Juvenile Life Research Articles

The Vulnerability of the Developing Brain: Analysis of Highly Expressed Genes in Infant C57BL/6 Mouse Hippocampus in Relation to Phenotypic Annotation Derived From Mutational Studies.

The hippocampus has been shown to have a major role in learning and memory, but also to participate in the regulation of emotions. However, its specific role(s) in memory is still unclear. Hippocampal damage or dysfunction mainly results in memory issues, especially in the declarative memory but, in animal studies, has also shown to lead to hyperactivity and difficulty in inhibiting responses previously taught. The brain structure is affected in neuropathological disorders, such as Alzheimer’s, epilepsy, and schizophrenia, and also by depression and stress. The hippocampus structure is far from mature at birth and undergoes substantial development throughout infant and juvenile life. The aim of this study was to survey genes highly expressed throughout the postnatal period in mouse hippocampus and which have also been linked to an abnormal phenotype through mutational studies to achieve a greater understanding about hippocampal functions during postnatal development. Publicly available gene expression data from C57BL/6 mouse hippocampus was analyzed; from a total of 5 time points (at postnatal day 1, 10, 15, 21, and 30), 547 genes highly expressed in all of these time points were selected for analysis. Highly expressed genes are considered to be of potential biological importance and appear to be multifunctional, and hence any dysfunction in such a gene will most likely have a large impact on the development of abilities during the postnatal and juvenile period. Phenotypic annotation data downloaded from Mouse Genomic Informatics database were analyzed for these genes, and the results showed that many of them are important for proper embryo development and infant survival, proper growth, and increase in body size, as well as for voluntary movement functions, motor coordination, and balance. The results also indicated an association with seizures that have primarily been characterized by uncontrolled motor activity and the development of proper grooming abilities. The complete list of genes and their phenotypic annotation data have been compiled in a file for easy access.

Second Chances: Why Michigan Should Categorically Prohibit the Sentence of Juvenile Life Without Parole

The United States is the only country in the world that sentences children to die in prison. This practice, known as juvenile life without parole (JLWOP), is condemned by the United Nations Convention on the Rights of the Child. Yet twenty-five states still permit the sentence, and Michigan houses one of the nation’s largest JLWOP populations. Despite the U.S. Supreme Court’s ban on some forms of JLWOP, more must be done to further limit the use of this sentence. The current JLWOP sentencing scheme is untenable, imposes a significant financial burden on taxpayers, and perpetuates racial inequality. This Note explores these reasons for eliminating the practice and ultimately urges Michigan to follow other states in enacting a categorical ban on JLWOP, either through judicial decision or legislative action.

The Criminal Offence of Child-on-Child Abuse With a Fatal Outcome

This research aims to analyse the legal protection for the child offenders in criminal offence of abuse with a fatal outcome, the judge's considerations in imposing imprisonment for the offence and the obstacles in the crime. Data obtained through empirical legal research. This research uses primary data obtained from empirical legal research in the form of interviews with respondents and informants and combines legal materials such as textbooks, theories, laws and regulations which are considered as secondary data. The results of the research showed that the legal protection provided to the child convicts is in the form of identity confidentiality, is treated well during the investigation process, is placed in a special place, the Judges in making considerations always refer to the mitigating factors such as the juvenile's age, the juvenile's mental state, the juvenile's background, the juvenile's family attitude and aggravating things such as a bad juvenile's life history and parents who are unable to educate them.. The things that indirectly hinder the process of settling this case are the parents negligence, lack of cooperation from both parties, and also the influence of gadgets. It is recommended to the law enforcement officers and Juvenile’s Special Development Institute should continue to cooperate in carrying out legal protection for child perpetrators according to applicable rules, the judge before imposing a prison sentence should prioritize the best interests of the child and to parents should contributing better in control the children's behavior.

Resource heterogeneity but not inbreeding affects growth and grouping behaviour in socially foraging juvenile cichlid fish

Abstract Spatial food distribution determines resource profitability, defensibility and encounter rate of foragers. Clumped food distribution can promote aggressiveness and resource monopolisation, in turn increasing within‐group variation in food intake and growth. However, the effects of food distribution may depend on foraging strategies. Little is known about the impact of spatial food heterogeneity on growth and grouping behaviour in social foragers in the absence of monopolisation. Social foraging is present in many fishes, particularly at early juvenile life stages when fish are especially sensitive to environmental variation. Here, a heterogeneous food distribution may impair foraging success and growth and juveniles may increase sociability to attain social information about food resources. We examined the impact of the spatial distribution of food as well as inbreeding on growth and social behaviour in juveniles of the cichlid fish Pelvicachromis pulcher. Inbred individuals often show poorer performance than outbred individuals (inbreeding depression), but inbreeding effects can be environment dependent. In the experiment, inbred and outbred fish were reared in a split‐clutch design either under homogeneously distributed or spatially clumped food conditions for 8 weeks starting 1 week after juveniles could actively feed. We documented growth and performed a shoaling assay and a sociality test (choice between a large vs. a small shoal) after 6 weeks. Spatial food distribution did not affect within‐group body length variation, but individuals reared under clumped food conditions were smaller. Shoals of the different feeding conditions differed in social behaviour. Shoals of the clumped treatment group showed higher variation in inter‐individual distances compared to shoals of the homogeneous treatment group. Furthermore, focal fish of the clumped treatment adjusted their association preference to the position of the groups' largest individual. We did not find significant inbreeding or environment‐dependent inbreeding effects regarding growth or social behaviour. Our study suggests that a clumped food distribution can impede localisation of food resources and thus growth in juvenile social foragers. Accordingly, in heterogeneous environments, the use of social information may be highly relevant to increase individuals' foraging success potentially explaining orientation on successful foragers, that is, large individuals. Inter‐individual variation in juvenile’s social behaviour may precede variation in food monopolisation capability and in growth emerging at later life stages. A free Plain Language Summary can be found within the Supporting Information of this article.

The contributions of individual traits to survival among terrestrial juvenile pond‐breeding salamanders

Abstract Individual survival is influenced by interactions between local environmental conditions and an organism's morphological, behavioural and physiological traits. Studies examining the effects of individual phenotypes on survival under variable conditions are relatively rare among early transitional life stages, although the vital rates of these life stages can importantly influence population dynamics. We experimentally examined the effects of initial body mass, movement, standard metabolic rate (SMR) and respiratory surface area water loss (RSAWL) on survival in the transitional juvenile life stage of two biphasic amphibian species (Ambystoma maculatum and A. opacum) in a 7‐month mark–recapture study under semi‐natural conditions. Juveniles with a larger initial body mass, lower initial SMR and/or a lower tendency to change locations had a higher likelihood of known survival. In contrast, we found no significant effect of RSAWL on juvenile survival. The relationships between individual phenotypes and survival did not differ between species, but equivalent species‐specific survival rates may have been attributed to larger initial body sizes in A. maculatum and lower SMR in A. opacum. Our results illuminate the complex ways in which individual traits influence survival during the early transitional life stage of two ambystomatid species under varying abiotic conditions. More generally, our findings illustrate potential advantages of simultaneously examining multiple traits to evaluate survival. A free Plain Language Summary can be found within the Supporting Information of this article.

Modelling the effects of variation in growth, recruitment, and harvest on lake sturgeon population viability and recovery

Abstract Regulatory agencies and fisheries managers tasked with implementing recovery plans for endangered species must frequently make decisions based on limited data, while also considering general uncertainty associated with prediction. Population viability analysis (PVA) is a modelling tool that is particularly useful for long‐lived species and can be applied even in the absence of robust estimates of life history parameters. As empirical data are accumulated over time, PVA inputs, model structure, and parameter estimates can be refined to increase model realism and accuracy. Since the first iterations of lake sturgeon (Acipenser fulvescens) PVA were run, approximately 15 years ago, based on conservative inputs for Canadian population units, important empirical data have accumulated from a variety of river systems that the species inhabits. Erratic recruitment patterns have been revealed, juvenile survival has been determined to be higher than initially believed, and growth rates have been found to vary by habitat (river) type. Exploiting an improved biological understanding of the species, somatic growth models derived from three well‐studied lake sturgeon populations were used to examine the effects of recruitment variability and incremental levels of adult harvest (mortality) on the probability of population recovery and risk of population decline. A total of 110 PVA scenarios (with 1,000 replicates per scenario) were run for each of the three somatic growth models (slow, medium, and fast). The PVA results suggest that the recovery potential for lake sturgeon populations may be higher than previous models, based on conservative inputs, have indicated. A few scenarios resulted in recovery after 100 years, and nearly half of the scenarios resulted in recovery after 250 years. Similarly, the probability of decline for small populations was most sensitive to adult harvest, with little change in the number of scenarios resulting in decline at the time points of 100, 250, and 500 years. A worked example highlights how the targeted monitoring of both juvenile and adult life stages can be used to evaluate the recovery potential of more than one population and prioritize management initiatives, such as harvest reduction and stocking.

Diet composition of abundant fish species in the shallow waters of the Todos os Santos Bay, Bahia, Brazil

Coastal habitats have great ecological importance with estuarine environments providing feeding sites for many fish species, especially during juvenile life stages. This study investigates the diet composition and trophic guild organization of the common and abundant ichthyofauna in shallow areas of the Todos os Santos Bay (TSB), Bahia, Brazil, and their relationships with environmental parameters. Six fish sampling campaigns were carried out in the shallow zones (infralittoral) of the Paraguaçu River estuary which encompasses the inner and outer (marine exposure) reaches of the TSB. The stomach contents of 1231 individuals belonging to common and abundant species were examined. A total of 32 food items were identified and fish were into four trophic guilds: detritivores, zoobenthivores I, zoobenthivores II, and zooplanktivores. The relationship between the guilds and environmental parameters showed that zoobenthivores II and zooplanktivores guilds had a positive relationship with salinity and pH, explaining 86% of data variability, though only the salinity variable was significant. This study provides basic information about the diet composition of common and abundant species in the TSB and their organization into trophic guilds. In addition, demonstrates that shallow waters fish across all guilds have broadly similar diets, comprising food items that are usually associated with bottom waters.

Carry-Over Effects of Desiccation Stress on the Oxidative Status of Fasting Anuran Juveniles.

Amphibians are sensitive to deteriorating environmental conditions, especially during transition to a terrestrial environment which is full of uncertainties. Harsh conditions, such as desiccation during earlier stages, affect different larval traits with possible carry-over effects on juvenile and adult life histories. The first consequences of the effects can be seen in juveniles in the challenges to find food and the ability to survive without it in a terrestrial habitat. Body size and the internal energy reserves acquired during the larval phase play an important role in this period. Herein, we tested how different water regimes (low water availability, desiccation and constant high-water availability) during larval development reflect on the oxidative status and ability of yellow belly toad (Bombina variegata) juveniles to endure short-term fasting. The desiccation regime significantly reduced the body size of metamorphs. The same was observed after 2 weeks of fasting, while the feeding treatment reduced differences mostly in the body mass of individuals from different water regimes. This was the result of a greater gain in mass in juveniles pre-exposed to desiccation. Pre-exposure to desiccation also modified the parameters of the antioxidant system (AOS) under feeding conditions, leading to higher values of superoxide dismutase, glutathione reductase and glutathione S-transferase, glutathione and sulfhydryl group concentrations, and lower glutathione peroxidase in comparison to juveniles reared under constant water. The increase in the AOS of juveniles can be considered as a physiological carry-over effect of desiccation, probably as the result of compensatory growth and/or earlier exposure to chronic stress. However, water levels during larval development did not exert significant effects on the oxidative status of juveniles subjected to food unavailability. Fasting juveniles, both control and desiccated, were exposed to oxidative stress, significantly higher lipid peroxide concentrations, lower superoxide dismutase, glutathione peroxidase, glutathione S-transferase, glutathione and sulfhydryl group values in comparison to feeding individuals. The lack of food in juvenile anurans activated the AOS response in the same manner, regardless of body size and stress pre-exposure, suggesting that the generally accepted hypothesis about the influence of metamorphic body size on the fitness of the postmetamorphic stage should be tested further.

Genotoxic Damage During Brain Development Presages Prototypical Neurodegenerative Disease.

Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS/PDC) is a disappearing prototypical neurodegenerative disorder (tau-dominated polyproteinopathy) linked with prior exposure to phytogenotoxins in cycad seed used for medicine and/or food. The principal cycad genotoxin, methylazoxymethanol (MAM), forms reactive carbon-centered ions that alkylate nucleic acids in fetal rodent brain and, depending on the timing of systemic administration, induces persistent developmental abnormalities of the cortex, hippocampus, cerebellum, and retina. Whereas administration of MAM prenatally or postnatally can produce animal models of epilepsy, schizophrenia or ataxia, administration to adult animals produces little effect on brain structure or function. The neurotoxic effects of MAM administered to rats during cortical brain development (specifically, gestation day 17) are used to model the histological, neurophysiological and behavioral deficits of human schizophrenia, a condition that may precede or follow clinical onset of motor neuron disease in subjects with sporadic ALS and ALS/PDC. While studies of migrants to and from communities impacted by ALS/PDC indicate the degenerative brain disorder may be acquired in juvenile and adult life, a proportion of indigenous cases shows neurodevelopmental aberrations in the cerebellum and retina consistent with MAM exposure in utero. MAM induces specific patterns of DNA damage and repair that associate with increased tau expression in primary rat neuronal cultures and with brain transcriptional changes that parallel those associated with human ALS and Alzheimer’s disease. We examine MAM in relation to neurodevelopment, epigenetic modification, DNA damage/replicative stress, genomic instability, somatic mutation, cell-cycle reentry and cellular senescence. Since the majority of neurodegenerative disease lacks a solely inherited genetic basis, research is needed to explore the hypothesis that early-life exposure to genotoxic agents may trigger or promote molecular events that culminate in neurodegeneration.

Effect of Long-Term Consumption of Poultry Egg Products on Growth, Body Composition, and Liver Gene Expression in Zebrafish, Danio rerio.

ABSTRACTBackgroundPoultry eggs are a low-cost, high-protein nutrient package that can be consumed as part of quality diets. However, consumption of poultry egg products is historically contentious, which highlights the importance of investigating impacts of long-term egg consumption on metabolic health.ObjectiveOur study utilized the zebrafish, Danio rerio, a newly defined model of human metabolic health, to understand the metabolic consequence of consuming egg products in lieu of other well-described protein sources.MethodsReference diets were formulated to contain multisource protein with casein and fish protein hydrolysate (CON; control protein sources), the protein sources that have been historically utilized in numerous reference diets. These proteins were then partially replaced with either whole egg (WE; protein and lipid source), egg white (EW; protein source), wheat gluten (WG; cereal protein source), or a high-lipid-content diet containing a multisource protein with casein and fish protein hydrolysate (HFCON; isonitrogenous and isolipidic with the WE diet) in a 34-wk trial (n = 8 tanks, 10 fish per tank). Daily feeding was initiated at the early juvenile life stage and terminated at the late reproductive adult stage.ResultsThe amino acid composition of control versus egg product diets did not vary substantially, although methionine and lysine were apparently limiting in fish fed WG. At termination, fish fed EW as the protein source had weight gain and body composition similar to those fed the CON diet. Fasting and postprandial blood glucose did not differ between any dietary treatment. Assessment of the liver transcriptome using RNAseq revealed no differential gene expression between zebrafish fed CON or WE diets. Zebrafish fed WG had lower weight gain in males.ConclusionsLong-term consumption of egg products promoted metabolic health equal to that of historically relevant proteins. These data support the value of egg products for maintaining long-term metabolic health in animal diets.

Forecasted Shifts in Thermal Habitat for Cod Species in the Northwest Atlantic and Eastern Canadian Arctic

Climate change will alter ecosystems and impose hardships on marine resource users as fish assemblages redistribute to habitats that meet their physiological requirements. Marine gadids represent some of the most ecologically and socio-economically important species in the North Atlantic, but face an uncertain future in the wake of rising ocean temperatures. We applied CMIP5 ocean temperature projections to egg survival and juvenile growth models of three northwest Atlantic coastal species of gadids (Atlantic cod, Polar cod, and Greenland cod), each with different thermal affinities and life histories. We illustrate how physiologically based species distribution models (SDMs) can be used to predict habitat distribution shifts and compare vulnerabilities of species and life stages with changing ocean conditions. We also derived an integrated habitat suitability index from the combined surfaces of each metric to predict areas and periods where thermal conditions were suitable for both life stages. Suitable thermal habitat shifted poleward for the juvenile life stages of all three species, but the area remaining differed across species and life stages through time. Arctic specialists like Polar cod are predicted to experience reductions in suitable juvenile habitat based on metrics of egg survival and growth potential. In contrast, habitat loss in boreal and subarctic species like Atlantic cod and Greenland cod may be dampened due to increases in suitable egg survival habitats as suitable juvenile growth potential habitats decrease. These results emphasize the need for mechanistic SDMs that can account for the combined effects of changing seasonal thermal requirements under varying climate change scenarios.

Projected redistribution of sea turtle foraging areas reveals important sites for conservation

Identification of important habitats of charismatic marine megafauna is essential to enhance our conservation capacity. Still, for species such as sea turtles that have a long-life span, a complex life history and a highly migratory nature, spatially delineating important marine areas is not a simple task. Even in the case that such areas are identified, our ability to draw effective measures and propose conservation prioritization schemes faces additional challenges, due to the dynamic climate-driven redistribution of habitats. Here, we compile a database on foraging locations of loggerhead sea turtles across the Mediterranean Sea and use climatic niche models to predict the distribution of foraging grounds for juvenile and adult life stages. We explore potential shifts due to future changes in ocean temperature and identify sites, considered as important for both life stages, that will persist under climate change. We found extensive areas which could host foraging sites for juvenile loggerheads, distributed at the central and western Mediterranean, while adults’ foraging grounds had a more sparse and patchy distribution, mostly at the central and eastern part of the basin. Under future changes, expansions prevail over contractions, but projected redistribution of foraging space for both life stages will probably lead to remarkable losses of climatic suitability at certain sites. The coverage of important areas, hosted primarily at the neritic zone, will be extended in the future. Our analyses add a missing dimension to conservation efforts, related to the basin-wide distribution of important areas, offering novel insights towards incorporating climate change into conservation planning.

Insulin signaling and osmotic stress response regulate arousal and developmental progression of C. elegans at hatching.

The progression of animal development from embryonic to juvenile life depends on the coordination of organism-wide responses with environmental conditions. We found that two transcription factors that function in interneuron differentiation in Caenorhabditis elegans, fax-1, and unc-42, are required for arousal and progression from embryogenesis to larval life by potentiating insulin signaling. The combination of mutations in either transcription factor and a mutation in daf-2 insulin receptor results in a novel perihatching arrest phenotype; embryos are fully developed but inactive, often remaining trapped within the eggshell, and fail to initiate pharyngeal pumping. This pathway is opposed by an osmotic sensory response pathway that promotes developmental arrest and a sleep state at the end of embryogenesis in response to elevated salt concentration. The quiescent state induced by loss of insulin signaling or by osmotic stress can be reversed by mutations in genes that are required for sleep. Therefore, countervailing signals regulate late embryonic arousal and developmental progression to larval life, mechanistically linking the two responses. Our findings demonstrate a role for insulin signaling in an arousal circuit, consistent with evidence that insulin-related regulation may function in control of sleep states in many animals. The opposing quiescent arrest state may serve as an adaptive response to the osmotic threat from high salinity environments.

Using upper thermal limits of Lampsilis bracteata (Texas fatmucket) from the North Llano and San Saba rivers, Texas to inform water management practices in the Edwards Plateau

Abstract Overexploitation of freshwater resources coupled with climate change can affect the flow and temperature regimes in rivers, which can be catastrophic for aquatic biota. The San Saba and Llano rivers, located in central Texas, are experiencing low flows and stream dewatering owing to over‐allocation. Both systems harbour imperilled species, including Lampsilis bracteata, Texas fatmucket, which has been proposed for listing under the US Endangered Species Act. It is suspected that elevated water temperatures are a contributing factor in its decline. The upper thermal tolerances of glochidia and juvenile life stages were evaluated within each river. Mussels were acclimated to 27°C and tested across a range of temperatures (30–39°C) in 24 h (glochidia) and 96 h (juveniles) laboratory tests. The resulting tolerances were related to in situ water temperature and discharge using a uniform continuous above‐threshold analysis. In the Llano, the 24 h LT50 (lethal temperature resulting in 50% mortality) was 31.8°C (95% CI 31.5–32.1°C), whereas the 96 h LT50 was 32.4°C (95% CI 32.1–32.7°C). In the San Saba, the 24 h LT50 was 34.7°C (95% CI 34.5–35.0°C), whereas the 96 h LT50 was 32.5°C (95% CI 32.2–32.9°C). LT50 thresholds were not exceeded for L. bracteata within the San Saba, but LT05 (lethal temperature resulting in 5% mortality) thresholds were exceeded. Water temperature loggers were lost in the Llano River as a result of a large flood; however, samples reported by the Texas Commission on Environmental Quality show that the LT05 and LT50 for both glochidia and juveniles were exceeded. Findings from this study indicate that thermal tolerances of L. bracteata vary by population and that low flows may be contributing to its decline. Our approach is non‐species and region specific, which means that the methods presented should help managers and conservationists evaluate whether reduced water quantity and elevated temperatures are exerting impacts on aquatic species within their region.

Additive effects of developmental acclimation and physiological syndromes on lifetime metabolic and water loss rates of a dry‐skinned ectotherm

Abstract Developmental plasticity and thermal acclimation can contribute to adaptive responses to climate change by altering functional traits related to energy and water balance regulation. How plasticity interacts with physiological syndromes through lifetime in long‐lived species is currently unknown. Here, we examined the impacts of long‐term thermal acclimation in a long‐lived temperate ectotherm Vipera aspis and its potential flexibility at adulthood for two related functional traits: standard metabolic rate (SMR) and total evaporative water loss (TEWL). We used climatic chambers to simulate three contrasted daily thermal cycles (warm, medium and cold) differing in mean temperatures (28, 24 and 20℃ respectively) and amplitudes (5, 10 and 13℃ respectively) during immature life (0 to 4 years of age). Individuals were then maintained under common garden conditions (medium cycle) for an additional 3‐year period (4–7 years of age). SMR and TEWL were repeatedly measured in the same individuals throughout life during and after the climate manipulation. Individuals reduced their SMR (negative compensation) when experiencing the warm cycle but flexibly adjusted their SMR to common garden conditions at adulthood. In addition, thermal conditions during the juvenile life stage led to changes in TEWL persisting until adulthood. We further found consistent intra‐individual variation for SMR and TEWL and a positive intra‐individual and inter‐individual covariation between them throughout life. Thus, plastic responses were combined with a physiological syndrome linking SMR and TEWL. Our study demonstrates the capacity of long‐lived organisms to flexibly shift their SMR to reduce daily maintenance costs in warmer and less variable thermal environments, which might be beneficial to low‐energy specialist organisms such as vipers. It further suggests that thermal conditions provide cues for developmental changes in TEWL. Beside plasticity, contrasted individual physiological syndromes could be selected for and contribute to the response to climate change. A free Plain Language Summary can be found within the Supporting Information of this article.

A Pandemic Term With "Highly Charged Issues": The U.S. Supreme Court 2020-2021.

The 2020-2021 U.S. Supreme Court Term was expected by experts to be uninteresting, but it proved to be quite the opposite. There were surprising unanimous decisions, and some unexpectedly “highly charged issues.” Several of the decisions will be important to mental health professionals (foster care and the conflict of gay and religious rights, juvenile life sentences, and “community caretaking”), and to health care providers more generally (the Affordable Care Act, Pharmacy Benefit Managers, and COVID cases). Other decisions of general interest included immigration cases, election laws, and college athletics. Some of the most important cases arose in the “Shadow Dockets,” an often-ignored series of orders by the Court. The article discusses the most important cases of the Term (including those in the Shadow Docket), analyzes the meaning of the Term, and looks to the cases to be decided next Term.

The Effects of Early Childhood Stress on Mortality under Neolithization in the Levant

Abstract. This study investigates the causal relationships among early-life health conditions, mortality across the lifespan, and population growth during neolithization in the Levant. We analyze a comprehensive sample of 558 human skeletons, associated with mortuary features from 24 Levantine sites spanning the transition to agriculture, from the Early Natufian period to the Pre-Pottery Neolithic C (Southern Levant) and Pottery Neolithic periods (Northern Levant), mainly covering 13,000-6,000 BC. We find that early-life stress—as preserved in linear enamel hypoplasias (LEH) that we recorded in the study sample—not only increased dramatically in prevalence with the adoption of agriculture and village life. Early-life stress was also strongly associated with mortality in the juvenile, adolescent, and younger-adult life stages (ca. 5-29 years). This statistical link is independent of analysis of raw life-stage-at-death distributions, which may be heavily biased by ancient age or sex-skewed funerary recruitment practices. According to our results, biological well-being deteriorated with the adoption of agriculture and village life between ca. 9,000-6,000 BC. We find that the transition to agriculture raised risks for premature mortality across the Levant. We suggest that in the regional transition to agriculture, mortality and fertility rose together in a fragile dynamic, the balance of which may have shifted in the 7th millennium BC, as a rapid rise in early-life stress exposures reduced average well-being.

Light Trapping Reveals Multiple Bigheaded Carp Spawns Upstream of Lock and Dam 19 in the Upper Mississippi River

AbstractThe Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis are two species of invasive bigheaded carp currently invading North American rivers and watersheds. Bigheaded carp were accidentally introduced into the lower Mississippi River basin in the early 1970s and have since invaded many water bodies in the Midwestern United States. Evidence of bigheaded carp reproduction and recruitment in the upper Mississippi River upstream of Lock and Dam 19 (LD19) at Keokuk, Iowa, thought to be a critical constriction point to their upstream establishment, has been limited to a few isolated detections of eggs, larvae, and juvenile life stages since 2012. Therefore, a more comprehensive assessment of bigheaded carp reproduction in this critical management zone was needed. We used quadrafoil light traps (n = 1,387) deployed during May–September 2016–2018 in Pools 17–19 of the Mississippi River to monitor for advanced larval bigheaded carp in low‐velocity habitats. Throughout the sampling period, we captured 1,747 larval and 35 postlarval bigheaded carp (N = 1,782). Bigheaded carp were collected on 15 sampling events that spanned from May 31, 2016, to September 13, 2018, with associated hatch dates estimated to represent 10 unique reproductive events from May 2016 to September 2018. The individual captures and backdated hatch estimates revealed a protracted spawning period of up to seven events in 2016, one event in 2017, and two events in 2018. Bigheaded carp were only captured in Pool 19, possibly due to the drifting requirements for egg maturation and the low‐velocity downstream reach of Pool 19. This research provides confirmation that bigheaded carp spawned upstream of LD19 are capable of transitioning past the yolk sac stage upstream of this bottleneck to more advanced larval stages. Knowledge of reproduction and larval retention and the field‐based evidence of protracted spawning fill critical research gaps needed for the management of bigheaded carp.

Trophic relationships between the crab Libinia ferreirae and its symbionts

Symbioses are ubiquitous in the animal kingdom. However, in most cases, the role of each member is relatively fixed, and it is rare for the same species to exhibit different symbiotic behaviours throughout its ontogeny. Here, we use stable isotope analyses of food resources to identify the relationships between the spider crab Libinia ferreirae as a symbiont of its jellyfish host during juvenile life stages and as a host for sea anemone epibionts on its carapace as an adult. We ask the following questions: How do the food sources used by the crab change between its juvenile and adult phase? How does the symbiotic relationship change when the crab develops from a juvenile into an adult? We were particularly interested in the extent to which L. ferreirae juveniles feed on jellyfish hosts versus planktonic prey during the juvenile symbiont phase and how adults feed on their epibionts during the free-living phase. δ13C of L. ferreirae differed between juvenile (associated with the jellyfish) and adult stages (free-living), unsurprisingly suggesting that there is little isotopic niche overlap between these life phases. SIMMr models using δ13C and δ15N of the crab and its potential food sources indicated that the juvenile crab symbionts did not derive any significant nutrition from medusae and relied predominantly on zooplankton prey. Since juvenile crabs do not have structures to capture zooplankton for feeding, we suggest that they may be kleptoparasites, stealing zooplankton food from their host, though further work is needed to identify the form that such a symbiosis might take. The nutrition of free-living crabs was predominantly derived from benthic algae and shrimps rather than from epibionts. These epibionts appear to use similar food resources as the host, suggesting a symbiotic relationship more akin to mutualism. Thus, the crabs move from a symbiosis in which they may act as parasites to one where they act as hosts. Such flexible approaches to symbioses may be more common than currently described, particularly in species with different functional roles during individual life stages.

Gut Microbiota Associated With Different Sea Lamprey (Petromyzon marinus) Life Stages.

Sea lamprey (SL; Petromyzon marinus), one of the oldest living vertebrates, have a complex metamorphic life cycle. Following hatching, SL transition into a microphagous, sediment burrowing larval stage, and after 2–10+ years, the larvae undergo a dramatic metamorphosis, transforming into parasitic juveniles that feed on blood and bodily fluids of fishes; adult lamprey cease feeding, spawn, and die. Since gut microbiota are critical for the overall health of all animals, we examined the microbiota associated with SLs in each life history stage. We show that there were significant differences in the gut bacterial communities associated with the larval, parasitic juvenile, and adult life stages. The transition from larval to the parasitic juvenile stage was marked with a significant shift in bacterial community structure and reduction in alpha diversity. The most abundant SL-associated phyla were Proteobacteria, Fusobacteria, Bacteroidetes, Verrucomicrobia, Actinobacteria, and Firmicutes, with their relative abundances varying among the stages. Moreover, while larval SL were enriched with unclassified Fusobacteriaceae, unclassified Verrucomicrobiales and Cetobacterium, members of the genera with fastidious nutritional requirements, such as Streptococcus, Haemophilus, Cutibacterium, Veillonella, and Massilia, were three to four orders of magnitude greater in juveniles than in larvae. In contrast, adult SLs were enriched with Aeromonas, Iodobacter, Shewanella, and Flavobacterium. Collectively, our findings show that bacterial communities in the SL gut are dramatically different among its life stages. Understanding how these communities change over time within and among SL life stages may shed more light on the role that these gut microbes play in host growth and fitness.