Refine
Document Type
- Article (33)
Language
- English (33)
Has Fulltext
- yes (33)
Is part of the Bibliography
- no (33)
Keywords
- - (7)
- phenotypic plasticity (5)
- climate change (4)
- genetic adaptation (3)
- local adaptation (3)
- Chiroptera (2)
- Percidae (2)
- biogeography (2)
- heritability (2)
- nervous system (2)
- ontogeny (2)
- zooplankton (2)
- Anthropized environments (1)
- Anyphaenidae (1)
- Approximate Bayesian Computation (1)
- Arachnida (1)
- Araneae (1)
- Araneoidea (1)
- Automated monitoring (1)
- Bacillus cereus biovar anthracis (1)
- Bayesian animal model (1)
- Bodian staining (1)
- Brachionus (1)
- BrdU (1)
- DNA degradation (1)
- DNA quality index (1)
- EdU (1)
- Elav (1)
- Fluidigm array (1)
- GABA (1)
- GBIF (1)
- Holarctic distribution (1)
- NAO (1)
- PCA (1)
- Prospero (1)
- RFamide (1)
- RRID: AB_2338006 (1)
- RRID: AB_2338362 (1)
- RRID: AB_2338459 (1)
- RRID: AB_2338914 (1)
- RRID: AB_2341179 (1)
- RRID: AB_261811 (1)
- RRID: AB_477585 (1)
- RRID: SCR_007370 (1)
- RRID: SCR_010279 (1)
- RRID: SCR_014199 (1)
- SIFamide (1)
- SNP (1)
- Snail (1)
- SoxB (1)
- Synspermiata (1)
- achaete–scute homolog (1)
- adoptive transfer (1)
- allatostatin (1)
- bat conservation (1)
- behavioural plasticity (1)
- biodiversity (1)
- biotic interactions (1)
- blood coagulation (1)
- brain tumor (1)
- camera trap (1)
- cell proliferation (1)
- chiroptera (1)
- climatic adaptation (1)
- cline (1)
- clonal (1)
- clonal reproduction (1)
- cold tolerance (1)
- common garden experiment (1)
- conservation management (1)
- counter‐gradient variation (1)
- crustaceans (1)
- cryofixation (1)
- cyanobacteria (1)
- deep learning (1)
- development (1)
- early experience (1)
- electron microscopy (1)
- environmental DNA (1)
- environmental DNA (eDNA) (1)
- environmental change (1)
- environmental gradient (1)
- environmental stress (1)
- evolutionary potential (1)
- experimental microcosms (1)
- extinction risk (1)
- extra-organismal DNA (1)
- fatty acid composition (1)
- food quality (1)
- food quantity (1)
- gene expression (1)
- genetic diversity (1)
- genitalia (1)
- genotype–environment interaction (1)
- geometric morphometrics (1)
- global warming (1)
- ground spiders (1)
- gustation (1)
- heat tolerance (1)
- hirudin (1)
- hirudin‐like factors (1)
- histamine (1)
- host genetic diversity (1)
- host‐plant preference (1)
- human disturbance (1)
- inbreeding (1)
- indirect effect (1)
- infrared light barrier (1)
- insect‐plant interaction (1)
- integrative taxonomy (1)
- interactive effect (1)
- intestinal parasite diversity (1)
- invasive route (1)
- invertebrate-derived DNA (iDNA) (1)
- larval fish (1)
- larval fishes (1)
- lifestyle (1)
- light intensity (1)
- light variability (1)
- macroecology (1)
- mammals (1)
- mate choice (1)
- mating success (1)
- mechanoreception (1)
- medicinal leeches (1)
- micro-CT (1)
- microbiome heterogeneity (1)
- morphological crypsis (1)
- morphometry (1)
- mortality costs (1)
- multiple resource limitation (1)
- myrmecomorphy (1)
- neural stem cell (1)
- neuroanatomy (1)
- neuroblast (1)
- niche evolution (1)
- niche following (1)
- noninvasive DNA (1)
- noninvasive sampling (1)
- nutrient supply (1)
- olfaction (1)
- olfactory (1)
- olfactory system (1)
- orb web (1)
- orcokinin (1)
- osmotolerance (1)
- paternity assignment (1)
- peracarida (1)
- phytoplankton (1)
- plant–insect interaction (1)
- population cycles (1)
- population dynamics (1)
- priming (1)
- protein expression (1)
- range dynamics (1)
- range expansion (1)
- regulatory networks (1)
- reproductive success (1)
- resource competition (1)
- rodents (1)
- rotifers (1)
- salinity acclimation (1)
- sensory ecology (1)
- serotonin (1)
- sexual selection (1)
- silk (1)
- species delimitation (1)
- species distribution modelling (1)
- species diversity (1)
- species traits (1)
- sperm transfer (1)
- spiders (1)
- spinnerets (1)
- stoichiometry (1)
- survival analysis (1)
- sylvatic anthrax (1)
- thermal melanisation (1)
- thermoregulation (1)
- thrombin inhibition (1)
- urban avoiders (1)
- urban dwellers (1)
- urbanity indices (1)
- urbanization (1)
- urban–rural gradient (1)
- visual neuropils (1)
- volumes (1)
- water deficit (1)
- water limitation (1)
- white rhinos (1)
- wildlife infectious diseases (1)
Institute
- Zoologisches Institut und Museum (33) (remove)
Publisher
- Wiley (33) (remove)
Copulatory mechanics of ghost spiders reveals a new self-bracing mechanism in entelegyne spiders
(2023)
Spiders evolved a distinctive sperm transfer system, with the male copulatory organs located on the tarsus of the pedipalps. In entelegyne spiders, these organs are usually very complex and consist of various sclerites that not only allow the transfer of the sperm themselves but also provide a mechanical interlock between the male and female genitalia. This interlocking can also involve elements that are not part of the copulatory organ such as the retrolateral tibial apophysis (RTA)—a characteristic of the most diverse group of spiders (RTA clade). The RTA is frequently used for primary locking i.e., the first mechanical engagement between male and female genitalia. Despite its functional importance, some diverse spider lineages have lost the RTA, but evolved an apophysis on the femur instead. It can be hypothesized that this femoral apophysis is a functional surrogate of the RTA during primary locking or possibly serves another function, such as self-bracing, which involves mechanical interaction between male genital structures themselves to stabilize the inserted pedipalp. We tested these hypotheses using ghost spiders of the genus Josa (Anyphaenidae). Our micro-computed tomography data of cryofixed mating pairs show that the primary locking occurs through elements of the copulatory organ itself and that the femoral apophysis does not contact the female genitalia, but hooks to a projection of the copulatory bulb, representing a newly documented self-bracing mechanism for entelegyne spiders. Additionally, we show that the femoral self-bracing apophysis is rather uniform within the genus Josa. This is in contrast to the male genital structures that interact with the female, indicating that the male genital structures of Josa are subject to different selective regimes.
Geometric regularity of spider webs has been intensively studied in orb‐weaving spiders, although it is not exclusive of orb weavers. Here, we document the geometrically regular, repetitive elements in the webs of the non‐orb‐weaving groups Leptonetidae and Telemidae for the first time. Similar to orb weavers, we found areas with regularly spaced parallel lines in the webs of Calileptoneta helferi, Sulcia sp., and cf. Pinelema sp. Furthermore, we provide a detailed account of the regular webs of Ochyrocera (Ochyroceratidae). The sections of the web with regularly disposed parallel lines are built as U‐shaped modules reminiscent of orb webs. It has been suggested that the regularly spaced parallel lines in the webs of Ochyroceratidae and Psilodercidae may be produced in a single sweep of their posterior lateral spinnerets, which have regularly spaced aciniform gland spigots, perhaps involving expansion of the spinnerets. To test this hypothesis, we compared the spacing between parallel lines with the spacing between spigots, searched for expansible membranes in the spinnerets, and examined the junctions of regularly spaced lines. The distance between parallel lines was 10–20 times the distance between spigots, and we found no expansible membranes, and the intersection of parallel lines are cemented, which opposes the single sweep hypothesis. Furthermore, we found cues of viscid silk in the parallel lines of the psilodercid Althepus and broadened piriform gland spigots that may be responsible of its production. Finally, we evaluated the presence or absence of geometrically regular web elements across the spider tree of life. We found reports of regular webs in 31 spider families, including 20 families that are not orb weavers and hypothesize that the two basic aspects of regularity (parallel lines spaced at regular intervals, and radial lines spaced at regular angles) probably appeared many times in the evolution of spiders.
Extra-organismal DNA (eoDNA) from material left behind by organisms (noninvasive DNA, e.g., feces, hair) or from environmental samples (eDNA, e.g., water, soil) is a valuable source of genetic information. However, the relatively low quality and quantity of eoDNA, which can be further degraded by environmental factors, results in reduced amplification and sequencing success. This is often compensated for through cost- and time-intensive replications of genotyping/sequencing procedures. Therefore, system- and site-specific quantifications of environmental degradation are needed to maximize sampling efficiency (e.g., fewer replicates, shorter sampling durations), and to improve species detection and abundance estimates. Using 10 environmentally diverse bat roosts as a case study, we developed a robust modeling pipeline to quantify the environmental factors degrading eoDNA, predict eoDNA quality, and estimate sampling-site-specific ideal exposure duration. Maximum humidity was the strongest eoDNA-degrading factor, followed by exposure duration and then maximum temperature. We also found a positive effect when hottest days occurred later. The strength of this effect fell between the strength of the effects of exposure duration and maximum temperature. With those predictors and information on sampling period (before or after offspring were born), we reliably predicted mean eoDNA quality per sampling visit at new sites with a mean squared error of 0.0349. Site-specific simulations revealed that reducing exposure duration to 2–8 days could substantially improve eoDNA quality for future sampling. Our pipeline identified high humidity and temperature as strong drivers of eoDNA degradation even in the absence of rain and direct sunlight. Furthermore, we outline the pipeline's utility for other systems and study goals, such as estimating sample age, improving eDNA-based species detection, and increasing the accuracy of abundance estimates.
Metabarcoding of invertebrate-derived DNA (iDNA) is increasingly used to describe vertebrate diversity in terrestrial ecosystems. Fly iDNA has also shown potential as a tool for detecting pathogens. Combining these approaches makes fly iDNA a promising tool for understanding the ecology and distribution of novel pathogens or emerging infectious diseases. Here, we use fly iDNA to explore the geographic distribution of Bacillus cereus biovar anthracis (Bcbva) along a gradient from the forest within Taï National Park, Côte d'Ivoire, out to surrounding villages. We tested fly pools (N = 100 pools of 5 flies) collected in the forest (N = 25 pools), along the forest edge (N = 50 pools), and near surrounding villages (N = 25 pools) for Bcbva. Using the same iDNA, we sought to reconstruct fly and mammal communities with metabarcoding, with the aim of investigating potential links with Bcbva detection. We detected Bcbva in 5/100 fly pools and positivity varied significantly across the habitat types (forest = 4/25, edge = 1/50, village = 0/25). It was possible to culture Bcbva from all positive fly pools, confirming their positivity, while sequencing of their whole genomes revealed a considerable portion of known genomic diversity for this pathogen. iDNA generated data about the mammal and fly communities in these habitats, revealing the highest mammal diversity in the forest and considerable changes in fly community composition along the gradient. Bcbva host range estimates from fly iDNA were largely identical to the results of long-term carcass monitoring efforts in the region. We show that fly iDNA can generate data on the geographic distribution and host range of a pathogen at kilometer scales, as well as reveal the pathogen's phylogenetic diversity. Our results highlight the power of fly iDNA for mammal biomonitoring and pathogen surveillance.
BatNet: a deep learning-based tool for automated bat species identification from camera trap images
(2023)
Automated monitoring technologies can increase the efficiency of ecological data collection and support data-driven conservation. Camera traps coupled with infrared light barriers can be used to monitor temperate-zone bat assemblages at underground hibernacula, where thousands of individuals of multiple species can aggregate in winter. However, the broad-scale adoption of such photo-monitoring techniques is limited by the time-consuming bottleneck of manual image processing. Here, we present BatNet, an open-source, deep learning-based tool for automated identification of 13 European bat species from camera trap images. BatNet includes a user-friendly graphical interface, where it can be retrained to identify new bat species or to create site-specific models to improve detection accuracy at new sites. Model accuracy was evaluated on images from both trained and untrained sites, and in an ecological context, where community- and species-level metrics (species diversity, relative abundance, and species-level activity patterns) were compared between human experts and BatNet. At trained sites, model performance was high across all species (F1-score: 0.98–1). At untrained sites, overall classification accuracy remained high (96.7–98.2%), when camera placement was comparable to the training images (<3 m from the entrance; <45° angle relative to the opening). For atypical camera placements (>3 m or >45° angle), retraining the detector model with 500 site-specific annotations achieved an accuracy of over 95% at all sites. In the ecological case study, all investigated metrics were nearly identical between human experts and BatNet. Finally, we exemplify the ability to retrain BatNet to identify a new bat species, achieving an F1-score of 0.99 while maintaining high classification accuracy for all original species. BatNet can be implemented directly to scale up the deployment of camera traps in Europe and enhance bat population monitoring. Moreover, the pretrained model can serve as a baseline for transfer learning to automatize the image-based identification of bat species worldwide.
Hibernation is a widespread adaptation in animals to seasonally changing environmental conditions. In the face of global anthropogenic change, information about plastic adjustments to environmental conditions and associated mortality costs are urgently needed to assess population persistence of hibernating species. Here, we used a five-year data set of 1047 RFID-tagged individuals from two bat species, Myotis nattereri and Myotis daubentonii that were automatically recorded each time they entered or left a hibernaculum. Because the two species differ in foraging strategy and activity pattern during winter, we expected species–specific responses in the timing of hibernation relative to environmental conditions, as well as different mortality costs of early departure from the hibernaculum in spring. Applying mixed-effects modelling, we disentangled population-level and individual-level plasticity in the timing of departure. To estimate mortality costs of early departure, we used both a capture mark recapture analysis and a novel approach that takes into account individual exposure times to mortality outside the hibernaculum. We found that the timing of departure varied between species as well as among and within individuals, and was plastically adjusted to large-scale weather conditions as measured by the NAO (North Atlantic Oscillation) index. Individuals of M. nattereri, which can exploit milder temperatures for foraging during winter, tuned departure more closely to the NAO index than individuals of M. daubentonii, which do not hunt during winter. Both analytical approaches used to estimate mortality costs showed that early departing individuals were less likely to survive until the subsequent hibernation period than individuals that departed later. Overall, our study demonstrates that individuals of long-lived hibernating bat species have the potential to plastically adjust to changing climatic conditions, although the potential for adjustment differs between species.
How well populations can cope with global warming will often depend on the evolutionary potential and plasticity of their temperature-sensitive, fitness-relevant traits. In Bechstein's bats (Myotis bechsteinii), body size has increased over the last decades in response to warmer summers. If this trend continues it may threaten populations as larger females exhibit higher mortality. To assess the evolutionary potential of body size, we applied a Bayesian ‘animal model’ to estimate additive genetic variance, heritability and evolvability of body size, based on a 25-year pedigree of 332 wild females. Both heritability and additive genetic variance were reduced in hot summers compared to average and cold summers, while evolvability of body size was generally low. This suggests that the observed increase in body size was mostly driven by phenotypic plasticity. Thus, if warm summers continue to become more frequent, body size likely increases further and the resulting fitness loss could threaten populations.
Comparative neuroanatomy of the central nervous system in web-building and cursorial hunting spiders
(2023)
Spiders (Araneae) include cursorial species that stalk their prey and more stationary species that use webs for prey capture. While many cursorial hunting spiders rely on visual cues, web-building spiders use vibratory cues (mechanosensation) for prey capture. We predicted that the differences in primary sensory input between the species are mirrored by differences in the morphology/architecture of the central nervous system (CNS). Here, we investigated the CNS anatomy of four spider species, two cursorial hunters Pardosa amentata (Lycosidae) and Marpissa muscosa (Salticidae), and two web-building hunters Argiope bruennichi (Araneidae) and Parasteatoda tepidariorum (Theridiidae). Their CNS was analyzed using Bodian silver impregnations, immunohistochemistry, and microCT analysis. We found that there are major differences between species in the secondary eye pathway of the brain that pertain to first-order, second-order, and higher order brain centers (mushroom bodies [MB]). While P. amentata and M. muscosa have prominent visual neuropils and MB, these are much reduced in the two web-building species. Argiope bruennichi lacks second-order visual neuropils but has specialized photoreceptors that project into two distinct visual neuropils, and P. tepidariorum lacks MB, suggesting that motion vision might be absent in this species. Interestingly, the differences in the ventral nerve cord are much less pronounced, but the web-building spiders have proportionally larger leg neuropils than the cursorial spiders. Our findings suggest that the importance of visual information is much reduced in web-building spiders, compared to cursorial spiders, while processing of mechanosensory information requires the same major circuits in both web-building and cursorial hunting spiders.
Animals face strong environmental variability even on short time scales particularly in shallow coastal habitats, forcing them to permanently adjust their metabolism. Respiration rates of aquatic ectotherms are directly influenced by water temperature, whereas ingestion rates might additionally be influenced by behavior. We aim to understand how respiration and ingestion rates of an aquatic invertebrate respond to changing temperature during a diurnal thermal fluctuation cycle and how both processes are related. We studied the benthopelagic mysid Neomysis integer as an important food web component of coastal ecosystems. Mysids were collected at the southern Baltic Sea coast and exposed in the laboratory to either constant temperature of 15°C or daily temperature fluctuation of 15 ± 5°C. Short-term (1–2 h) respiration and ingestion rates were measured at four equidistant time points within 24 h and did not differ among time points at constant temperature, but differed among time points in the fluctuating treatment. Respiration was highest at the thermal maximum and lowest at the thermal minimum. Ingestion rates showed the opposite pattern under fluctuation, likely due to differences in underlying thermal performance curves. When temperature transited the average, the direction of temperature change influenced the animals' response in respiration and ingestion rates differently. Our results suggest that respiration is not only instantaneously affected by temperature, but also influenced by the previously experienced direction of thermal change. Our experiment, using an important non-model organism, delivered new insights on the relationship between the crucial organismal processes ingestion and respiration under thermal variability.
In mandibulate arthropods, the primary olfactory centers, termed olfactory lobes in crustaceans, are typically organized in distinct fields of dense synaptic neuropils called olfactory glomeruli. In addition to olfactory sensory neuron terminals and their postsynaptic efferents, the glomeruli are innervated by diverse neurochemically distinctive interneurons. The functional morphology of the olfactory glomeruli is understudied in crustaceans compared with insects and even less well understood and described in a particular crustacean subgroup, the Peracarida, which embrace, for example, Amphipoda and Isopoda. Using immunohistochemistry combined with confocal laser scanning microscopy, we analyzed the neurochemistry of the olfactory pathway in the amphipod Parhyale hawaiensis. We localized the biogenic amines serotonin and histamine as well as the neuropeptides RFamide, allatostatin, orcokinin, and SIFamide. As for other classical neurotransmitters, we stained for γ-aminobutyric acid and glutamate decarboxylase and used choline acetyltransferase as indicator for acetylcholine. Our study is another step in understanding principles of olfactory processing in crustaceans and can serve as a basis for understanding evolutionary transformations of crustacean olfactory systems.
Abstract
Climate change may force organisms to adapt genetically or plastically to new environmental conditions. Invasive species show remarkable potential for rapid adaptation. The ovoviviparous New Zealand mud snail (NZMS), Potamopyrgus antipodarum, has successfully established across Europe with two clonally reproducing mitochondrial lineages since its arrival in the first half of the 19th century. Its remarkable variation in shell morphology was shown to be fitness relevant. We investigated the effects of temperature on shell morphology across 11 populations from Germany and the Iberian Peninsula in a common garden across three temperatures. We analyzed size and shape using geometric morphometrics. For both, we compared reaction norms and estimated heritabilities. For size, the interaction of temperature and haplotype explained about 50% of the total variance. We also observed more genotype by environment interactions indicating a higher degree of population differentiation than in shape. Across the three temperatures, size followed the expectations of the temperature‐size rule, with individuals growing larger in cold environments. Changes in shape may have compensated for changes in size affecting space for brooding embryos. Heritability estimates were relatively high. As indicated by the very low coefficients of variation for clonal repeatability (CVA), they can probably not be compared in absolute terms. However, they showed some sensitivity to temperature, in haplotype t more so than in z, which was only found in Portugal. The low CVA values indicate that genetic variation among European populations is still restricted with a low potential to react to selection. A considerable fraction of the genetic variation was due to differences between the clonal lineages. The NZMS has apparently not been long enough in Europe to accumulate significant genetic variation relevant for morphological adaptation. As temperature is obviously not the sole factor influencing shell morphology, their interaction will probably not be a factor limiting population persistence under a warming climate in Europe.
Abstract
Surface waters are warming due to climate change, potentially pushing aquatic organisms closer to their thermal tolerance limits. However, cyanobacterial blooms are expected to occur more often with rising temperature, increasing the likelihood of poor‐quality food available for herbivorous zooplankton. Zooplankton can adapt locally by genetic differentiation or via adaptive phenotypic plasticity to increasing temperatures, but there is limited knowledge on how these processes may be affected by food quality limitation imposed by cyanobacteria.
To test the effects of cyanobacteria‐mediated food quality on local temperature adaptation, we measured juvenile somatic growth and reproduction of five Daphnia magna clones from different latitudinal origin grown on three food qualities at 20, 24, and 28°C. Additionally we estimated short‐term heat tolerance, measured as knockout time (time to immobility) at lethally high temperature, of two clones acclimated to the three temperatures and two food quality levels to test for the effects of food quality on adaptive plastic responses.
As expected, clones from lower latitudes showed on average better somatic growth and reproduction than clones from higher latitudes at higher temperatures. However, the difference in somatic growth diminished with increasing cyanobacteria abundance in the diet, suggesting constraints on local genetic adaptation under predicted decreases in food quality. As expected, short‐term heat tolerance of the clones generally increased with increasing acclimation temperature. However, heat tolerance of animals acclimated to the highest temperature was larger when grown at medium than at good food quality, whereas the opposite response was observed for animals acclimated to the lowest temperature. This suggests a better adaptive phenotypic response of animals to elevated temperatures under higher cyanobacteria abundance, and thus shows an opposite pattern to the results for somatic growth.
Overall, we demonstrate that food quality limitation can mediate responses of D. magna life history traits and heat tolerance to increasing temperatures, and that the effects differ depending on the time scale studied, that is, mid‐term (somatic growth) versus short‐term (tolerance to acute heat stress). These aspects will need further attention to accurately predict of how organisms will cope with future global warming by local adaptation and adaptive phenotypic plasticity.
Primary producer communities are often growth-limited by essential nutrients such as nitrogen (N) and phosphorus (P). The magnitude of limitation and whether N, P or both elements are limiting autotroph growth depends on the supply and ratios of these essential nutrients. Previous studies identified single, serial or co-limitation as predominant limitation outcomes in autotroph communities by factorial nutrient additions. Little is known about potential consequences of such scenarios for herbivores and whether their growth is primarily affected by changes in autotroph quantity or nutritional quality. We grew a community of phytoplankton species differing in various food quality aspects in experimental microcosms at varying N and P concentrations resulting in three different N:P ratios. At carrying capacity, N, P, both nutrients or none were added to reveal which nutrients were limiting. The nutrient-supplied communities were fed to the generalist herbivorous rotifer Brachionus calyciflorus to investigate how changing phytoplankton biomass and community composition affect herbivore abundance. We found phytoplankton being growth-limited either by N alone (single limitation) or serially, i.e. primarily by N and secondarily by P, altering available food quantity for rotifers. Rotifer growth showed a different response pattern compared to phytoplankton, suggesting that apart from food quantity food quality aspects played a substantial role in the transfer from primary to secondary production. The combined addition of N and P to phytoplankton had generally a positive effect on herbivore growth, whereas adding non-limiting nutrients had a rather detrimental effect probably due to stoichiometrically imbalanced food in terms of nutrient excess. Our experiment shows that adding various nutrients to primary producer communities will not always lead to increased autotroph and herbivore growth, and that differences between autotroph and herbivore responses under co-limiting conditions can be partly well explained by concepts of ecological stoichiometry theory.
Abstract
Pikeperch (Sander lucioperca) has become a species of interest in aquaculture. It is a popular and economically valuable food fish and can produce high numbers of offspring. However, during early development, there are transition phases when high mortality rates concur with growth changes, vital organ transformations and a limited energy budget. Up to now, no study focused on the developmental adaption of muscle tissue in pikeperch, regardless of muscle tissue influencing essential traits such as locomotion and thus the competence to hunt prey and avoid predators. In the present study, therefore, the developmental myogenesis of pikeperch was analysed using specimens from early embryonic to larval development. Myogenic and developmental genes were utilized to gain insights into transcriptomic regulation during these stages by applying a nanofluidic qPCR approach. Result, three phases of myogenic gene expression, during somitogenesis, during the late embryonic development and during the larval development were detected. Increased myostatin expression showed an interim arrest of muscle formation between embryonic and larval myogenesis. Expression patterns of satellite cell gene markers indicated an accumulation of stem cells before myogenesis interruption. The here gained data will help to broaden the knowledge on percid myogenesis and can support pikeperch rearing in aquaculture.
Human habitat disturbance affects both species diversity and intraspecific genetic diversity, leading to correlations between these two components of biodiversity (termed species–genetic diversity correlation, SGDC). However, whether SGDC predictions extend to host‐associated communities, such as the intestinal parasite and gut microbial diversity, remains largely unexplored. Additionally, the role of dominant generalist species is often neglected despite their importance in shaping the environment experienced by other members of the ecological community, and their role as source, reservoir and vector of zoonotic diseases. New analytical approaches (e.g. structural equation modelling, SEM) can be used to assess SGDC relationships and distinguish among direct and indirect effects of habitat characteristics and disturbance on the various components of biodiversity.
With six concrete and biologically sound models in mind, we collected habitat characteristics of 22 study sites from four distinct landscapes located in central Panama. Each landscape differed in the degree of human disturbance and fragmentation measured by several quantitative variables, such as canopy cover, canopy height and understorey density. In terms of biodiversity, we estimated on the one hand, (a) small mammal species diversity, and, on the other hand, (b) genome‐wide diversity, (c) intestinal parasite diversity and (d) gut microbial heterogeneity of the most dominant generalist species (Tome's spiny rat, Proechimys semispinosus). We used SEMs to assess the links between habitat characteristics and biological diversity measures.
The best supported SEM suggested that habitat characteristics directly and positively affect the richness of small mammals, the genetic diversity of P. semispinosus and its gut microbial heterogeneity. Habitat characteristics did not, however, directly impact intestinal parasite diversity. We also detected indirect, positive effects of habitat characteristics on both host‐associated assemblages via small mammal richness. For microbes, this is likely linked to cross species transmission, particularly in shared and/or anthropogenically altered habitats, whereas host diversity mitigates parasite infections. The SEM revealed an additional indirect but negative effect on intestinal parasite diversity via host genetic diversity.
Our study showcases that habitat alterations not only affect species diversity and host genetic diversity in parallel, but also species diversity of host‐associated assemblages. The impacts from human disturbance are therefore expected to ripple through entire ecosystems with far reaching effects felt even by generalist species.
Urbanization is a major contributor to the loss of biodiversity. Its rapid progress is mostly at the expense of natural ecosystems and the species inhabiting them. While some species can adjust quickly and thrive in cities, many others cannot. To support biodiversity conservation and guide management decisions in urban areas, it is important to find robust methods to estimate the urban affinity of species (i.e. their tendency to live in urban areas) and understand how it is associated with their traits. Since previous studies mainly relied on discrete classifications of species' urban affinity, often involving inconsistent assessments or variable parameters, their results were difficult to compare. To address this issue, we developed and evaluated a set of continuous indices that quantify species' urban affinity based on publicly available occurrence data. We investigated the extent to which a species' position along the urban affinity gradient depends on the chosen index and how this choice affects inferences about the relationship between urban affinity and a set of morphological, sensory and functional traits. While these indices are applicable to a wide range of taxonomic groups, we examined their performance using a global set of 356 bat species. As bats vary in sensitivity to anthropogenic disturbances, they provide an interesting case study. We found that different types of indices resulted in different rankings of species on the urban affinity spectrum, but this had little effect on the association of traits with urban affinity. Our results suggest that bat species predisposed to urban life are characterized by low echolocation call frequencies, relatively long call durations, small body size and flexibility in the selection of the roost type. We conclude that simple indices are appropriate and practical, and propose to apply them to more taxa to improve our understanding of how urbanization favours or filters species with particular traits.
How organisms that are part of the same trophic network respond to environmental variability over small spatial scales has been studied in a multitude of systems. Prevailing theory suggests a large role for plasticity in key traits among interacting species that allows matching of life cycles or life‐history traits across environmental gradients, for instance insects tracking host‐plant phenology across variable environments (Posledovich et al. 2018). A key aspect that remains understudied is the extent of intrapopulation variability in plasticity and whether stressful conditions canalize plasticity to an optimal level, or alternatively if variation in plasticity indeed could increase fitness in itself via alternative strategies. In a From the Cover article in this issue of Molecular Ecology, Kahilainen et al. (2022) investigate this issue in a classical insect study system, the metapopulation of the Glanville fritillary butterfly (Melitea cinxia) in the Åland archipelago of Finland. The authors first establish how a key host plant responds to water limitation, then quantify among‐family variation in larval growth and development across control and water‐limited host plants. Finally, they use RNA sequencing to gain mechanistic insights into some of these among‐family differences in larval performance in response to host‐plant variation, finding results suggesting the existence of heritable, intrapopulation variability in ecologically relevant plasticity. This final step represents a critically important and often overlooked component of efforts to predict sensitivity of biological systems to changing environmental conditions, since it provides a key metric of adaptive resilience present in the system.
Abstract
The neritid snail Theodoxus fluviatilis has formed regional subgroups in northern Europe, where it appears in both freshwater (FW) and brackish water (BW) in coastal areas of the Baltic Sea. These ecotypes show clear differences in osmotolerance and in the modes of accumulating organic osmolytes under hyperosmotic stress. We reasoned that the expression patterns of soluble proteins in the two ecotypes may differ as well. BW snails have to deal with a higher salinity (up to 20‰) than FW snails (0.5‰) and also cope with frequent fluctuations in environmental salinity that occur after heavy rains or evaporation caused by extended periods of intense sunshine. Therefore, the protein expression patterns of specimens collected at five different FW and BW sites were analyzed using 2D SDS‐PAGE, mass spectrometry, and sequence comparisons based on a transcriptome database for Theodoxus fluviatilis. We identified 89 differentially expressed proteins. The differences in the expression between FW and BW snails may be due to phenotypic plasticity, but may also be determined by local genetic adaptations. Among the differentially expressed proteins, 19 proteins seem to be of special interest as they may be involved in mediating the higher tolerance of BW animals towards environmental change compared with FW animals.
Abstract
Background
Several leech species of the genera Hirudo, Hirudinaria, and Whitmania are widely used in traditional Chinese medicine (TCM) for the oral treatment of disorders associated with blood stasis. Among them, the non‐hematophagous leech Whitmania pigra expresses a variety of components that have the potential to act on the vertebrate blood coagulation system.
Objective
Whether the thrombin inhibitor hirudin, probably the most prominent leech‐derived anticoagulant, is actually present in Whitmania pigra, is still a matter of debate. To answer that open question was the aim of the study.
Methods
We identified several putative hirudin‐encoding sequences in transcriptome data of Whitmania pigra. Upon gene synthesis and molecular cloning the respective recombinant proteins were expressed in Escherichia coli, purified, processed, and eventually functionally characterized for thrombin‐inhibitory potencies in coagulation assays.
Results
We were successful in the identification and functional characterization of several putative hirudins in Whitmania pigra. Some, but not all, of these factors are indeed thrombin inhibitors. Whitmania pigra hence expresses both hirudins (factors that inhibit thrombin) and hirudin‐like factors (that do not or only very weakly inhibit thrombin). Furthermore, we revealed the exon/intron structures of the corresponding genes. Coding sequences of some putative hirudins of Whitmania pigra were present also in transcriptome datasets of Hirudo nipponia, a hematophagous leech that is likewise used in TCM.
Conclusions
Based on both structural and functional data we provide very strong evidence for the expression of hirudins in Whitmania pigra. This is the first description of hirudins in a non‐hematophagous leech.
Abstract
Sander lucioperca is an organism of growing importance for the aquaculture industry. Nonetheless, the rearing of S. lucioperca larvae is proving to be a difficult task as it is facing a high mortality rate during hatching and the change to exogenous feeding. To gain insight into growth patterns during this period, the authors analysed pikeperch embryos and larvae from 9 days before hatching to 17 days after hatch. Hereby they were able to describe a natural development by using close to natural conditions based on using a direct flow‐through supply of lake fresh water on specimens from a local wild population. The results show that between the early embryonic stages a steady growth was visible. Nonetheless, in between hatching and the start of exogenous feeding, a phase of growth stagnation took place. In the following larval stages, an increased growth with large size variations between individual specimens appeared. Both factors are conspicuous as they can indicate a starting point for cannibalism. With this analysis, the authors can provide a fundament to support the upcoming research on S. lucioperca and aid to optimize size‐sorting procedures for a higher survival of pikeperch stock in aquaculture.