A sensitive sentinel: Chironomus xanthus as a bioindicator of freshwater sediment quality in Southern Latin America.

NR5A nuclear receptors coordinately regulate locust metamorphic transition and fecundity.

Abstract The hedgehog grain aphid (HGA), Sipha maydis Passerini (Hemiptera: Aphididae), is a significant pest of cereal crops and is present in the United States. Like other aphids, it exhibits wing polymorphism, producing both winged and apterous morphs influenced by environmental factors such as temperature and host plant quality. This study evaluated the effects of temperature and host plant species on life history traits and wing induction under controlled laboratory conditions. Two weeks after nymphs being placed on host plants, a significant interaction between host plant and temperature was observed for number of aphids and winged morph proportion. The highest aphid populations occurred on wheat and barley at 30 °C (356 ± 70 and 344 ± 42, respectively), while sorghum supported consistently lower populations, peaking at 15 °C (37 ± 4). Wing induction was greatest on sorghum and barley at 25 °C (26.9 ± 7.5% and 10.1 ± 1.6%, respectively), while no differences were observed among temperatures on wheat (x̄ = 9.2 ± 2.0%), suggesting that the host may have induced a stress-related morphological response to promote dispersal, particularly on sorghum, the least suitable host. Supercooling points (SCPs) of winged and apterous adults reared at 25 °C were also measured. While SCPs did not differ significantly between morphs, they varied by host plant: aphids reared on wheat froze at −16.7 °C, compared to −18.7 °C on sorghum and −18.6 °C on barley, indicating host-mediated cold tolerance. These findings underscore the ecological plasticity of HGA and provide valuable insights for improving outbreak prediction and integrated pest management strategies across diverse environmental conditions.

Abstract Metabolism and activity should be tightly linked; metabolism provides energy for activity, and general activity may often affect the rate at which animals acquire resources that drive metabolism. However, little is known about the ways metabolism and activity covary in ecologically germane contexts in natural populations. To explore this in more detail, we collected repeated measures of instantaneous metabolic rates and associated changes in activity levels in house sparrows (Passer domesticus) in response to shifts between stimulated and unstimulated contexts. Using a reaction norm approach and mixed-effects models, we examined among-individual variation in metabolism during inactivity (intercept/resting metabolic rate; RMR) and the rate of change in metabolism associated with changes in activity and time since a transition in the level of external stimuli (slope/metabolic plasticity). Individuals exhibited significantly repeatable differences in both inactive metabolism and metabolic slopes with respect to time (but not activity) during stages of the experiment designed to ramp up or ramp down responses. Individuality persisted after accounting for potential causes of variation. Our results indicate consistent differences in how individuals alter metabolic rate across time after changes in stimulation, raising questions about underlying processes contributing to and maintaining such variation. Similar analyses incorporating physiological and life history traits may reveal important relationships that allow for the maintenance of individual variation in metabolic plasticity. Our framework of treating metabolic rate as a reaction norm across time and activity uncovers ecologically relevant individual variation that holds promise for further investigations into the context-dependent link between metabolism and behavior.

Significant losses of managed honey bees (Apis mellifera) have been documented in recent years, driven by multiple stressors including parasites, pesticide exposure, and environmental change. To mitigate escalating hive losses, some beekeepers in Southern California collect and propagate locally occurring, free-living colonies, often referred to as "survivor" or "Californian" honey bees, that persist with limited human intervention. We conducted a cross-sectional survey of beekeepers managing colonies in Southern California to compare management practices and reported outcomes across stock types. Beekeepers clustered into 3 groups: those managing only commercial colonies (35.3%), only Californian colonies (29.4%), or a mixture of both (35.3%). Respondents indicated that management practices had been adapted when keeping Californian honey bees and reported reduced expenditures associated with queen replacement and disease management. These bees were widely perceived to possess beneficial traits, including greater colony persistence and potential climate resilience. However, quantitative analyses did not detect significant differences in reported parasite prevalence among stock types, highlighting the importance of distinguishing perception from measured outcomes. Additional studies are needed to evaluate characteristics such as defensiveness, productivity, and seasonal survival using standardized approaches. Overall, our findings suggest that Californian stock may represents a viable and potentially cost-effective component of sustainable apiculture. Further research is required to clarify the ecological, genetic, and physiological mechanisms underlying beneficial key life-history traits, which may involve tolerance, resistance, or their interaction. Such knowledge would provide a foundation for future breeding efforts aimed at developing honey bee populations that are robust to multiple ecological stressors.

Dispersal strategies are critical life history traits influencing bio-geographical, ecological, and evolutionary patterns and processes including range-expansion and contractions, abiotic and biotic interactions, and rates of speciation. Yet, dispersal strategies are challenging to study because they are complex suites of morphological, physiological, and behavioral traits. Thus, our understanding of how and why dispersal strategies evolve remains incomplete. Wing dimorphisms have evolved repeatedly within nearly every major insect order and are characterized by the co-occurrence of fully winged dispersing and short- or wingless non-dispersing morphs within species or populations, making them ideal model systems for studying the evolution of alternative dispersal strategies. Forty years ago, Derek Roff proposed that wing dimorphisms are a threshold trait which evolves as an intermediate step on the trajectory toward complete loss of flight, driven by the high physiological and life history costs of dispersal. Here, we synthesize recent mechanistic studies of wing-morph determination along with new phylogenetic reconstructions of wing dimorphism in the well-developed model Gryllus field crickets to update and refine our evolutionary hypotheses and identify critical areas for future inquiry.

Understanding lineage divergence is crucial for uncovering cryptic biodiversity. Adaptive divergence, geographic isolation and life-history traits drive speciation in heterogeneous environments. The gentoo penguin complex (Pygoscelis spp.), historically treated as a single species, provides an ideal system to examine divergence across its full distribution. Here, we show the existence of four divergent evolutionary lineages (northern, southern, southeastern, and eastern), supported by phylogenomic and lineage-specific selective pressures, despite ancestral gene flow. South Georgia and Macquarie individuals whose status has been debated, were included. Genomic scans reveal lineage-specific signals of positive selection in genes related to thermoregulation, oxygen transport, metabolism, and skeletal development, consistent with ecological and morphological differentiation across the Antarctic Polar Front. Future niche projections indicate severe habitat losses for three lineages, whereas the southern gentoo may expand its range. We propose a taxonomic revision recognizing four distinct gentoo penguinspecies, including Pygoscelis kerguelensis sp. nov., with important conservation implications.

What feathers reveal about metal concentrations in bird tissues: An analysis of the global literature.

Figs and fig wasps represent one of the most intimate examples of plant-pollinator coevolution. As figs diversified into geographically isolated populations, both figs and fig wasps underwent selective pressures driven by local adaptation and coevolution. Ficus pumila comprises two ecologically distinct varieties: the creeping fig (F. pumila var. pumila), which is widely distributed across the lowlands of East Asia, and the jelly fig (F. pumila var. awkeotsang), endemic to Taiwan and found at mid-elevations. To elucidate how codiversification with fig hosts influences the evolutionary trajectories of fig wasps, we analyzed the genomes of Wiebesia sp. 2 and sp. 3, the respective pollinators of creeping fig and jelly fig. Our demographic analysis indicates that vicariance during the Last Glacial Period facilitated ecological differentiation between these two fig-fig wasp pairs. Through comparative and population genomic analyses, we identified selection signals linked to habitat adaptation, with evolutionary rates corresponding to the life history traits of their host figs. Variations in host preference behavior, chemosensory gene expression, and adaptive duplications in olfactory receptors highlight potential mechanisms for adaptation to host floral scents. These findings collectively underscore how the obligate mutualism between figs and their pollinating wasps allows the ecological traits and habitat preferences of fig hosts to shape the evolutionary pathways of their pollinators, leaving distinct molecular imprints in the fig wasp genomes. This study demonstrates the capacity of tightly intertwined life cycles between plants and pollinators to drive adaptation and diversification.

Choice of traits defines the scope for assisted evolution of corals under climate change.

Plastic pollution poses a threat to marine mammals across the globe. However, quantitative research on the impacts of plastic pollution in marine mammals is lacking because of the ethical and practical issues that prevent experimentation on these species and the opportunistic nature of observational studies. Trait-based vulnerability indices offer a way to estimate the relative vulnerability of marine species to environmental stressors based on available knowledge about species life-history traits. To develop a relative global vulnerability index to macroplastic pollution for marine mammals (117 species), we applied an existing framework for assessing species vulnerability to macroplastic based on three components of vulnerability-likelihood of exposure, species sensitivity, and population resilience. We identified 11 traits to assess marine mammal species' likelihood of exposure (three traits), sensitivity (four traits), and population resilience to macroplastics (four traits). Using species trait data, we assigned each species a score for each trait. Weighting all three components of vulnerability equally, these scores were summed to provide each species a relative vulnerability score. On average, sirenians were most vulnerable to macroplastic interactions, whereas pinnipeds and fissipeds were least vulnerable, though within-order variation in vulnerability occurred. Through the global application of this vulnerability framework, we highlight its value for informing research and management needs to better reduce the impacts of macroplastic pollution on marine mammals and marine species more broadly.

Age at first reproduction is an important life-history trait that marks the beginning of reproductive allocation in long-lived organisms and drives patterns of life-history strategies. Demographic factors and environmental conditions likely affect age at first reproduction through multiple pathways: food resources availability and energy storage from birth to recruitment, competition for breeding sites and mate availability. Using a unique 35-year dataset of individual-based mark-recapture data from a wandering albatross (Diomedea exulans) population at Crozet (southern Indian Ocean), we investigated how demographic factors and environment influence age at first reproduction. The population experienced major fluctuations, declining by 50% in the 1970s before partially recovering in the 1980s. It was also exposed to important environmental changes, including variations in large-scale climate phenomena and changes in subtropical anticyclone systems like the Mascarene high pressure system. We used multi-event hidden Markov models to estimate age-specific survival and breeding probabilities for each sex separately. From these models, we estimated the age at first reproduction through absorbing Markov chains while accounting for imperfect detection. We investigated how demographic factors (population density at birth and mate availability at recruitment) and environmental conditions (at birth and recruitment) influenced age at first reproduction through their effects on survival and breeding probabilities. Age at first reproduction declined across cohorts for both sexes from 1970 to the mid-1980s, then stabilized. Females recruited at 9.0 years in early cohorts versus 7.5 years in later ones; males declined from 10.2 to 9.2 years. Environmental conditions at birth, particularly the El Niño Southern Oscillation and the Mascarene high, influenced recruitment timing through delayed effects of natal condition on breeding probability rather than survival. Mate availability strongly facilitated earlier recruitment in both sexes, while natal population density delayed male recruitment specifically. Recruitment timing in wandering albatrosses is shaped primarily by developmental programming during the natal period rather than by immediate environmental triggers at sexual maturity, with mate availability and population density modulating these early-life effects in sex-specific ways. Given that recruitment is an important life-history event linked to population-level reproductive rates, accurate demographic projections require models accounting for cohort-specific effects under changing environments.

Intensively monitored watersheds provide long-term data sets for evaluating land management activities and can also identify causal mechanisms for population-level changes in aquatic species including life history diversity in salmonids. The influence of dam removal (ecosystem restoration), conservation hatchery practices, and an in-river fishing moratorium (i.e., management actions) on life history diversity in salmonids has not been fully evaluated. We used scale and genetic samples collected during intensive monitoring following these management actions in the Elwha River to determine their influence on the expression of life history traits in Oncorhynchus mykiss. We evaluated adult migratory patterns, age at migration, and degree of repeat spawning to determine if they changed through time, in both hatchery- and natural-origin individuals. We also assessed if genetic diversity shifted through time, reflecting demographic changes after these management actions. Using age data from scales, together with run timing data, we identified 39 different O. mykiss life history (hatchery- and natural-origin) strategies in the Elwha River from 2013 to 2024 based on age at migratory events. The number of life history strategies identified increased from 18 strategies during dam removal impacts to 38 strategies after dam removal impacts; however, this difference was largely due to differences in temporal and spatial sampling effort through time. Life history diversity and the increase from during- to post-dam removal impacts were much greater for natural-origin than for hatchery-origin O. mykiss . Although life history diversity appeared to increase over time, overall genetic structure decreased, and diversity was largely unchanged. Resident and anadromous individuals were observed, with anadromous individuals displaying winter and summer migration timing. Winter steelhead smolt age, time spent at sea, total age, and repeat spawning life histories varied by period and origin. Intensive monitoring allowed us to document the combined positive influence of large-scale dam removal, conservation hatchery supplementation, and a fishing moratorium on life history diversification in O. mykiss in the Elwha River.

Links of ploidy with other traits and distributions of nonnative species in North American flora.

Magnetic fields are abiotic environmental factors that can cause a wide range of biological effects at both the cellular and whole-organism levels. In this study, we investigated the effects of a static magnetic field (SMF, 110 mT) on life history traits and antioxidant defence mechanisms during the preadult development of Lymantria dispar. SMF exposure did not affect the mass of younger larvae, whereas older larvae and pupae showed significantly reduced mass compared to controls. Estimated larval mortality was higher in the SMF group, while developmental duration was significantly prolonged in the fifth larval instar and in both male and female pupae. SMF induced stage-dependent modifications in antioxidant defence. Superoxide dismutase activity and catalase activities were significantly increased, predominantly in later developmental stages, while glutathione reductase and glutathione S-transferase showed instar-dependent responses. In addition, the content of total and oxidised glutathione was significantly higher in the fifth and sixth instars of SMF-exposed larvae compared to controls. The study shows that static magnetic field exposure can interfere with normal developmental processes and redox homeostasis in insects, implying potential adaptive mechanisms under stressful conditions.

Plastic pollution is a pervasive global threat, yet population-level impacts on wildlife remain poorly resolved for most taxa. Sable Shearwaters (Ardenna carneipes) offer a rare opportunity, exhibiting some of the highest documented plastic burdens of any seabird and demonstrating clear physiological and demographic harm even at low exposure levels. Their case reveals that the widespread assumption of minimal plastic impact is largely founded on a lack of evidence rather than evidence of no effect, driven by the difficulty of detecting mortality and sublethal effects in complex marine systems. Their shared life history and anatomical traits make their responses to plastics broadly indicative of what many species may experience as global plastic inputs continue to rise. As international policy efforts stall, these findings highlight the urgency of anticipatory, rather than reactive, research and governance. Extreme-exposure systems like Sable Shearwaters provide essential early warning signals that must inform rapid conservation and regulatory action.

Population density often modifies the phenotypes of the members of the population. Such density-dependent phenotypic plasticity can affect basic life history traits of the organisms. In insects, a frequently observed expression of such plasticity is the crowding response (CR), where individuals growing at high densities develop faster and attain lower final sizes compared to those at low densities. This plastic change qualitatively differs from the general stress response where lower final sizes are associated with longer development periods. The adaptive significance of CR, as well as the nature of the cues that trigger CR, remains poorly understood. We performed a series of experiments to identify proximate signals leading to CR in the geometrid moth Hypomecis atomaria, a species in which larvae reared in groups consistently pupate earlier and at lower weights than those reared in isolation. Our findings reveal that CR is also induced in complete darkness, suggesting that visual cues of high population densities do not play a decisive role. CR was triggered when the larvae were separated by a mesh barrier, preventing tactile interaction between them. The presence of heterospecific lepidopteran larvae also triggered CR, though to varying degrees. By contrast, neither the presence of dipteran insects in the rearing environment nor human-inflicted tactile stimulation affected the growth schedules of H. atomaria larvae. We conclude that CR is likely induced either by chemical signals or substrate-borne vibrations caused by other larvae. In any case, CR is not a highly specific response to high densities of conspecifics, nor is it a very general reaction to unspecific disturbances. This allows us to narrow down the set of potential adaptive explanations for the phenomenon.

By limiting the efficacy of selection, random drift is expected to play a major role in genome evolution. Formalizing this idea, the nearly-neutral theory predicts that the ratio of non-synonymous over synonymous polymorphism () within populations, and divergence () between species, should both correlate negatively with . This has previously been tested in mammals and other groups. However, most studies have focused on either or on , thus not addressing the problem across evolutionary scales. In addition, many studies at the macro scale have used life-history traits (LHT) as a proxy of , assuming that large-bodied organisms have lower than small-bodied species. However, this assumption itself has rarely been validated against more objective measures of , such as genetic diversity , in part because estimates are scarce. Here we propose an integrative test of the nearly-neutral predictions on 150 mammalian species, using 6000 orthologous genes, spanning the macro and the micro-evolutionary scale, using for the latter a measure of heterozygosity on each of the assembled diploid genomes. At the micro scale, we observe, for the first time in mammalian nuclear genomes, a relationship between and . At the macro scale, we confirm the positive correlation between and LHT but, more importantly, establish that LHT and are correlated with , although weakly so. Together, these results provide the first global test of the nearly-neutral theory in mammals across time scales, suggesting all variables are correlated with a single hidden variable: .

Most plant viruses depend upon arthropod vectors for their transmission among plant hosts. There are shreds of evidence of insect vectors and host manipulations by plant viruses for facilitating virus transmission. Fig mosaic disease is a globally distributed viral plant disease for which only fig mosaic virus (FMV) has been identified as the causal agent. In this study, we investigated the effect of FMV on the fitness of its mite vector using an age-stage two-sex life table approach, which provided detailed life stage durations of each nymph and adult (both sexes). To do this, the life history traits of the FMV-viruliferous (V) and non-viruliferous (NV) mite colonies on the healthy fig leaves and FMV-viruliferous mites on FMV-infected fig leaves (VL) were analyzed. Seventy pairs of adult mites from each colony (same age) were released on uninfected and infected fig leaves in a Petri dish, and placed in a growth chamber at 28 ± 2°C and 12:12 (L: D) photoperiod. Our results showed that the non-viruliferous mites survived longer, produced higher number of offspring, and showed less mortality, while the viruliferous mites completed their pre-adult development faster than the non-viruliferous mites. Despite these differences, there were no significant differences in the population growth parameters of the viruliferous mites compared to the non-viruliferous mites. This suggests that FMV may exert subtle fitness trade-offs on its vector, balancing potential fitness costs to ensure successful transmission.

Gene drives offer revolutionary potential for the management of problematic plant populations, such as invasive weeds and herbicide-resistant species, by rapidly spreading desired genetic alterations. Two recent studies have provided experimental demonstrations of engineered CRISPR gene drive systems in plants (CAIN and ClvR). However, the successful application of such systems in the field will critically depend on an accurate understanding of plant-specific life-history traits, especially seed dormancy, a ubiquitous yet frequently overlooked eco-evolutionary force. In this study, we develop a comprehensive modelling framework for gene drives in plant populations that incorporates a persistent soil seed bank. We show how the presence of a seed bank can substantially slow gene drive spread but also reduce the genetic load required to achieve population elimination. Furthermore, we show that seed banks substantially increase the required introduction frequency of threshold-dependent gene drives, which could prevent establishment in some cases, yet also provide an intrinsic biosafety mechanism for confining a highly efficient drive to a target population. Our study highlights the need to incorporate seed-bank dynamics into gene drive strategies to ensure realistic predictions and successful field applications.