Conditions experienced during early life stages may influence an array of fitness-relevant phenotypes, especially in oviparous ectotherms. The pond slider ( Trachemys scripta ) has two life stages particularly vulnerable to the influence of ambient conditions: the egg stage and hatchling overwintering stage. We aimed to determine the influence of both incubation temperature and overwinter environment on hatchling turtle performance. In 2019 and 2020, we incubated pond slider eggs at five constant temperatures (24°C, 26°C, 28°C, 30°C, 32°C). After hatching, turtles were distributed to two housing treatments that simulated overwintering in a terrestrial nest or an aquatic environment. In the spring following hatching, we conducted righting response trials, which are frequently used performance measures that may be associated with coordination and neuromuscular function. Our linear mixed-effects models show that incubation temperature, overwinter environment, and their interaction significantly influenced hatchling phenotypes (e.g., shell and tail dimensions, body mass) and righting performance (e.g., total righting response time, latency to right). Aquatically overwintering hatchlings that were incubated at cooler temperatures righted themselves faster than those incubated at warmer temperatures. This relationship did not exist in terrestrially overwintering hatchlings, which had faster overall righting times that were not affected by incubation temperature, suggesting overwintering in the nest may better equip hatchlings for post-emergence dispersals over land.
Depletion of dissolved oxygen (DO; hypoxia) and its influence on sensitive fauna and vulnerable life stages is an emerging concern in lotic freshwater ecosystems. A species particularly vulnerable to hypoxia is the Eastern Hellbender-a large-bodied, fully aquatic salamander which relies on cutaneous respiration and has evolved to thrive in cold, well-oxygenated streams. Adult hellbenders nest in benthic stream microhabitats which are vulnerable to DO depletion caused by loss of riparian forest cover that increases sedimentation and solar radiation. Hellbender populations are experiencing declines characterized by reduced recruitment in areas with low forest cover, but the influence of hypoxia on hellbender embryonic development is unknown. We hypothesized that hellbender embryos are sensitive to hypoxic conditions because of their high degree of habitat specialization. We conducted two experiments where we exposed freshly laid eggs to a range of DO concentrations in the lab (3-10 mg/L). In both experiments we found that hellbender embryos reared in our lowest DO treatments of 3 and 5 mg/L had an average viability 51% and 34% lower than each experiment's 10 mg/L treatment, respectively. In addition, eggs reared in these low DO concentrations had significantly lower hatching success, a higher percentage of premature hatchlings, and produced hatchlings with smaller morphometrics compared to higher DO treatments. In our second experiment, we also continued to track hatchlings at least 14 days post hatching and demonstrated that premature hatchlings had a high probability of dying within weeks of hatching. Our results indicate that hellbender embryos require DO concentrations of > 5 mg/L for proper development, thus placing them on the more sensitive end of the hypoxia tolerance continuum for freshwater taxa. Our experiments confirmed hellbender embryonic sensitivity to environmentally relevant reductions in DO concentrations and identified future research and conservation needs related to the development of hellbender embryos in the field.
Conspecific competitive interactions occur in a variety of contexts, including for resources and territory. These competitive interactions can vary in frequency and duration. The amount of aggression displayed and whether individuals alter their aggressive response during longer competitive bouts may be impacted by individual differences in stress response and behavior. The maternal environment, including maternal stress and the maternal microbiome, can have sex-specific, developmental effects on offspring's physiology and aggressive behavior. We tested whether the maternal environment affects changes to offspring aggressive behavior during long competitive bouts in Siberian hamsters (Phodopus sungorus). We exposed pregnant females to one of four treatments (social stressor, microbiome manipulation, combined social stress and microbiome manipulation, or no treatment) for ten days. Using a resident-intruder behavioral paradigm, adolescent offspring were exposed to a same-sex intruder for 15 min. We assessed differences in offspring behavioral responses during the first and last 5 min of the competitive interaction. All offspring displayed less aggression during the last 5 min compared to the first 5 min, regardless of maternal treatment. Regardless of maternal treatment, both female and male offspring reduced social behavior towards the intruder, while increasing non-social and decreasing anxiety like behavior across the 15-min trial. Our results are consistent with habituation towards an intruder and indicate that early development does not affect habituation during aggression with a conspecific, further confirming the complexity and highly conserved mechanisms involved in habituation.
Living organisms face stressful situations and use endocrine mechanisms, such as glucocorticoid production, to maintain homeostasis. Although glucocorticoids are essential for basal function, their secretion increases when organisms face stressful situations. In species with temperature-dependent sex determination (TSD), like Caiman latirostris, an increase in these hormones could also alter the sex ratio. In this study, we applied a dose of exogenous corticosterone (70 ng/egg) at developmental stage 20 to assess its effects on sex determination, incubation period (IP), and morphometric traits -including snout-vent length, total length, and body mass- in embryos and hatchlings. Eggs (n = 184) were incubated at 32°C, a temperature that typically produces both sexes. Corticosterone treatment significantly reduced the IP (CORT: 74 ± 2 days; CONTROL: 78 ± 2; z = -9.91, p < 0.01), without affecting hatching success. Morphometric traits did not differ significantly between treatments in either embryos or hatchlings (all p > 0.05). However, a marked shift in sex ratio was observed: while a 30% male to 70% female ratio was expected, corticosterone treatment reversed this pattern, resulting in 75% males and 25% females (χ² = 6.125, p = 0.013). These results indicate that corticosterone can induce male-biased sex differentiation and accelerate hatching without compromising morphological development or hatchling viability. While this mechanism could confer a advantage at the individual level by allowing earlier hatching, it is crucial to investigate whether it carries long-term costs, both in the growth and survival of the offspring and in population dynamics due to the altered sex ratio.
An optimal glucocorticoid stress response is essential because it allows animals to adjust their phenotype to constantly changing environments. Considerable progress has been made regarding our understanding of how various cellular mechanisms of glucocorticoid action modulate animals' stress response phenotype. However, a potentially overlooked mediator of glucocorticoid production and individual's stress response phenotype is the endoplasmic reticulum (ER) and its unfolded protein response (UPR), given that all steroid hormones are synthesised within the mitochondria and the ER. We hypothesise that UPR regulates glucocorticoid synthesis, and ER stress induction would inhibit glucocorticoid production in the adrenal cortex. We conducted in vivo and in vitro studies using outbred deer mice Peromyscus maniculatus and Y-1 adrenal cell lines respectively to investigate the effects of ER stress and UPR on adrenocorticotropic hormone induced glucocorticoid production. Specifically, we tested if induction and alleviation of ER stress using tunicamycin and tauroursodeoxycholic acid, respectively, would affect corticosterone production in deer mice and Y-1 cells and the protein expression of a steroidogenic enzyme in Y-1 cells. We showed that ER stress and UPR modulate glucocorticoid production at both the cell and whole-organism levels, but this is achieved independent of alteration in protein level of 21-Hydroxylase.
The river nerite Theodoxus fluviatilis (Linneaus, 1758) is an euryhaline osmoconformer found in freshwater (FW) and brackish water (BW) habitats across Europe and western Asia. In northern Germany, T. fluviatilis forms regional subgroups, the FW and the BW ecotypes. Members of these ecotypes differ in shell morphology and in shell size as well as in their metabolic pathways of accumulating organic osmolytes under hyperosmotic stress. Oxygen consumption rates were measured, as a noninvasive fitness-indicator, of animals exposed to external media with different salinities. The BW water snails were exposed to hyper- and hyposaline conditions, while the FW snails were naturally only exposed to hyperosmotic conditions. Respiration rates in specimens of the BW ecotype stayed more or less constant overall in all salinities tested. While the BW snails' respiration rates were not affected by the salinity treatment per se, they were affected by the sequence of salinity treatments that they were exposed to (hyperosmotic conditions first vs. hypoosmotic conditions first). Respiration rates strongly declined in the FW ecotype individuals with increasing medium salinity. We suggest that the hypersaline conditions pose greater stress for the animals than the hyposaline conditions because of the higher metabolic activities required for tissue volume regulation.
The muskrat (Ondatra zibethicus) is a small, semi-aquatic rodent notable for its scent glands, which secrete a substance containing muscone. Melatonin (MLT) has been demonstrated to reduce oxidative stress, inflammation, and apoptosis. However, its role in the development of muskrat scent glands remains unclear. This study investigated the effects of 20 mg MLT on the scent glands of muskrat. The results showed that administration of 20 mg MLT resulted in polarized changes in gland weight: some individuals (M-A group) exhibited a decrease in gland weight, while others (group M-B) showed an increase. We observed that MLT treatment significantly upregulated the mRNA levels of PI3K, Bcl-2, and JNK in the scent glands of the M-A group. However, MLT did not demonstrate significant activation of the downstream signaling pathways of PI3K (Akt, p21, CDK1, and Cyclin B1), mitochondrial apoptosis markers (Bax, Caspase9, CytC), or the FGF 20-H-Ras-MAPK 1 signaling axis. Our findings provide preliminary insights into the impact of MLT on the development and secretion of scent in muskrat, offering important reference points for future related research.
Many animals undergo irreversible ontogenetic color changes (OCCs), yet these changes are often overlooked despite their potential ethological relevance. The problem is compounded when OCCs involve wavelengths invisible to humans. Wall lizards can perceive ultraviolet (UV) light, and their conspicuous ventral and ventrolateral coloration-including UV-reflecting patched-likely serves social communication. Here, we describe OCCs in the ventral (throat and belly) and ventrolateral (outer ventral scales, OVS) coloration of juvenile common wall lizards (Podarcis muralis) as perceived by conspecifics. We measured reflectance in hatchling and yearling lizards raised under semi-natural conditions and used visual modeling to estimate chromatic distances within individuals and across life stages (i.e., hatchlings, yearlings, and adults). Hatchlings typically exhibit UV-enhanced white (UV+white) on their ventral surfaces (throat, belly, and OVS), a color that is likely discriminable to conspecifics from the most frequent adult colors in the throat (i.e. orange, yellow, and UV-reduced white; UV-white) and OVS (i.e., UV-blue). The prevalence of UV+white decreases with age, with the decline being less pronounced in female bellies. OCCs to UV-blue in the OVS are more apparent in males than in females and appear delayed relative to changes in the throat and belly. While throat colors in yearlings are indistinguishable to conspecifics from adult throat colors, yearling UV-blue patches remain chromatically distinct from those of adults. This delay may reflect variations in the mechanisms of color production or distinct selective pressures acting on these patches. Overall, our results show that OCCs in P. muralis fulfill a key requirement for social signals by being perceptible to conspecifics. This supports the hypothesis that OCCs may play a role mediating interactions between juveniles and adults, as well as delaying the onset of colors involved in social communication.
The serine/threonine phosphatase PP1γ2 plays a critical role in modulating epididymal sperm maturation and motility. Our previous work demonstrated that PP1γ2 regulates these processes in tree shrews via phosphorylation and dephosphorylation. This study further investigates the interactions among PP1γ2, SRC tyrosine kinase, and protein kinase A (PKA), along with their molecular mechanisms in regulating epididymal sperm motility in tree shrews.Using Western blotting, immunokinase assays, co-immunoprecipitation, and Ser/Thr phosphatase activity assays, we characterized key signaling dynamics. Results showed that Ser/Thr phosphatase activity was significantly higher in caput than in cauda epididymal spermatozoa (p < 0.05). Inhibiting PKA and SRC significantly increased Ser/Thr phosphatase activity and reduced cauda sperm motility (p < 0.05). Conversely, SRC activation with sc-3052 significantly reduced phosphatase activity in caput sperm (p < 0.05). We also found that SRC interacts with PP1γ2 in caudal sperm, and that both SRC and PKA activities were higher in caudal than in caput sperm, with SRC acting downstream of PKA. These results suggest that SRC kinase regulates sperm motility by inhibiting PP1γ2-mediated Ser/Thr phosphatase activity, under the regulatory control of PKA. This study provides a foundation for further investigation into PP1γ2's functions and reproductive regulatory mechanisms in tree shrew sperm.
Infectious diseases represent a major threat to the survival of endangered sea turtles. The immune response in these animals is configured early in development and is heavily influenced by the incubation environment. While maternal traits are known to influence offspring immune function in some reptiles, their role in shaping immune responses in sea turtle hatchlings remains poorly understood. The hemolytic capacity, a key component of the innate immune system, shows stability across incubation environments, suggesting that it might be shaped by maternal factors rather than by environmental variation. Herein, the relationship between the hemolytic capacity of hatchlings challenged with lipopolysaccharide (LPS) and maternal characteristics, including hemolytic response and body size, was studied. Blood samples and morphologic measurements were collected from nesting females over 2 years. Each clutch was entirely relocated to individual shaded nests for incubation. Upon emergence, one hatchling per nest was injected intraperitoneally with phosphate-buffered saline (PBS) and another hatchling with LPS. 4 h later, hatchlings were euthanized and blood samples were collected. The results showed that hatchling's hemolytic capacity was positively associated with maternal hemolysis and body mass, but negatively linked to maternal straight carapace length. Lipopolysaccharide challenge did not significantly modify the hemolytic capacity of hatchlings. Although based on a limited sample size due to the species' protected status and technical constraints of ecoimmunological research in wild animals, these findings suggest a possible influence of maternal attributes on offspring immune function. They also suggest that hemolytic capacity is a robust early-life immune defense in hatchlings.
Assessments of the interplay between physiology and whole-organism performance are fundamental to understand how individuals function in different ecological contexts. Here, we investigated the relationship between locomotor performance, androgen levels, and metabolic capacity of muscle tissues in the lizard Tropidurus catalanensis. We hypothesized that faster individuals would exhibit higher circulating androgen concentrations and greater metabolic capacity in skeletal and cardiac muscles, regardless of body size. We measured morphological variables, maximum sprint speed (v), plasma testosterone concentration, and the maximum activity of the enzymes lactate dehydrogenase (LDH) and citrate synthase (CS) in the gastrocnemius, iliofibularis, and cardiac muscles of adult males. We found that intraspecific variations in v were not explained by body size, plasma testosterone concentration, nor by the activity of LDH or CS in skeletal muscles. The absence of an effect of testosterone on locomotion suggests that androgen concentrations may change in response to other factors, such as environmental stressors or reproductive state. Our results indicated that the fastest lizards also had the highest CS activity in the heart. This relationship suggests that cardiac oxidative capacity plays an important role in clearing metabolites in the postexercise recovery phase. We also found a positive relationship between CS and LDH in all tissues, suggesting a functional complementarity between glycolytic and aerobic pathways that should be relevant in situations that require rapid alternation between bursts of speed and endurance, such as predator evasion or thermoregulation. Ultimately, our results highlight the importance of integrating performance and physiological traits to understand interactions between animals and their environment.
Identifying individuals over time and across contexts is essential in many scientific fields. There are a variety of well-established methods for uniquely marking individuals (e.g., visible implant elastomer, barcodes, paint). However, for some species, life history stages, and/or experiments, existing methods are not sufficient. Here, we describe procedures for how two tagging methods-a tattoo ink injection method and a fishing line piercing method - can be used with the youngest, smallest juveniles of the African cichlid fish, Astatotilapia burtoni, which are too small for the methods used with adults. With the tattoo method, we injected tattoo ink into the dorsal muscle. Different colors and injection locations can be used to distinguish among individuals over a period of weeks (up to 4 weeks, average 2.5-3 weeks under our conditions). Because fish this young and small are sensitive to handling and injection, we also include physiological data showing fish recover well from anesthetization and tagging. With the piercing method, very thin fishing line is threaded through the dorsal muscle and tied into a barbell or loop. Unique colors and patterns can be used to distinguish among individuals over a period of months. Because a physical tag might impede normal movement in a very small fish, we also include data from an open field exploration test showing similar behavior between tagged and control (non-tagged) juveniles. We expect these effective and inexpensive methods to be useful for a variety of small species and will facilitate early-life, developmental, and longitudinal research.
Systematics has become an essential aspect of managing and conserving species from the order Crocodilia. All members of the group are listed in CITES appendices, and to control illegal traffic of animals and subproducts, we must be able to correctly assess the specific identity of the samples. Genetic DNA barcoding is a very efficient tool for species identification in the animal kingdom, based on the sequencing of a region of a mitochondrial gene, the Cytochrome oxidase subunit I (COI). Our principal aims were to design specific primers that allow obtaining this sequence from the genetic material of the caiman species and test the potential utility of barcoding in forensic studies, as well as verify the correct identification of different collections. We successfully obtained barcodes using our designed primers to amplify caiman samples, studying a fragment of 610 bp. We also compared sequences (N = 290) from public databases of all the species included in the Order Crocodilia, obtaining a tree that resulted in a similar current crocodilian phylogeny. The primers designed can be applied to obtain barcodes from samples of other crocodilian species, and this information can contribute significantly to forensic and systematic studies.
Fungal pathogens pose a growing threat to vertebrate biodiversity. In snakes, Ophidiomyces ophidiicola (Oo) has garnered particular concern, although its impact in Europe remains poorly understood. We conducted a season-long, standardized survey of dice snakes (Natrix tessellata) along the northern shore of Lake Como (Italy) to quantify Oo and ophidiomycosis prevalence, identify the circulating strain, and explore the association with environmental, morphological and behavioral traits. Between March and October 2024, we collected 96 N. tessellata samples (23 sheds and swabs from 73 live individuals; scale clips were also collected from 60 out of the 73 live individuals). These samples were analyzed through qPCR, histopathology, and direct field observations. After excluding four recaptures, the dataset comprised 92 N. tessellata samples (23 sheds and swabs from 69 individuals), of which 49 tested positive for Oo (53.3%). Among live individuals, 26 tested positive (37.7%). Of these, 21 showed clinical signs (i.e., skin lesions; 80.8%), and histology confirmed ophidiomycosis in 10 of 20 tested Oo-positive samples (47.6%). Among the five Oo-positive snakes without skin lesions, only one showed histological evidence of ophidiomycosis. This resulted in "at least apparent" ophidiomycosis (i.e., pooling the case-classification categories "Apparent ophidiomycosis", "Ophidiomycosis" and "Ophidiomycosis and Oo shedder") being confirmed in 22 out of 69 live snakes (31.9%), corresponding to an overall disease prevalence of 23.9% (22 out of 92) across the full sample set. All sequenced samples belonged to clade II. Bayesian models revealed that skin lesions predicted both Oo detection and ophidiomycosis, while snout-vent length was inversely related to both pathogen presence and disease, suggesting age-linked susceptibility. Both Oo-positive and diseased snakes had lower body temperatures but showed no clear preference for warmer substrates, suggesting limited or absent behavioral fever. Body-condition index (BCI) did not differ between Oo/disease-positive and Oo/disease-negative snakes, suggesting possible host tolerance. An assessment of antipredator behavior revealed a marked reduction in musking among Oo-positive snakes, potentially compromising antipredator defenses. Our findings identify N. tessellata as a possible model for European ophidiomycosis research and highlight the need for multi-season capture-recapture studies.
Body size strongly influences the life history, behavior, and ecology of vertebrates, yet few studies have quantified biomechanical performance across ontogeny, and turtles are rarely examined in this context. The Northern Giant Musk Turtle (Staurotypus triporcatus), which inhabits a wide range of wetlands throughout much of Central America, faces frequent predation attempts from crocodiles (Crocodylus moreletii and C. acutus) and consumes a diet dominated by hard-bodied prey (e.g., gastropods, palm seeds). Using a force transducer and high-speed camera, we quantified maximum bite performance and lunge kinematics across a broad size range and among five populations of Northern Giant Musk Turtles. Bite force scaled positively with straight carapace length but did not vary among populations or sexes, despite noticeable morphological variation among populations. Most morphometrics scaled with negative allometry relative to straight carapace length, except shell height, which scaled isometrically. These results suggest that increasing shell volume may be prioritized over other morphological traits, possibly reflecting the importance of shell morphology in surviving predation attempts, maximizing female reproductive capacity, or both. Additionally, lunge speed was independent of body size, suggesting that juveniles may compensate for their small size by lunging at velocities comparable to adults. Together, these findings highlight the complex scaling relationships of S. triporcatus and underscore the interplay between morphology, performance, and ecology in shaping survival and reproductive strategies.
The southern alligator lizard ( Elgaria multicarinata ) exhibits prolonged mate-holding behavior. This behavior maybe be underpinned by a phenomenon known as sustained force, observed in the jaw muscles of this species, in which the muscle fails to relax between subsequent contractions. However, it is not clear if sustained force is unique to the jaw muscles used in mate-holding, or what the mechanisms responsible for this phenomenon are. In situ and in vitro muscle preparations were used to determine peak force, sustained force, and relaxation rate in the jaw-adductor complex, the iliotibialis 2 (IT2), and the gastrocnemius muscles of E. multicarinata during repeated contractions to determine if sustained force is unique to the jaw. There was a significant effect of muscle on sustained force with only the jaw muscles exhibiting sustained force. To determine if sustained force was due to a slowing of relaxation or the engagement of a passive element such as the molecular spring titin, the inter-contraction interval was increased in the jaw-adductor complex to allow for greater relaxation time. There was a significant effect of inter-contraction interval on sustained force with sustained force being lost and the muscle fully relaxing and force returning to baseline between contractions with a longer inter-contraction interval. The uniqueness of sustained force to the jaw muscle provides support for it being an adaptation for mate-holding that may observed in multiple vertebrate groups. The loss of sustained force with increased inter-contraction interval implicates changes to relaxation process in the mechanism of the development of sustained force. This suggests that this is a fundamentally different mechanism from the catch mechanism used for prolonged maintenance of force in some invertebrates.
Exposure to altered nighttime lighting conditions has become common in today's modern world. Light at night disrupts circadian processes that govern feeding patterns, sleep/wake cycles, and metabolic homoeostasis, increasing the risk of developing pathologies associated with cardiometabolic disease. Yet, the underlying mechanism(s) responsible for mediating the resulting physiological outcomes are not clear. Mitochondrial function may provide valuable insight into the physiological costs associated with light at night, given that mitochondria contribute to variation in metabolic performance that underpin human diseases. In this study, 36 male and female wild-derived house mice (Mus musculus) were exposed to continuous light, darkness, or a control light cycle for 6 weeks. We examined animals' bioenergetic capacity at the whole-organism and subcellular level while also measuring changes in body condition and oxidative damage. We found that 6 weeks of constant light and darkness resulted in negligible changes in all our variables of interest. We did not detect strong mitochondrial responses in the liver or skeletal muscle of either sex exposed to constant light or darkness. Furthermore, we did not detect any difference in mitochondrial volume or lipid peroxidation in the liver between treatment groups. Lastly, there was no difference in body condition between treatment groups. Our data indicate that wild-derived mice are able to circumvent challenges of an altered light environment and escape physiological consequences.
Immune-neuroendocrine characteristics can be used to classify individuals according to their physiological profiles or phenotypes (INPs). In avian models such as quail and domestic chickens, three subgroups based on INPs have been defined: Lewis-like (pro-inflammatory polarization), Fischer-like (anti-inflammatory polarization), and an intermediate INP. This study investigates the stability and alterations of INPs throughout ontogeny, from juvenile to adult stages in four time-points including an exposure to unpredictable and diverse chronic stress (CS) during early adulthood. We measured corticosterone levels, pro- (IFN-γ and IL-1β) and anti-inflammatory (IL-13, IL-4) cytokines, phytohemagglutinin (PHA-P) lymphoproliferative response, anti-sheep red blood cells antibody (Ab SRBC) response, and leukocyte distribution frequency. Cluster analyses were conducted to classify bird based on their similarities across all analyzed variables, to thereby establish their INP at each time point. The extreme Lewis- or Fischer-like profiles were less represented in juvenile and pre-stress adult birds showing a higher proportion of individuals with an intermediate profile. Following CS exposure, the prevalence of Lewis-like and Fischer-like profiles increased. This shift persisted 10 weeks later as birds matured to an advanced egg-laying stage, with females predominantly exhibiting the Fischer-like INP, and males the Lewis-like INP. The observed shift in INP distribution following CS towards more polarized Lewis- and Fisher-like profiles implies a more even representation of the three observed profiles and may reflect inter-individual differences in physiological response to CS associated to particular coping strategies. A more even INPs distribution could provide the population with a greater advantage when facing diverse environmental challenges.
Light is an important factor affecting the behavior and physiology of organisms. As a phototactic organism, studying the effects of different colors of light on the mating, development, and reproduction of Drosophila melanogaster helps elucidate the important influence of spectral sensitivity on organisms. This study explored the effects of white light (400 lux, control), green light (400 lux, wavelength to which fruit flies are most spectrally sensitive), red light (400 lux, wavelength to which fruit flies are least spectrally sensitive), and dim-green light (225 lux, green-band irradiance matched to the white control) on the sexual vitality, development, and reproductive capacity of fruit flies under group-housed conditions. The results revealed that 1 h of green light exposure per day significantly shortened mating latency and mating duration, accelerated pupation time, raised the egg‑to‑pupa conversion rate, and increased the number of offspring. In contrast, there was no significant difference in various indicators between the white, red, and dim-green light groups. This study explored the important role of light intensity and spectral sensitivity in regulating the mating and reproduction processes of fruit flies and provides more evidence for comparative research on the behavioral and physiological effects of light on different organisms.
Rapidly increasing anthropogenic CO2 can impose physiological challenges for fish species that are thought to be tolerant. We tested the hypothesis that elevated pCO2 will affect the routine activity and escape response by affecting energy metabolism and/or the muscle physiology of coastal fish. We exposed threespine stickleback (Gasterosteus aculeatus) to pCO2 of ~ 700 µatm (pH 7.9 representing current levels), ~ 1400 µatm (pH 7.6 representing upwelling events) and ~ 3500 µatm (pH 7.3 representing a future predicted scenario for coastal areas) for 2 weeks. Baseline activity was significantly higher in fish exposed to 1400 µatm compared to the control at both sampling points, while the escape response was lower (p < 0.05). Metabolic rate was not different (p > 0.05), but lactate dehydrogenase activity was significantly higher at 3500 µatm compared to control fish after the first week (p < 0.05), while no difference was found in muscle histology between treatments or time points. Our study demonstrates that the baseline activity and escape responses of adult marine coastal fish were temporarily affected by the current level of ocean acidification, but this was not due to changes in metabolism or muscle function, but potentially neuronal effects of high pCO2. Our study shows that ocean acidification might affect predator-prey interactions during current upwelling events and in the future.
