UNASSIGNED: Valproic acid (VPA) is the most widely used chemical to develop the preclinical model of autism spectrum disorder (ASD). However, in addition to inducing autism, it causes different teratogenic effects like teeth malformation, tail kink, and abnormal body growth in offspring. So far, no study has explored VPA-induced maternal misbehavior, miscarriage, and maternal cannibalism. We aimed to determine the cannibalistic effects of VPA in pregnant female Wistar rats and VPA\'s influence on causing miscarriage frequency.
UNASSIGNED: Our study was conducted on pregnant Wistar rats. On gestation day (GD) 12.5, they were treated with VPA (600 mg/kg intraperitoneal) dissolved in saline at 250 mg/mL concentration. The observations were mean litter size, mean male/female pups, mean mortality, maternal cannibalism, mean number of pups alive, cannibalism of malformed pups, miscarriage, survival analysis of pups, and odds and risk ratio were calculated for deaths observed in both study (control and VPA-treated) groups. The study was conducted till the weaning period.
UNASSIGNED: VPA-exposed pregnant females portrayed significantly decreased litter size (P<0.0001), significantly higher cannibalistic behavior (P=0.0023), and significantly higher cannibalism of malformed pups (P=0.0484) than the control group. VPA had caused complete pregnancy loss (miscarriage) in 5 pregnant females. Moreover, the VPA group\'s mortality percentage (P=0.0019) was significantly higher than the control group.
UNASSIGNED: Overall, VPA has marked teratogenic effects (anatomical and morphological changes in offspring) with maternal behavior disruption, which causes cannibalism in Wistar female rats. The current manuscript findings can aid in investigating the novel mechanisms involved in maternal behavior disruption during the development of the VPA autism model.

Agonistic behaviors are crucial and ubiquitous among animals for the competition of limited resources. Although the study of aggression has been a popular topic, plenty of studies focused on model organisms, and typically on crayfish and lobsters for crustaceans. Variations of the agonistic behaviors and the underpinning eliciting cues of other crustaceans therefore have not been fully explored. In the present study, we targeted Stenopus, a genus of shrimp-like crustaceans that displays prominent agonistic behaviors when encountering conspecifics of the same sex owing to their monogamous social structure. Using S. hispidus (Olivier, 1811) and S. cyanoscelis (Goy, 1984) as representatives, we characterized their agonistic behaviors and fighting pattern, conducted experiments to investigate the contribution of visual, olfactory and tactile cues to inducing aggression, and examined the effects of antennal and antennular ablation on their agonistic interactions. A total of seven agonistic behaviors were documented, where antennal entwining and tactile contact is the major driver and seemingly important cue, respectively, in inducing agonistic behaviors in Stenopus. Although ablation of antennae and antennules did not inhibit fighting, behavioral changes, such as the prolonged agonistic interactions and the delayed establishment of dominance were observed, suggesting a reduction of aggressiveness. A comparison of agonistic behaviors with other crustaceans showed that certain features appeared to be unique or distinct in Stenopus, including the potential functional overlap of antennae and antennules, a higher aggressiveness of the fighting behaviors, and the exhibition of crouching behavior by submissive individuals. The present study provides a crucial background understanding for subsequent research on Stenopus and paves the way for its establishment as another crustacean model for studying aggression.

As reproduction phenologies shift with climate change, populations can experience intraspecific priority effects, wherein early hatching cohorts experience an advantage over late-hatching cohorts, resulting in altered demography. Our study objective was to identify how variation in egg hatching phenology alters intraspecific interactions in small-mouthed salamanders, Ambystoma texanum. We addressed two research questions: (Q1) How are demographic responses altered by variation in the temporal duration of hatching between cohorts, and (Q2) How does the seasonality of hatching delays affect demographic responses? We manipulated hatching phenologies of A. texanum eggs and reared larvae in outdoor mesocosms to metamorphosis. For Q1, hatching delay exhibited non-linear relationships with survival and body size, with the greatest asynchrony in cohort additions resulting in the highest mortality and largest body sizes. For Q2, hatching delay effects were stronger (i.e., survival was lower and body sizes larger) when they occurred later in the season, potentially due to temperature differences that larvae experienced. Overall, our results demonstrate that changes in intraspecific interactions due to phenological shifts can be context-dependent, depending on the strength (i.e., temporal duration) and seasonality of such processes. Identifying context-dependencies of phenological shifts will be critical for predicting changes in organismal demographics with climatic shifts.

BACKGROUND: Seasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e. comparable systems without migration.
METHODS: In this study, we estimate the impact of Arctic charr (Salvelinus alpinus) migration on riverine ecosystem structure, by comparing multiple streams with strictly resident populations above natural migration barriers with streams below those barriers harboring partially migratory populations. We compared density estimates and size structure between above and below populations. Diet differences were examined through the analysis of stomach contents, changes in trophic position were examined by using stable isotopes. To infer growth rate of resident individuals, back-growth calculation was performed using otoliths.
RESULTS: We find higher densities of small juveniles in partially migratory populations, where juvenile Arctic charr show initially lower growth, likely due to higher intraspecific competition. After reaching a size, where they can start feeding on eggs and smaller juveniles, which are both more frequent in partially migratory populations, growth surpasses that of resident populations. Cannibalism induced by high juvenile densities occurred almost exclusively in populations with migration and represents an altered energy pathway to the food web. The presence of large cannibalistic charr feeding on smaller ones that have a similar trophic level as charr from strictly resident populations (based on stomach content) coupled with steeper δ15N-size regression slopes illustrate the general increase of food chain length in systems with migration.
CONCLUSIONS: Our results thus suggest that the consumption of migration-derived resources may result in longer food chains through middle-up rather than bottom-up effects. Furthermore, by occupying the apex of the food chain and feeding on juvenile conspecifics, resident individuals experience reduced competition with their young counterparts, which potentially balances their fitness with migratory individuals.

BACKGROUND: Male courtship investment may evolve in response to the male\'s expectation of future mating opportunities or the degree of female control during mating interactions. We used a comparative approach to test this hypotheses by assessing the courtship and mating behaviors of five widow spider species (genus Latrodectus) under common laboratory conditions. We predicted male investment in courtship would be higher in species where males mate only once because of high cannibalism rates (monogyny, L. geometricus, L. hasselti, L. mirabilis), compared to species with rare cannibalism (L. mactans, L. hesperus) in which males should reserve energy for future mating opportunities. Increased male investment, measured as courtship duration, might also evolve with increased female control over mating outcomes if females prefer longer courtships. We tested this by assessing the frequency of copulations, timing of sexual cannibalism, and the degree of female-biased size dimorphism, which is expected to be negatively correlated with the energetic cost of rebuffing male mating attempts.
RESULTS: Copulation frequency was consistently lower in species with extreme female-skewed size dimorphism, and where sexual cannibalism was more prevalent, suggesting the importance of female control for mating outcomes. We confirmed significant interspecific variation in average courtship duration, but contrary to predictions, it was not predicted by male mating system, and there was no consistent link between courtship duration and sexual size dimorphism.
CONCLUSIONS: We show that the degree of sexual dimorphism is not only correlated with sexual cannibalism, but also with mating success since restriction of male copulation frequency by female Latrodectus affects paternity. However, predictions about male mating system or female control affecting courtship duration were not supported. We propose that the form of female control over mating and cannibalism, and male responses, might be more informative for understanding the evolution of courtship duration. For example, male tactics to avoid female aggression may drive lower courtship duration in species like L. mirabilis. Nonetheless, our results differ from inferences based on published studies of each species in isolation, illuminating the need for standardized data collection for behavioural comparative studies.

We used computer simulations of growth, mating and death of cephalopods and fishes to explore the effect of different life-history strategies on the relative prevalence of alternative male mating strategies. Specifically, we investigated the consequences of single or multiple matings per lifetime, mating strategy switching, cannibalism, resource stochasticity, and altruism towards relatives. We found that a combination of single (semelparous) matings, cannibalism and an absence of mating strategy changes in one lifetime led to a more strictly partitioned parameter space, with a reduced region where the two mating strategies co-exist in similar numbers. Explicitly including Hamilton\'s rule in simulations of the social system of a Cichlid led to an increase of dominant males, at the expense of both sneakers and dwarf males (\"super-sneakers\"). Our predictions provide general bounds on the viable ratios of alternative male mating strategies with different life-histories, and under possibly rapidly changing ecological situations.

Parasites are known to have direct effects on host dispersal ability and motivation. Yet, parasites have a variety of impacts on host populations, including shaping predation and cannibalism rates, and therefore may also have indirect effects on host dispersal; these indirect pathways have not been studied. We tested the hypothesis that parasites influence host dispersal through effects on cannibalism using backswimmers (Notonecta undulata) and Hydrachnidia freshwater mites. Mite parasitism impedes swimming in backswimmers, which we found increased their vulnerability to cannibalism. We imposed a manipulation that varied cannibalism rates across experimental populations consisting of a mix of backswimmers with and without simulated parasites. Using simulated parasites allowed us to examine the effects of cannibalism without introducing infection risk. We found that the odds of dispersal for infected backswimmers increased by 2.25× with every 10% increase in the risk of being cannibalized, and the odds of dispersal for healthy backswimmers increased by 2.34× for every additional infected backswimmer they consumed. Our results suggest that cannibalism was used as an energy source for dispersal for healthy individuals, while the risk of being eaten motivated dispersal in infected individuals. These results elucidate the complex ways that parasites impact host populations and strengthen our understanding of host-parasite interactions, including host and parasite population stability and spread. This article is part of the theme issue \'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics\'.

Ecological interactions among hosts are critical to consider when predicting disease dynamics. Most theory predicts that intraguild predation (IGP) and cannibalism negatively impact parasite populations, but this is based primarily on assumptions of simple or single-host life cycles. Here we investigate the effects of cannibalism in a size-structured host population on two digenean trematodes that have complex, multihost life cycles. A high incidence of cannibalism among paratenic hosts produced higher parasite infection loads and abundance, whereas cannibalism among obligate hosts reduced parasite abundances. We attributed this difference to trophic transmission aggregating parasites in larger, potentially fitter hosts and also to transmission among paratenic hosts via cannibalism. Moreover, we found evidence of indirect competitive interactions between parasites that can also increase infections at small scales. Our results show there are multiple mechanisms through which high cannibalism environments can benefit parasites that use paratenic hosts and trophic transfer to complete their life cycles.

Factors that increase reproductive variance among individuals act to reduce effective population size (Ne), which accelerates the loss of genetic diversity and decreases the efficacy of purifying selection. These factors include sexual cannibalism, offspring investment and mating system. Pre-copulatory sexual cannibalism, where the female consumes the male prior to mating, exacerbates this effect. We performed comparative transcriptomics in two spider species, the cannibalistic Trechaleoides biocellata and the non-cannibalistic T. keyserlingi, to generate genomic evidence to support these predictions. First, we estimated heterozygosity and found that genetic diversity is relatively lower in the cannibalistic species. Second, we calculated dN/dS ratios as a measure of purifying selection; a higher dN/dS ratio indicated relaxed purifying selection in the cannibalistic species. These results are consistent with the hypothesis that sexual cannibalism impacts operational sex ratio and demographic processes, which interact with evolutionary forces to shape the genetic structure of populations. However, other factors such as the mating system and life-history traits contribute to shaping Ne. Comparative analyses across multiple contrasting species pairs would be required to disentangle these effects. Our study highlights that extreme behaviours such as pre-copulatory cannibalism may have profound eco-evolutionary effects.

The fall armyworm (FAW) Spodoptera frugiperda (Lepidoptera, Noctuidae) has now become an invasive pest of global concern. The pest was first detected in Central and Western Africa in early 2016. Sustainable management options explored by stakeholders during early FAW invasion in Africa included the use of biopesticides and biological control. The current study aimed to compare the susceptibility of FAW larvae to SfMNPV with the assumption that the virus isolated from FAW populations in Africa has higher virulence compared with an isolate from Argentina (SfMNPV-ARG). We also hypothesized that host plant plays a role in SfMNPV efficacy and that cannibalism mediates horizontal and vertical transmission of the virus. This work provides pioneering data on the virulence of the new SfMNPV isolate from Nigeria (SfMNPV-KA1), which proved more effective than its exotic counterpart from Argentina (SfMNPV-ARG). The host plant effect made a significant difference between maize and onion with more FAW death in the larvae fed with contaminated onion 5 days post treatment. The study demonstrates and discusses the effect of cannibalism on virus transmission.