Small Species Research Articles

Ultrasonic vocalisation rate tracks the diurnal pattern of activity in winter phenotype Djungarian hamsters (Phodopus sungorus).

Vocalisations are increasingly being recognised as an important aspect of normal rodent behaviour yet little is known of how they interact with other spontaneous behaviours such as sleep and torpor, particularly in a social setting. We obtained chronic recordings of the vocal behaviour of adult male and female Djungarian hamsters (Phodopus sungorus) housed under short photoperiod (8h light, 16h dark, square wave transitions), in different social contexts. The animals were kept in isolation or in same-sex sibling pairs, separated by a grid which allowed non-physical social interaction. On approximately 20% of days hamsters spontaneously entered torpor, a state of metabolic depression that coincides with the rest phase of many small mammal species in response to actual or predicted energy shortages. Animals produced ultrasonic vocalisations (USVs) with a peak frequency of 57kHz in both social and asocial conditions and there was a high degree of variability in vocalisation rate between subjects. Vocalisation rate was correlated with locomotor activity across the 24-h light cycle, occurring more frequently during the dark period when the hamsters were more active and peaking around light transitions. Solitary-housed animals did not vocalise whilst torpid and animals remained in torpor despite overlapping with vocalisations in social-housing. Besides a minor decrease in peak USV frequency when isolated hamsters were re-paired with their siblings, changing social contexts did not influence vocalisation behaviour or structure. In rare instances, temporally overlapping USVs occurred when animals were socially-housed and were grouped in such a way that could indicate coordination. We did not observe broadband calls (BBCs) contemporaneous with USVs in this paradigm, corroborating their correlation with physical aggression which was absent from our experiment. Overall, we find little evidence to suggest a direct social function of hamster USVs. We conclude that understanding the effects of vocalisations on spontaneous behaviours, such as sleep and torpor, will inform experimental design of future studies, especially where the role of social interactions is investigated.

A guide to antimicrobial options for common small ruminant diseases

There are few antibiotics approved for use in small ruminant species in the United States. According to the Animal Medicinal Drug Use Clarification Act (AMDUCA), extralabel drug use may only be employed under the direction of a licensed veterinar­ian in the context of a valid veterinarian-client-patient relation­ship. However, with the implementation of FDA Guidance for Industry #263, producers will no longer have access to antibiot­ics which were previously available over the counter and could have been utilized in an extralabel manner without veterinary oversight. The aim of this discussion is to provide veterinarians with a logical approach to selecting appropriate antibiotics for use in small ruminants.

The holocentricity in the dioecious nutmeg (Myristica fragrans) is not based on major satellite repeats

Holocentric species are characterized by the presence of centromeres throughout the length of the chromosomes. We confirmed the holocentricity of the dioecious, small chromosome-size species Myristica fragrans based on the chromosome-wide distribution of the centromere-specific protein KNL1, α-tubulin fibers, and the cell cycle-dependent histone H3 serine 28 phosphorylation (H3S28ph) mark. Each holocentromere is likely composed of, on average, ten centromere units, but none of the identified and in situ hybridized high-copy satellite repeats is centromere-specific. No sex-specific major repeats are present in the high-copy repeat composition of male or female plants, or a significant difference in genome size was detected. Therefore, it is unlikely that M. fragrans possesses heteromorphic sex chromosomes.

Studies on chevron crickets: Minarisoma gen. nov. (Orthoptera, Anostostomatidae), a new genus and a new species from South Africa

A new genus, Minarisomagen. nov., is described to include three small species of South African distribution: Minarisoma landeckisp. nov. (type species), Minarisoma crassipescomb. nov., and M. tigrinumcomb. nov. These species were previously assigned to the genus Onosandrus. Minarisomagen. nov. marks the ninth genus of king crickets known from southern Africa. A comprehensive key to the identification of species within this newly established taxon is presented. In conclusion, the taxonomic relationships of South African taxa are discussed.

The function of brown adipose tissue at different sites of the body in Brandt's voles during cold acclimation

Ambient temperatures have great impacts on thermoregulation of small mammals. Brown adipose tissue (BAT), an obligative thermogenic tissue for small mammals, is localized not only in the interscapular depot (iBAT), but also in supraclavicular, infra/subscapular, cervical, paravertebral, and periaortic depots. The iBAT is known for its cold-induced thermogenesis, however, less has been paid attention to the function of BAT at other sites. Here, we investigated the function of BAT at different sites of the body during cold acclimation in a small rodent species. As expected, Brandt's voles (Lasiopodomys brandtii) consumed more food and reduced the body mass gain when they were exposed to cold. The voles increased resting metabolic rate and maintained a relatively lower body temperature in the cold (36.5 ± 0.27 °C) compared to those in the warm condition (37.1 ± 0.36 °C). During cold acclimation, the uncoupling protein 1 (UCP1) increased in aBAT (axillary), cBAT (anterior cervical), iBAT (interscapular), nBAT (supraclavicular), and sBAT (suprascapular). The levels of proliferating cell nuclear antigen (PCNA), a marker for cell proliferation, were higher in cBAT and iBAT in the cold than in the warm group. The pAMPK/AMPK and pCREB/CREB were increased in cBAT and iBAT during cold acclimation, respectively. These data indicate that these different sites of BAT play the cold-induced thermogenic function for small mammals.

A New Name for Plants Previously Called Parablechnum christii (Blechnaceae) in Costa Rica and Panama

The name Parablechnum christii (C. Chr.) Gasper & Salino has been applied to a small species with few pairs of short pinnae that is endemic to Costa Rica and Panama. After reviewing type material of this name, we conclude that it has been misapplied and is, in fact, a synonym of P. falciforme (Liebm.) Gasper & Salino, an older name. Because the specimens previously identified as P. christii lack a name, we propose P. talamancanum S. Molino & R. C. Moran for these plants. The species is endemic to the mountains of Costa Rica and Panama, from 1200 to 3350 m.

Quasi-equilibrium chemical evolution in starless cores

Abstract The chemistry of H2O, CO and other small molecular species in an isolated pre-stellar core, L1544, has been assessed in the context of a comprehensive gas-grain chemical model, coupled to an empirically constrained physical/dynamical model. Our main findings are (i) that the chemical network remains in near equilibrium as the core evolves towards star formation and the molecular abundances change in response to the evolving physical conditions. The gas-phase abundances at any time can be calculated accurately with equilibrium chemistry, and the concept of chemical clocks is meaningless in molecular clouds with similar conditions and dynamical time scales, and (ii) A comparison of the results of complex and simple chemical networks indicates that the abundances of the dominant oxygen and carbon species, H2O, CO, C, and C+ are reasonably approximated by simple networks. In chemical equilibrium, the time-dependent differential terms vanish and a simple network reduces to a few algebraic equations. This allows rapid calculation of the abundances most responsible for spectral line radiative cooling in molecular clouds with long dynamical time scales. The dust ice mantles are highly structured and the ice layers retain a memory of the gas-phase abundances at the time of their deposition. A complex (gas-phase and gas-grain) chemical structure therefore exists, with cosmic-ray induced processes dominating in the inner regions. The inferred H2O abundance profiles for L1544 require that the outer parts of the core and also any medium exterior to the core are essentially transparent to the interstellar radiation field.

The curious case of small mammal community in a rice-Pantanal agroecosystem of Brazil: A tale of multiple diversity metrics

To understand how certain types of agroecosystem management provide resources for biodiversity and conservation opportunities beyond protected areas, it is necessary to consider the cumulative effects on a local scale. Our study focuses on a rice-Pantanal wetland agricultural system within Brazil, where our goals were: i) to quantify the impact of rice paddies on taxonomic, functional, and phylogenetic diversity metrics of small mammals as biodiversity indicators, ii) to compare diversity indices based on incidence and abundance data. We carried out a thorough assessment to sample small mammal species in both the rice paddy and the adjacent legal reserve by employing a multiple diversity metrics approach. We captured the small mammals until reaching saturation on the species accumulation curve over 12,774 trap nights, resulting in 447 individuals, 10 species, including seven rodents and three marsupial species. Abundance-based beta-diversity between rice-paddy and forest reserve were higher (0.95) than incidence-based estimate (0.33). The species composition differed between the legal reserve (8 spp.) and the rice paddy (7 spp.), with the reserve exhibiting higher taxonomic diversity values compared to the rice paddy. In terms of functional and phylogenetic diversity, overall, the rice paddy exhibited higher values for the incidence-based metrics and the abundance-based metrics indicated that the reserve was more diverse. We conclude that Neotropical Pantanal rice fields retain substantial functional and phylogenetic diversities, providing suitable habitats for species thriving in open and semi-aquatic environments. Simultaneously, the legal reserve retains an essential aspect of functional diversity, when considering abundance, needed to maintain ecosystem resilience and stability. Proper abundance estimation is thus a key parameter for accurately evaluating the role of agricultural landscapes as biodiversity conservation opportunities beyond protected areas. Abundance-based indices should be used to correctly evaluate the contribution of each habitat to agroecosystem sustainability, especially in seasonal or extreme event-prone environments.

Photochemistry of Photoinduced-Reaction Generated Bubbles.

UV light can create and grow bubbles (herein referred to as PIRGBs for photoinduced-reaction generated bubbles) at liquid/solid interfaces through photoinduced reactions that produce gases. Unlike the simple experience of blowing water bubbles through a straw, in which the bubbles quickly move away from their nucleation sites, not only can a deep UV laser beam create PIRGBs in liquid acetone, but also can hold and grow them. Free bubbles could be attracted to the excitation region from millimeters away, indicating that the reactions cause radial inward flow on the liquid surface. The radial flow can be due to imbalanced surface tensions at the interfaces. Raman measurements reveal that the gases in the PIRGBs include C2H6, CO, and H2, and in liquid acetone, sp2-carbon species are detected upon the UV excitation. Time series Raman measurement discloses a photocarbonization process in which small acyclic carbon species gradually form small clusters with carbon rings and eventually produce a large piece of amorphous carbon at the top of a PIRGB in pure liquid acetone. The photocarbonization may open new avenues for development of carbonaceous materials. Using PIRGB, miniature or microscale gas production reactors can be developed for producing gases.

Solvation Properties of Neutral Gold Species in Supercritical Water Studied By THz Spectroscopy.

Supercritical water provides distinctly different solvation properties compared to what is known from liquid water. Despite its prevalence deep in the Earth's crust and its role in chemosynthetic ecosystems in the vicinity of hydrothermal vents, molecular insights into its solvation mechanisms are still very scarce compared to what is known for liquid water. Recently, neutral metal particles have been detected in hydrothermal fluids and proposed to explain the transport of gold species to ore deposits on Earth. Using ab initio molecular dynamics, we elucidate the solvation properties of small gold species at supercritical conditions. The neutral metal clusters themselves contribute enormous THz intensity not because of their intramolecular vibrations, but due to their pronounced electronic polarization coupling to the dynamical supercritical solvent, leading to a continuum absorption up to about 1000 cm-1 . On top, long-lived interactions between the gold clusters and solvation water leads at these supercritical conditions to a sharp THz resonance that happens to be close to the one due to H-bonding in liquid water at ambient conditions. The resulting distinct resonances can be used to analyse the solvation properties of neutral metal particles in supercritical aqueous solutions.

Variation pattern of crustacean zooplankton in a bigheaded carps-dominated reservoir

The relationship between crustacean zooplankton and (planktivorous) fish has not been well clarified in bigheaded-carps-dominated reservoirs, for most of the past studies to explore that kind of knowledge above are often obtained from the studies in temperate lakes and/or shallow lakes. The limitation of these studies is that crustacean zooplankton lack of either large grazers such as the bigheaded carps or the vertical migrating space for zooplankton to avoid predation by planktivorous fish. Reservoirs are more and more important drinking water source for human consumption, so a better environmental management of reservoirs will rely on a better understanding on the relationship between zooplankton and fish in bigheaded carp dominated reservoirs. To help reach that goal, we investigated the structure and variation of zooplankton and studied the relationship between zooplankton and fish in Tangpu reservoir, Zhejiang province, China. Our results showed that the species of crustacean zooplankton were richer. A total of 59 species of crustacean zooplankton were detected, including 33 species of copepods and 26 species of cladoceran, and dominated by larger species. The density of crustacean zooplankton varied between 15.5–68.5 ind./L with an annual average density of 24.9 ± 14.4 ind./L, it is higher in this planktivorous carps dominated deep reservoir than in many carp-less-dominated reservoirs or in shallow lakes. We also found that zooplankton and fish had a differential vertical distribution, i.e., zooplankton occurred 5 m–10 m but fish occurred 0.5 m–10 m in many months of the year. This could well explain why zooplankton were not reduced and not dominated by small species in bigheaded carps dominated reservoir, so we concluded that in planktivorous carp dominated deep reservoir ecosystems, zooplankton might not compete directly with planktivorous carps for phytoplankton, instead by distributing or migrating to deeper water column, they may survive and thrive on the phytoplankton in deeper column and the detritus resulted from the feces of planktivorous fish, thus might be able to coordinately improve water quality with planktivorous fish.

Linking anatomical and histological traits of the digestive tract to resource consumption and assimilation of omnivorous tetra fishes.

This study explores the interplay between digestive tract traits, food intake, and assimilation in omnivorous tetra fishes (Psalidodon bifasciatus, P. aff. gymnodontus, and Bryconamericus ikaa) from the Iguaçu River basin, an ecologically significant region known for high endemism. We hypothesize that variations in digestive tracts across species would be associated with differences in diet, isotopic composition in fish tissues, and overall diet assimilation. To test this, we employed stereoscopic and light microscopy to characterize the gross anatomy, histomorphology, and histochemistry of fish digestive tracts. Additionally, we used stomach content and stable isotope analyses to trace fish diets. While these tetra fishes shared histological structures, disparities were noted in anatomical digestive traits and diet preferences. The smallest species, B. ikaa, with a shorter intestine, had fewer pyloric caeca and primarily consumed animal-based diets. Conversely, P. bifasciatus and P. aff. gymnodontus, with longer intestines, displayed numerous pyloric caeca and consumed a balanced mix of animal and plant items. Despite anatomical and dietary differences, all three species predominantly assimilated animal-origin food. The tetra fishes had histological variations among digestive tract segments, with the esophagus having the thickest muscular layer, gradually thinning towards the posterior intestine. The final portion of the intestine exhibited a significant expansion in the lumen perimeter, while the esophagus had the smallest lumen area. Goblet cells were most concentrated in the posterior intestine for all species. The gross anatomy of these tetra fishes aligns with their omnivorous habit, while diet assimilation was dominated by animal-origin food. These findings provide crucial insights into the structural and tissue characteristics of their digestive systems, laying the groundwork for deeper exploration into the physiological aspects of their digestive tracts and enhancing our understanding of their feeding strategies.

Vertically Aligned Pt/MXene/Carbon Nanotubes Aerogels for Superior Hydrogen Evolution Reaction

Herein, we propose a one-step directional-freezing strategy to fabricate 3D vertically aligned aerogel (VA) of Ti3C2Tx MXene/carbon nanotubes (MC) decorated with small Pt species (denoted as Pt@MC-VA) as a self-standing electrode for robust electrocatalytic hydrogen evolution reaction (HER) at ampere-level current density. Numerous small Pt nanoclusters and single-atoms species are spontaneously reduced and anchored on the aerogel skeleton, revealing high intrinsic activity. The MXene nanosheets firmly fixed by carbon nanotubes cooperatively construct the porous frameworks, which greatly reinforces the overall mechanical strength and serves as high-speed path for electron transport. Moreover, the 3D self-supported and super-wettable frameworks with vertically aligned and run-through microchannels significantly facilitate the electrolyte infiltration and the immediate removal of gaseous products at high current densities. Based on these combined advantages, the Pt@MC-VA electrode exhibits a significantly improved electrocatalytic activity with overpotentials as low as 208 and 249 mV to reach high current densities up to 500 and 1000 mA cm-2, respectively, and a good long-term stability for at least 24 h at 500 mA cm-2.

Voloshinoides simplex sp. nov. and Cribellopsis? kharaibensis sp. nov. (Foraminifera): new constraints for Lower Cretaceous (upper Barremian–lowermost Aptian) stratigraphy of the Arabian Plate (Kharaib Formation, Hawar Member, UAE)

Larger benthic foraminifera such as orbitolinids are particularly important in Lower and mid-Cretaceous biostratigraphy of neritic deposits of the Arabian Plate. These data are supplemented by a few non-orbitolinid taxa. Among these, two new species are described herein as Voloshinoides simplex and Cribellopsis? kharaibensis from upper Barremian–lowermost Aptian inner platform limestones of the Kharaib Formation and the Hawar Member cropping out in Wadi Rahabah, United Arabian Emirates. V. simplex sp. nov. represents the oldest and most primitive species of the genus Voloshinoides Barnard and Banner, exhibiting a simple and poorly developed exoskeleton. C.? kharaibensis represents a rather small species exhibiting a primitive marginal zone that lacks intercalary beams. The assignment of the taxonomic status is provisional awaiting some structural clarifications. While C.? kharaibensis is restricted to the upper Barremian Kharaib Formation, V. simplex reaches into the lower part of the lowermost Aptian Hawar Member.

Small skeletons show size-specific scaling: an exploration of allometry in the mammalian lumbar spine.

Studies of vertebrate bone biomechanics often focus on skeletal adaptations at upper extremes of body mass, disregarding the importance of skeletal adaptations at lower extremes. Yet mammals are ancestrally small and most modern species have masses under 5 kg, so the evolution of morphology and function at small size should be prioritized for understanding how mammals subsist. We examined allometric scaling of lumbar vertebrae in the small-bodied Philippine endemic rodents known as cloud rats, which vary in mass across two orders of magnitude (15.5 g-2700 g). External vertebral dimensions scale with isometry or positive allometry, likely relating to body size and nuances in quadrupedal posture. In contrast to most mammalian trabecular bone studies, bone volume fraction and trabecular thickness scale with positive allometry and isometry, respectively. It is physiologically impossible for these trends to continue to the upper extremes of mammalian body size, and we demonstrate a fundamental difference in trabecular bone allometry between large- and small-bodied mammals. These findings have important implications for the biomechanical capabilities of mammalian bone at small body size; for the selective pressures that govern skeletal evolution in small mammals; and for the way we define 'small' and 'large' in the context of vertebrate skeletons.

Metabolomic Profiling and DNA-Fingerprinting of Newly Recorded White-Flowered Populations of Salvia lanigera Poir. in Egypt.

Salvia lanigera Poir. is a small herbaceous perennial species with violet flowers that grows in low-altitude deserts, and sandy loam. During the collection of S. lanigera,unusual populations with white flowers werefound. Therefore, the two populations (violet- and white-flowered) were subjected to comparative investigations, including DNA fingerprinting, chemical composition, and biological evaluation. The two populations showed DNA variations, with 6.66% polymorphism in ISSR and 25% in SCoT markers. GC/MS and UHPLC/HRMS of aqueous methanol extracts, led to the tentative identification of 43 and 50 compounds in both populations. In addition, the structures of nine compounds, including four first-reported compounds in the species, were confirmed by NMR. Furthermore, the total extracts exhibited weak radical scavenging activity against DPPH and a lower inhibitory effect towards acetylcholinesterase. In conclusion, the obtained data suggested that the white-colored flower could be an additional important character record for the Egyptian S. lanigera.

Body size responses to urban temperature variations are driven by life history traits in spiders

Abstract Urban ecosystems exhibit altered environmental conditions compared to the rural surroundings, including higher temperatures, the so‐called urban heat island (UHI) effect. Along urbanisation gradients, temperature variations occur at various scales ranging from the landscape to the microhabitat, with possible consequences on living organisms. As ectothermic animals, arthropods are particularly affected by UHIs because warming may directly induce physiological effects on their metabolism. Body size is a commonly used metric to investigate arthropod responses to thermal stress, but the scale‐dependent role of temperature variation as predictor of body size remains unclear. To assess temperature–size relationships across spatial scales and test if a common pattern to several species emerges, we performed morphological measurements on 2283 individuals representing 11 spider species belonging to Hahniidae, Linyphiidae, Lycosidae and Tetragnathidae. Spiders were collected on 36 grasslands distributed along a broad UHI gradient. Intraspecific shifts in body size were related to temperature in the Lycosids Pardosa prativaga and Pardosa pullata at the landscape and local scales, respectively, whereas no clear effects were observed regarding the other examined species. In both species, sex was an important endogenous factor that modulated individual responses; females were more affected than males by temperature. The contrasting amplitudes of the responses observed among Lycodids and the other species indicate that large, low dispersive and univoltine species are under a stronger influence of temperature than small bivotline species that can disperse aerially. Our results on spiders highlight that considering species‐specific life history traits helps to understand contrasting responses among species, and this may be essential for drawing general patterns of phenotypic changes among arthropods under anthropogenic warming. Read the free Plain Language Summary for this article on the Journal blog.

Transect walks and malaise traps differ in temperature sensitivity but reveal consistent drivers of pollinator richness

Abstract While transect walks have long been the preferred monitoring method for many flying insect taxa, malaise traps combined with DNA metabarcoding have gained growing prominence. However, it remains unclear whether both methods reveal comparable species richness and the same ecological drivers along environmental gradients. We selected three groups of pollinators (wild bees, hoverflies and butterflies) and one group of herbivores (grasshoppers) as functionally important and conservation‐relevant model groups, comparing results of both methods along an elevational gradient in the German Alps. Across the study region, both methods detected a similarly high species richness of pollinators with ~50% overlap of species pools, but transect walks revealed more species per site, especially in higher elevations and under low temperatures. Body size spectra differed between methods, with on average more large butterfly and more small bee species in transect walks. Nevertheless, temperature and flower richness were consistent drivers of pollinator richness, independent of the sampling method. Grasshopper richness from transect walks was considerably higher than from malaise traps. Both methods identified temperature and only malaise traps also identified management as drivers of grasshopper richness. We conclude that malaise traps are principally suitable substitutes for the more time‐consuming pollinator transect walks. However, the effectiveness of these passive traps is more susceptible to changes in sampling temperature, and in some pollinator groups, body size classes are presented differently, which is important to consider during analyses. For grasshoppers, transect walks appear to be more suitable to assess species richness, as considerably more species can be monitored.

Methods to estimate body temperature and energy expenditure dynamics in fed and fasted laboratory mice: effects of sleep deprivation and light exposure.

Monitoring body temperature and energy expenditure in freely-moving laboratory mice remains a powerful methodology used widely across a variety of disciplines-including circadian biology, sleep research, metabolic phenotyping, and the study of body temperature regulation. Some of the most pronounced changes in body temperature are observed when small heterothermic species reduce their body temperature during daily torpor. Daily torpor is an energy saving strategy characterized by dramatic reductions in body temperature employed by mice and other species when challenged to meet energetic demands. Typical measurements used to describe daily torpor are the measurement of core body temperature and energy expenditure. These approaches can have drawbacks and developing alternatives for these techniques provides options that can be beneficial both from an animal-welfare and study-complexity perspective. First, this paper presents and assesses a method to estimate core body temperature based on measurements of subcutaneous body temperature, and second, a separate approach to better estimate energy expenditure during daily torpor based on core body temperature. Third, the effects of light exposure during the habitual dark phase and sleep deprivation during the light period on body temperature dynamics were tested preliminary in fed and fasted mice. Together, the here-published approaches and datasets can be used in the future to assess body temperature and metabolism in freely-moving laboratory mice.

Predicting resilience of migratory birds to environmental change.

The pace and scale of environmental change represent major challenges to many organisms. Animals that move long distances, such as migratory birds, are especially vulnerable to change since they need chains of intact habitat along their migratory routes. Estimating the resilience of such species to environmental changes assists in targeting conservation efforts. We developed a migration modeling framework to predict past (1960s), present (2010s), and future (2060s) optimal migration strategies across five shorebird species (Scolopacidae) within the East Asian-Australasian Flyway, which has seen major habitat deterioration and loss over the last century, and compared these predictions to empirical tracks from the present. Our model captured the migration strategies of the five species and identified the changes in migrations needed to respond to habitat deterioration and climate change. Notably, the larger species, with single or few major stopover sites, need to establish new migration routes and strategies, while smaller species can buffer habitat loss by redistributing their stopover areas to novel or less-used sites. Comparing model predictions with empirical tracks also indicates that larger species with the stronger need for adaptations continue to migrate closer to the optimal routes of the past, before habitat deterioration accelerated. Our study not only quantifies the vulnerability of species in the face of global change but also explicitly reveals the extent of adaptations required to sustain their migrations. This modeling framework provides a tool for conservation planning that can accommodate the future needs of migratory species.