Offspring Population Research Articles

Genetic Diversity and Differences among Three F1 Families and Two Wild Populations of Genus Scylla Using Microsatellite Markers

Genetic diversity is the determinant of the allocation of germplasm resources in the genetic improvement of aquaculture species. In this study, three F1 families, including a hybrid Scylla family (S. paramamosain ♂ × S. serrata ♀), a paternal family of S. paramamosain, a maternal family of S. serrata, and two wild populations, including a paternal population of S. paramamosain and a maternal population of S. serrata, were used to investigate the genetic diversity and genetic difference. The results indicated that 98 alleles of nine microsatellites loci were observed in five Scylla populations. The highest average value of Ho (observed heterozygosity), He (expected heterozygosity), and PIC (polymorphic information content) of the wild S. paramamosain population were 0.790, 0.799, and 0.771, respectively, suggesting the wild paternal population has high genetic diversity. The comparative analysis of PIC, Fst (fixation index), and HWE (Hardy–Weinberg equilibrium) indicated that the paternal S. paramamosain may be more suitable for artificial breeding than the maternal S. serrata from the perspective of allele frequency. Analysis of molecular variance analysis (AMOVA) showed that the total genetic variation mainly occurred within populations (73.28%), demonstrating that artificial breeding may induce genetic differentiation of the family groups of Scylla. The results of the analysis of Fst value, UPGMA (unweighted pair-group mean analysis) dendrogram, and genetic diversity indicated that the F1 hybrid offspring had a close genetic distance and high genetic identity with the paternal S. paramamosain populations. It indicated that the F1 hybrid offspring showed potential paternal genetic affinities and a similar potential for artificial breeding with S. paramamosain. The study will provide valuable information to evaluate the difference in the genetic diversity and population structure between hybrid offspring and distinct parental populations of Scylla.

Studies on the effect evaluation of stock enhancement and mating strategy of Sepia esculenta based on release—Recapture survey

The golden cuttlefish, Sepia esculenta Hoyle, 1885, is an economically important cephalopod, and its resources have declined significantly due to overfishing and habitat destruction. In order to recover the natural resources, stock enhancement of golden cuttlefish has been conducted for a few years in Shandong Province, China. However, little information has been reported concerning the effectiveness and genetic effect of the massive releases. In the present study, microsatellite markers were employed to trace the whole process of S. esculenta stock enhancement in Qingdao at 2016. Furthermore, the pedigree of hatchery populations (broodstock and offsprings) was traced to detect the mating behaviors of S. esculenta. In summary, the high genetic diversity and similar genetic variability with wild population were detected, and the effective population sizes (Ne) of broodstock, offspring and wild populations were high. Only 3 individuals were identified from 372 captured samples, accounting for 0.806%. We speculated small number of marked individuals may be the key factor for low recapture rate. Furthermore, we found a male broodstock mated with two female parents, this indicated complicated promiscuity behavior of S. esculenta.

A fast sampling based evolutionary algorithm for million-dimensional multiobjective optimization

With their complexity and vast search space, large-scale multiobjective optimization problems (LSMOPs) challenge existing multiobjective evolutionary algorithms (MOEAs). Recently, several large-scale multiobjective evolutionary algorithms have been developed to tackle LSMOPs. Unlike conventional MOEAs that concentrate on selection operations in the objective space, large-scale MOEAs emphasize operations in the decision space, such as offspring generation, to tackle the large number of decision variables. Nevertheless, most present large-scale MOEAs experience difficulty effectively and efficiently solving LSMOPs with tens of thousands or more decision variables or exhibit poor versatility in solving different LSMOPs. We propose a fast large-scale MOEA framework with reference-guided offspring generation, named FLEA, aiming at these issues. Generally, FLEA constructs several reference vectors in the decision space to steer the sampling of promising solutions during offspring generation. A parameter is used to allocate computation resources between the convergence and diversity of the offspring population adaptively. Without computationally expensive problem reformulation or decision variable analysis techniques, the proposed method can significantly accelerate the search speed of conventional MOEAs in solving LSMOPs. FLEA is examined on various LSMOPs with up to 1.6 million decision variables, demonstrating its superior effectiveness, efficiency, and versatility in large-scale multiobjective optimization.

The sublethal and transgenerational effects of pyridaben on fitness and induced tolerance in Panonychus citri

Panonychus citri is a dominant citrus pest mite in the world. Pesticide-induced population resurgence is a concern for environmental and resistance risk assessment in mite control. To evaluate the effective mite management strategies, the sublethal and transgenerational effects of pyridaben on P. citri were assessed using life-table parameters. Two segregated pyridaben-resistant and susceptible strains (previously obtained from the crossing between laboratory susceptible strain and pyridaben-resistant population) were used in our study. After exposure to LC30 pyridaben, the fecundity of Pyr_Control and Pyr_Rs strains were both significantly reduced in the parental generation (F0). Life-table results showed that LC30 pyridaben significantly induced the fecundity of both strains in F1 generation (egg stage was prolonged as well). Interestingly, this effect also stimulated the fecundity of F2 generation in Pyr_Control strain. But no significant effects were observed in Pyr_Rs strain. While detoxification enzyme assays indicated that only the activity of P450s was significantly activated by LC30 pyridaben in Pyr_Control and Pyr_Rs strains (1.242- fold and 1.355-fold increase, respectively). The expressions of P450 gene (CYP4CL2) and reproduction-related gene (Pc_Vg) were determined and the results showed that the expression of Pc_Vg of pyridaben treated mites in F0 generation was significantly reduced in both strains. In Pyr_Control and Pyr_Rs strains, the significant upregulation CYP4CL2 (2.029-fold and 2.516-fold increase, respectively) and PcVg (1.771-fold and 2.924-fold increase, respectively) of F1 generation suggested there were delayed hormesis effects on reproduction and developed tolerance to pyridaben. No significant difference was found between LC30 treatments and controls in F2 generation of both strains. These results provided evidence that transgenerational hormesis effects of low concentration of pyridaben might lead to mite population outbreak and resistance risk in the field through stimulating the reproduction and developing tolerance to pyridaben. Furthermore, LC30 pyridaben could affect the offspring populations of susceptible strain in the longer-term as compared to resistant strain.

Detection and investigation of atypical porcine pestivirus in a swine production system.

A commercial farrow-to-finish farm was suspicious of atypical porcine pestivirus (APPV) after observing clinical signs of congenital tremors (CT) and splay leg (SL) of newborn pigs. If introduced onto the farrow-to-finish, the two potential routes of introduction could be through replacement gilts or incoming semen doses. Therefore, this study aimed to determine the prevalence of clinical APPV within the sampled population, identify the route of APPV introduction to this system, and determine prevalence of detectable APPV RNA within a population of gilt multiplication farm offspring through an isolation nursery and finisher barn. Farrowing records were analyzed for the presence of CT or SL and corresponding parity of the dam. Overall, prevalence of clinically affected litters within batch farrowing groups ranged from 0 to 31%. Phylogenetic analysis was conducted on a serum sample from a gilt at the isolation nursery, semen dose for the farrow-to-finish farm, and serum of a CT piglet. Results indicated that the virus circulating in clinically affected piglets was most similar to an incoming semen dose (98.9% nucleotide identity). Blood samples were collected at four time points and revealed APPV clinical prevalence was 37.5–77.5% during the nursery phase and 0–26% during the finisher phase. Oral fluids were also collected during the finisher phase and APPV clinical prevalence was 100% for all sampling time points. In summary, introduction of APPV into naïve herds is associated with increased clinical CT and SL cases and is detectable in asymptomatic pigs during the nursery and finisher production phases. This study found that potential screening tests for APPV could include oral fluids or qRT-PCR analysis of semen doses especially when trying to identify prevalence levels on naïve farm.

Genome-wide association study identified genes associated with ammonia nitrogen tolerance in Litopenaeus vannamei.

Ammonia nitrogen tolerance is an economically important trait of the farmed penaeid shrimp Litopenaeus vannamei. To identify the genes associated with ammonia nitrogen tolerance, we performed an extreme phenotype genome-wide association study method (XP-GWAS) on a population of 200 individuals. The single nucleotide polymorphism (SNP) genotyping array method was used to construct the libraries and 36,048 SNPs were genotyped. Using the MLM, FarmCPU and Blink models, six different SNPs, located on SEQ3, SEQ4, SEQ5, SEQ7 and SEQ8, were determined to be significantly associated with ammonia nitrogen tolerance. By integrating the results of the GWAS and the biological functions of the genes, seven candidate genes (PDI, OZF, UPF2, VPS16, TMEM19, MYCBP2, and HOX7) were found to be associated with ammonia nitrogen tolerance in L. vannamei. These genes are involved in cell transcription, cell division, metabolism, and immunity, providing the basis for further study of the genetic mechanisms of ammonia nitrogen tolerance in L. vannamei. Further candidate gene association analysis in the offspring population revealed that the SNPs in the genes zinc finger protein OZF-like (OZF) and homeobox protein Hox-B7-like (HOX7) were significantly associated with ammonia nitrogen tolerance trait of L. vannamei. Our results provide fundamental genetic information that will be useful for further investigation of the molecular mechanisms of ammonia nitrogen tolerance. These associated SNPs may also be promising candidates for improving ammonia nitrogen tolerance in L. vannamei.

Genetic structure and trait variation within a maple hybrid zone underscore North China as an overlooked diversity hotspot

Tertiary relict flora in East Asia can be divided into northern and southern regions. North China is a diversity hotspot because it can be the secondary contact zone of ancient lineages from the two regions. To test the extent of ancient lineages hybridization and distinguish between the putative species pair Acer pictum subsp. mono and Acer truncatum, we conducted genetic and ecological studies within a maple hybrid zone in North China. Our results suggest that the two lineages of Acer coexist in the hybrid zone and that adult and offspring populations show typical bimodal genetic patterns. Hybrid individuals are established at intermediate altitudes between the two parental lineages. Flowering phenology is divergent between lineages, whereas the complex sexual system of Acer may ensure pollination among lineages. Leaf and fruit morphologies are different between the northern and southern origin lineages, corresponding to A. pictum subsp. mono and A. truncatum, respectively. Reduced gene flow between lineages suggests that they should be considered as two species. However, large morphological variations within each species and the existence of hybrids offer low reliability of species identification based solely on morphological traits. Our study underscores North China as an overlooked diversity hotspot that requires further study in the future.

Accurate predictions of barley phenotypes using genomewide markers and environmental covariates

AbstractPredicting the performance of new plant genotypes under new environmental conditions could accelerate the development of locally adapted and climate resilient cultivars. Enabling these predictions may rely on extending the genomewide prediction framework to include environmental covariates (EC), but such models have generally been tested under limited, less breeding‐realistic contexts. Using a barley (Hordeum vulgare L.) multi‐environment dataset, our objectives were to compare multi‐environment prediction models and scenarios that target genotypes from different breeding generations, use different levels and timescales of ECs, and are applied to different agronomic and quality traits. When predicting the phenotypes of previously tested genotypes in untested environments, models that included the interaction of genomewide markers and pre‐selected in‐season ECs resulted in more accurate predictions (rMG or rMP) within (rMG = 0.56–0.94) and across (rMP = 0.63–0.87) environments; similar accuracy was achieved within (rMP = 0.46–0.89) and across (rMP = 0.87–0.95) locations when using only ECs from realistically available historical climate data. Shifting the prediction target to a distinct, untested offspring population slightly reduced model performance within environments or locations, but rMP across environments (rMP = 0.60–0.86) or locations (rMP = 0.87–0.94) remained very high. Though we achieved moderately high rMP for most traits in the challenging scenario of predicting the offspring population in holdout environments, the similarity between training and target environments, like that between populations, will be a limiting factor for enabling accurate predictions of new genotypes under new growing conditions.

Cohort profile: The Growing Up Healthy Study (GUHS)-A prospective and observational cohort study investigating the long-term health outcomes of offspring conceived after assisted reproductive technologies.

Worldwide, over 8 million children and adults are conceived following assisted reproductive technologies (ART), and their long-term health is of consequential public health interest. The objective of this paper is to describe the Growing up Healthy Study (GUHS) cohort in detail, publicise it and invite collaboration. Combining the data collected in the GUHS with other cohorts or databases will improve the much-needed knowledge about the effects of ART, and allow for better understanding of the long-term health outcomes of offspring conceived after ART. The GUHS cohort is a prospective observational study of adolescents and young adults conceived after assisted reproductive technologies (ART). It was established to determine if the long-term health of offspring conceived by ART differs from that of the general population. This was investigated by comparing a substantial number of health parameters to those of a representative population of offspring conceived without ART. The n = 303 GUHS participants were born between 1991–2001 in the two fertility clinics operating at the time in Perth, Western Australia, and undertook assessments at ages 14, 17 and 20, replicating the pre-defined study protocols from the reference cohort—the Raine Study. Participants were comprehensively phenotyped through detailed questionnaires, anthropometry, biochemical analyses, as well as age-specific assessments (asthma, atopy, cardiometabolic health, body composition, mental health, thyroid function, epigenetics and vision). To date the GUHS cohort has been used to study the methylation, cardiometabolic, and thyroid profiles, as well as respiratory and mental health. To summarise, the GUHS cohort provides a valuable addition to the limited knowledge of the long-term health outcomes of ART-conceived offspring.

Effects of artificial mating on genomic selection of resistance against Cryptocaryon irritans in large yellow croaker

Genomic selection has been widely used in aquaculture breeding of major aquaculture species. However, the complex environment and mass spawning characteristics make most of the current aquaculture species reproduce the next generation through natural mating, which results in uneven parental contributions, difficulty in tracking high-quality individuals and risk of inbreeding. In this study, we compared the difference in resistance to Cryptocaryon irritans (C. irritans) between artificial insemination pairing and natural mating in large yellow croaker. The reference group consisted of two challenge experimental groups in 2018 and 2020, with 487 and 260 samples, respectively. A total of 381 candidates were selected from the resistant to C. irritans strain (G2) of large yellow croaker constructed in 2019 and genotyped by using 55 K array. The BayesB models and survival time were used to calculate the genomic estimated breeding value (GEBV) of candidates. Finally, a candidate parents population consists of 35 females and 15 males with high estimated breeding value and mature gonads were selected from the resistance against C. irritans strain of large yellow croaker and reproduced two offspring populations due to the characteristics of spawning for two consecutive nights. A natural mating population (T group) was produced on the first spawning night of the parent population, and an artificial mating population contained 19 full-sib and half-sib families (F group) was produced on the second spawning night by the same parents. In addition, a natural mating population (C group) was produced by the unselected strain. A C. irritans infection challenge with duration of 120 h was conducted to compare the performance of disease resistance between the T, F, and C groups. The results showed that the survival rate for T and C groups was 9.85% and 0%, respectively, and the survival rate for F group was ranged from 0% to 63.83%, which 10 families survived significantly longer than the T group. The result showed that the artificially mated can achieved higher phenotypic progress than random mating in the selected breeding of large yellow croaker. This study provides reference for improvement of genomic selection strategy in aquatic species.

Improved mayfly algorithm based on hybrid mutation

To improve the diversity and performance of the mayfly algorithm (MA), this letter adopts the mutation strategies in the process of MA. The opposition-based learning (OBL) and Cauchy mutation strategies are used to mutate the global optimal solution, and the artificial mutation operator is used in the offspring population. The hybrid mutation strategies are used in a cascaded structure. The performance of the proposed algorithms is demonstrated in simulations comparatively.

Triglyceride-Associated Epigenetic Markers and Diet and Lifestyle Habits in the Framingham Heart Study

ObjectivesThe current evidence has shown that environmental and lifestyle factors (e.g., diet, physical activity, tobacco smoking, alcohol) are associated with DNA methylation patterns. However, the mechanisms underlying the relation between diet and other exposures and epigenetic profiles are not well understood. To reduce such knowledge gap, we investigated the links between lifestyle, including diet, and methylation marks with plasma triglyceride concentrations (TG).MethodsWe first conducted an epigenome-wide association study (EWAS) (Illumina HumanMethylation450 BeadChip) for TG in the Framingham Heart Study Offspring population (n = 2,178). We then examined the relationships between dietary and lifestyle-related variables, collected over 13 years, and differential DNA methylation marks associated with the last TG measures (exam 8). Second, we conducted a mediation analysis to examine the potential causal relationship between diet-related variables and TG.ResultsThe EWAS analyses revealed 28 TG-associated DNA methylation sites at 19 regions (e.g., ABCG1, CPT1A, DHCR24, PHGDH, SLC7A11, SLC43A1, SREBF1, TXNIP). Within those methylation sites, we identified 427 significant associations between these DNA methylation sites and one or more dietary and lifestyle-related variables after accounting for multiple testing. The two most significant and consistent associations between TG-associated DNA methylation markers and diet were alcohol (g/day) and carbohydrate intake (% total energy), with P-values ranging from 10^(−4) to 10^(−56). Mediation analyses demonstrated that alcohol and carbohydrate intake independently affect TG via DNA methylation markers as mediators. For seven of the 19 identified differential DNA-methylation regions, higher alcohol intake was associated with decreased methylation and higher TG. In contrast, increased carbohydrate intake was associated with higher DNA methylation at two epigenetic loci (CPT1A and SLC7A11) and lower TG.ConclusionsOur findings indicate that dietary factors (i.e., alcohol and carbohydrate) are associated with specific DNA methylation markers that could mediate some of the observed associations between diet and cardiometabolic risk factors.Funding SourcesThis work was funded by the US Department of Agriculture, under agreement no. 8050-51,000-107-000D.

Sublethal Effects of Three Insecticides on Development and Reproduction of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Spodoptera frugiperda is a serious invasive pest, which has attracted attention globally in recent years. Research on the sublethal effects of common insecticides on S. frugiperda is important for its comprehensive management in the field. In this paper, the sublethal effects have been studied for S. frugiperda exposed to the LC30 concentration of three insecticides, chlorantraniliprole, dinotefuran, and beta-cypermethrin. The results showed that the pupation rates of the treatment groups were significantly lower than that of control group, but there were no significant differences in the eclosion rate. Chlorantraniliprole and beta-cypermethrin significantly inhibited fecundity of the F0 and F1 generations, and the number of eggs laid per female decreased by 67.4% and 43.1%, respectively, and that of the F1 generation decreased by 28.0% and 21.7%, respectively. The intrinsic growth rate (rm), net growth rate (R0), and weekly growth rate (λ) of the F0 generation in the chlorantraniliprole and beta-cypermethrin treatment groups were significantly lower than those in the control group. Additionally, dinotefuran had a certain role in promoting oviposition in the F0 and F1 generations, which may stimulate the growth of offspring population and cause the resurgence of pests. The results provide a reference for the effective implementation of the IPM plan in the field to control S. frugiperda.

Research on improved genetic simulated annealing algorithm for multi-UAV cooperative task allocation

In order to solve the cooperative search problem of multiple unmanned aerial vehicles (multi-UAVs) in a large-scale area, we propose a genetic algorithm (GA) incorporating simulated annealing (SA) for solving the task region allocation problem among multi-UAVs on the premise that the large area is divided into several small areas. Firstly, we describe the problem to be solved, and regard the task areas allocation problem of multi-UAVs as a multiple traveling salesman problem (MTSP). And the objective function is established under the premise that the number of task areas to be searched by each UAV is balanced. Then, we improve the GA, using the advantages of the SA can jump out of the local optimal solution to optimize the new population of offspring generated by GA. Finally, the validity of the algorithm is verified by using the TSPLIB database, and the set MTSP problem is solved. Through a series of comparative experiments, the validity of GAISA and the superiority of solving the MTSP problem can be demonstrated.

Adaptive evolution strategy with ensemble of mutations for Reinforcement Learning

Evolving the weights of learning networks through evolutionary computation (neuroevolution) has proven scalable over a range of challenging Reinforcement Learning (RL) control tasks. However, similar to most black-box optimization problems, existing neuroevolution approaches require an additional adaptation process to effectively balance exploration and exploitation through the selection of sensitive hyper-parameters throughout the evolution process. Therefore, these methods are often plagued by the computation complexities of such adaptation processes which often rely on a number of sophisticatedly formulated strategy parameters. In this paper, Evolution Strategy (ES) with a simple yet efficient ensemble of mutation strategies is proposed. Specifically, two distinct mutation strategies coexist throughout the evolution process where each strategy is associated with its own population subset. Consequently, elites for generating a population of offspring are realized by co-evaluation of the combined population. Experiments on testbed of six (6) black-box optimization problems which are generated using a classical control problem and six (6) proven continuous RL agents demonstrate the efficiency of the proposed method in terms of faster convergence and scalability than the canonical ES. Furthermore, the proposed Adaptive Ensemble ES (AEES) shows an average of 5 - 10000x and 10 - 100x better sample complexity in low and high dimension problems, respectively than their associated base DRL agents.

Comparison of lipid metabolism between broodstock and hybrid offspring in the hepatopancreas of juvenile shrimp (Macrobrachium nipponense): Response to chronic ammonia stress.

Ammonia nitrogen is a major pollutant that causes great physiological harm to crustaceans in culture. In this study, we conducted a 28 day chronic ammonia nitrogen stress experiment with broodstock populations (Dianshan, DS) and hybrid offspring populations (DS ♀ × CD (Changjiang ♂ × Dongting ♀), SCD) exposed to 0, 1 and 10mg/L of ammonia concentrations. A 28 day feeding trial and chronic ammonia nitrogen stress were used to investigate the effects on the growth performance, histological structure and lipid metabolism of juvenile shrimp, Macrobrachium nipponense. Our results indicated that survival rates in the SCD groups were significantly higher than those in the DS groups, whereas weight and length gain rates were not significantly different between the groups (p > 0.05). Histological structure results showed that the number of vacuoles in the DS group was significantly higher than that in the SCD group and hepatopancreas cell structures were disrupted in the ammonia treatment groups. The results of oil red staining showed that the number of lipid droplets increased significantly with the increase in ammonia concentration. As the ammonia concentration increased, fatty acid contents, lipid enzyme activities and lipid metabolism-related gene expression all tended to rise. In conclusion, ammonia nitrogen exposure caused damage to the hepatopancreas structure of juvenile shrimp and disturbed the lipid metabolism of the hepatopancreas. In addition, the SCD population had stronger stress resistance than the DS population when subjected to the same concentration of ammonia nitrogen stress.

Can double PPO mutations exist in the same allele and are such mutants functional?

BACKGROUNDResistance to protoporphyrinogen oxidase (PPO)‐inhibiting herbicides is endowed primarily by target‐site mutations at the PPX2 gene that compromise binding of the herbicide to the catalytic domain. In Amaranthus spp. PPX2, the most prevalent target mutations are deletion of the G210 codon, and the R128G and G339A substitutions. These mutations strongly affect the dynamic of the PPO2 binding pocket, resulting in reduced affinity with the ligand. Here we investigated the likelihood of co‐occurrence of the most widespread target site mutations in the same PPX2 allele.RESULTSPlants carrying R128G+/+ ΔG210+/−, where + indicates presence of the mutation, were crossed with each other. The PPX2 of the offspring was subjected to pyrosequencing and E. coli‐based Sanger sequencing to determine mutation frequencies and allele co‐occurrence. The data show that R128G ΔG210 can occur in one allele only; the second allele carries only one mutation. Double mutation in both alleles is less likely because of significant loss of enzyme activity. The segregation of offspring populations derived from a cross between heterozygous plants carrying ΔG210 G399A also showed no co‐occurrence in the same allele. The offspring exhibited the expected mutation distribution patterns with few exceptions.CONCLUSIONSHomozygous double‐mutants are not physiologically viable. Double‐mutant plants can only exist in a heterozygous state. Alternatively, if two mutations are detected in one plant, each mutation would occur in a separate allele. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sex ratio in the mother's environment affects offspring population dynamics: maternal effects on population regulation.

Classic population regulation theories usually concern the influence of immediate factors on current populations, but studies investigating the effect of parental environment factors on their offspring populations are scarce. The maternal environments can affect offspring life-history traits across generations, which may affect population dynamics and be a mechanism of population regulation. In cyclical parthenogens, sexual reproduction is typically linked with dormancy, thereby providing a negative feedback to population growth. In this study, we manipulated population sex ratios in the mother's environment to investigate whether this factor affected future population dynamics by regulating offspring sexual reproduction in the rotifer Brachionus calyciflorus. Compared with females in male-biased environments, those in female-biased environments produced fewer mictic (sexual) offspring, and their amictic (asexual) offspring also produced a lower proportion of mictic females at a gradient of population densities. Moreover, populations that were manipulated under male-biased conditions showed significantly smaller population sizes than those under female-biased conditions. Our results indicated that in cyclical parthenogens, mothers could adjust the sexual reproduction of their offspring in response to the current population sex ratio, thus providing fine-scale regulation of population dynamics in addition to population density.

Reproductive consequences of transient pathogen exposure across host genotypes and generations.

To maximize fitness upon pathogenic infection, host organisms might reallocate energy and resources among life‐history traits, such as reproduction and defense. The fitness costs of infection can result from both immune upregulation and direct pathogen exploitation. The extent to which these costs, separately and together, vary by host genotype and across generations is unknown. We attempted to disentangle these costs by transiently exposing wild isolates and a lab‐domesticated strain of Caenorhabditis elegans nematodes to the pathogen Staphylococcus aureus, using exposure to heat‐killed pathogens to distinguish costs due to immune upregulation and pathogen exploitation. We found that host nematodes exhibit a short‐term delay in offspring production when exposed to live and heat‐killed pathogen, but their lifetime fecundity (total offspring produced) recovered to control levels. We also found genetic variation between host isolates for both cumulative offspring production and magnitude of fitness costs. We further investigated whether there were maternal pathogen exposure costs (or benefits) to offspring and revealed a positive correlation between the magnitude of the pathogen‐induced delay in the parent's first day of reproduction and the cost to offspring population growth. Our findings highlight the capacity for hosts to recover fecundity after transient exposure to a pathogen.

Cross-border reproductive care: an Ethics Committee opinion

Cross-border reproductive care is a growing worldwide phenomenon, raising questions about why assisted reproductive technology patients travel for care, what harms and benefits may result, and what duties health care providers may have in advising and treating the patients who travel for reproductive services. Cross-border care may benefit or harm assisted reproductive technology stakeholders, including patients, offspring, providers, gamete donors, gestational carriers, and local populations in destination countries. This document replaces the previous document of the same name, last published in2016.