interdependence and cooperation, we propose that socioecologies can create positive interdependencies among strangers and pave the way for the formation of stable coalitions and groups through reciprocity and reputation-based partner selection. Such groups are marked by in-group bounded, parochial cooperation together with an array of social institutions for managing the commons, allowing groups to scale in size and complexity while avoiding the breakdown of cooperation. Our analysis reveals how distinct group cultures can endogenously emerge from reciprocal cooperation, shows that social identification and group commitment are likely consequences rather than causes of group cooperation, and explains when intergroup relations gravitate toward peaceful coexistence, integration, or conflict.

The paradox of cooperation among selfish cancer cells.

It is traditionally assumed that during cancer development, tumor cells abort their initially cooperative behavior (i.e., cheat) in favor of evolutionary strategies designed solely to enhance their own fitness (i.e., a "selfish" life style) at the expense of that of the multicellular organism. However, the growth and progress of solid tumors can also involve cooperation among these presumed selfish cells (which, by definition, should be noncooperative) and with stromal cells. The ultimate and proximate reasons behind this paradox are not fully understood. Here, in the light of current theories on the evolution of cooperation, we discuss the possible evolutionary mechanisms that could explain the apparent cooperative behaviors among selfish malignant cells. In addition to the most classical explanations for cooperation in cancer and in general (by-product mutualism, kin selection, direct reciprocity, indirect reciprocity, network reciprocity, group selection), we propose the idea that "greenbeard" effects are relevant to explaining some cooperative behaviors in cancer. Also, we discuss the possibility that malignant cooperative cells express or co-opt cooperative traits normally expressed by healthy cells. We provide examples where considerations of these processes could help understand tumorigenesis and metastasis and argue that this framework provides novel insights into cancer biology and potential strategies for cancer prevention and treatment.

China's Livestreaming Local Officials: An Experiment in Popular Digital Communications

AbstractIn 2020, hundreds of sub-national government officials and Chinese Communist Party cadres undertook a months-long experiment in livestreaming and social commerce. These sectors are among the most dynamic in the Chinese internet economy and culture, yet Chinese officials have generally resisted engaging with popular and celebrity cultures, even as institutions have begun to expand and modernize their digital operations. Why, then, did a substantial cohort of local officials undertake this experiment? The proximate reason was that they wanted to help local producers hit by the pandemic and to meet their own pending poverty alleviation targets. However, the significance of the case is broader, reflecting the central state and Party's revised thinking on political communications in an era of internet celebrity and self-media and the propensity for local officials to innovate and experiment in the field of digital and popular communication. Investigating empirically how and how effectively livestreaming was employed at the local level helps us to illuminate these dynamics. To facilitate the study, we investigated how officials understood and performed internet celebrity through in-person semi-structured interviews and a three-month virtual ethnographic study.

« Dicitur lupus, quia in die comedit unam gallinam »: Beyond the Metaphor: Lupus Disease between the Middle Ages and the Early Modern Period

In the Middle Ages, a severe ulcerative lesion of the lower limbs consuming a sick person’s flesh was named lupus because it was metaphorically associated with the wolf, probably with respect to the feared anthropophagic characteristic of this beast. Thirteenth-century theologians’ commentaries on the Bible linked lupus with morbus regius, a polysemic term that could denote jaundice, scrophula or leprosy. Moreover, for reasons of lexical proximity, lupus was at times confused with lupia, a subcutaneous swelling. The aim of this article is to present an inquiry of the earliest appearance of lupus as nosographic name and its exact meaning(s) and possible synonyms found in different sources, as well as a study on the competition among these different diseases names. The investigation will serve as a significant heuristic example for the purpose of demonstrating the overall complexity of the nosologic lexicon of the past.

Growth in High-Skilled Mexican Migration Northward: American and Canadian Destinations

As migration of university-educated Mexicans to both the United States and Canada has begun to increase, the greater opportunities Canada’s expanding points-based selection system offers for the highly skilled to become permanent residents highlights a question: which factors may induce high-skilled Mexicans to prefer Canadian destinations versus American? Using traditional migration theories to frame interviews with a volunteer sample of 40 young university-educated Mexicans, this study confirms that reasons of proximity, climate, and culture often favor American destinations, while reasons of social acceptance, social welfare, and personal security favor Canadian. Importantly, urban-specific preferences matter. Those factors favoring U.S. destinations in general lead many to prefer southern-tier U.S. cities traditional for less-skilled Mexican migration. Those considering northern U.S. cities often prefer a Canadian choice. Canadian competitiveness in the northern urban market suggests that increased awareness of Canadian immigration opportunities could significantly boost skilled Mexican migration to Canada.

Colonial Institutions and Civil War: Indirect Rule and Maoist Insurgency in India by Shivaji Mukherjee

The rise in intrastate conflict since the end of WWII has drawn much attention to the various incentives and opportunities that underpin violent rebellion, often resulting in protracted insurgencies. In his book Colonial Institutions and Civil War, Shivaji Mukherjee explores the breakout of insurgent movements in the era of decolonization since the 1950s. In particular, Mukherjee examines the role played by historical colonial institutions in shaping local socioeconomic and political structures that make the emergence and persistence of insurgencies more likely. Much of the literature focused on exploring the causes of terrorism, insurgencies, and civil war tends to place emphasis on the proximate reasons that trigger political violence by nonstate actors—for example, poverty, ethnic grievances, and exploitable natural resources like drug cultivation. Per Mukherjee, while these factors are important, they are inadequate in providing a comprehensive explanation of the contours of insurgencies, especially their occurrence in specific locations. In his work, Mukherjee takes into account a longer time horizon to move beyond studying proximate reasons of insurgencies and instead places the spotlight on colonial-era policies that established the structural conditions conducive to violent movements.

Family Planning in the Sierra Leone Ebola Outbreak: Women's Proximal and Distal Reasoning.

Sierra Leone was highly impacted by the 2014-2016 West Africa Ebola outbreak, with 3,955 recorded deaths. Already stressed maternal health services were deeply affected by the outbreak due to fears of viral transmission, reallocation of maternity staff, and broader policies to stop transmission including travel restrictions. This research sought to explore women's perspectives on delaying pregnancy during the Ebola outbreak using family planning methods. Qualitative data collection took place in Kambia District in 2018 and included 35 women participants, with women who were either family planning users or nonusers at the time of the outbreak. Women reported a variety of reasons for choosing to take or not to take family planning during the outbreak, which we categorized as proximal (directly related to the outbreak) or distal (not directly outbreak related). Proximal reasons to take family planning included to avoid interacting with health care spaces where Ebola could be transmitted, to avoid the economic burden of additional children in a time when economic activities were curtailed and to return to school when education resumed postoutbreak. Distal reasoning included gender roles affecting women's decision making to seek family planning, concerns related to the physiological side effects of family planning, and the economic burden of paying for family planning. Women's perspectives for choosing to take or not take family planning during the Sierra Leone Ebola crisis had not been explored prior to this paper. Using the lens of family planning to consider how women choose to access health care in an outbreak gives us a unique perspective into how all health care interactions are impacted by a generalized outbreak of Ebola, and how outbreak responses struggle to ensure such services remain a priority.

Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities: A mesocosm experiment

Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors.We investigated the responses of phytoplankton EPA and DHA concentrations to warming (IPCC climate scenario) and nutrient additions in mesocosms which had been run continuously at varying temperature and nutrient levels for 15 years prior to this study. Nutrient treatment had a significant effect on phytoplankton EPA and DHA concentrations and about 59 % of the variation in EPA and DHA concentrations could be explained by changes in the phytoplankton community structure. Increased biomass of diatoms corresponded with high EPA and DHA concentrations, while cyanobacteria/chlorophyte dominated mesocosm had low EPA and DHA concentrations. Warming had only a marginal effect on the EPA and DHA concentrations in these mesocosms. However, a significant interaction was observed with warming and N:P ratio.Our findings indicate that direct nutrient/temperature effects on algal physiology and PUFA metabolism were negligible and the changes in EPA and DHA concentrations were mostly related to the phytoplankton community structure and biomass. These results also imply that in shallow temperate lakes eutrophication, leading to increased dominance of cyanobacteria, will probably be a greater threat to phytoplankton EPA and DHA production than warming. EPA and DHA are nutritionally important for upper trophic level consumers and decreased production may impair secondary production.

Why People Keep an Intimate Relationship : Investigating Ultimate and Proximate Reasons.

Forming long-term intimate relationships constitutes an important aspect of human nature. Within the context of an evolutionary theoretical framework, the current research has attempted to investigate what motivates people to keep an intimate relationship. Using a combination of qualitative research methods in a sample of 131 Greek-speaking participants, 58 reasons that motivated individuals to keep their intimate relationship were identified. Using quantitative research methods in a sample of 789 Greek-speaking participants who were in an intimate relationship, these reasons were classified in nine broad factors and two broader domains. Having a supporting and compatible partner with whom one shares similar goals, and with whom one has good sex and a strong emotional attachment, were rated among the most important factors motivating participants to keep their relationship. Moreover, as indicated by the domain means, participants were more strongly motivated to keep their intimate relationship if their partners had desirable attributes, such as providing them with support, and less so by their own attributes, such as fear of loneliness. Significant effects of sex, age, marital status, presence of children, and years in a relationship were found for several factors.

Philomatry in plants: why do so many species have limited seed dispersal?

Many have noted limited seed dispersal of plants in diverse environments and attempted evolutionary explanations for it. Although philopatric ("love of fatherland") is used by zoologists to describe organisms that remain near their place of origin, philomatric ("love of motherland") is proposed as more appropriate for plants because seeds develop on the maternal parent, fecundity and dispersal are maternally influenced characteristics, and the term dovetails with the mother-site hypothesis (MSH) for the evolution of restricted dispersal. Proximate reasons for philomatry include intrinsic drivers such as morphological features of diaspores and where on the maternal parent they are produced. Extrinsic drivers include local environmental conditions, surrounding vegetation, and ineffective dispersal agents. The MSH proposes that selection should favor philomatry in a population adapted to a particular habitat because offspring will likewise be adapted to that same habitat. Several studies show philomatry can mitigate distance-dependent costs of dispersing into surrounding inhospitable areas. Undispersed diaspores can eliminate energetic costs of accessory structures or biochemicals needed by dispersible diaspores, but it is unclear whether these costs are significant to the evolution of philomatry. Disadvantages of limited dispersal are inability to escape deteriorating habitat conditions, inability to colonize new habitats, and inbreeding among offspring. Heterocarpic species offset these disadvantages by producing dispersed plus undispersed diaspores. A conceptual framework is presented relating dispersal distance to the probability of seedling establishment. Future research should recognize dispersal as a covarying syndrome of multiple life history traits and focus on ecological selection agents that favor philomatry.

Self-Medication Practices and Associated Factors in the Prevention and/or Treatment of COVID-19 Virus: A Population-Based Survey in Nigeria.

Background: The anxiety caused by the emergence of the novel coronavirus disease (COVID-19) globally has made many Nigerians resort to self-medication for purported protection against the disease, amid fear of contracting it from health workers and hospital environments. Therefore, this study aimed to estimate the knowledge level, causes, prevalence, and determinants of self-medication practices for the prevention and/or treatment of COVID-19 in Nigeria.Methods: A web-based cross-sectional survey was conducted between June and July 2020 among the Nigerian population, using a self-reported questionnaire. Statistical analysis of descriptive, bivariate, and multivariate analyses was done using STATA 15.Results: A total of 461 respondents participated in the survey. Almost all the respondents had sufficient knowledge about self-medication (96.7%). The overall prevalence of self-medication for the prevention and treatment of COVID-19 was 41%. The contributing factors were fear of stigmatization or discrimination (79.5%), fear of being quarantine (77.3%), and fear of infection or contact with a suspected person (76.3%). The proximal reasons for self-medication were emergency illness (49.1%), delays in receiving hospital services (28.1%), distance to the health facility (23%), and proximity of the pharmacy (21%). The most commonly used drugs for self-medication were vitamin C and multivitamin (51.8%) and antimalarials (24.9%). These drugs were bought mainly from pharmacies (73.9%). From the multivariable logistic regression model, males (OR: 0.79; 95% CI: 0.07–0.54), and sufficient knowledge on SM (OR: 0.64; 95% CI: 0.19–0.77) were significantly associated with self-medication.Conclusion: The key finding of this study was the use of different over-the-counter medications for the prevention (mainly vitamin C and multivitamins) and treatment (antibiotics/antimicrobial) of perceived COVID-19 infection by Nigerians with mainly tertiary education. This is despite their high knowledge and risk associated with self-medication. We suggest that medication outlets, media and community should be engaged to support the rational use of medication.

Decentralization and Citizens’ Participation in Local Governance: Does Trust and Transparency Matter? – An Empirical Study

The wind of change that swept across the African continent and other developing countries ensuingly engendered the need to institute measures that would bring government to the people’s doorstep. This led to the prioritization and touting of decentralization. Against the backdrop of the proximate reason to accelerate public access to government, the express expectation was that a germane space would be created to enhance participation. However, the validity of this postulation is yet to be realized. The study, therefore, set out to examine the relationship between decentralization and people’s participation, with the mediating role of trust and transparency. Results of data analysis (561 respondents), using the structural equation modelling technique, established not only the appropriateness of the proposed study model, but also, the imperativeness of the trust and transparency to decentralization and participation. The implications of the study are delineated for effective policy and practice.

When and why do sit-and-wait social spiders disperse?

Abstract Dispersal is inherent to all living organisms. Sit-and-wait predators such as social spiders, with their sedentary lifestyles, present an intriguing and underexplored case to examine the proximate and ultimate reasons for dispersal. Though a reduction in dispersal tendencies must accompany the evolution of sociality in spiders, a fraction of the colony may disperse in groups or individually in many species. Such group or solitary dispersal by female social spiders in specific life stages, can lead to colony fission or colony foundation. Males move between colonies, however, there are no direct estimations of male dispersal distances for any species. The structured populations and high inbreeding within colonies suggest that dispersal events occur over limited spatial scales and may be mediated by extrinsic and intrinsic factors. Future studies exploring complex relationships between environmental variables, phenotypes of individuals, colony state and dispersal are advocated. Another area of interest is probing the dispersal process itself to understand the mechanisms of information transfer between individuals at the onset of dispersal. This involves designing studies to examine how break-away groups reach a consensus on when to disperse and where to go.

Responses of Watsonia fourcadei and other geophytes to burning and slashing treatments in South Outeniqua Sandstone Fynbos

The often mass flowering of Watsonia and other geophyte species in the first year after a fire in the South African fynbos vegetation is well known, but it has rarely been quantified. Many fynbos geophytes also flower after the fynbos canopy was physically removed, but these flowering responses have also not been quantified. A study comparing the flowering response of geophytes after physical removal versus fire removal of the fynbos canopy was conducted to establish to what degree these species are fire dependant. It was also done to improve our understanding of fynbos geophyte ecology, especially towards establishing if the flowering response of these plants is due to fire related factors per se, or not.Vegetative growth, flowering response, seed set and seedling establishment of Watsonia fourcadei were recorded after two treatments, burning and physical removal of vegetation (slashing) in two veld ages (5- and 16 years). Responses of other co-occurring geophytic species to these treatments were also recorded. The number of vegetatively active W. fourcadei plants doubled and flowering percentage increased from 2.3% to 38.7% in the first year after the fire. In the second year after the fire the number of vegetatively active W. fourcadei plants was similar to those in the first year after the fire, but flowering percentage decreased to pre-fire levels. About 50% of W. fourcadei plants were dormant 5 years after the fire and > 90% were dormant in 16-year old fynbos. Flowering percentages of W. fourcadei in slashed 5-year old fynbos did not differ significantly from burned 16-year old fynbos. The flowering stimulus of W. fourcadei was thus not due to fire associated factors per se. Seed predation of W. fourcadei seed capsules decreased from 46.9% before the fire to 7.1% after the fire. Number of viable seed released increased from 15.8 seed mˉ² pre-fire to 1170.5 seed mˉ² post-fire and 233.1 seedlings mˉ² established after the fire. The 74-fold increase in seed release in the burned fynbos could not be ascribed to higher cross pollination success as about 40% of the flowers were autogamous. The number of vegetatively active geophytic species increased from 2.3 species mˉ² pre-fire to 7.9 species mˉ² post-fire in 16-year old burned fynbos and 4.0 species mˉ² in the slashed fynbos. Most (76%) of these geophytic species flowered after the fynbos was burned and 24% of the species flowered in the slashed fynbos. Only some of the geophytic species were thus dependent on fire to stimulate flowering. A repeated short cycle disturbance regime (ca. 5 years) of burning and/or slashing may result in a super-abundance of Watsonia plants that can displace smaller geophytic species. Previous hypotheses on proximate reasons for the Watsonia post-fire flowering that are rejected are: (i) greater visibility of the plants; (ii) heating of the soil and corms by fire and; (iii) increased availability of phosphorous and/or other minerals in the post-fire environment. Smoke as a factor to induce flowering in W. fourcadei growing under natural conditions is questioned.

Editors' note: Intrathecal IgM production is a strong risk factor for early conversion to multiple sclerosis

In their prospective, observational cohort of 150 patients with clinically isolated syndrome (CIS) or early relapsing-remitting multiple sclerosis (RRMS), Drs. Pfuhl et al. found that intrathecal IgM levels were significantly and independently predictive of conversion from CIS to RRMS. In a multivariable Cox regression, the presence of intrathecal IgM antibodies even outperformed oligoclonal bands and intrathecal IgG antibodies as a predictor for later RRMS. Drs. Alcalá et al. recount their previously published, similar findings. They also suggest that the presence of intrathecal IgM levels could guide the decision to treat with disease-modifying therapies. That said, fewer than one-quarter of all patients in this cohort with CIS or RRMS harbored intrathecal IgM antibodies. As Pfuhl et al. emphasized, the proximate reason for intrathecal IgM antibodies and clinical course of patients with and without such antibodies needs further exploration. Although there is much we still do not fully understand, all investigators recommend leveraging these and other biomarkers of disease activity to individualize care for patients with multiple sclerosis. In their prospective, observational cohort of 150 patients with clinically isolated syndrome (CIS) or early relapsing-remitting multiple sclerosis (RRMS), Drs. Pfuhl et al. found that intrathecal IgM levels were significantly and independently predictive of conversion from CIS to RRMS. In a multivariable Cox regression, the presence of intrathecal IgM antibodies even outperformed oligoclonal bands and intrathecal IgG antibodies as a predictor for later RRMS. Drs. Alcalá et al. recount their previously published, similar findings. They also suggest that the presence of intrathecal IgM levels could guide the decision to treat with disease-modifying therapies. That said, fewer than one-quarter of all patients in this cohort with CIS or RRMS harbored intrathecal IgM antibodies. As Pfuhl et al. emphasized, the proximate reason for intrathecal IgM antibodies and clinical course of patients with and without such antibodies needs further exploration. Although there is much we still do not fully understand, all investigators recommend leveraging these and other biomarkers of disease activity to individualize care for patients with multiple sclerosis.

Falling stroke rates during COVID-19 pandemic at a comprehensive stroke center

IntroductionAlthough there is evidence to suggest a high rate of cerebrovascular complications in patients with SARS-CoV-2 infection, anecdotal reports indicate a falling rate of new ischemic stroke diagnoses. We conducted an exploratory single-center analysis to estimate the change in number of new stroke diagnoses in our region, and evaluate the proximate reasons for this change during the COVID-19 pandemic at a tertiary care center in New Jersey. Patients and methodsA Comprehensive Stroke Center prospective cohort was retrospectively analyzed for the number of stroke admissions, demographic features, and short-term outcomes 5 months prior to 3/1/2020 (pre-COVID-19), and in the 6 weeks that followed (COVID-19 period). The primary outcome was the number of new acute stroke diagnoses before and during the COVID-19 period, as well as the potential reasons for a decline in the number of new diagnoses. ResultsOf the 328 included patients, 53 (16%) presented in the COVID-19 period. There was a mean fall of 38% in new stroke diagnoses (mean 1.13/day [SD 1.07] from 1.82/day [SD 1.38], p<0.01), which was related to a 59% decline in the number of daily transfers from referral centers (p<0.01), 25% fewer telestroke consultations (p=0.08), and 55% fewer patients presenting directly to our institution by private vehicle (p<0.01) and 29% fewer patients through emergency services (p=0.09). There was no significant change in the monthly number of strokes due to large vessel occlusion (LVO), however the proportion of new LVOs nearly doubled in the COVID-19 period (38% vs. 21%, p=0.01). ConclusionsThe observations at our tertiary care center corroborate anecdotal reports that the number of new stroke diagnoses is falling, which seems related to a smaller proportion of patients seeking healthcare services for milder symptoms. These preliminary data warrant validation in larger, multi-center studies.

Measuring Well-Being in Italian (Eco)regions

The scientific community has been studying for some time a measure capable of quantifying and monitoring the well-being of the population in the territories; this measure cannot be represented exclusively by economic components but also by dimensions that represent different domains of a mainly demographic-social nature. This paper aims to consider well-being from a multidimensional point of view and measure it for the 7983 Italian municipalities in order to highlight differences and similarities. To go down to such a fine territorial detail, it was necessary to use indicators implemented by administrative sources collected in a recently published portal. The application of composite indices allows a one-dimensional measurement that makes a complex phenomenon such as well-being more readable. From a territorial point of view, moreover, the work aims to overcome the administrative division already criticized in literature because it does not allow a reading corresponding to the real behaviors and lifestyles of citizens, embracing a classification more appropriate to the objective of the study. Since the elementary indicators taken into consideration are in some way influenced by reasons of proximity and/or territorial conformation, it was decided to use the classification in Ecoregions of Italy to assess whether the well-being, within the same municipality, “moves” in relation to the municipalities ecologically homogeneous. The results of the analyses present numerous aspects of originality in which the Ecoregions draw an interesting geography of the country.

Warming effects on soil respiration in moss-dominated crusts in the Tengger Desert, northern China

Despite the important role of biological soil crusts in the soil carbon cycles of desert ecosystems, the responses of soil respiration in biological soil crust-dominated areas to warming are not well understood. The goal of this study was to investigate the expected increases in temperature on soil respiration both diurnally and seasonally in biological soil crust-dominated areas. We used open-top chambers to simulate warming in the Shapotou region in the Tengger Desert, northern China. An automated soil respiration system was used to measure the soil respiration rates in moss-dominated crusts. The measured environmental variables included the precipitation, volumetric soil water content, air temperature and soil temperature at depths of 0, 5, 10, 20, and 50 cm. The response of soil respiration to warming is a function of soil moisture following rainfall in desert ecosystems. Our results showed that 1.5 °C of simulated warming significantly decreased soil respiration, indicating that the inhibition of soil respiration was likely due to the reduction in soil water content at a relatively high temperature. Over daily cycles, hourly soil respiration rates have commonly been related to hourly temperatures. The observed diel hysteresis between hourly soil respiration and temperature resulted in semielliptical hysteresis loops, and the temperature often lagged behind soil respiration for several hours. The lag times between soil respiration and temperature were significantly and positively related to the depth of the soil temperature measurements. The proximate reason for the diel hysteresis between soil respiration and temperature was likely a mismatch between the depth of CO2 production and the depth of the temperature measurements. Our results indicate that warming increases the response of soil respiration to soil water availability in biological soil crust-dominated desert ecosystems. Therefore, the accelerated drying effect of warming on soil respiration and diel soil respiration patterns between soil respiration and temperature at different depths should be considered in future soil carbon cycle models for biological soil crust-dominated desert ecosystems.

Breeding versus survival: proximate causes of abrupt population decline under environmental change in a desert rodent, the midday gerbil (Meriones meridianus).

Studying abrupt ecological shifts under gradual environmental change caused, in particular, by human activity is important for understanding the fundamental aspects and underlying mechanisms of ecological resilience. One of the rare well-documented examples of an abrupt ecological shift is the delayed step transition of the population of a desert rodent, the midday gerbil (Meriones meridianus), from high-abundance (1994-2002) to low-abundance (2003-2017) regimes. This was in response to landscape transformation from desert to steppe caused by the drastic reduction of livestock in the rangelands of southern Russia after the collapse of the USSR in the early 1990s. In this study, we tested whether demographic parameters were correlated with the observed abrupt downward population shift. We found that reproductive activity (the percentage of breeding females, the number of litters, fecundity and the number of young recruited per female) showed no trend over time and did not differ between periods of high and low abundance. In contrast, the adult sex ratio (SR = males: females) decreased significantly with time and was as much as twice more female-biased for the low-abundance population regime. However, SR was not related to any reproductive parameter, including the percentage of breeding females. We conclude that proximate reasons for an abrupt population decline in M. meridianus are not associated with the changes in breeding patterns or mate limitation caused by the Allee effect but relate to the increased mortality as a result of the desert landscape being fragmented by steppezation. The mortality is expected to be higher for males as the mobile and dispersing sex.