Biogeography of Parasitic Nematode Communities in the Galápagos Giant Tortoise: Implications for Conservation Management

The Galápagos giant tortoise is an icon of the unique, endemic biodiversity of Galápagos, but little is known of its parasitic fauna. We assessed the diversity of parasitic nematode communities and their spatial distributions within four wild tortoise populations comprising three species across three Galápagos islands, and consider their implication for Galápagos tortoise conservation programmes. Coprological examinations revealed nematode eggs to be common, with more than 80% of tortoises infected within each wild population. Faecal samples from tortoises within captive breeding centres on Santa Cruz, Isabela and San Cristobal islands also were examined. Five different nematode egg types were identified: oxyuroid, ascarid, trichurid and two types of strongyle. Sequencing of the 18S small-subunit ribosomal RNA gene from adult nematodes passed with faeces identified novel sequences indicative of rhabditid and ascaridid species. In the wild, the composition of nematode communities varied according to tortoise species, which co-varied with island, but nematode diversity and abundance were reduced or altered in captive-reared animals. Evolutionary and ecological factors are likely responsible for the variation in nematode distributions in the wild. This possible species/island-parasite co-evolution has not been considered previously for Galápagos tortoises. We recommend that conservation efforts, such as the current Galápagos tortoise captive breeding/rearing and release programme, be managed with respect to parasite biogeography and host-parasite co-evolutionary processes in addition to the biogeography of the host.     

Feeding Habits of Introduced Black Rats,Rattus rattus,in Nesting Colonies of Galapagos Petrel on San Cristóbal Island,Galapagos

Introduced rodents are responsible for ecosystem changes in islands around the world. In the Galapagos archipelago, their effects on the native flora and fauna are adverse, including the extinction of endemic rodents in some islands and the reduction in the reproductive success of the Galapagos petrel (Pterodroma phaeopygia) in its nesting zones. Understanding the feeding behavior of introduced rodents and their trophic interactions with native and non-native species on islands, can assist in the design of management strategies and conservation plans of invasive and endemic species respectively. Four petrel nesting colonies were monitored during June 2013 on San Cristóbal Island (El Plátano, El Junco, San Joaquín, and La Comuna). The feeding habits of black rats were evaluated by analyzing stomach contents and stable isotopes in hair. Three species of introduced rodents were captured. R. rattus was the most abundant at all sites (n=43, capture success (CS) = 55.8%), followed by the house mouse, Mus musculus (n = 17, CS = 37.8%), and the Norwegian rat, R. norvegicus (n = 4, CS = 4.5%), captured only at La Comuna. The omnivorous black rat ate mostly plants (98%) and arthropods (2%). Intact seeds of Miconia robinsoniana were the main food at all sites (relative abundance=72.1%, present in 95% of the analyzed stomachs), showing the black rats’ possible role in the archipelago as endemic seed dispersers. There was no evidence of petrel’s intake; however, its possible consumption is not discarded at all. The δ¹⁵N and δ¹³C analysis corroborated the primarily herbivorous diet of black rats. The isotopic signatures of the three rodent species reflect the inter- and intra-specific differential use of food resources. Black rat showed a wider diet in La Comuna, which was related to a lower availability of its primary prey and its ability to adapt to the available resources in its habitat.     

What's History Got to Do with It? A Response to Seddon's Definition of Reintroduction

A recent article in Restoration Ecology by Philip Seddon aims at unraveling the definitions of various types of species translocations—from reintroductions to assisted colonization—and points out the slippery slope of misused words. I argue here that defining reintroduction is not as straightforward as Seddon presents it. Commonly used definitions of what constitutes a reintroduction all include some reference to “historical” conditions, but what exactly that encompasses is left open. I examine two parts of the reintroduction confusion: first, how the guidance documents and laws define reintroduction and second, how these definitions might be interpreted when reintroductions are presented in public forums. Rather than moving away from reintroductions toward interventions of other names, I encourage scientists to use a broad definition of reintroduction presented by the IUCN to open up reintroduction as a viable label for bringing a species back to an area regardless of when it was previously there or why it became extinct.     

The Lengthening of a Giant Protein: When, How, and Why?

Subcommissural organ (SCO)-spondin is a giant glycoprotein of more than 5000 amino acids found in Vertebrata, expressed in the central nervous system and constitutive of Reissner’s fiber. For the first time, in situ hybridization performed on zebrafish (Danio rerio) embryos shows that the gene encoding this protein is expressed transitionally in the floor plate, the ventral midline of the neural tube, and later in the diencephalic third ventricle roof, the SCO. The modular organization of the protein in Echinodermata (Strongylocentrotus purpuratus), Urochordata (Ciona savignyi and C. intestinalis), and Vertebrata (Teleostei, Amphibia, Aves and Mammalia) is also described. As the thrombospondin type 1 repeat motifs represent an increasingly large part of the protein during Deuterostomia evolution, the duplication mechanisms leading to this complex organization are examined. The functional significance of the particularly well-preserved arrangement of the series of SCO-spondin repeat motifs and thombospondin type 1 repeats is discussed. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Is Demography Destiny? Application of Machine Learning Techniques to Accurately Predict Population Health Outcomes from a Minimal Demographic Dataset

For years, we have relied on population surveys to keep track of regional public health statistics, including the prevalence of non-communicable diseases. Because of the cost and limitations of such surveys, we often do not have the up-to-date data on health outcomes of a region. In this paper, we examined the feasibility of inferring regional health outcomes from socio-demographic data that are widely available and timely updated through national censuses and community surveys. Using data for 50 American states (excluding Washington DC) from 2007 to 2012, we constructed a machine-learning model to predict the prevalence of six non-communicable disease (NCD) outcomes (four NCDs and two major clinical risk factors), based on population socio-demographic characteristics from the American Community Survey. We found that regional prevalence estimates for non-communicable diseases can be reasonably predicted. The predictions were highly correlated with the observed data, in both the states included in the derivation model (median correlation 0.88) and those excluded from the development for use as a completely separated validation sample (median correlation 0.85), demonstrating that the model had sufficient external validity to make good predictions, based on demographics alone, for areas not included in the model development. This highlights both the utility of this sophisticated approach to model development, and the vital importance of simple socio-demographic characteristics as both indicators and determinants of chronic disease.     

Giant Cells: Contradiction to Two-Hit Model of Tuber Formation?

Tuberous sclerosis (TSC) is an autosomal dominant disease characterized by the formation of hamartomatous lesions in many organs, including brain, heart or kidneys. It has been found that TSC is caused by the mutation in one of the two tumor suppressor genes: TSC1 or TSC2, encoding hamartin and tuberin, respectively. According to Knudson’s two-hit model of tumorigenesis, second-hit mutation and resulting loss of heterozygosity (LOH) of a tumor suppressor gene is necessary for tumor formation. In fact, LOH is commonly found in several types of hamartomas formed in the process of tuberous sclerosis, but, interestingly, not in brain lesions, containing characteristic giant cells. In this paper, we review literature covering origination of giant cells and present several hypotheses explaining why in spite of the presence of hamartin and tuberin, brain lesions form in TSC patients.     

Can We Infer Island Introduction and Naturalization Rates from Inventory Data? Evidence from Introduced Plants in Galapagos

Studies of human-mediated rates of introduction of organisms to islands are few, results fall into two models (linear and exponential), and relationships with human population and activities are obscure. Owing to their late settlement and good scientific record, data from Galapagos may be exceptionally informative. The rate of introduction of vascular plant species to Galapagos has been suggested to be exponential, paralleling the rise in human population. However, detailed reconstruction of growth in numbers of introduced plant species, based on historical and recent records, reveals changes in study criteria over the last two centuries, which obscure the true introduction rate. At first, cultivated species were deliberately excluded from most studies. From the 1960s, naturalized cultivated species were included more consistently, but non-naturalized species were still excluded. From the mid-1980s, the latter were deliberately included. Accidental introductions increased linearly from 1807 (the first records) to the present. Escapes from cultivation show increases in rate around 1906 and in the period 1970–1990, the latter coinciding with the first studies directed at areas affected by human activities. Non-naturalized cultivated species rose abruptly from the late 1980s, as they became deliberately studied. There seems to be no direct link with human population size. Data represent rate of discovery rather than true introduction rate, and the changing overall rate reflects changing botanical interests and research effort. Data from other islands also suggest that linear increases in naturalized plants are the norm. Galapagos data do not permit confident statements about the introduction rate of cultivated species, but suggest that this may depend more on human activities than human population size.     

Specific Binding of Chloride Ions to Lipid Vesicles and Implications at?Molecular Scale

Biological membranes composed of lipids and proteins are in contact with electrolytes like aqueous NaCl solutions. Based on molecular dynamics studies it is widely believed that Na⁺ ions specifically bind to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes, whereas Cl⁻ ions stay in solution. Here, we present a careful comparison of recent data from electrophoresis and isothermal titration calorimetry experiments as well as molecular dynamics simulations suggesting that in fact both ions show very similar affinities. The corresponding binding constants are 0.44(±0.05) M⁻¹ for Na⁺ and 0.40(±0.04) M⁻¹ for Cl⁻ ions. This is highlighted by our observation that a widely used simulation setup showing asymmetric affinities of Na⁺ and Cl⁻ for POPC bilayers overestimates the effect of NaCl on the electrophoretic mobility of a POPC membrane by an order of magnitude. Implications for previous simulation results on the effect of NaCl on polarization of interfacial water, transmembrane potentials, and mechanisms for ion transport through bilayers are discussed. Our findings suggest that a range of published simulations results on the interaction of NaCl with phosphocholine bilayers have to be reconsidered and revised and that force field refinements are necessary for reliable simulation studies of membranes at physiological conditions on a molecular level.     

Giant Cells: Contradiction to Two-Hit Model of Tuber Formation?

1. Tuberous sclerosis (TSC) is an autosomal dominant disease characterized by the formation of hamartomatous lesions in many organs, including brain, heart or kidneys. It has been found that TSC is caused by the mutation in one of two tumor suppressor genes: TSC1 or TSC2, encoding hamartin and tuberin, respectively. 2. According to Knudson's two-hit model of tumorigenesis, second-hit mutation and resulting loss of heterozygosity (LOH) of a tumor suppressor gene is necessary for tumor formation. In fact, LOH is commonly found in several types of hamartomas formed in the process of tuberous sclerosis, but, interestingly, not in brain lesions, containing characteristic giant cells. 3. In the present paper we review literature covering origination of giant cells and present several hypotheses explaining why in spite of the presence of hamartin and tuberin, brain lesions form in TSC patients.     

Implications of dealing with airborne substances and reactive oxygen species: what mammalian lungs, animals, and plants have to say?

A gas-exchange structure interacts with the environment andis constantly challenged by contaminants that may elicit defenseresponses, thus compromising its primary function. It is alsoexposed to high concentrations of O₂ that can generate reactiveoxygen species (ROS). Revisiting the lung of mammals, an integrativepicture emerges, indicating that this bronchi-alveolar structuredeals with inflammation in a special way, which minimizes compromisingthe gas-exchange role. Depending on the challenge, pro-inflammatoryor antiinflammatory responses are elicited by conserved molecules,such as surfactant proteins A and D. An even broader picturepoints to the participation of airway sensors, responsive toinflammatory mediators, in a loop linking the immunologicaland nervous systems and expanding the role played by respiratoryorgans in functions other than gas-exchange. A byproduct ofexposure to high concentration of O₂ is the formation of superoxide(), hydrogen peroxide (H₂O₂),hydroxyl radical (HO^•), and other ROS, which are knownto be toxic to different types of cells, including the lungepithelium. A balance between antioxidants and oxidants exists;in pulmonary epithelial cells high intracellular and extracellularlevels of antioxidants are found. Antioxidant adaptations relatedto plant and animal life-styles involve a broad range of overlappingstrategies based on well-conserved molecules. Glutathione (GSH)is an abundant and ubiquitous thiol-tripeptide antioxidant,also present in lungs, whose role in providing information onthe intracellular redox state of animals and plants is wellestablished. In these organisms, GSH influences gene expressionassociated with stress, maximizing defense responses. Severalenzymatic antioxidants, such as glutathione peroxidase (GPx),glutathione reductase, glutathione S-transferase, and glucose6-phosphate dehydrogenase participate in the redox system; inanimals that are stress-tolerant GPx is a key element againstoxidative assaults. Most importantly, alternative roles of ROSas signaling molecules have been found in all plants and animals.For example, alveolar macrophages produce that act as second messengers, in addition tohaving a bactericidal role. The nonradical ROS H₂O₂ signalsinflammation in mammalian lungs, apoptosis in different animaltissues, and is also involved in stomatal closure, root development,gene expression, and defense responses of plants. Antioxidantadaptations in some water-breathing animals involve the excretionof H₂O₂ by diffusion through gas-exchange structures. The finebalance among a multitude of factors and cells makes the differencebetween damage and protection in animals and plants. Knowledgeabout the mechanisms and consequences of these molecular interactionsis now starting to be integrated.     

The Advantages of Demographic Change after the Wave: Fewer and Older,but Healthier,Greener, and More Productive?

Population aging is an inevitable global demographic process. Most of the literature on the consequences of demographic change focuses on the economic and societal challenges that we will face as people live longer and have fewer children. In this paper, we (a) briefly describe key trends and projections of the magnitude and speed of population aging; (b) discuss the economic, social, and environmental consequences of population aging; and (c) investigate some of the opportunities that aging societies create. We use Germany as a case study. However, the general insights that we obtain can be generalized to other developed countries. We argue that there may be positive unintended side effects of population aging that can be leveraged to address pressing environmental problems and issues of gender inequality and intergenerational ties.     

Involving Stakeholders’ Knowledge in Co-designing Social Valuations of Biodiversity and Ecosystem Services: Implications for Decision-Making

Ecosystems - We contribute to addressing two gaps that reduce the utility of ecosystem sciences for decision-making: lack of standard methods for using stakeholders’ knowledge to co-design...     

When and where to count? Implications of migratory connectivity and nonbreeding distribution to population censuses in a migratory bird population

Migratory connectivity is a metric of the co-occurrence of migratory animals originating from different breeding sites, and like their spatial dispersion, can vary substantially during the annual cycle. Together, both these properties affect the optimal times and sites of population censusing. We tracked taiga bean geese (Anser fabalis fabalis) during 2014–2021 to study their migratory connectivity and nonbreeding movements and determine optimal periods to assess the size of their main flyway population. We also compared available census data with tracking data, to examine how well two existing censuses covered the population. Daily Mantel's correlation between breeding and nonbreeding sites lay between 0 and 0.5 during most of the nonbreeding season, implying birds from different breeding areas were not strongly separated at other times in the annual cycle. However, the connectivity was higher among birds from the westernmost breeding areas compared to the birds breeding elsewhere. Daily Minimum Convex Polygons showed tracked birds were highly aggregated at census times, confirming their utility. The number of tracked birds absent at count sites during the censuses however exceeded numbers double-counted at several sites, indicating that censuses might have underestimated the true population size. Our results show that connectivity can vary in different times during the nonbreeding period, and should be studied throughout the annual cycle. Our results also confirm previous studies, which have found that estimates using marked individuals usually produce higher population size estimates than total counts. This should be considered when using total counts to assess population sizes in the future.     

Outcomes of a ‘One Health’ Monitoring Approach to a Five-Year Beaver (Castor fiber) Reintroduction Trial in Scotland

Recent advances in noninvasive detection methods for mycobacterial infection in primates create new opportunities for exploring the epidemiology of tuberculosis in free-living species. Chimpanzees (Pan troglodytes schweinfurthii) and baboons (Papio anubis) in Gombe National Park, Tanzania, were screened for infection with pathogens of the Mycobacterium tuberculosis Complex using Fecal IS6110 PCR; none was positive. This study demonstrates the feasibility of large-scale mycobacterial screening in wild primates.     

Are Ecosystem Composition,Structure, and Functional Status Related to Restoration Success? A Test from Semiarid Mediterranean Steppes

Theoretical models emphasize the importance of considering the composition, structure, and functioning of an ecosystem when restoring it. However, there is a lack of empirical studies evaluating how these ecosystem attributes are linked, if any, to the success of restoration actions. We conducted experimental plantings of the native late‐successional shrub Pistacia lentiscus in 10 semiarid steppes located in southeast Spain and related seedling survival rates to measures of ecosystem structure and composition and to surrogates of ecosystem functioning. Seedling survival widely differed among the studied steppes and 17 months after planting ranged from 0 to 89%. Mortality occurred mostly during the first summer in the field, coinciding with a strong drought lasting 3 months. Survival was lower in the steppes located at the highest altitudes and with the highest values of total plant cover, species richness, shrub cover, and functionality. Seedling survival was mainly controlled by abiotic conditions and showed a negative relationship with some of the surrogates of ecosystem functioning evaluated. Our results suggest, but cannot confirm, that the functional status of the ecosystem may not limit the early stages of establishment of P. lentiscus in semiarid steppes and that abiotic conditions play an overriding role in this process. If true, its introduction in these areas would not necessarily need a previous phase of recovery of ecosystem functions like nutrient cycling and infiltration.     

Statistical Analysis of Peptide-Induced Graded and All-or-None Fluxes in?Giant Vesicles

Antimicrobial, cytolytic, and cell-penetrating peptides induce pores or perturbations in phospholipid membranes that result in fluxes of dyes into or out of lipid vesicles. Here we examine the fluxes induced by four of these membrane-active peptides in giant unilamellar vesicles. The type of flux is determined from the modality of the distributions of vesicles as a function of their dye content using the statistical Hartigan dip test. Graded and all-or-none fluxes correspond to unimodal and bimodal distributions, respectively. To understand how these distributions arise, we perform Monte Carlo simulations of peptide-induced dye flux into vesicles using a very simple model. The modality of the distributions depends on the rate constants of pore opening and closing, and dye flux. If the rate constants of pore opening and closing are both much smaller than that of dye flux through the pore, all-or-none influx occurs. However, if one of them, especially the rate constant for pore opening, increases significantly relative to the flux rate constant, the process becomes graded. In the experiments, we find that the flux type is the same in giant and large vesicles, for all peptides except one. But this one exception indicates that the flux type cannot be used to unambiguously predict the mechanism of membrane permeabilization by the peptides.