Life cycle exposure to titanium dioxide nanoparticles (TiO2-NPs) induces filial toxicity and population decline in the nematode Caenorhabditis elegans

Titanium dioxide nanoparticle (TiO2-NP) exposure has raised significant concern due to their potential toxicity and adverse ecological impacts. Despite their ubiquitous presence in various environmental compartments, the long-term consequences of TiO2-NPs remain poorly understood. In this study, we combined data of in vivo toxicity and modeling to investigate the potential negative impacts of TiO2-NP exposure. We employed the nematode Caenorhabditis elegans, an environmental organism, to conduct a full life cycle TiO2-NP toxicity assays. Moreover, to assess the potential impact of TiO2-NP toxicity on population dynamics, we applied a stage-constructed matrix population model (MPM). Results showed that TiO2-NPs caused significant reductions in reproduction, survival, and growth of parental C. elegans (P0) at the examined concentrations. Moreover, these toxic effects were even more pronounced in the subsequent generation (F1) when exposed to TiO2-NPs. Furthermore, parental TiO2-NP exposure resulted in significant toxicity in non-exposed C. elegans progeny (TiO2-NPs free), adversely affecting their reproduction, survival, and growth. MPM analysis revealed decreased transition probabilities of surviving (Pi), growth (Gi), and fertility (Fi) in scenarios with TiO2-NP exposure. Additionally, the population growth rate (λmax) was found to be less than 1 in both P0 and F1, indicating a declining population trend after successive generations. Sensitivity analysis pinpointed L1 larvae as the most vulnerable stage, significantly contributing to the observed population decline in both P0 and F1 generations under TiO2-NP exposure. Our findings provide insight into the potential risk of an environmental organism like nematode by life cycle exposure to TiO2-NPs.

Microplastics as an emerging threat to amphibians: Current status and future perspectives

Given their pervasiveness in the environment, particularly in aquatic ecosystems, plastics are posing a growing concern worldwide. Many vertebrates and invertebrates in marine, freshwater, and terrestrial ecosystems exhibit microplastic (MP) uptake and accumulation. Some studies have indicated the fatal impacts of MPs on animals and their possible transfer through food chains. Thus, it is crucial to study MP pollution and its impacts on environment-sensitive and globally threatened animal groups, such as amphibians, which also play an important role in the energy transfer between ecosystems. Unfortunately, research in this field is lacking and sources of organized information are also scarce. Hence, we systematically reviewed published literature on MPs in amphibians to fill the existing knowledge gap. Our review revealed that most of the previous studies have focused on MP bioaccumulation in amphibians, whereas, only a few research highlighted its impacts. We found that more than 80% of the studied species exhibited MP accumulation. MPs were reported to persist in different organs for a long time and get transferred to other trophic levels. They can also exhibit cytotoxic and mutagenic effects and may have fatal impacts. Moreover, they can increase the disease susceptibility of amphibians. Our study concludes the MPs as a potential threat to amphibians and urges increasing the scope and frequency of research on MP pollution and its impacts on this vulnerable animal group. We also provide a generalized method for studying MPs in amphibians with future perspectives and research directions. Our study is significant for extending the knowledge of MPs and their impacts on amphibians and guiding prospective research.

The Formal Demography of Peak Population

When will the human population peak? In this article, we build on classical results by Ansley Coale, who showed that when fertility declines steadily, births reach their maximum before fertility reaches replacement level, and the decline in total population size does not occur until several decades after fertility has reached that level. We extend Coale's results by modeling longevity increases, net immigration, and a slowdown in fertility decline that resembles current projections. With these extensions, our models predict a typical lag between replacement-level fertility and population decline of about 35 to 40 years, consistent with projections by the United Nations and about 15 years longer than the lag predicted by Coale. Our analysis helps reveal underlying factors in the timing of peak population.

Patients with diabetes in regions with population decline and likelihood of receiving diabetes management education and screenings for related complications in Korea

OBJECTIVE

Many municipal districts in Korea face population decline owing to overall population decreases and aging. We investigated the association between geographic rurality and likelihood of receiving diabetes management education and diabetic retinopathy and diabetes-related kidney disease screenings among adults with diabetes.

METHODS

Patient data were obtained from the 2021 Korea Community Health Survey (27,391 individuals; aged ≥19 years and physician-diagnosed with diabetes mellitus). Geographic rurality was categorized based on population decline as follows: with, at risk of, or without population decline. The association between geographic rurality and likelihood of receiving diabetes management education and diabetic retinopathy and diabetes-related kidney disease screenings was examined using multilevel logistic regression analyses.

RESULTS

Among 27,391 patients with diabetes, 31.1% received diabetes education; 40.0% and 46.4% were screened for diabetic retinopathy and diabetes-related kidney disease, respectively. Individuals residing in regions with population decline were less likely to receive diabetes education (odds ratio [OR] 0.62, 95% CI 0.50-0.75) and diabetic retinopathy (OR 0.79, 95% CI 0.70-0.90) and diabetes-related kidney disease (OR 0.64, 95% CI 0.55-0.75) screenings, as compared with their counterparts.

CONCLUSIONS

Our findings highlight the importance of increased monitoring and providing diabetes education and screenings for patients with diabetes living in rural areas.

Population decline in a Pleistocene refugium: Stepwise, drought-related dieback of a South Australian eucalypt

Refugia can facilitate the persistence of species under long-term environmental change, but it is not clear if Pleistocene refugia will remain functional as anthropogenic climate change progresses. Dieback in populations restricted to refugia therefore raises concerns about their long-term persistence. Using repeat field surveys, we investigate dieback in an isolated population of Eucalyptus macrorhyncha during two droughts and discuss prospects for its continued persistence in a Pleistocene refugium. We first confirm that the Clare Valley in South Australia has constituted a long-term refugium for the species, with the population being genetically highly distinct from other conspecific populations. However, the population lost >40 % of individuals and biomass through the droughts, with mortality being just below 20 % after the Millennium Drought (2000-2009) and almost 25 % after the Big Dry (2017-2019). The best predictors of mortality differed after each drought. While north-facing aspect of a sampling location was significant positive predictor after both droughts, biomass density and slope were significant negative predictors only after the Millennium Drought, and distance to the north-west corner of the population, which intercepts hot, dry winds, was a significant positive predictor after the Big Dry only. This suggests that more marginal sites with low biomass and sites located on flat plateaus were more vulnerable initially, but that heat-stress was an important driver of dieback during the Big Dry. Therefore, the causative drivers of dieback may change during population decline. Regeneration occurred predominantly on southern and eastern aspects, which would receive the least solar radiation. While this refugial population is experiencing severe decline, some gullies with lower solar radiation appear to support relatively healthy, regenerating stands of red stringybark, providing hope for persistence in small pockets. Monitoring and managing these pockets during future droughts will be essential to ensure the persistence of this isolated and genetically unique population.

eDNA testing reveals surprising findings on fish population dynamics in Thailand

COVID-19, a global health concern, has an effect on all aspects of the economy. The aquaculture and fishing industries were severely harmed as a result of the closures in multiple nations. Regular systems for inventory monitoring, production, and supply were disrupted. Cancellation of programmes for research, fieldwork, sampling, and tagging influences management-required data. For effective species management, fish dispersion assessments are indispensable. However, due to the difficulty of accessing sampling sites and the associated costs, there is frequently a lack of comprehensive information regarding the distribution and abundance of organisms. The COVID-19 prohibition made fish monitoring more problematic. Due to constant pressure, populations of the stone lapping minnow (Garra cambodgiensis), one of Thailand's overfished fish, are rapidly declining. Therefore, eDNA-based monitoring was devised and implemented to reveal the likely dispersal of the species in Thailand prior to and following the lockdown. At 28 locations within the Chao Phraya River Basin, water samples were collected. qPCR was used to determine the presence or absence of G. cambodgiensis in water samples. In 78 of 252 water samples, a wide range of computed copy numbers for G. cambodgiensis eDNA was observed. It was discovered that samples collected in 2021 (after the lockdown) contain a higher concentration of G. cambodgiensis eDNA than samples collected in 2018 or 2019 (prior to the lockdown). The closure appears to be a boon and may result in a substantial restocking of the fish we have studied. Overall, eDNA-based analysis is an extremely promising new survey instrument.

Population genomics reveals moderate genetic differentiation between populations of endangered Forest Musk Deer located in Shaanxi and Sichuan

Background

Many endangered species exist in small, genetically depauperate, or inbred populations, hence promoting genetic differentiation and reducing long-term population viability. Forest Musk Deer (Moschus berezovskii) has been subject to illegal hunting for hundreds of years due to the medical and commercial values of musk, resulting in a significant decline in population size. However, it is still unclear to what extent the genetic exchange and inbreeding levels are between geographically isolated populations. By using whole-genome data, we reconstructed the demographic history, evaluated genetic diversity, and characterized the population genetic structure of Forest Musk Deer from one wild population in Sichuan Province and two captive populations from two ex-situ centers in Shaanxi Province.

Results

SNP calling by GATK resulted in a total of 44,008,662 SNPs. Principal component analysis (PCA), phylogenetic tree (NJ tree), ancestral component analysis (ADMIXTURE) and the ABBA-BABA test separated Sichuan and Shaanxi Forest Musk Deer as two genetic clusters, but no obvious genetic differentiation was observed between the two captive populations. The average pairwise F_ST value between the populations in Sichuan and Shaanxi ranged from 0.05–0.07, suggesting a low to moderate genetic differentiation. The mean heterozygous SNPs rate was 0.14% (0.11%—0.15%) for Forest Musk Deer at the genomic scale, and varied significantly among three populations (Chi-square = 1.22, p < 0.05, Kruskal–Wallis Test), with the Sichuan population having the lowest (0.11%). The nucleotide diversity of three populations varied significantly (p < 0.05, Kruskal–Wallis Test), with the Sichuan population having the lowest genetic θ_π (1.69 × 10^–3).

Conclusions

Genetic diversity of Forest Musk Deer was moderate at the genomic scale compared with other endangered species. Genetic differentiation between populations in Sichuan and Shaanxi may not only result from historical biogeographical factors but also be associated with contemporary human disturbances. Our findings provide scientific aid for the conservation and management of Forest Musk Deer. They can extend the proposed measures at the genomic level to apply to other musk deer species worldwide.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08896-9.

Whole-lake nanosilver additions reduce northern pike (Esox lucius) growth

Nanosilver (AgNP) is an anti-microbial agent widely used in consumer products, with significant potential for these nanoparticles to be released into aquatic environments. Laboratory studies involving short-term exposures of fish to AgNP show a range of toxicological effects, but these studies do not address potential responses in long-lived organisms resulting from chronic exposures. A collaborative study involving additions of AgNP to environmentally relevant concentrations over two field seasons took place at the IISD-Experimental Lakes Area, providing an opportunity to study the impacts of chronic exposures to long-lived fish species. In the present study, we evaluated the abundance and growth of an apex predator, Northern Pike (Esox lucius), collected from Lake 222 before, during and after the AgNP dosing period and compared results to those from a nearby unmanipulated lake (Lake 239). While the abundance of Northern Pike from Lake 222 during the study period was essentially stable, per capita availability of their primary prey species, Yellow Perch (Perca flavescens) declined by over 30%. Northern Pike fork length- and weight-at-age (indices of growth rate) declined following AgNP additions, most notably in age 4 and 5 fish. No similar changes in prey availability or growth were observed in Northern Pike from the reference lake. Body condition did not change in Northern Pike collected from either Lake 222 or Lake 239. Our results indicate that declines in the growth of Northern Pike chronically exposed to AgNP likely resulted from reduced prey availability but direct sublethal effects from AgNP exposure could also have been a factor. The persistence of reduced growth in Northern Pike two years after the cessation of AgNP additions highlight the potential legacy impacts of this contaminant once released into aquatic ecosystems.

Spatially structured freshwater fish population dynamics at the River Basin District scale: Implication for environmental management and fish conservation

European Union environmental policy has created a unique regulatory framework to favour aquatic ecosystem management and biodiversity conservation across European countries. Identifying the spatial structure of freshwater fish population dynamics is crucial to define region-specific management and conservation planning. To implement evidence-driven management and conservation decisions at a regional scale we assessed spatial heterogeneity in common freshwater fish population dynamics in France with a focus on trends in River Basin Districts (RBDs). The abundance and biomass growth rates of 18 common European freshwater fish species were estimated with state-space models on 546 sites distributed across the 5 main RBDs sampled in France between 1990 and 2011. Anguilla anguilla, Rutilus rutilus, Salmo trutta fario and Esox spp. exhibited large scale decline in abundance and/or biomass in several RBDs. The other species showed spatial heterogeneity in population growth rates. The main declines were observed in the Adour-Garonne and Loire-Bretagne RBDs, where management and conservation measures are urgently needed to halt the erosion of freshwater fish populations. In each of the 5 investigated RBDs, our results highlight areas where most of the common species we studied exhibited negative population growth rates. Freshwater fish surveys provide the fundamental information necessary to inform the European environmental policies and local environmental management needed to restore freshwater biodiversity. The next steps are to identify the main drivers of freshwater biodiversity erosion in the areas where we demonstrated major declines and to define the most cost-effective restoration measures.

Trends in sympatric otariid populations suggest resource limitations in the Peruvian Humboldt Current System

Sympatric species evolve mechanisms to avoid competition and coexist. In the Humboldt Current System (HCS), populations of South American sea lions (SASL, Otaria byronia) and South American fur seals (SAFS, Arctocephalus australis) fluctuate mostly due to ENSO events and prey availability. We evaluate population trajectories of Peruvian sympatric otariids and discuss mechanisms for competition and/or resource limitation. For this purpose, we analyzed population trajectories of SASL and SAFS in a sympatric breeding site in Punta San Juan, Peru between 2001 and 2019. Wavelet analysis was used to extract trends and derivatives to estimate rates and turning points. Age-class proportions and biomass times series were constructed from weekly counts and evaluated. Both populations show a growth phase and subsequent decline. SAFS started to decline ~2.25 years before and at a rate 1.5 times faster than SASL. Decrease in juvenile age-class suggests that resource limitation is the main contributing factor for current population decline.

Population and Climate Change: Consensus and Dissensus among Demographers

What role does population play in thinking about the problem of climate change and some of its solutions? In a survey conducted between February and April 2020, we asked European demographers to state their views on the relationship between climate change and population developments, and asked them to rate their concern about climate change and other socio-demographic issues. We found that climate change is at the top of the list of demographers' concerns, but that their sense of urgency with respect to taking action to redress global warming is not matched by their belief that population policy can make a crucial difference in reducing CO2 emissions: demographers are highly divided on the question whether the global population size should be reduced to lower CO2 emissions, as well as on the question whether family planning is an effective policy instrument.

Evidence of genetic structure in the wide-ranging bearded vulture (Gypaetus barbatus (Linnaeus, 1758))

BACKGROUND

The bearded vulture is sparsely distributed across a wide geographic range that extends over three continents (Africa, Europe and Asia). Restriction to high-altitude mountainous habitats, low breeding rates, lack of food and a heightened level of persecution have left many local populations severely diminished or extinct. Understanding the genetic connectivity and population structure of this threatened vulture species is critical for accurately assessing their conservation status, and for appropriately managing local populations through captive breeding programmes or translocations. Previous genetic assessments of the species were mainly focused on the European and Asian populations and included limited representation of the geographically isolated southern African population. A single mitochondrial study, which focused on the African populations of the bearded vulture, detected limited genetic differentiation between populations in Ethiopia and southern Africa, with reduced haplotype diversity in the southern Africa population. In this study, we extend the previous genetic assessments of the species by examining the phylogeography and genetic connectivity of global G. barbatus populations using a panel of 14 microsatellite loci.

RESULTS

Analyses revealed spatially correlated genetic differentiation between regional populations and low levels of gene flow between these population fragments. In contrast to the mitochondrial data, the microsatellite data support the management of genetically different populations as separate entities.

CONCLUSIONS

Low genetic diversity and geographic isolation are known to adversely affect the evolutionary potential of a species in the long-term. The high inbreeding found in the southern African G. barbatus and, to a lesser extent, the northern African populations highlights the need for conservation programmes to effectively manage populations of this species and maintain extant genetic diversity.

Pesticide exposure affects reproductive capacity of common toads (Bufo bufo) in a viticultural landscape

Amphibian populations are declining worldwide at alarming rates. Among the large variety of contributing stressors, chemical pollutants like pesticides have been identified as a major factor for this decline. Besides direct effects on aquatic and terrestrial amphibian stages, sublethal effects like impairments in reproduction can affect a population. Therefore, we investigated the reproductive capacity of common toads (Bufo bufo) in the pesticide-intensive viticultural landscape of Palatinate in Southwest Germany along a pesticide gradient. In a semi-field study, we captured reproductively active common toad pairs of five breeding ponds with different pesticide contamination level and kept them in a net cage until spawning. Toads from more contaminated ponds showed an increased fecundity (more eggs) but decreased fertilization rates (fewer hatching tadpoles) as well as lower survival rates and reduced size in Gosner stage 25, suggesting that the higher exposed populations suffer from long-term reproductive impairments. In combination with acute toxicity effects, the detected sublethal effects, which are mostly not addressed in the ecological risk assessment of pesticides, pose a serious threat on amphibian populations in agricultural landscapes.

Demography, genetics, and decline of a spatially structured population of lekking bird

Understanding the mechanisms underlying population decline is a critical challenge for conservation biologists. Both deterministic (e.g. habitat loss, fragmentation, and Allee effect) and stochastic (i.e. demographic and environmental stochasticity) demographic processes are involved in population decline. Simultaneously, a decrease of population size has far-reaching consequences for genetics of populations by increasing the risk of inbreeding and the strength of genetic drift, which together inevitably results in a loss of genetic diversity and a reduced effective population size ([Formula: see text]). These genetic factors may retroactively affect vital rates (a phenomenon coined 'inbreeding depression'), reduce population growth, and accelerate demographic decline. To date, most studies that have examined the demographic and genetic processes driving the decline of wild populations have neglected their spatial structure. In this study, we examined demographic and genetic factors involved in the decline of a spatially structured population of a lekking bird, the western capercaillie (Tetrao urogallus). To address this issue, we collected capture-recapture and genetic data over a 6-years period in the Vosges Mountains (France). Our study showed that the population of T. urogallus experienced a severe decline between 2010 and 2015. We did not detect any Allee effect on survival and recruitment. By contrast, individuals of both sexes dispersed to avoid small subpopulations, thus suggesting a potential behavioral response to a mate finding Allee effect. In parallel to this demographic decline, the population showed low levels of genetic diversity, high inbreeding and low effective population sizes at both subpopulation and population levels. Despite this, we did not detect evidence of inbreeding depression: neither adult survival nor recruitment were affected by individual inbreeding level. Our study underlines the benefit from combining demographic and genetic approaches to investigate processes that are involved in population decline.

Vector-Borne Pathogens in Ectoparasites Collected from High-Elevation Pika Populations

The American pika, Ochotona princeps, is projected to decline throughout North America as climate change reduces its range, and pikas have already disappeared from several locations. In addition to climate, disease spillover from lower elevation mammalian species might affect pikas. We sampled pika fleas in Colorado and Montana across elevations ranging from 2896 to 3612 m and screened them for the presence of DNA from rodent-associated bacterial pathogens (Bartonella species and Yersinia pestis) to test the hypothesis that flea exchange between pikas and rodents may lead to occurrence of rodent-associated pathogens in pika ectoparasites. We collected 275 fleas from 74 individual pikas at 5 sites in Colorado and one site in Montana. We found that 5.5% of 275 pika fleas in this study tested positive for rodent-associated Bartonella DNA but that variation in Bartonella infection prevalence in fleas among sites was not driven by elevation. Specifically, we detected DNA sequences from two loci (gltA and rpoB) that are most similar to Bartonella grahamii isolates collected from rodents in Canada. We did not detect Y. pestis DNA in our survey. Our results demonstrate evidence of rodent-associated flea-borne bacteria in pika fleas. These findings are also consistent with the hypothesis that rodent-associated pathogens could be acquired by pikas. Flea-borne pathogen spillover from rodents to pikas has the potential to exacerbate the more direct effects of climate that have been suggested to drive pika declines.

Population decline in tree swallows (Tachycineta bicolor) linked to climate change and inclement weather on the breeding ground

Population decline and the threat of extinction are realities currently facing many species. Yet, in most cases, the detailed demographic data necessary to identify causes of population decline are unavailable. Using 43 years (1975-2017) of data from a box-nesting population of tree swallows (Tachycineta bicolor), we identified reduced survival of offspring as a probable demographic cause of population decline. Poor fledging success was associated with increased predation and poor weather conditions during early nestling development. Low juvenile survival and subsequent recruitment was linked to poor weather conditions during the post-fledging period and may also be linked to conditions on the wintering grounds. Regional weather conditions during critical stages of breeding (early nestling and post-fledging) have become progressively worse over the 43-year study period. None of the other factors linked to offspring survival have similarly deteriorated. Overall, our results suggest tree swallows should be added to the growing list of species challenged by climate change, and that other species of aerial insect specialists may face similar impacts of climate change.

Predicting hedgehog mortality risks on British roads using habitat suitability modelling

Road vehicle collisions are likely to be an important contributory factor in the decline of the European hedgehog (Erinaceus europaeus) in Britain. Here, a collaborative roadkill dataset collected from multiple projects across Britain was used to assess when, where and why hedgehog roadkill are more likely to occur. Seasonal trends were assessed using a Generalized Additive Model. There were few casualties in winter-the hibernation season for hedgehogs-with a gradual increase from February that reached a peak in July before declining thereafter. A sequential multi-level Habitat Suitability Modelling (HSM) framework was then used to identify areas showing a high probability of hedgehog roadkill occurrence throughout the entire British road network (∼400,000 km) based on multi-scale environmental determinants. The HSM predicted that grassland and urban habitat coverage were important in predicting the probability of roadkill at a national scale. Probabilities peaked at approximately 50% urban cover at a one km scale and increased linearly with grassland cover (improved and rough grassland). Areas predicted to experience high probabilities of hedgehog roadkill occurrence were therefore in urban and suburban environments, that is, where a mix of urban and grassland habitats occur. These areas covered 9% of the total British road network. In combination with information on the frequency with which particular locations have hedgehog road casualties, the framework can help to identify priority areas for mitigation measures.

Scenario-based land abandonment projections: Method, application and implications

Land abandonment, e.g. agricultural land abandonment, can result in various social and ecological impacts. It would thus be helpful if the extent and spatial pattern of future land abandonment could be projected. However, the trajectory of future land abandonment generally depends on various factors, including biophysical conditions and future changes in socioeconomic indicators in the area. In this study, we developed a general framework for a scenario-based land abandonment projection, featuring a coupled regional economic and spatially explicit land change modeling approach. We applied this framework in selected municipalities in Fukushima Prefecture, Japan, under two socioeconomic development scenarios (2014-2050): low population and economic growth (LL scenario) and high population and economic growth (HH scenario). The case study results, which are also visualized through a set of hot spot maps, revealed that agricultural land abandonment would be more intense under the HH scenario due to the much higher future decline in farmer population driven by the shift in people's employment and main source of livelihood. Under the LL scenario, residential and urban land abandonment would be more profound because of the much higher future decline in total population. In general, our results provide insights into some plausible future socioeconomic changes, their interplay and their consequent land abandonment in the case study area, which would be useful in the context of forward-looking adaptive development planning. The proposed framework can be applied to other case study areas.

Population Genomics and Structure of the Critically Endangered Mariana Crow (Corvus kubaryi)

The Mariana Crow, or Åga (Corvus kubaryi), is a critically endangered species (IUCN -International Union for Conservation of Nature), endemic to the islands of Guam and Rota in the Mariana Archipelago. It is locally extinct on Guam, and numbers have declined dramatically on Rota to a historical low of less than 55 breeding pairs throughout the island in 2013. Because of its extirpation on Guam and population decline on Rota, it is of critical importance to assess the genetic variation among individuals to assist ongoing recovery efforts. We conducted a population genomics analysis comparing the Guam and Rota populations and studied the genetic structure of the Rota population. We used blood samples from five birds from Guam and 78 birds from Rota. We identified 145,552 candidate single nucleotide variants (SNVs) from a genome sequence of an individual from Rota and selected a subset of these to develop an oligonucleotide in-solution capture assay. The Guam and Rota populations were genetically differentiated from each other. Crow populations sampled broadly across their range on Rota showed significant genetic structuring – a surprising result given the small size of this island and the good flight capabilities of the species. Knowledge of its genetic structure will help improve management strategies to help with its recovery.

How much genetic variation is stored in the endangered and fragmented shrub Tetraena mongolica Maxim?

Tetraena mongolica Maxim (Zygophyllaceae) is an endangered species endemic to western Inner Mongolia and China, and is currently threatened by habitat loss and human over-exploitation. We explored the genetic background, its genetic diversity, population structure, and demographic history, based on 12 polymorphic nuclear microsatellite loci. Our results indicated high genetic diversity in extant populations, but no distinguishable gene cluster corresponding with a specific biogeography. Population demography analysis using a MSVAR indicated a strong, recent population decline approximately 5,455 years ago. These results suggest that the Yellow River and Zhuozi Mountain range may not prevent pollination between populations. Finally, we surmised that the population demography of T. mongolica was likely to have been affected by early mankind activities.

Restating the Case for a Sharp Population Decline in Lemur catta

As with many other species in the primate order, ring-tailed lemurs (Lemur catta) are threatened with extinction. Our articles documented declines in wild ring-tailed lemur populations and noted that fewer than 2,500 wild ring-tailed lemurs are known to persist in 32 [Gould and Sauther: Primate Conservation 2016; 30: 89-101] and 34 [LaFleur et al.: Folia Primatologica 2017; 87: 320-330] sites. A criticism of our articles [Murphy et al.: International Journal of Primatology 2017; 38: 623-628] suggested that we have inadequately sampled ring-tailed lemur populations and habitats, and misused the literature. We disagree, and provide both a detailed rebuttal and responses to specific critique points herein. Moreover, we restate our case outlining a dramatic decline of ring-tailed lemurs resulting from anthropogenic pressures (deforestation, severe habitat fragmentation, extraction for the pet and bushmeat trades). We pose several thought-provoking questions as to when is the appropriate time for researchers to "sound the alarm" about a species' decline, and remain committed to understanding the drivers of unsustainable exploitation of this emblematic lemur, and preventing their extinction in the wild.

Bisphenol risk in fish exposed to a contamination gradient: Triggering of spatial avoidance

Bisphenol A (BPA) is an emerging contaminant widely used in various industrial products. Sublethal toxicity of BPA on aquatic organisms is expected to occur at a concentration of around 500 μg L^-1, which is much higher than environmentally realistic concentrations found in water bodies (up to 0.41 μg L^-1). However, there is no information concerning how a BPA contamination gradient could affect the spatial displacement of organisms. We hypothesized that fish might be able to detect an environmentally realistic BPA contamination gradient and avoid potential toxic effects due to continuous exposure. Therefore, the objectives of this work were: (i) to determine if BPA could trigger an avoidance response in the freshwater fish Poecilia reticulata; (ii) to assess whether BPA-driven avoidance occurs at environmentally relevant concentrations; and (iii) to estimate the population immediate decline (PID) at the local scale, considering avoidance and mortality as endpoints. Avoidance experiments were performed in a seven-compartment non-forced exposure system, in which a BPA contamination gradient was simulated. The results indicated that BPA triggered avoidance in P. reticulata. In a traditional forced acute toxicity test, lethal effects in 50% of the population occurred at a BPA concentration of 1660 μg L^-1, while in the non-forced system with a BPA concentration gradient, avoidance of 50% of the population occurred at a concentration four orders of magnitude lower (0.20 μg L^-1). At environmentally relevant BPA concentrations, PID was mainly determined by the avoidance response. Avoidance in P. reticulata populations is expected to occur at BPA concentrations below those that cause sublethal effects on fish and are considered safe by international agencies (≤1 μg L^-1). The approach used in the present study represents a valuable tool for use in environmental risk assessment strategies, providing a novel and ecologically relevant response that is complementary to traditional ecotoxicological tests.

Investigation into diseases in free-ranging ring-necked pheasants (Phasianus colchicus) in northwestern Germany during population decline with special reference to infectious pathogens

The population of ring-necked pheasants (Phasianus colchicus) is decreasing all over Germany since the years 2008/2009. Besides impacts of habitat changes caused by current rates of land conversion, climatic influences or predators, a contribution of infectious pathogens needs also to be considered. Infectious and non-infectious diseases in free-living populations of ring-necked pheasants have been scarcely investigated so far. In the present study, carcasses of 258 deceased free-ranging pheasants of different age groups, predominantly adult pheasants, collected over a period of 4 years in the states of Lower Saxony, North Rhine–Westphalia and Schleswig-Holstein, were examined pathomorphologically, parasitologically, virologically and bacteriologically, with a focus set on infectious pathogens. A periocular and perinasal dermatitis of unknown origin was present in 62.3% of the pheasants. Additional alterations included protozoal cysts in the skeletal musculature (19.0%), hepatitis (21.7%), enteritis (18.7%), gastritis (12.6%), and pneumonia (11.7%). In single cases, neoplasms (2.6%) and mycobacteriosis (1.7%) occurred. Further findings included identification of coronaviral DNA from trachea or caecal tonsils (16.8%), siadenoviral DNA (7.6%), avian metapneumoviral RNA (6.6%), and infectious bursal disease viral RNA (3.7%). Polymerase chain reaction (PCR) on herpesvirus, avian influenza virus (AIV), paramyxovirus type 1 (PMV-1), avian encephalomyelitis virus (AEV), and chlamydia were negative. Based on the present results, there is no indication of a specific pathogen as a sole cause for population decline in adult pheasants. However, an infectious disease can still not be completely excluded as it may only affect reproduction effectivity or a certain age group of pheasants (e.g., chicks) which were not presented in the study.

Associations of gender role attitudes with fertility intentions: A Japanese population-based study on single men and women of reproductive ages

OBJECTIVES

Japan has been experiencing low fertility for many years. In this study, I investigated the relationship between gender role attitudes and fertility intentions among Japanese single men and women of reproductive ages.

STUDY DESIGN

Utilizing the Longitudinal Survey of Adults in the 21st Century data, 8944 men and 7924 women aged 20-34 years with single, childless status were analyzed. Gender role attitudes were assessed by participants' preferences for the division of labor between a man and a woman: income earning, housework, and childcare. Those who preferred men to earn income and women to perform housework and childcare were considered to have traditional attitudes, whereas those who preferred women and men to share these responsibilities were considered to have egalitarian attitudes.

MAIN OUTCOME MEASURES

Outcomes were fertility intentions measured by a desire to have children and ideal number of children. Logistic regression analyses were conducted.

RESULTS

Egalitarian attitudes about income earning and housework were associated with low fertility intentions (a lesser desire for children) compared to traditional attitudes: adjusted odds ratios were 1.56 [1.36, 1.80] for men and 1.47 [1.26, 1.72] for women with income earning. Men's preference for sharing childcare responsibility was associated with high fertility intentions.

CONCLUSIONS

Japanese society has not shifted away from the traditional division of labor despite the increase in female labor force participation. Low fertility intentions among Japanese men and women with egalitarian attitudes suggest that institutional support for balancing work and family may be necessary to improve the low fertility trend.

[Regional differences in the development of hospitalizations : An effect of different demographic trends?]

Population aging and population decline in many regions of the Federal Republic of Germany are key elements of demographic change. In the regions concerned there is a rising number of older people and, simultaneously, a declining population. So far, the consequences of regional shrinkage and growth for inpatient care don't seem to have been analysed very well. This paper analyses the influence of population aging and declining/increasing population (demographic factors) as well as other, non-demographic factors on the number of hospitalizations in Germany and the Federal States since 2000.One result of the analysis is that there are major differences between the Federal States. The analysis shows, for example, an increase of hospitalizations in Berlin while in Saxony-Anhalt the number of hospitalizations declines. The increase in Berlin was the result of population aging and, to a lower extent, an increase in population. In Saxony-Anhalt the declining population resulted in a decreasing number of hospitalizations. Population aging and non-demographic factors were not able to compensate this trend.Overall, the effect of demographic factors on the number of hospitalizations remains constant over time. Short-term changes of hospitalizations are due to non-demographic factors, such as epidemiological trends, (for example trends of incidence or prevalence), or structural changes of health care service (for example patients shifting between different sectors of health care or the introduction of new reimbursement systems).

Assessing the Decrease in the Surgical Population of the University of Puerto Rico-Affiliated Hospitals

OBJECTIVE

To evaluate the magnitude of the decrease in the surgical population of the University of Puerto Rico (UPR)-affiliated hospitals.

METHODS

We examined all the surgical cases that were entered into the Surgical Database from January 1, 2013, through December 31, 2015. This database collects patient and procedural information from the surgical services of the UPR-affiliated hospitals. Thus, the number of surgical patients for the 3-year study period was determined and their characteristics recorded. The group was subdivided into 3 subgroups, according to year: 2013, 2014, and 2015. All the variables studied were tabulated for the 3 subgroups and the values compared. The differences between subgroups were evaluated using the chi2 test or ANOVA, whichever was appropriate, with a p-value of less than 0.05 being considered significant.

RESULTS

During the 3-year period, the Surgical Database collected information on 14,626 cases. The mean age of the group was 48 (±23) years. The gender distribution indicated that 55% of the sample members were women and 45% were men. A 14% decline in the number of surgical cases occurred from 2013 through 2015. The changes were not limited to a decline in numbers; the patients were sicker, as evidenced by a statistically significant (p<0.05) increase in the number of patients who presented with an American Society of Anesthesiologist (ASA) physical status classification of 3 or higher.

CONCLUSION

A moderately steady decline in the number of surgical cases at the UPR-affiliated hospitals was noted. We believe multiple factors are responsible for this trend, such as a decreasing population and the current economic and healthcare crises occurring in Puerto Rico.

No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads

The parasitic chytrid fungus Batrachochytrium dendrobatidis (Bd) can cause the lethal disease chytridiomycosis in amphibians and therefore may play a role in population declines. The yellow-bellied toad Bombina variegata suffered strong declines throughout western and northwestern parts of its range and is therefore listed as highly endangered for Germany and the federal state of Hesse. Whether chytridiomycosis may play a role in the observed local declines of this strictly protected anuran species has never been tested. We investigated 19 Hessian yellow-bellied toad populations for Bd infection rates, conducted capture-mark-recapture studies in 4 of them over 2 to 3 yr, examined survival histories of recaptured infected individuals, and tested whether multi-locus heterozygosity of individuals as well as expected heterozygosity and different environmental variables of populations affect probabilities of Bd infection. Our results show high prevalence of Bd infection in Hessian yellow-bellied toad populations, but although significant decreases in 2 populations could be observed, no causative link to Bd as the reason for this can be established. Mass mortalities or obvious signs of disease in individuals were not observed. Conversely, we show that growth of Bd-infected populations is possible under favorable habitat conditions and that most infected individuals could be recaptured with improved body indices. Neither genetic diversity nor environmental variables appeared to affect Bd infection probabilities. Hence, genetically diverse amphibian specimens and populations may not automatically be less susceptible for Bd infection.

Yangtze River, an insignificant genetic boundary in tufted deer (Elaphodus cephalophus): the evidence from a first population genetics study

Great rivers were generally looked at as the geographical barrier to gene flow for many taxonomic groups. The Yangtze River is the third largest river in the world, and flows across South China and into the East China Sea. Up until now, few studies have been carried out to evaluate its effect as a geographical barrier. In this study, we attempted to determine the barrier effect of the Yangtze River on the tufted deer (Elaphodus cephalophus) using the molecular ecology approach. Using mitochondrial DNA control region (CR) sequences and 13 nuclear microsatellite loci, we explored the genetic structure and gene flow in two adjacent tufted deer populations (Dabashan and Wulingshan populations), which are separated by the Yangtze River. Results indicated that there are high genetic diversity levels in the two populations, but no distinguishable haplotype group or potential genetic cluster was detected which corresponded to specific geographical population. At the same time, high gene flow was observed between Wulingshan and Dabashan populations. The tufted deer populations experienced population decrease from 0.3 to 0.09 Ma BP, then followed by a distinct population increase. A strong signal of recent population decline (T = 4,396 years) was detected in the Wulingshan population by a Markov-Switching Vector Autoregressions(MSVAR) process population demography analysis. The results indicated that the Yangtze River may not act as an effective barrier to gene flow in the tufted deer. Finally, we surmised that the population demography of the tufted deer was likely affected by Pleistocene climate fluctuations and ancient human activities.

Continent-wide survey reveals massive decline in African savannah elephants

African elephants (Loxodonta africana) are imperiled by poaching and habitat loss. Despite global attention to the plight of elephants, their population sizes and trends are uncertain or unknown over much of Africa. To conserve this iconic species, conservationists need timely, accurate data on elephant populations. Here, we report the results of the Great Elephant Census (GEC), the first continent-wide, standardized survey of African savannah elephants. We also provide the first quantitative model of elephant population trends across Africa. We estimated a population of 352,271 savannah elephants on study sites in 18 countries, representing approximately 93% of all savannah elephants in those countries. Elephant populations in survey areas with historical data decreased by an estimated 144,000 from 2007 to 2014, and populations are currently shrinking by 8% per year continent-wide, primarily due to poaching. Though 84% of elephants occurred in protected areas, many protected areas had carcass ratios that indicated high levels of elephant mortality. Results of the GEC show the necessity of action to end the African elephants' downward trajectory by preventing poaching and protecting habitat.

Nighttime lights and population changes in Europe 1992-2012

Nighttime satellite photographs of Earth reveal the location of lighting and provide a unique view of the extent of human settlement. Nighttime lights have been shown to correlate with economic development and population but little research has been done on the link between nighttime lights and population change over time. We explore whether population decline is coupled with decline in lighted area and how the age structure of the population and GDP are reflected in nighttime lights. We examine Europe between the period of 1992 and 2012 using a Geographic Information System and regression analysis. The results suggest that population decline is not coupled with decline in lighted area. Instead, human settlement extent is more closely related to the age structure of the population and to GDP. We conclude that declining populations will not necessarily lead to reductions in the extent of land development.

Beyond the disease: Is Toxoplasma gondii infection causing population declines in the eastern quoll (Dasyurus viverrinus)?

Disease is often considered a key threat to species of conservation significance. For some, it has resulted in localised extinctions and declines in range and abundance. However, for some species, the assertion that a disease poses a significant threat of extinction is based solely on correlative or anecdotal evidence, often inferred from individual clinical case reports. While a species' susceptibility to a disease may be demonstrated in a number of individuals, investigations rarely extend to measuring the impact of disease at the population level and its contribution, if any, to population declines. The eastern quoll (Dasyurus viverrinus) is a medium-sized Australian marsupial carnivore that is undergoing severe and rapid decline in Tasmania, its last refuge. Reasons for the decline are currently not understood. Feral cats (Felis catus) may be undergoing competitive release following the ongoing decline of the Tasmanian devil (Sarcophilus harrisii), with cats suppressing eastern quolls through increased predation, competition, exclusion or exposure to diseases such as toxoplasmosis. To investigate the effects of Toxoplasma gondii infection, eastern quoll populations at four sites were regularly screened for the seroprevalence of T. gondii-specific IgG antibodies. Seroprevalence was approximately five times higher at sites with declining quoll populations, and there was a negative association between seroprevalence and quoll abundance. However, T. gondii infection did not reduce quoll survival or reproduction. Despite a high susceptibility to T. gondii infection, eastern quoll populations do not appear to be limited by the parasite or its resultant disease. Significantly higher seroprevalence is a signal of greater exposure to feral cats at sites where eastern quolls are declining, suggesting that increased predation, competition or exclusion by feral cats may be precipitating population declines.

Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)

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Trypanosomes in Australian marsupials comprise a heterogeneous community.

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The woylie was the only species found co-infected with different trypanosomes.

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Some of the trypanosomes found are able to colonize several tissues in the host.

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Trypanosoma copemani is able to invade cells in vitro.

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Association between T.copemani and mixed infections with the decline of the woylie.

While much is known of the impact of trypanosomes on human and livestock health, trypanosomes in wildlife, although ubiquitous, have largely been considered to be non-pathogenic. We describe the genetic diversity, tissue tropism and potential pathogenicity of trypanosomes naturally infecting Western Australian marsupials. Blood samples collected from 554 live-animals and 250 tissue samples extracted from 50 carcasses of sick-euthanized or road-killed animals, belonging to 10 species of marsupials, were screened for the presence of trypanosomes using a PCR of the 18S rDNA gene. PCR results revealed a rate of infection of 67% in blood and 60% in tissues. Inferred phylogenetic trees using 18S rDNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) sequences showed the presence of eight genotypes that clustered into three clades: a clade including Trypanosoma copemani, a new clade closely related to Trypanosoma gilletti, and a clade including Trypanosoma H25 from an Australian kangaroo. Trypanosome infections were compared in a declining and in a stable population of the endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata). This marsupial showed high rates of infection with Clade A genotypes (96%) in the declining population, whereas in the stable population, Clade B genotypes were predominant (89%). Mixed infections were common in woylies from the declining but not from the stable population. Histopathological findings associated with either mixed or single infections involving Clade A genotypes, showed a strong inflammatory process and tissue degeneration predominantly in heart, oesophagus and tongue. Trypanosomes were successfully grown in culture and for the first time we demonstrate that a genotype within Clade A has the capacity to not only colonize different tissues in the host but also to invade cells in vitro. These results provide evidence for the potential role of trypanosomes in the decline of a formerly abundant marsupial that is now critically endangered.