Journal of Experimental Biology最新文献

Predicting success is a common goal for ecologists and sports scientists, yet these disciplines rarely interact. Sports scientists often use tests of closed-skill or game performances, but these are often critiqued for their inherent uncertainties in predicting success. In contrast, ecologists embrace variance, measuring traits under controlled conditions to make probabilistic predictions of success. Integrating ecological perspectives could enhance team selection efficiency in youth sports. Here, we demonstrate this concept using territorial contests in crayfish. Like sports, individual traits in crayfish can be measured rapidly but do not perfectly predict contest outcome. First, we simulated populations of 100 male and 100 female crayfish that competed in 20 rounds of contests and estimated how many individuals must be selected to ensure the top 10% of performers are included. Selections were based on individual traits (body length, claw size and strength) and/or contest outcomes. When few contests have occurred, the top 10% of individuals were most efficiently selected on individual traits but increasingly more on contests as rounds progressed. Empirical data supported these theoretical simulations. We staged 10 rounds of contests among 27 male and 32 female Cherax destructor. After two rounds, ∼21 individuals were needed to capture the top 3; by round 10, ∼5 were required. Taken together, our study provides an initial but compelling demonstration of how ecological models can help improve talent identification strategies in sport. Such an adaptive selection framework efficiently narrows down selection of high-performing individuals under uncertainty and has the potential to be applied to reintroduction and translocation strategies in conservation.

The intertidal zone experiences significant fluctuations in temperature and pH, posing significant challenges to marine organisms. Perinereis aibuhitensis, a eurythermal and euryhaline polychaete inhabiting estuaries, where pH is often lower than in the open ocean and further reduced within sediments, has probably evolved robust adaptations to such stresses. We investigated its behavioral, physiological and metabolic responses under combined temperature (15°C, 20°C, 25°C) and seawater acidification (pH 5.5, 6.7, 8.0) conditions. Perinereis aibuhitensis exhibited stable behavioral performance and metabolic homeostasis under control conditions (20°C, pH 8.0). It maintained burrowing activity and activated physiological and metabolic regulation at pH 6.7. However, its motion significantly declined with failed behavioral regulation under pH 5.5: radial undulation duration decreased by 97.63% and pumping volume by 97.97%. Energy was reallocated toward antioxidant defense and maintenance of basic physiological functions, reflected in downregulation of the γ-aminobutyric acid (GABA) metabolic pathway alongside upregulation of ABC transporters and arachidonic acid metabolism. At 25°C, combined warming and acidification disrupted energy allocation under pH 5.5. This disruption was accompanied by enhanced motion, which further constrained energy allocation, leading to significant oxidative damage (malondialdehyde content increased by 94.54%) and concurrently impairing tryptophan metabolism, glycerophospholipid metabolism and ABC transporter function, with the entire cascade ultimately collapsing its adaptive mechanisms. This demonstrates that severe acidification, especially under warming, compromises bioturbation and metabolic stability in P. aibuhitensis, with potential negative impacts on polychaete communities and their vital ecological functions in intertidal ecosystems. Our findings provide critical insights for predicting climate change impacts on marine infauna.

Environmental signals exert influences not only on the current generation, but also extend to subsequent generations, even when these signals no longer persist. These transgenerational effects can be mediated through several mechanisms, including epigenetic inheritance and composition of the gut microbiome. In this study, we investigated the contribution of the microbiome to diet-induced transgenerational effects on reproductive dormancy. Multiple strains of Drosophila simulans were subjected to a shift from a sugar-rich to a sugar-poor diet and the impact of this diet switch on dormancy was determined over multiple generations. Consistent with significant transgenerational effects, we observed a gradual reduction in dormancy incidence with an increasing number of generations exposed to the new, sugar-poor diet. Despite the variation in dormancy induced by the dietary shift, the microbiome composition remained largely stable. Consequently, we conclude that these transgenerational effects are not determined by changes in the bacterial microbiome composition.

As climate change intensifies drought, understanding how animals maintain fitness under water stress is essential for predicting ecological resilience. Terrestrial animals use diverse behavioural and physiological strategies to avoid dehydration, yet the associated physiological and fitness costs remain poorly understood. Because water balance is tightly linked to nutrient acquisition and metabolism, mechanisms that enhance hydration may alter how animals allocate key macronutrients across vital functions. Here, we investigated how maintaining water balance - via increased water intake or reduced water loss - shapes nutrient allocation and trade-offs in the cabbage white butterfly (Pieris rapae), a species in which males transfer nutrient- and water-rich nuptial gifts to females during mating. Using controlled humidity treatments and stable-isotope tracing, we quantified how the hydric environment and mating status influence female allocation of nutrients - including nuptial gift-derived amino acids - to storage, fecundity and catabolism. We found that females in dry environments maintained water balance largely by acquiring nuptial gifts and by reducing respiratory water loss. However, dry conditions still altered nutrient allocation: females invested more lipids into eggs at the expense of long-term storage, and they reduced catabolism of an essential amino acid derived from the nuptial gift. These results show that mechanisms supporting water balance can indirectly reshape nutrient-use strategies, revealing physiological trade-offs that may influence longer-term fitness. More broadly, our findings highlight the tight coupling between water and nutrient economies and emphasize the need for a nutrient-explicit framework for understanding how animals cope with increasing aridity.

Developmental biology and evolutionary theory have traditionally emphasized gene mutations as the primary drivers of new traits, with natural selection shaping the resulting variation. However, recent insights highlight the role of environmental factors during development in shaping trait evolution. In this Commentary, I introduce the 'environmentally dependent developmental induction' (EDDI) model, which proposes that phenotypic evolution is driven not only by genetic changes but also by environmentally induced modifications to the core developmental program. Using cardiogenesis as an example, I argue that environmental triggers such as oxygen levels and mechanical forces expand the genotypic toolkit available to heart development, activating new pathways that lead to the emergence of novel cardiac structures. These lineage-specific environmental changes might thus influence the differentiation of cardiac progenitor cells, resulting in modifications to the cardiac building plan. The EDDI model provides a novel explanation for how the basic cardiac plan was expanded during evolution while simultaneously explaining why cardiogenesis is vulnerable to malformations, even in the absence of genetic defects.

Hydrostatic pressure in the marine environment increases linearly with depth, and organisms at 1000 m experience pressures 100 times greater than those at sea surface level. Previous work has examined the effects of pressure on neuron and nervous system activity in some organisms, as well as the various biochemical adaptations of deep-water species. However, the effects of pressure on other biological tissues are not well understood. In this study, we took the shallow-water jellyfish Aurelia aurita and exposed it to pressures of up to 30 MPa (equivalent to 3000 m depth). We observed behavioral and kinematic changes that are likely due to mechanical effects of hydrostatic pressure on the swimming muscles and bell mesoglea. The pulsation rate of the bell was found to correlate with hydrostatic pressure, although the effect was small relative to the variability between individuals. Both the maximum contraction and relaxation rates of the bell were found to be significantly reduced at high pressure (30 MPa) relative to near-surface pressure (<1 MPa). The changes in pulse frequency and relaxation rate were both fully and immediately reversed upon release of pressure, but the change to contraction rate was not. Because bell contraction is controlled by muscle fibers and relaxation is controlled by elastic fibers in the mesoglea, the differential effects on contraction versus relaxation suggest that different tissues are affected differently by pressure. This opens the way for future work on how individual organisms can adapt to different environments.

The mountain pine beetle (Dendroctonus ponderosae) is an eruptive bark beetle that overwinters as a freeze-avoidant larvae under the bark of pine hosts. In recent years, D. ponderosae has undergone a climate change-driven range expansion into previously unsuitable habitats with historically more severe winter conditions. Dendroctonus ponderosae overwinters in a non-feeding dormant phase, and energy use is important to post-overwintering fitness. Little is known about how D. ponderosae balances energy supply and demand during overwintering. We quantified shifts in energy reserve (supply) and Complex I activity (as an index of demand) in D. ponderosae during natural overwintering and simulated early winter onset. We collected D. ponderosae larvae from infested lodgepole pine in the autumn (October), winter (January) and spring (April), and sampled a portion of these animals. During autumn and winter, another set of larvae were subjected to either mild overwintering conditions at 6°C or an experimental cold stress of stepwise decreases in temperature to test how an early onset of cold conditions influences the energetic status of overwintering individuals. Dendroctonus ponderosae larvae exposed to natural winter conditions accumulated lipids and proteins early in overwintering, which were then available for later use. Early exposure to cold stress in the autumn before full winter acclimatization, however, depleted energy reserves. These findings suggest that the timing and regulation of seasonal acclimatization in D. ponderosae have important implications for energy use that can influence subsequent fitness, and thus warming of the overwintering period may facilitate early winter feeding and enhance energy gain of D. ponderosae larvae, which could further exacerbate the spread and impact of this pest.

The effect of global warming on rising aquatic temperatures is producing ever-steeper thermoclines. Fish encountering these sharp changes in water temperature might experience an acute-warming stress. Temperature is the most dominant environmental factor affecting heart function in fish, and without compensatory mechanisms as temperatures rise (e.g. higher heart rate), it could imperil cardiovascular performance. To enhance heart function during acute warming, fish release adrenaline to boost Ca2+ influx in heart cells (cardiomyocytes). However, the relationship between acute warming, elevated heart rate, adrenergic stimulation and intracellular Ca2+ handling is not well understood at the cellular level. In this study, we investigated the interplay between these key functional drivers in isolated ventricular cardiomyocytes of rainbow trout, at either their acclimation temperature of 10°C or following acute warming (22°C). A subset of cardiomyocytes from each group was treated with adrenaline, sarcoplasmic reticulum (SR) inhibitors (that inhibit intracellular Ca2+ cycling via the SR) or both, whereas pacing frequency was simultaneously increased (simulating faster heart rate). Using epifluorescent microscopy, we measured intracellular Ca2+ transients (Δ[Ca2+]i) and Ca2+-cycling kinetics. Across all pacing frequencies, we found no differences in Δ[Ca2+]i between control (untreated) 10°C and 22°C cardiomyocytes, and that adrenaline had a positive inotropic effect at both temperatures, but was less effective at 22°C. SR inhibition had no effect on Δ[Ca2+]i, but was associated with a greater incidence of irregular Δ[Ca2+]i. Our data suggest that acute thermal stress can disrupt Ca2+-homeostatic mechanisms in trout cardiomyocytes, potentially disrupting whole-heart contractility as global temperatures rise.

The two huge Mauthner neurons (MNs) form the center of the fast-start network in the hindbrain of fish. Their activation initiates a rapid turning maneuver, the so-called C-start, within milliseconds. Here, we recorded intracellularly from the MNs of goldfish to quantify the spatiotemporal flow of visual information from the two eyes, the optic nerves, and the ipsilateral and contralateral hemispheres of the optic tectum (OT) to each MN. Strong light flashes delivered to one eye induced postsynaptic potentials (PSPs) in both MNs after a delay of 35 ms. By directly stimulating the optic nerve, we show that most of this time (80%) is needed for transduction and processing in the retina. Visual stimulation of the eye and direct electrical stimulation of the optic nerve was effective regardless of which eye or which optic nerve was stimulated. Stimulating any region of the ipsilateral or contralateral OT caused PSPs in both MNs. Remarkably, the PSPs induced by our brief visual and electrical stimuli were of remarkably complex structure and long duration. The connectivity pattern and PSP durations we describe here suggest an arrangement that supports a high degree of flexibility in C-start directionality and the integration of sensory information that arrives with different delays in a natural encounter.

Despite its economic and ecological importance, little is known about the learning abilities of the South American bumblebee Bombus pauloensis. To date, no studies have explored the visual learning capacity of its foragers, potential differences between non-pollen and pollen foragers, the effect of body size on learning, or male learning abilities. Here, we investigated the visual learning performance of workers, taking into account forager type (pollen versus non-pollen foragers) and body size. As a complementary analysis, we assessed the same variables in males. Our results show that both female foragers and males of this South American bumblebee can learn to associate a specific color with a sugar reward and do not exhibit color bias for the tested colors (blue and yellow). We found no significant differences in color learning ability or body size between pollen and non-pollen foragers. Additionally, body size significantly influenced visual learning performance during the testing phase. This study provides new insights into the visual learning abilities of both foragers and males in the South American bumblebee Bombus pauloensis, enriching the understanding of cognition of native pollinators.